2016 |
Musumeci, Chiara ; Osella, Silvio ; Ferlauto, Laura ; Niedzialek, Dorota ; Grisanti, Luca ; Bonacchi, Sara ; Jouaiti, Abdelaziz ; Milita, Silvia ; Ciesielski, Artur ; Beljonne, David ; Hosseini, Mir Wais ; Samori, Paolo Influence of the supramolecular order on the electrical properties of 1D coordination polymers based materials Journal Article In: NANOSCALE, 8 (4), pp. 2386–2394, 2016, ISSN: 2040-3364. @article{musumeci_influence_2016, title = {Influence of the supramolecular order on the electrical properties of 1D coordination polymers based materials}, author = {Musumeci, Chiara and Osella, Silvio and Ferlauto, Laura and Niedzialek, Dorota and Grisanti, Luca and Bonacchi, Sara and Jouaiti, Abdelaziz and Milita, Silvia and Ciesielski, Artur and Beljonne, David and Hosseini, Mir Wais and Samori, Paolo}, doi = {10.1039/c5nr07776a}, issn = {2040-3364}, year = {2016}, date = {2016-01-01}, journal = {NANOSCALE}, volume = {8}, number = {4}, pages = {2386--2394}, abstract = {The generation, under self-assembly conditions, of coordination polymers on surface based combinations of a terpyridine-antracene-pyridine based tecton and Co(II) or Pd(II) cations is primarily governed by the coordination geometry of the metal center (octahedral and square planar respectively). While the octahedral Co(II) based polymer self-assembles in insulating films exhibiting randomly oriented crystalline domains, the planarity of Pd(II) based polymers leads to the formation of conductive p-p stacked fibrillar structures exhibiting anisotropically oriented domains. In the latter case, the favorable pi-pi and anthracene- anthracene wavefunction overlaps along the fiber direction are responsible for the large electronic couplings between adjacent chains, whereas small electronic couplings are instead found along individual polymer chains. These results provide important guidelines for the design of conductive metal coordination polymers, highlighting the fundamental role of both intra- as well as inter-chain interactions, thus opening up new perspectives towards their application in functional devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The generation, under self-assembly conditions, of coordination polymers on surface based combinations of a terpyridine-antracene-pyridine based tecton and Co(II) or Pd(II) cations is primarily governed by the coordination geometry of the metal center (octahedral and square planar respectively). While the octahedral Co(II) based polymer self-assembles in insulating films exhibiting randomly oriented crystalline domains, the planarity of Pd(II) based polymers leads to the formation of conductive p-p stacked fibrillar structures exhibiting anisotropically oriented domains. In the latter case, the favorable pi-pi and anthracene- anthracene wavefunction overlaps along the fiber direction are responsible for the large electronic couplings between adjacent chains, whereas small electronic couplings are instead found along individual polymer chains. These results provide important guidelines for the design of conductive metal coordination polymers, highlighting the fundamental role of both intra- as well as inter-chain interactions, thus opening up new perspectives towards their application in functional devices. |
Lehn, Manfred ; Namikawa, Yoshinori ; Sorger, Christoph ; van Straten, Duco On symplectic hypersurfaces Inproceedings In: {Kollar, J; Fujino, O; Mukai, S; Nakayama, N} (Ed.): Minimal Models and Extreme Rays (Kyoto, 2011), pp. 277–298, Kyoto Univ, Res Inst Math Sci, 2016, ISBN: 978-4-86497-036-5. @inproceedings{lehn_symplectic_2016, title = {On symplectic hypersurfaces}, author = {Lehn, Manfred and Namikawa, Yoshinori and Sorger, Christoph and van Straten, Duco}, editor = {{Kollar, J and Fujino, O and Mukai, S and Nakayama, N}}, isbn = {978-4-86497-036-5}, year = {2016}, date = {2016-01-01}, booktitle = {Minimal Models and Extreme Rays (Kyoto, 2011)}, volume = {70}, pages = {277--298}, publisher = {Kyoto Univ, Res Inst Math Sci}, series = {Advanced Studies in Pure Mathematics}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Stadler, Adrian-Mihail ; Ramirez, Juan ; Lehn, Jean-Marie ; Vincent, Bruno Supramolecular reactions of metallo-architectures: Ag-2-double-helicate/Zn-4-grid, Pb-4-grid/Zn-4-grid interconversions, and Ag-2-double-helicate fusion Journal Article In: CHEMICAL SCIENCE, 7 (6), pp. 3689–3693, 2016, ISSN: 2041-6520. @article{stadler_supramolecular_2016, title = {Supramolecular reactions of metallo-architectures: Ag-2-double-helicate/Zn-4-grid, Pb-4-grid/Zn-4-grid interconversions, and Ag-2-double-helicate fusion}, author = {Stadler, Adrian-Mihail and Ramirez, Juan and Lehn, Jean-Marie and Vincent, Bruno}, doi = {10.1039/c5sc04403k}, issn = {2041-6520}, year = {2016}, date = {2016-01-01}, journal = {CHEMICAL SCIENCE}, volume = {7}, number = {6}, pages = {3689--3693}, abstract = {Supramolecular reactions are of importance in many fields. We report herein three examples where complexes of hydrazone-based ligands are involved. A Ag-2-double-helicate was converted, by treatment with Zn(OTf)(2), into a Zn-4-grid (exchange of metal ions and change of the nature of the initial complex). A Pb-4-grid was converted, upon reaction with ZnCl2 or ZnBr2, into a Zn-4-grid (exchange of metal ions, but conservation of the nature of the initial complex). The reverse conversions were also achieved. The fusion of a Ag-2-double-helicate with another Ag-2-double-helicate was performed (exchange of ligands, but conservation of the nature of the complexes) and resulted in a mixture of three helicates (two homostranded ones and one heterostranded one).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Supramolecular reactions are of importance in many fields. We report herein three examples where complexes of hydrazone-based ligands are involved. A Ag-2-double-helicate was converted, by treatment with Zn(OTf)(2), into a Zn-4-grid (exchange of metal ions and change of the nature of the initial complex). A Pb-4-grid was converted, upon reaction with ZnCl2 or ZnBr2, into a Zn-4-grid (exchange of metal ions, but conservation of the nature of the initial complex). The reverse conversions were also achieved. The fusion of a Ag-2-double-helicate with another Ag-2-double-helicate was performed (exchange of ligands, but conservation of the nature of the complexes) and resulted in a mixture of three helicates (two homostranded ones and one heterostranded one). |
Kovaricek, P; Meister, A C; Flidrova, K; Cabot, R; Kovarickova, K; Lehn, J -M Competition-driven selection in covalent dynamic networks and implementation in organic reactional selectivity Journal Article In: CHEMICAL SCIENCE, 7 (5), pp. 3215–3226, 2016, ISSN: 2041-6520. @article{kovaricek_competition-driven_2016, title = {Competition-driven selection in covalent dynamic networks and implementation in organic reactional selectivity}, author = {Kovaricek, P. and Meister, A. C. and Flidrova, K. and Cabot, R. and Kovarickova, K. and Lehn, J. -M.}, doi = {10.1039/c5sc04924e}, issn = {2041-6520}, year = {2016}, date = {2016-01-01}, journal = {CHEMICAL SCIENCE}, volume = {7}, number = {5}, pages = {3215--3226}, abstract = {Competition among reagents in dynamic combinatorial libraries of increased complexity leads to reactional self-sorting (improved regioselectivity) in mixtures of aldehydes and oligoamines. High selectivity of a given library component is transferred to a different reacting component of low selectivity through a network of underlying equilibrating reactions which provide component exchange between all species. The selectivity of various carbonyl compounds in reactions with amines was also assessed towards the formation of defined sequences of residues along oligoamine chains. The approach was further exploited for defining selective dynamic protecting groups (DPGs), based on the reversible linkage between the substrate and the protecting group. They represent an intermediate approach between the conventional protecting groups and the protecting-group-free approach in organic synthesis. Removal of the protecting group is effected via dynamic exchange trapping by formation of a more stable product. The establishment of equilibrium eliminates the need for isolation and purification of the dynamically protected intermediate(s) and enables as well the selective sequential derivatisation of oligoamines. The DPG concept can be generalised to other reversible reactions and can thus represent a valuable alternative in the design of total synthesis of complex molecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Competition among reagents in dynamic combinatorial libraries of increased complexity leads to reactional self-sorting (improved regioselectivity) in mixtures of aldehydes and oligoamines. High selectivity of a given library component is transferred to a different reacting component of low selectivity through a network of underlying equilibrating reactions which provide component exchange between all species. The selectivity of various carbonyl compounds in reactions with amines was also assessed towards the formation of defined sequences of residues along oligoamine chains. The approach was further exploited for defining selective dynamic protecting groups (DPGs), based on the reversible linkage between the substrate and the protecting group. They represent an intermediate approach between the conventional protecting groups and the protecting-group-free approach in organic synthesis. Removal of the protecting group is effected via dynamic exchange trapping by formation of a more stable product. The establishment of equilibrium eliminates the need for isolation and purification of the dynamically protected intermediate(s) and enables as well the selective sequential derivatisation of oligoamines. The DPG concept can be generalised to other reversible reactions and can thus represent a valuable alternative in the design of total synthesis of complex molecules. |
Licsandru, Erol-Dan ; Schneider, Susanne ; Tingry, Sophie ; Ellis, Thomas ; Moulin, Emilie ; Maaloum, Mounir ; Lehn, Jean-Marie ; Barboiu, Mihail ; Giuseppone, Nicolas Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof Journal Article In: NANOSCALE, 8 (10), pp. 5605–5611, 2016, ISSN: 2040-3364. @article{licsandru_self-assembly_2016, title = {Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof}, author = {Licsandru, Erol-Dan and Schneider, Susanne and Tingry, Sophie and Ellis, Thomas and Moulin, Emilie and Maaloum, Mounir and Lehn, Jean-Marie and Barboiu, Mihail and Giuseppone, Nicolas}, doi = {10.1039/c5nr06977g}, issn = {2040-3364}, year = {2016}, date = {2016-01-01}, journal = {NANOSCALE}, volume = {8}, number = {10}, pages = {5605--5611}, abstract = {Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Biocompatible silica-based mesoporous materials, which present high surface areas combined with uniform distribution of nanopores, can be organized in functional nanopatterns for a number of applications. However, silica is by essence an electrically insulating material which precludes applications for electro-chemical devices. The formation of hybrid electroactive silica nanostructures is thus expected to be of great interest for the design of biocompatible conducting materials such as bioelectrodes. Here we show that we can grow supramolecular stacks of triarylamine molecules in the confined space of oriented mesopores of a silica nanolayer covering a gold electrode. This addressable bottom-up construction is triggered from solution simply by light irradiation. The resulting self-assembled nanowires act as highly conducting electronic pathways crossing the silica layer. They allow very efficient charge transfer from the redox species in solution to the gold surface. We demonstrate the potential of these hybrid constitutional materials by implementing them as biocathodes and by measuring laccase activity that reduces dioxygen to produce water. |
2015 |
Vodola, Davide ; Lepori, Luca ; Ercolessi, Elisa ; Pupillo, Guido Long-range Ising and Kitaev models: phases, correlations and edge modes Journal Article In: NEW JOURNAL OF PHYSICS, 18 , 2015, ISSN: 1367-2630. @article{vodola_long-range_2015, title = {Long-range Ising and Kitaev models: phases, correlations and edge modes}, author = {Vodola, Davide and Lepori, Luca and Ercolessi, Elisa and Pupillo, Guido}, doi = {10.1088/1367-2630/18/1/015001}, issn = {1367-2630}, year = {2015}, date = {2015-12-01}, journal = {NEW JOURNAL OF PHYSICS}, volume = {18}, abstract = {We analyze the quantum phases, correlation functions and edge modes for a class of spin-1/2 and fermionic models related to the one-dimensional Ising chain in the presence of a transverse field. These models are the Ising chain with anti-ferromagnetic long-range interactions that decay with distance. r as 1/r(alpha), as well as a related class of fermionic Hamiltonians that generalize the Kitaev chain, where both the hopping and pairing terms are long-range and their relative strength can be varied. For these models, we provide the phase diagram for all exponents a, based on an analysis of the entanglement entropy, the decay of correlation functions, and the edge modes in the case of open chains. We demonstrate that violations of the area law can occur for alpha greater than or similar to 1, while connected correlation functions can decay with a hybrid exponential and power-law behavior, with a power that is alpha-dependent. Interestingly, for the fermionic models we provide an exact analytical derivation for the decay of the correlation functions at every alpha. Along the critical lines, for all models breaking of conformal symmetry is argued at low enough a. For the fermionic models we show that the edge modes, massless for alpha greater than or similar to 1, can acquire a mass for alpha textbackslashtextbackslashtextless 1. The mass of these modes can be tuned by varying the relative strength of the kinetic and pairing terms in the Hamiltonian. Interestingly, for the Ising chain a similar edge localization appears for the first and second excited states on the paramagnetic side of the phase diagram, where edge modes are not expected. We argue that, at least for the fermionic chains, these massive states correspond to the appearance of new phases, notably approached via quantum phase transitions without mass gap closure. Finally, we discuss the possibility to detect some of these effects in experiments with cold trapped ions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We analyze the quantum phases, correlation functions and edge modes for a class of spin-1/2 and fermionic models related to the one-dimensional Ising chain in the presence of a transverse field. These models are the Ising chain with anti-ferromagnetic long-range interactions that decay with distance. r as 1/r(alpha), as well as a related class of fermionic Hamiltonians that generalize the Kitaev chain, where both the hopping and pairing terms are long-range and their relative strength can be varied. For these models, we provide the phase diagram for all exponents a, based on an analysis of the entanglement entropy, the decay of correlation functions, and the edge modes in the case of open chains. We demonstrate that violations of the area law can occur for alpha greater than or similar to 1, while connected correlation functions can decay with a hybrid exponential and power-law behavior, with a power that is alpha-dependent. Interestingly, for the fermionic models we provide an exact analytical derivation for the decay of the correlation functions at every alpha. Along the critical lines, for all models breaking of conformal symmetry is argued at low enough a. For the fermionic models we show that the edge modes, massless for alpha greater than or similar to 1, can acquire a mass for alpha textbackslashtextbackslashtextless 1. The mass of these modes can be tuned by varying the relative strength of the kinetic and pairing terms in the Hamiltonian. Interestingly, for the Ising chain a similar edge localization appears for the first and second excited states on the paramagnetic side of the phase diagram, where edge modes are not expected. We argue that, at least for the fermionic chains, these massive states correspond to the appearance of new phases, notably approached via quantum phase transitions without mass gap closure. Finally, we discuss the possibility to detect some of these effects in experiments with cold trapped ions. |
Galstyan, Anzhela ; Naziruddin, Abbas Raja ; Cebrian, Cristina ; Iordache, Adriana ; Daniliuc, Constantin G; De Cola, Luisa ; Strassert, Cristian A Correlating the Structural and Photophysical Features of Pincer Luminophores and Monodentate Ancillary Ligands in Pt-II Phosphors Journal Article In: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, (36), pp. 5822–5831, 2015, ISSN: 1434-1948. @article{galstyan_correlating_2015, title = {Correlating the Structural and Photophysical Features of Pincer Luminophores and Monodentate Ancillary Ligands in Pt-II Phosphors}, author = {Galstyan, Anzhela and Naziruddin, Abbas Raja and Cebrian, Cristina and Iordache, Adriana and Daniliuc, Constantin G. and De Cola, Luisa and Strassert, Cristian A.}, doi = {10.1002/ejic.201500949}, issn = {1434-1948}, year = {2015}, date = {2015-12-01}, journal = {EUROPEAN JOURNAL OF INORGANIC CHEMISTRY}, number = {36}, pages = {5822--5831}, abstract = {Phosphorescent Pt-II complexes featuring pincer luminophores of 2,6-bis(1,2,4-triazolyl)pyridine (H(2)L1) and 2,6-bis(pyrazolyl)pyridine (H(2)L3) with a bulky adamantyl or tolyl substituent (H(2)L4) are systematically compared, and their structural features are correlated with their photophysical properties. The combination with 4-amylpyridine (Py), triphenylphosphine (P) or benzimidazol-2-ylidene (N-heterocyclic carbene, NHC) donors as monodentate ancillary ligands gave a series of highly luminescent triplet emitters with variable aggregation properties. The molecular structures of four of these complexes, namely, Pt-L1-P, Pt-L1-NHC, Pt-L3-P, and Pt-L4-P were garnered from single-crystal X-ray diffraction analysis. The coordination complexes displayed green phosphorescence in solution and in the solid state. In doped poly(methyl methacrylate) (PMMA) matrices, most of the complexes exhibited high phosphorescence quantum yields, which reached 59% for Pt-L3-P. A comparative analysis between the spectroscopic data and the computed parameters derived from time-dependent density functional theory (TD-DFT) calculations suggests that the emission originates from metal-perturbed ligand-centered excited triplet states ((MP)-M-3-LC). The radiationless deactivation rate constants of the emissive states can be correlated with the aggregation properties derived from the substitution pattern at the tridentate luminophores and the ancillary ligands, whereas the radiative rate constants are determined by the electronic structures of the complexes. We found that Pt-II complexes containing pyrazolate donors showed an enhanced charge-transfer character in the excited state, whereas bulky adamantyl moieties and triphenylphosphine ancillary ligands suppress bimolecular aggregation and quenching phenomena.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Phosphorescent Pt-II complexes featuring pincer luminophores of 2,6-bis(1,2,4-triazolyl)pyridine (H(2)L1) and 2,6-bis(pyrazolyl)pyridine (H(2)L3) with a bulky adamantyl or tolyl substituent (H(2)L4) are systematically compared, and their structural features are correlated with their photophysical properties. The combination with 4-amylpyridine (Py), triphenylphosphine (P) or benzimidazol-2-ylidene (N-heterocyclic carbene, NHC) donors as monodentate ancillary ligands gave a series of highly luminescent triplet emitters with variable aggregation properties. The molecular structures of four of these complexes, namely, Pt-L1-P, Pt-L1-NHC, Pt-L3-P, and Pt-L4-P were garnered from single-crystal X-ray diffraction analysis. The coordination complexes displayed green phosphorescence in solution and in the solid state. In doped poly(methyl methacrylate) (PMMA) matrices, most of the complexes exhibited high phosphorescence quantum yields, which reached 59% for Pt-L3-P. A comparative analysis between the spectroscopic data and the computed parameters derived from time-dependent density functional theory (TD-DFT) calculations suggests that the emission originates from metal-perturbed ligand-centered excited triplet states ((MP)-M-3-LC). The radiationless deactivation rate constants of the emissive states can be correlated with the aggregation properties derived from the substitution pattern at the tridentate luminophores and the ancillary ligands, whereas the radiative rate constants are determined by the electronic structures of the complexes. We found that Pt-II complexes containing pyrazolate donors showed an enhanced charge-transfer character in the excited state, whereas bulky adamantyl moieties and triphenylphosphine ancillary ligands suppress bimolecular aggregation and quenching phenomena. |
Caballero, David ; Comelles, Jordi ; Piel, Matthieu ; Voituriez, Raphael ; Riveline, Daniel Ratchetaxis: Long-Range Directed Cell Migration by Local Cues Journal Article In: TRENDS IN CELL BIOLOGY, 25 (12, SI), pp. 815–827, 2015, ISSN: 0962-8924. @article{caballero_ratchetaxis:_2015, title = {Ratchetaxis: Long-Range Directed Cell Migration by Local Cues}, author = {Caballero, David and Comelles, Jordi and Piel, Matthieu and Voituriez, Raphael and Riveline, Daniel}, doi = {10.1016/j.tcb.2015.10.009}, issn = {0962-8924}, year = {2015}, date = {2015-12-01}, journal = {TRENDS IN CELL BIOLOGY}, volume = {25}, number = {12, SI}, pages = {815--827}, abstract = {Directed cell migration is usually thought to depend on the presence of long-range gradients of either chemoattractants or physical properties such as stiffness or adhesion. However, in vivo, chemical or mechanical gradients have not systematically been observed. Here we review recent in vitro experiments, which show that other types of spatial guidance cues can bias cell motility. Introducing local geometrical or mechanical anisotropy in the cell environment, such as adhesive/topographical microratchets or tilted micropillars, show that local and periodic external cues can direct cell motion. Together with modeling, these experiments suggest that cell motility can be viewed as a stochastic phenomenon, which can be biased by various types of local cues, leading to directional migration.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Directed cell migration is usually thought to depend on the presence of long-range gradients of either chemoattractants or physical properties such as stiffness or adhesion. However, in vivo, chemical or mechanical gradients have not systematically been observed. Here we review recent in vitro experiments, which show that other types of spatial guidance cues can bias cell motility. Introducing local geometrical or mechanical anisotropy in the cell environment, such as adhesive/topographical microratchets or tilted micropillars, show that local and periodic external cues can direct cell motion. Together with modeling, these experiments suggest that cell motility can be viewed as a stochastic phenomenon, which can be biased by various types of local cues, leading to directional migration. |
Palma, Carlos-Andres ; Ciesielski, Artur ; Oener, Murat Anil ; Schaeffer, Gael ; Lehn, Jean-Marie ; Barth, Johannes V; Samori, Paolo Two-dimensional soft supramolecular networks Journal Article In: CHEMICAL COMMUNICATIONS, 51 (97), pp. 17297–17300, 2015, ISSN: 1359-7345. @article{palma_two-dimensional_2015, title = {Two-dimensional soft supramolecular networks}, author = {Palma, Carlos-Andres and Ciesielski, Artur and Oener, Murat Anil and Schaeffer, Gael and Lehn, Jean-Marie and Barth, Johannes V. and Samori, Paolo}, doi = {10.1039/c5cc07204b}, issn = {1359-7345}, year = {2015}, date = {2015-12-01}, journal = {CHEMICAL COMMUNICATIONS}, volume = {51}, number = {97}, pages = {17297--17300}, abstract = {Two flexible multivalent molecular units are employed to self-assemble highly regular supramolecular porous networks at the solid/liquid interface. Scanning tunnelling microscopy imaging corroborated with molecular dynamics simulations make it possible to elucidate the conformational freedom behind the binding motif, which identify the architecture as a highly regular soft network.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two flexible multivalent molecular units are employed to self-assemble highly regular supramolecular porous networks at the solid/liquid interface. Scanning tunnelling microscopy imaging corroborated with molecular dynamics simulations make it possible to elucidate the conformational freedom behind the binding motif, which identify the architecture as a highly regular soft network. |
Kulchat, Sirinan ; Lehn, Jean-Marie Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts Journal Article In: CHEMISTRY-AN ASIAN JOURNAL, 10 (11), pp. 2484–2496, 2015, ISSN: 1861-4728. @article{kulchat_dynamic_2015, title = {Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts}, author = {Kulchat, Sirinan and Lehn, Jean-Marie}, doi = {10.1002/asia.201500604}, issn = {1861-4728}, year = {2015}, date = {2015-11-01}, journal = {CHEMISTRY-AN ASIAN JOURNAL}, volume = {10}, number = {11}, pages = {2484--2496}, abstract = {Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (S(N)2 and S(N)2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 degrees C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic covalent libraries (DCLs) of quaternary ammonium cations were set up by reversible nucleophilic substitution (S(N)2 and S(N)2) exchange reactions of ammonium salts and tertiary amines. The reactions were conducted at 60 degrees C to generate thermodynamically and kinetically controlled mixtures of quaternary ammonium compounds and tertiary amines, and were accelerated by using iodide as a nucleophilic catalyst. Microwave irradiation was used to assist the exchange reaction between the pyridinium salts and pyridine derivatives. Finally, experiments towards the generation of dynamic ionic liquids were performed. The results of this study pave the way for the extension of dynamic combinatorial chemistry to nucleophilic substitution reactions. |
Lechner, Wolfgang ; Cinti, Fabio ; Pupillo, Guido Tunable defect interactions and supersolidity in dipolar quantum gases on a lattice potential Journal Article In: PHYSICAL REVIEW A, 92 (5), 2015, ISSN: 1050-2947. @article{lechner_tunable_2015, title = {Tunable defect interactions and supersolidity in dipolar quantum gases on a lattice potential}, author = {Lechner, Wolfgang and Cinti, Fabio and Pupillo, Guido}, doi = {10.1103/PhysRevA.92.053625}, issn = {1050-2947}, year = {2015}, date = {2015-11-01}, journal = {PHYSICAL REVIEW A}, volume = {92}, number = {5}, abstract = {Point defects in self-assembled crystals, such as vacancies and interstitials, attract each other and form stable clusters. This leads to a phase separation between perfect crystalline structures and defect conglomerates at low temperatures. We propose a method that allows one to tune the effective interactions between point defects from attractive to repulsive by means of external periodic fields. In the quantum regime, this allows one to engineer strongly correlated many-body phases. We exemplify the microscopic mechanism by considering dipolar quantum gases of ground-state polar molecules and weakly bound molecules of strongly magnetic atoms trapped in a weak optical lattice in a two-dimensional configuration. By tuning the lattice depth, defect interactions turn repulsive, which allows us to deterministically design a novel supersolid phase in the continuum limit.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Point defects in self-assembled crystals, such as vacancies and interstitials, attract each other and form stable clusters. This leads to a phase separation between perfect crystalline structures and defect conglomerates at low temperatures. We propose a method that allows one to tune the effective interactions between point defects from attractive to repulsive by means of external periodic fields. In the quantum regime, this allows one to engineer strongly correlated many-body phases. We exemplify the microscopic mechanism by considering dipolar quantum gases of ground-state polar molecules and weakly bound molecules of strongly magnetic atoms trapped in a weak optical lattice in a two-dimensional configuration. By tuning the lattice depth, defect interactions turn repulsive, which allows us to deterministically design a novel supersolid phase in the continuum limit. |
Diaz-Mendez, Rogelio ; Mezzacapo, Fabio ; Cinti, Fabio ; Lechner, Wolfgang ; Pupillo, Guido Monodisperse cluster crystals: Classical and quantum dynamics Journal Article In: PHYSICAL REVIEW E, 92 (5), 2015, ISSN: 1539-3755. @article{diaz-mendez_monodisperse_2015, title = {Monodisperse cluster crystals: Classical and quantum dynamics}, author = {Diaz-Mendez, Rogelio and Mezzacapo, Fabio and Cinti, Fabio and Lechner, Wolfgang and Pupillo, Guido}, doi = {10.1103/PhysRevE.92.052307}, issn = {1539-3755}, year = {2015}, date = {2015-11-01}, journal = {PHYSICAL REVIEW E}, volume = {92}, number = {5}, abstract = {We study the phases and dynamics of a gas of monodisperse particles interacting via soft-core potentials in two spatial dimensions, which is of interest for soft-matter colloidal systems and quantum atomic gases. Using exact theoretical methods, we demonstrate that the equilibrium low-temperature classical phase simultaneously breaks continuous translational symmetry and dynamic space-time homogeneity, whose absence is usually associated with out-of-equilibrium glassy phenomena. This results in an exotic self-assembled cluster crystal with coexisting liquidlike long-time dynamical properties, which corresponds to a classical analog of supersolid behavior. We demonstrate that the effects of quantum fluctuations and bosonic statistics on cluster-glassy crystals are separate and competing: Zero-point motion tends to destabilize crystalline order, which can be restored by bosonic statistics.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We study the phases and dynamics of a gas of monodisperse particles interacting via soft-core potentials in two spatial dimensions, which is of interest for soft-matter colloidal systems and quantum atomic gases. Using exact theoretical methods, we demonstrate that the equilibrium low-temperature classical phase simultaneously breaks continuous translational symmetry and dynamic space-time homogeneity, whose absence is usually associated with out-of-equilibrium glassy phenomena. This results in an exotic self-assembled cluster crystal with coexisting liquidlike long-time dynamical properties, which corresponds to a classical analog of supersolid behavior. We demonstrate that the effects of quantum fluctuations and bosonic statistics on cluster-glassy crystals are separate and competing: Zero-point motion tends to destabilize crystalline order, which can be restored by bosonic statistics. |
Bertucci, Alessandro ; Prasetyanto, Eko Adi ; Septiadi, Dedy ; Manicardi, Alex ; Brognara, Eleonora ; Gambari, Roberto ; Corradini, Roberto ; De Cola, Luisa Combined Delivery of Temozolomide and Anti-miR221 PNA Using Mesoporous Silica Nanoparticles Induces Apoptosis in Resistant Glioma Cells Journal Article In: SMALL, 11 (42), pp. 5687–5695, 2015, ISSN: 1613-6810. @article{bertucci_combined_2015, title = {Combined Delivery of Temozolomide and Anti-miR221 PNA Using Mesoporous Silica Nanoparticles Induces Apoptosis in Resistant Glioma Cells}, author = {Bertucci, Alessandro and Prasetyanto, Eko Adi and Septiadi, Dedy and Manicardi, Alex and Brognara, Eleonora and Gambari, Roberto and Corradini, Roberto and De Cola, Luisa}, doi = {10.1002/smll.201500540}, issn = {1613-6810}, year = {2015}, date = {2015-11-01}, journal = {SMALL}, volume = {11}, number = {42}, pages = {5687--5695}, abstract = {Mesoporous silica nanoparticles (MSNPs), 100 nm in size, incorporating a Cy5 fluorophore within the silica framework, are synthesized and loaded with the anti-cancer drug temozolomide (TMZ), used in the treatment of gliomas. The surface of the particles is then decorated, using electrostatic interactions, with a polyarginine-peptide nucleic acid (R8-PNA) conjugate targeting the miR221 microRNA. The multi-functional nanosystem thus obtained is rapidly internalized into glioma C6 or T98G cells. The anti-miR activity of the PNA is retained, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) measurements and induction of apoptosis is observed in temozolomide-resistant cell lines. The TMZ-loaded MSNPs show an enhanced pro-apoptotic effect, and the combined effect of TMZ and R8-PNA in the MSNPs shows the most effective induction of apoptosis (70.9% of apoptotic cells) thus far achieved in the temozolomide-resistant T98G cell line.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Mesoporous silica nanoparticles (MSNPs), 100 nm in size, incorporating a Cy5 fluorophore within the silica framework, are synthesized and loaded with the anti-cancer drug temozolomide (TMZ), used in the treatment of gliomas. The surface of the particles is then decorated, using electrostatic interactions, with a polyarginine-peptide nucleic acid (R8-PNA) conjugate targeting the miR221 microRNA. The multi-functional nanosystem thus obtained is rapidly internalized into glioma C6 or T98G cells. The anti-miR activity of the PNA is retained, as confirmed by reverse transcription polymerase chain reaction (RT-PCR) measurements and induction of apoptosis is observed in temozolomide-resistant cell lines. The TMZ-loaded MSNPs show an enhanced pro-apoptotic effect, and the combined effect of TMZ and R8-PNA in the MSNPs shows the most effective induction of apoptosis (70.9% of apoptotic cells) thus far achieved in the temozolomide-resistant T98G cell line. |
Marbach, Sophie ; Godeau, Amelie Luise ; Riveline, Daniel ; Joanny, Jean-Francois ; Prost, Jacques Theoretical study of actin layers attachment and separation Journal Article In: EUROPEAN PHYSICAL JOURNAL E, 38 (11), 2015, ISSN: 1292-8941. @article{marbach_theoretical_2015, title = {Theoretical study of actin layers attachment and separation}, author = {Marbach, Sophie and Godeau, Amelie Luise and Riveline, Daniel and Joanny, Jean-Francois and Prost, Jacques}, doi = {10.1140/epje/i2015-15122-4}, issn = {1292-8941}, year = {2015}, date = {2015-11-01}, journal = {EUROPEAN PHYSICAL JOURNAL E}, volume = {38}, number = {11}, abstract = {We use the theory of active gels to study theoretically the merging and separation of two actin dense layers akin to cortical layers of animal cells. The layers bind at a distance equal to twice the thickness of a free layer, thus forming a single dense layer, similar in this sense to a lamellipodium. When that unique layer is stretched apart, it is resilient to break apart up to a critical length larger than twice the thickness of a free layer. We show that this behavior can result from the high contractile properties of the actomyosin gel due to the activity of myosin molecular motors. Furthermore, we establish that the stability of the stretched single layer is highly dependent on the properties of the gel. Indeed, the nematic order of the actin filaments along the polymerizing membranes is a destabilizing factor.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We use the theory of active gels to study theoretically the merging and separation of two actin dense layers akin to cortical layers of animal cells. The layers bind at a distance equal to twice the thickness of a free layer, thus forming a single dense layer, similar in this sense to a lamellipodium. When that unique layer is stretched apart, it is resilient to break apart up to a critical length larger than twice the thickness of a free layer. We show that this behavior can result from the high contractile properties of the actomyosin gel due to the activity of myosin molecular motors. Furthermore, we establish that the stability of the stretched single layer is highly dependent on the properties of the gel. Indeed, the nematic order of the actin filaments along the polymerizing membranes is a destabilizing factor. |
Haar, Sebastien ; El Gemayel, Mirella ; Shin, Yuyoung ; Melinte, Georgian ; Squillaci, Marco A; Ersen, Ovidiu ; Casiraghi, Cinzia ; Ciesielski, Artur ; Samori, Paolo Enhancing the Liquid-Phase Exfoliation of Graphene in Organic Solvents upon Addition of n-Octylbenzene Journal Article In: SCIENTIFIC REPORTS, 5 , 2015, ISSN: 2045-2322. @article{haar_enhancing_2015, title = {Enhancing the Liquid-Phase Exfoliation of Graphene in Organic Solvents upon Addition of n-Octylbenzene}, author = {Haar, Sebastien and El Gemayel, Mirella and Shin, Yuyoung and Melinte, Georgian and Squillaci, Marco A. and Ersen, Ovidiu and Casiraghi, Cinzia and Ciesielski, Artur and Samori, Paolo}, doi = {10.1038/srep16684}, issn = {2045-2322}, year = {2015}, date = {2015-11-01}, journal = {SCIENTIFIC REPORTS}, volume = {5}, abstract = {Due to a unique combination of electrical and thermal conductivity, mechanical stiffness, strength and elasticity, graphene became a rising star on the horizon of materials science. This two-dimensional material has found applications in many areas of science ranging from electronics to composites. Making use of different approaches, unfunctionalized and non-oxidized graphene sheets can be produced; among them an inexpensive and scalable method based on liquid-phase exfoliation of graphite (LPE) holds potential for applications in opto-electronics and nanocomposites. Here we have used n-octylbenzene molecules as graphene dispersion-stabilizing agents during the graphite LPE process. We have demonstrated that by tuning the ratio between organic solvents such as N-methyl-2-pyrrolidinone or ortho-dichlorobenzene, and n-octylbenzene molecules, the concentration of exfoliated graphene can be enhanced by 230% as a result of the high affinity of the latter molecules for the basal plane of graphene. The LPE processed graphene dispersions were further deposited onto solid substrates by exploiting a new deposition technique called spincontrolled drop casting, which was shown to produce uniform highly conductive and transparent graphene films.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Due to a unique combination of electrical and thermal conductivity, mechanical stiffness, strength and elasticity, graphene became a rising star on the horizon of materials science. This two-dimensional material has found applications in many areas of science ranging from electronics to composites. Making use of different approaches, unfunctionalized and non-oxidized graphene sheets can be produced; among them an inexpensive and scalable method based on liquid-phase exfoliation of graphite (LPE) holds potential for applications in opto-electronics and nanocomposites. Here we have used n-octylbenzene molecules as graphene dispersion-stabilizing agents during the graphite LPE process. We have demonstrated that by tuning the ratio between organic solvents such as N-methyl-2-pyrrolidinone or ortho-dichlorobenzene, and n-octylbenzene molecules, the concentration of exfoliated graphene can be enhanced by 230% as a result of the high affinity of the latter molecules for the basal plane of graphene. The LPE processed graphene dispersions were further deposited onto solid substrates by exploiting a new deposition technique called spincontrolled drop casting, which was shown to produce uniform highly conductive and transparent graphene films. |
Yang, Sheng ; Brueller, Sebastian ; Wu, Zhong-Shuai ; Liu, Zhaoyang ; Parvez, Khaled ; Dong, Renhao ; Richard, Fanny ; Samori, Paolo ; Feng, Xinliang ; Muellen, Klaus Organic Radical-Assisted Electrochemical Exfoliation for the Scalable Production of High-Quality Graphene Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (43), pp. 13927–13932, 2015, ISSN: 0002-7863. @article{yang_organic_2015, title = {Organic Radical-Assisted Electrochemical Exfoliation for the Scalable Production of High-Quality Graphene}, author = {Yang, Sheng and Brueller, Sebastian and Wu, Zhong-Shuai and Liu, Zhaoyang and Parvez, Khaled and Dong, Renhao and Richard, Fanny and Samori, Paolo and Feng, Xinliang and Muellen, Klaus}, doi = {10.1021/jacs.5b09000}, issn = {0002-7863}, year = {2015}, date = {2015-11-01}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {137}, number = {43}, pages = {13927--13932}, abstract = {Despite the intensive research efforts devoted to graphene fabrication over the past decade, the production of high-quality graphene on a large scale, at an affordable cost, and in a reproducible manner still represents a great challenge. Here, we report a novel method based on the controlled electrochemical exfoliation of graphite in aqueous ammonium sulfate electrolyte to produce graphene in large quantities and with outstanding quality. Because the radicals (e.g., HO center dot) generated from water electrolysis are responsible for defect formation on graphene during electrochemical exfoliation, a series of reducing agents as additives (e.g., (2,2,6,6-tetramethylpiperidin-1-yl) oxyl (TEMPO), ascorbic acid, and sodium borohydride) have been investigated to eliminate these radicals and thus control the exfoliation process. Remarkably, TEMPO-assisted exfoliation results in large graphene sheets (5-10 mu m on average), which exhibit outstanding hole mobilities (similar to 405 cm(2) V-1 s(-1)), very low Raman I-D/I-G ratios (below 0.1), and extremely high carbon to oxygen (C/O) ratios (similar to 25.3). Moreover, the graphene ink prepared in dimethylformamide can exhibit concentrations as high as 6 mg mL(-1) thus qualifying this material for intriguing applications such as transparent conductive films and flexible supercapacitors. In general, this robust method for electrochemical exfoliation of graphite offers great promise for the preparation of graphene that can be utilized in industrial applications to create integrated nanocomposites, conductive or mechanical additives, as well as energy storage and conversion devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Despite the intensive research efforts devoted to graphene fabrication over the past decade, the production of high-quality graphene on a large scale, at an affordable cost, and in a reproducible manner still represents a great challenge. Here, we report a novel method based on the controlled electrochemical exfoliation of graphite in aqueous ammonium sulfate electrolyte to produce graphene in large quantities and with outstanding quality. Because the radicals (e.g., HO center dot) generated from water electrolysis are responsible for defect formation on graphene during electrochemical exfoliation, a series of reducing agents as additives (e.g., (2,2,6,6-tetramethylpiperidin-1-yl) oxyl (TEMPO), ascorbic acid, and sodium borohydride) have been investigated to eliminate these radicals and thus control the exfoliation process. Remarkably, TEMPO-assisted exfoliation results in large graphene sheets (5-10 mu m on average), which exhibit outstanding hole mobilities (similar to 405 cm(2) V-1 s(-1)), very low Raman I-D/I-G ratios (below 0.1), and extremely high carbon to oxygen (C/O) ratios (similar to 25.3). Moreover, the graphene ink prepared in dimethylformamide can exhibit concentrations as high as 6 mg mL(-1) thus qualifying this material for intriguing applications such as transparent conductive films and flexible supercapacitors. In general, this robust method for electrochemical exfoliation of graphite offers great promise for the preparation of graphene that can be utilized in industrial applications to create integrated nanocomposites, conductive or mechanical additives, as well as energy storage and conversion devices. |
Orgiu, E; George, J; Hutchison, J A; Devaux, E; Dayen, J F; Doudin, B; Stellacci, F; Genet, C; Schachenmayer, J; Genes, C; Pupillo, G; Samori, P; Ebbesen, T W Conductivity in organic semiconductors hybridized with the vacuum field Journal Article In: NATURE MATERIALS, 14 (11), pp. 1123+, 2015, ISSN: 1476-1122. @article{orgiu_conductivity_2015, title = {Conductivity in organic semiconductors hybridized with the vacuum field}, author = {Orgiu, E. and George, J. and Hutchison, J. A. and Devaux, E. and Dayen, J. F. and Doudin, B. and Stellacci, F. and Genet, C. and Schachenmayer, J. and Genes, C. and Pupillo, G. and Samori, P. and Ebbesen, T. W.}, doi = {10.1038/NMAT4392}, issn = {1476-1122}, year = {2015}, date = {2015-11-01}, journal = {NATURE MATERIALS}, volume = {14}, number = {11}, pages = {1123+}, abstract = {Much effort over the past decades has been focused on improving carrier mobility in organic thin-film transistors by optimizing the organization of the material or the device architecture. Here we take a different path to solving this problem, by injecting carriers into states that are hybridized to the vacuum electromagnetic field. To test this idea, organic semiconductors were strongly coupled to plasmonic modes to form coherent states that can extend over as many as 105 molecules and should thereby favour conductivity. Experiments show that indeed the current does increase by an order of magnitude at resonance in the coupled state, reflecting mostly a change in field-effect mobility. A theoretical quantum model confirms the delocalization of thewavefunctions of the hybridized states and its effect on the conductivity. Our findings illustrate the potential of engineering the vacuum electromagnetic environment to modify and to improve properties of materials.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Much effort over the past decades has been focused on improving carrier mobility in organic thin-film transistors by optimizing the organization of the material or the device architecture. Here we take a different path to solving this problem, by injecting carriers into states that are hybridized to the vacuum electromagnetic field. To test this idea, organic semiconductors were strongly coupled to plasmonic modes to form coherent states that can extend over as many as 105 molecules and should thereby favour conductivity. Experiments show that indeed the current does increase by an order of magnitude at resonance in the coupled state, reflecting mostly a change in field-effect mobility. A theoretical quantum model confirms the delocalization of thewavefunctions of the hybridized states and its effect on the conductivity. Our findings illustrate the potential of engineering the vacuum electromagnetic environment to modify and to improve properties of materials. |
Greb, Lutz ; Eichhoefer, Andreas ; Lehn, Jean-Marie Synthetic Molecular Motors: Thermal N Inversion and Directional Photoinduced C=N Bond Rotation of Camphorquinone Imines Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (48), pp. 14345–14348, 2015, ISSN: 1433-7851. @article{greb_synthetic_2015, title = {Synthetic Molecular Motors: Thermal N Inversion and Directional Photoinduced C=N Bond Rotation of Camphorquinone Imines}, author = {Greb, Lutz and Eichhoefer, Andreas and Lehn, Jean-Marie}, doi = {10.1002/anie.201506691}, issn = {1433-7851}, year = {2015}, date = {2015-11-01}, journal = {ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, volume = {54}, number = {48}, pages = {14345--14348}, abstract = {The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. The thermal isomerization proceeds by linear N inversion, whereas the photoinduced process occurs through C=N bond rotation with preferred directionality as a result of diastereoisomerism. Thereby, these imines are arguably the simplest example of synthetic molecular motors. The generality of the orthogonal trajectories of the thermal and photochemical pathways allows for the postulation that every suitable chiral imine qualifies, in principle, as a molecular motor driven by light or heat.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The thermal and photochemical E/Z isomerization of camphorquinone-derived imines was studied by a combination of kinetic, structural, and computational methods. The thermal isomerization proceeds by linear N inversion, whereas the photoinduced process occurs through C=N bond rotation with preferred directionality as a result of diastereoisomerism. Thereby, these imines are arguably the simplest example of synthetic molecular motors. The generality of the orthogonal trajectories of the thermal and photochemical pathways allows for the postulation that every suitable chiral imine qualifies, in principle, as a molecular motor driven by light or heat. |
Niess, Frederic ; Duplan, Vincent ; Diercks, Christian S; Sauvage, Jean-Pierre Contractile and Extensible Molecular Figures-of-Eight Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (41), pp. 14393–14400, 2015, ISSN: 0947-6539. @article{niess_contractile_2015, title = {Contractile and Extensible Molecular Figures-of-Eight}, author = {Niess, Frederic and Duplan, Vincent and Diercks, Christian S. and Sauvage, Jean-Pierre}, doi = {10.1002/chem.201502216}, issn = {0947-6539}, year = {2015}, date = {2015-10-01}, journal = {CHEMISTRY-A EUROPEAN JOURNAL}, volume = {21}, number = {41}, pages = {14393--14400}, abstract = {Two large rings, 66-(m-66) and 78-membered (m-78) rings, each one incorporating two pairs of transition-metal-complexing units, have been prepared. The coordinating fragments are alternating bi- and tridentate chelating groups, namely, 2,9-diphenyl-1,10-phenanthroline (dpp) and 2,2', 2', 6 `'-terpyridine (terpy) respectively. Both macrocycles form molecular figures-of-eight in the presence of Fe-II, affording a classical bis-terpy complex as the central core. The larger m-78 ring can accommodate a four-coordinate Cu-I center with the formation of a Cu(dpp)(2)(+) central complex and a highly twisted figure-of-eight backbone, whereas m-66 is too small to coordinate Cu-I. Macrocycle m-78 thus affords stable complexes with both Fe-II and Cu-I; the ligand around the metal changes from (terpy)(2) to (dpp)(2). This bimodal coordination situation allows for a large amplitude rearrangement of the organic backbone. When coordinated to preferentially octahedrally coordinated Fe-II or Cu-II, the height of the molecule along the coordinating axis of the tridentate terpy ligands is only about 11 angstrom, whereas the height of the molecule along the same vertical axis is several times as large for the tetrahedral Cu-I complex. Chemically or electrochemically driven contraction and extension motions along a defined axis make this figure-of-eight particularly promising as a new class of molecular machine prototype for use as a constitutive element in muscle-like dynamic systems.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two large rings, 66-(m-66) and 78-membered (m-78) rings, each one incorporating two pairs of transition-metal-complexing units, have been prepared. The coordinating fragments are alternating bi- and tridentate chelating groups, namely, 2,9-diphenyl-1,10-phenanthroline (dpp) and 2,2', 2', 6 `'-terpyridine (terpy) respectively. Both macrocycles form molecular figures-of-eight in the presence of Fe-II, affording a classical bis-terpy complex as the central core. The larger m-78 ring can accommodate a four-coordinate Cu-I center with the formation of a Cu(dpp)(2)(+) central complex and a highly twisted figure-of-eight backbone, whereas m-66 is too small to coordinate Cu-I. Macrocycle m-78 thus affords stable complexes with both Fe-II and Cu-I; the ligand around the metal changes from (terpy)(2) to (dpp)(2). This bimodal coordination situation allows for a large amplitude rearrangement of the organic backbone. When coordinated to preferentially octahedrally coordinated Fe-II or Cu-II, the height of the molecule along the coordinating axis of the tridentate terpy ligands is only about 11 angstrom, whereas the height of the molecule along the same vertical axis is several times as large for the tetrahedral Cu-I complex. Chemically or electrochemically driven contraction and extension motions along a defined axis make this figure-of-eight particularly promising as a new class of molecular machine prototype for use as a constitutive element in muscle-like dynamic systems. |
Mahato, R N; Luelf, H; Siekman, M H; Kersten, S P; Bobbert, P A; de Jong, M P; De Cola, L; van der Wiel, W G Ultrahigh magnetoresistance at room temperature in molecular wires (Retraction of vol 341, pg 257, 2013) Journal Article In: SCIENCE, 350 (6257), pp. 170, 2015, ISSN: 0036-8075. @article{mahato_ultrahigh_2015, title = {Ultrahigh magnetoresistance at room temperature in molecular wires (Retraction of vol 341, pg 257, 2013)}, author = {Mahato, R. N. and Luelf, H. and Siekman, M. H. and Kersten, S. P. and Bobbert, P. A. and de Jong, M. P. and De Cola, L. and van der Wiel, W. G.}, doi = {10.1126/science.350.6257.170-a}, issn = {0036-8075}, year = {2015}, date = {2015-10-01}, journal = {SCIENCE}, volume = {350}, number = {6257}, pages = {170}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
d'Avenia , M; Citro, R; De Marco, M; Veronese, A; Rosati, A; Visone, R; Leptidis, S; Philippen, L; Vitale, G; Cavallo, A; Silverio, A; Prota, C; Gravina, P; De Cola, A; Carletti, E; Coppola, G; Gallo, S; Provenza, G; Bossone, E; Piscione, F; Hahne, M; De Windt, L J; Turco, M C; De laurenzi, V A novel miR-371a-5p-mediated pathway, leading to BAG3 upregulation in cardiomyocytes in response to epinephrine, is lost in Takotsubo cardiomyopathy Journal Article In: CELL DEATH & DISEASE, 6 , 2015, ISSN: 2041-4889. @article{davenia_novel_2015, title = {A novel miR-371a-5p-mediated pathway, leading to BAG3 upregulation in cardiomyocytes in response to epinephrine, is lost in Takotsubo cardiomyopathy}, author = {d'Avenia, M. and Citro, R. and De Marco, M. and Veronese, A. and Rosati, A. and Visone, R. and Leptidis, S. and Philippen, L. and Vitale, G. and Cavallo, A. and Silverio, A. and Prota, C. and Gravina, P. and De Cola, A. and Carletti, E. and Coppola, G. and Gallo, S. and Provenza, G. and Bossone, E. and Piscione, F. and Hahne, M. and De Windt, L. J. and Turco, M. C. and De laurenzi, V.}, doi = {10.1038/cddis.2015.280}, issn = {2041-4889}, year = {2015}, date = {2015-10-01}, journal = {CELL DEATH & DISEASE}, volume = {6}, abstract = {Molecular mechanisms protecting cardiomyocytes from stress-induced death, including tension stress, are essential for cardiac physiology and defects in these protective mechanisms can result in pathological alterations. Bcl2-associated athanogene 3 (BAG3) is expressed in cardiomyocytes and is a component of the chaperone-assisted autophagy pathway, essential for homeostasis of mechanically altered cells. BAG3 ablation in mice results in a lethal cardiomyopathy soon after birth and mutations of this gene have been associated with different cardiomyopathies including stress-induced Takotsubo cardiomyopathy (TTC). The pathogenic mechanism leading to TTC has not been defined, but it has been suggested that the heart can be damaged by excessive epinephrine (epi) spillover in the absence of a protective mechanism. The aim of this study was to provide more evidence for a role of BAG3 in the pathogenesis of TTC. Therefore, we sequenced BAG3 gene in 70 TTC patients and in 81 healthy donors with the absence of evaluable cardiovascular disease. Mutations and polymorphisms detected in the BAG3 gene included a frequent nucleotide change g2252c in the BAG3 3'-untranslated region (3'-UTR) of Takotsubo patients (P textbackslashtextbackslashtextless 0.05), resulting in loss of binding of microRNA-371a-5p (miR-371a-5p) as evidenced by dual-luciferase reporter assays and argonaute RNA-induced silencing complex catalytic component 2/pull-down assays. Moreover, we describe a novel signaling pathway in cardiomyocytes that leads to BAG3 upregulation on exposure to epi through an ERK-dependent upregulation of miR-371a-5p. In conclusion, the presence of a g2252c polymorphism in the BAG3 3'-UTR determines loss of miR-371a-5p binding and results in an altered response to epi, potentially representing a new molecular mechanism that contributes to TTC pathogenesis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular mechanisms protecting cardiomyocytes from stress-induced death, including tension stress, are essential for cardiac physiology and defects in these protective mechanisms can result in pathological alterations. Bcl2-associated athanogene 3 (BAG3) is expressed in cardiomyocytes and is a component of the chaperone-assisted autophagy pathway, essential for homeostasis of mechanically altered cells. BAG3 ablation in mice results in a lethal cardiomyopathy soon after birth and mutations of this gene have been associated with different cardiomyopathies including stress-induced Takotsubo cardiomyopathy (TTC). The pathogenic mechanism leading to TTC has not been defined, but it has been suggested that the heart can be damaged by excessive epinephrine (epi) spillover in the absence of a protective mechanism. The aim of this study was to provide more evidence for a role of BAG3 in the pathogenesis of TTC. Therefore, we sequenced BAG3 gene in 70 TTC patients and in 81 healthy donors with the absence of evaluable cardiovascular disease. Mutations and polymorphisms detected in the BAG3 gene included a frequent nucleotide change g2252c in the BAG3 3'-untranslated region (3'-UTR) of Takotsubo patients (P textbackslashtextbackslashtextless 0.05), resulting in loss of binding of microRNA-371a-5p (miR-371a-5p) as evidenced by dual-luciferase reporter assays and argonaute RNA-induced silencing complex catalytic component 2/pull-down assays. Moreover, we describe a novel signaling pathway in cardiomyocytes that leads to BAG3 upregulation on exposure to epi through an ERK-dependent upregulation of miR-371a-5p. In conclusion, the presence of a g2252c polymorphism in the BAG3 3'-UTR determines loss of miR-371a-5p binding and results in an altered response to epi, potentially representing a new molecular mechanism that contributes to TTC pathogenesis. |
Caballero, David ; Voituriez, Raphael ; Riveline, Daniel The cell ratchet: Interplay between efficient protrusions and adhesion determines cell motion Journal Article In: CELL ADHESION & MIGRATION, 9 (5), pp. 327–334, 2015, ISSN: 1933-6918. @article{caballero_cell_2015, title = {The cell ratchet: Interplay between efficient protrusions and adhesion determines cell motion}, author = {Caballero, David and Voituriez, Raphael and Riveline, Daniel}, doi = {10.1080/19336918.2015.1061865}, issn = {1933-6918}, year = {2015}, date = {2015-10-01}, journal = {CELL ADHESION & MIGRATION}, volume = {9}, number = {5}, pages = {327--334}, abstract = {Many physiological and pathological processes involve directed cell motion. In general, migrating cells are represented with a polarized morphology with extending and retracting protrusions at the leading edge. However, cell motion is a more complex phenomenon. Cells show heterogeneous morphologies and high protrusive dynamics is not always related to cell shape. This prevents the quantitative prediction of cell motion and the identification of cellular mechanisms setting directionality. Here we discuss the importance of protrusion fluctuations in directed cell motion. We show how their spatiotemporal distribution and dynamics determine the fluctuations and directions of cell motion for NIH3T3 fibroblasts plated on micro-patterned adhesive ratchets.(1) We introduce efficient protrusions and direction index which capture short-term cell motility over hours: these new read-outs allow the prediction of parameters characteristic for the long-term motion of cells over days. The results may have important implications for the study of biological phenomena where directed cell migration is involved, in morphogenesis and in cancer.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many physiological and pathological processes involve directed cell motion. In general, migrating cells are represented with a polarized morphology with extending and retracting protrusions at the leading edge. However, cell motion is a more complex phenomenon. Cells show heterogeneous morphologies and high protrusive dynamics is not always related to cell shape. This prevents the quantitative prediction of cell motion and the identification of cellular mechanisms setting directionality. Here we discuss the importance of protrusion fluctuations in directed cell motion. We show how their spatiotemporal distribution and dynamics determine the fluctuations and directions of cell motion for NIH3T3 fibroblasts plated on micro-patterned adhesive ratchets.(1) We introduce efficient protrusions and direction index which capture short-term cell motility over hours: these new read-outs allow the prediction of parameters characteristic for the long-term motion of cells over days. The results may have important implications for the study of biological phenomena where directed cell migration is involved, in morphogenesis and in cancer. |
Cecchini, Marco Quantum Corrections to the Free Energy Difference between Peptides and Proteins Conformers Journal Article In: JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 11 (9), pp. 4011–4022, 2015, ISSN: 1549-9618. @article{cecchini_quantum_2015, title = {Quantum Corrections to the Free Energy Difference between Peptides and Proteins Conformers}, author = {Cecchini, Marco}, doi = {10.1021/acs.jctc.5b00260}, issn = {1549-9618}, year = {2015}, date = {2015-09-01}, journal = {JOURNAL OF CHEMICAL THEORY AND COMPUTATION}, volume = {11}, number = {9}, pages = {4011--4022}, abstract = {The calculation of the free energy of conformation is key in understanding the function of biomolecules and has attracted significant interest in recent years. Most current computational approaches evaluate the difference in conformational free energy in the classical limit based on the common “dogma” that only the lowest-frequency modes make a significant contribution to it, i.e. they assume that quantum mechanical corrections are negligible. Here, I show for three biomolecular systems described in the rigid-rotor, harmonic-oscillator approximation that the zero-point energy contribution, although small, is not negligible even at room temperature. I find that a quantum correction arises from the intermediate-frequency vibrational modes and that its magnitude is strongly correlated with the number of atoms in the system. A straightforward, though approximate, way to account for this quantum correction in the calculation of conformational free-energy differences by classical molecular dynamics is presented. The relevance of the quantum correction analyzed in this paper is discussed in the context of conventional force fields for proteins.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The calculation of the free energy of conformation is key in understanding the function of biomolecules and has attracted significant interest in recent years. Most current computational approaches evaluate the difference in conformational free energy in the classical limit based on the common “dogma” that only the lowest-frequency modes make a significant contribution to it, i.e. they assume that quantum mechanical corrections are negligible. Here, I show for three biomolecular systems described in the rigid-rotor, harmonic-oscillator approximation that the zero-point energy contribution, although small, is not negligible even at room temperature. I find that a quantum correction arises from the intermediate-frequency vibrational modes and that its magnitude is strongly correlated with the number of atoms in the system. A straightforward, though approximate, way to account for this quantum correction in the calculation of conformational free-energy differences by classical molecular dynamics is presented. The relevance of the quantum correction analyzed in this paper is discussed in the context of conventional force fields for proteins. |
Cecchini, Marco ; Changeux, Jean-Pierre The nicotinic acetylcholine receptor and its prokaryotic homologues: Structure, conformational transitions & allosteric modulation Journal Article In: NEUROPHARMACOLOGY, 96 (B, SI), pp. 137–149, 2015, ISSN: 0028-3908. @article{cecchini_nicotinic_2015, title = {The nicotinic acetylcholine receptor and its prokaryotic homologues: Structure, conformational transitions & allosteric modulation}, author = {Cecchini, Marco and Changeux, Jean-Pierre}, doi = {10.1016/j.neuropharm.2014.12.006}, issn = {0028-3908}, year = {2015}, date = {2015-09-01}, journal = {NEUROPHARMACOLOGY}, volume = {96}, number = {B, SI}, pages = {137--149}, abstract = {Pentameric ligand-gated ion channels (pLGICs) play a central role in intercellular communications in the nervous system by converting the binding of a chemical messenger - a neurotransmitter - into an ion flux through the postsynaptic membrane. Here, we present an overview of the most recent advances on the signal transduction mechanism boosted by X-ray crystallography of both prokaryotic and eukaryotic homologues of the nicotinic acetylcholine receptor (nAChR) in conjunction with time-resolved analyses based on single-channel electrophysiology and Molecular Dynamics simulations. The available data consistently point to a global mechanism of gating that involves a large reorganization of the receptor mediated by two distinct quaternary transitions: a global twisting and a radial expansion/contraction of the extracellular domain. These transitions profoundly modify the organization of the in,terface between subunits, which host several sites for orthosteric and allosteric modulatory ligands. The same mechanism may thus mediate both positive and negative allosteric modulations of pLGICs ligand binding at topographically distinct sites. The emerging picture of signal transduction is expected to pave the way to new pharmacological strategies for the development of allosteric modulators of nAChR and pLGICs in general. This article is part of the Special Issue entitled `The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'. (C) 2015 Elsevier Ltd. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pentameric ligand-gated ion channels (pLGICs) play a central role in intercellular communications in the nervous system by converting the binding of a chemical messenger - a neurotransmitter - into an ion flux through the postsynaptic membrane. Here, we present an overview of the most recent advances on the signal transduction mechanism boosted by X-ray crystallography of both prokaryotic and eukaryotic homologues of the nicotinic acetylcholine receptor (nAChR) in conjunction with time-resolved analyses based on single-channel electrophysiology and Molecular Dynamics simulations. The available data consistently point to a global mechanism of gating that involves a large reorganization of the receptor mediated by two distinct quaternary transitions: a global twisting and a radial expansion/contraction of the extracellular domain. These transitions profoundly modify the organization of the in,terface between subunits, which host several sites for orthosteric and allosteric modulatory ligands. The same mechanism may thus mediate both positive and negative allosteric modulations of pLGICs ligand binding at topographically distinct sites. The emerging picture of signal transduction is expected to pave the way to new pharmacological strategies for the development of allosteric modulators of nAChR and pLGICs in general. This article is part of the Special Issue entitled `The Nicotinic Acetylcholine Receptor: From Molecular Biology to Cognition'. (C) 2015 Elsevier Ltd. All rights reserved. |
Aliprandi, Alessandro ; Genovese, Damiano ; Mauro, Matteo ; De Cola, Luisa Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications Journal Article In: CHEMISTRY LETTERS, 44 (9), pp. 1152–1169, 2015, ISSN: 0366-7022. @article{aliprandi_recent_2015, title = {Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications}, author = {Aliprandi, Alessandro and Genovese, Damiano and Mauro, Matteo and De Cola, Luisa}, doi = {10.1246/cl.150592}, issn = {0366-7022}, year = {2015}, date = {2015-09-01}, journal = {CHEMISTRY LETTERS}, volume = {44}, number = {9}, pages = {1152--1169}, abstract = {Supramolecular weak interactions can be used for preparing functional self-assembled architectures by powerful bottom-up approaches. In particular, when closed-shell metallophilic and pi-pi interactions between adjacent transition-metal complexes are established, profound changes in compounds' properties are obtained and novel features often achieved. In this Review, the most recent advances in the field of luminescent platinum(II) complexes aggregating through Pt-Pt interactions are highlighted and their potential application in different fields presented and discussed.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Supramolecular weak interactions can be used for preparing functional self-assembled architectures by powerful bottom-up approaches. In particular, when closed-shell metallophilic and pi-pi interactions between adjacent transition-metal complexes are established, profound changes in compounds' properties are obtained and novel features often achieved. In this Review, the most recent advances in the field of luminescent platinum(II) complexes aggregating through Pt-Pt interactions are highlighted and their potential application in different fields presented and discussed. |
Greco, Arianna ; Maggini, Laura ; De Cola, Luisa ; De Marco, Rossella ; Gentilucci, Luca Diagnostic Implementation of Fast and Selective Integrin-Mediated Adhesion of Cancer Cells on Functionalized Zeolite L Monolayers Journal Article In: BIOCONJUGATE CHEMISTRY, 26 (9), pp. 1873–1878, 2015, ISSN: 1043-1802. @article{greco_diagnostic_2015, title = {Diagnostic Implementation of Fast and Selective Integrin-Mediated Adhesion of Cancer Cells on Functionalized Zeolite L Monolayers}, author = {Greco, Arianna and Maggini, Laura and De Cola, Luisa and De Marco, Rossella and Gentilucci, Luca}, doi = {10.1021/acs.bioconjchem.5b00350}, issn = {1043-1802}, year = {2015}, date = {2015-09-01}, journal = {BIOCONJUGATE CHEMISTRY}, volume = {26}, number = {9}, pages = {1873--1878}, abstract = {The rapid and exact identification and quantification of specific biomarkers is a key technology for always achieving more efficient diagnostic methodologies. We present the first application of a nanostructured device constituted of patterned self-assembled monolayers of disk-shaped zeolite L coated with the cyclic integrin ligand c[RGDfK] via isocyanate linker, to the rapid detection of cancer cells. With its high specificity toward He La and Glioma cells and fast adhesion ability, this biocompatible monolayer is a promising platform for implementation in diagnostics and personalized therapy formulation devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The rapid and exact identification and quantification of specific biomarkers is a key technology for always achieving more efficient diagnostic methodologies. We present the first application of a nanostructured device constituted of patterned self-assembled monolayers of disk-shaped zeolite L coated with the cyclic integrin ligand c[RGDfK] via isocyanate linker, to the rapid detection of cancer cells. With its high specificity toward He La and Glioma cells and fast adhesion ability, this biocompatible monolayer is a promising platform for implementation in diagnostics and personalized therapy formulation devices. |
Samori, P; Kinloch, I A; Feng, X; Palermo, V Graphene-based nanocomposites for structural and functional applications: using 2-dimensional materials in a 3-dimensional world Journal Article In: 2D MATERIALS, 2 (3), 2015, ISSN: 2053-1583. @article{samori_graphene-based_2015, title = {Graphene-based nanocomposites for structural and functional applications: using 2-dimensional materials in a 3-dimensional world}, author = {Samori, P. and Kinloch, I. A. and Feng, X. and Palermo, V.}, doi = {10.1088/2053-1583/2/3/030205}, issn = {2053-1583}, year = {2015}, date = {2015-09-01}, journal = {2D MATERIALS}, volume = {2}, number = {3}, abstract = {Graphene-based composites are currently the only application of graphene already commercialized on a large scale. However, the performance of such products is not comparable to that of pristine graphene sheets, measured at the nanoscale, which easily outperform well-established materials such as steel, silicon, or copper. Akey reason for this difference in properties is that it is not yet fully understood how two-dimensional (2D) -based composites work at the nanoscale level and, more importantly, what is the ultimate performance (mechanical, electrical, etc.) that can be achieved when they are included in a bulk material. In the first year of the ramp-up phase of the Flagship, the `Nanocomposites' work package has studied how to improve the processing, interaction, and performance of graphene and related materials (GRMs) in three-dimensional (3D) composites. This article offers a quick overview of some of the main results obtained within this rapidly evolving field.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene-based composites are currently the only application of graphene already commercialized on a large scale. However, the performance of such products is not comparable to that of pristine graphene sheets, measured at the nanoscale, which easily outperform well-established materials such as steel, silicon, or copper. Akey reason for this difference in properties is that it is not yet fully understood how two-dimensional (2D) -based composites work at the nanoscale level and, more importantly, what is the ultimate performance (mechanical, electrical, etc.) that can be achieved when they are included in a bulk material. In the first year of the ramp-up phase of the Flagship, the `Nanocomposites' work package has studied how to improve the processing, interaction, and performance of graphene and related materials (GRMs) in three-dimensional (3D) composites. This article offers a quick overview of some of the main results obtained within this rapidly evolving field. |
Dryzhakov, Marian ; Hellal, Malik ; Wolf, Elena ; Falk, Florian C; Moran, Joseph Nitro-Assisted Bronsted Acid Catalysis: Application to a Challenging Catalytic Azidation Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (30), pp. 9555–9558, 2015, ISSN: 0002-7863. @article{dryzhakov_nitro-assisted_2015, title = {Nitro-Assisted Bronsted Acid Catalysis: Application to a Challenging Catalytic Azidation}, author = {Dryzhakov, Marian and Hellal, Malik and Wolf, Elena and Falk, Florian C. and Moran, Joseph}, doi = {10.1021/jacs.5b06055}, issn = {0002-7863}, year = {2015}, date = {2015-08-01}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {137}, number = {30}, pages = {9555--9558}, abstract = {A cocatalytic effect of nitro compounds is described for the B(C6F5)(3)center dot H2O catalyzed azidation of tertiary aliphatic alcohols, enabling catalyst turnover for the first time and With a broad range of substrates. Kinetic investigations into this surprising effect reveal that nitro compounds induce a switch from first order concentration dependence in Bronsted acid to second order concentration dependence in Bronsted acid and second order dependence in the nitro compounds. Kinetic, electronic, and spectroscopic evidence suggests that higher order hydrogen-bonded aggregates of nitro compounds and acids are the kinetically competent Bronsted acid catalysts. Specific weak H-bond accepting additives may offer a new general approach to accelerating Bronsted acid catalysis in solution.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A cocatalytic effect of nitro compounds is described for the B(C6F5)(3)center dot H2O catalyzed azidation of tertiary aliphatic alcohols, enabling catalyst turnover for the first time and With a broad range of substrates. Kinetic investigations into this surprising effect reveal that nitro compounds induce a switch from first order concentration dependence in Bronsted acid to second order concentration dependence in Bronsted acid and second order dependence in the nitro compounds. Kinetic, electronic, and spectroscopic evidence suggests that higher order hydrogen-bonded aggregates of nitro compounds and acids are the kinetically competent Bronsted acid catalysts. Specific weak H-bond accepting additives may offer a new general approach to accelerating Bronsted acid catalysis in solution. |
Kurapati, Rajendra ; Russier, Julie ; Squillaci, Marco A; Treossi, Emanuele ; Menard-Moyon, Cecilia ; Esau Del Rio-Castillo, Antonio ; Vazquez, Ester ; Samori, Paolo ; Palermo, Vincenzo ; Bianco, Alberto Dispersibility-Dependent Biodegradation of Graphene Oxide by Myeloperoxidase Journal Article In: SMALL, 11 (32), pp. 3985–3994, 2015, ISSN: 1613-6810. @article{kurapati_dispersibility-dependent_2015, title = {Dispersibility-Dependent Biodegradation of Graphene Oxide by Myeloperoxidase}, author = {Kurapati, Rajendra and Russier, Julie and Squillaci, Marco A. and Treossi, Emanuele and Menard-Moyon, Cecilia and Esau Del Rio-Castillo, Antonio and Vazquez, Ester and Samori, Paolo and Palermo, Vincenzo and Bianco, Alberto}, doi = {10.1002/smll.201500038}, issn = {1613-6810}, year = {2015}, date = {2015-08-01}, journal = {SMALL}, volume = {11}, number = {32}, pages = {3985--3994}, abstract = {Understanding human health risk associated with the rapidly emerging graphene-based nanomaterials represents a great challenge because of the diversity of applications and the wide range of possible ways of exposure to this type of materials. Herein, the biodegradation of graphene oxide (GO) sheets is reported by using myeloperoxidase (hMPO) derived from human neutrophils in the presence of a low concentration of hydrogen peroxide. The degradation capability of the enzyme on three different GO samples containing different degree of oxidation on their graphenic lattice, leading to a variable dispersibility in aqueous media is compared. hMPO fails in degrading the most aggregated GO, but succeeds to completely metabolize highly dispersed GO samples. The spectroscopy and microscopy analyses provide unambiguous evidence for the key roles played by hydrophilicity, negative surface charge, and colloidal stability of the aqueous GO in their biodegradation by hMPO catalysis.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding human health risk associated with the rapidly emerging graphene-based nanomaterials represents a great challenge because of the diversity of applications and the wide range of possible ways of exposure to this type of materials. Herein, the biodegradation of graphene oxide (GO) sheets is reported by using myeloperoxidase (hMPO) derived from human neutrophils in the presence of a low concentration of hydrogen peroxide. The degradation capability of the enzyme on three different GO samples containing different degree of oxidation on their graphenic lattice, leading to a variable dispersibility in aqueous media is compared. hMPO fails in degrading the most aggregated GO, but succeeds to completely metabolize highly dispersed GO samples. The spectroscopy and microscopy analyses provide unambiguous evidence for the key roles played by hydrophilicity, negative surface charge, and colloidal stability of the aqueous GO in their biodegradation by hMPO catalysis. |
Ratjen, Lars ; Vantomme, Ghislaine ; Lehn, Jean-Marie Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (28), pp. 10070–10081, 2015, ISSN: 0947-6539. @article{ratjen_strain-induced_2015, title = {Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines}, author = {Ratjen, Lars and Vantomme, Ghislaine and Lehn, Jean-Marie}, doi = {10.1002/chem.201501192}, issn = {0947-6539}, year = {2015}, date = {2015-07-01}, journal = {CHEMISTRY-A EUROPEAN JOURNAL}, volume = {21}, number = {28}, pages = {10070--10081}, abstract = {The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by (HNMR)-H-1 spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The displacement of molecular structures from their thermodynamically most stable state by imposition of various types of electronic and conformational constraints generates highly strained entities that tend to release the accumulated strain energy by undergoing either structural changes or chemical reactions. The latter case amounts to strain-induced reactivity (SIR) that may enforce specific chemical transformations. A particular case concerns dynamic covalent chemistry which may present SIR, whereby reversible reactions are activated by coupling to a high-energy state. We herewith describe such a dynamic covalent chemical (DCC) system involving the reversible imine formation reaction. It is based on the formation of strained macrocyclic bis-imine metal complexes in which the macrocyclic ligand is in a high energy form enforced by the coordination of the metal cation. Subsequent demetallation generates a highly strained free macrocycle that releases its accumulated strain energy by hydrolysis and reassembly into a resting state. Specifically, the metal-templated condensation of a dialdehyde with a linear diamine leads to a bis-imine [1+1]-macrocyclic complex in which the macrocyclic ligand is in a coordination-enforced strained conformation. Removal of the metal cation by a competing ligand yields a highly reactive [1+1]-macrocycle, which then undergoes hydrolysis to transient non-cyclic aminoaldehyde species, which then recondense to a strain-free [2+2]-macrocyclic resting state. The process can be monitored by (HNMR)-H-1 spectroscopy. Energy differences between different conformational states have been evaluated by Hartree-Fock (HF) computations. One may note that the stabilisation of high-energy molecular forms by metal ion coordination followed by removal of the latter, offers a general procedure for producing out-of-equilibrium molecular states, the fate of which may then be examined, in particular when coupled to dynamic covalent chemical processes. |
Richmond, Edward ; Moran, Joseph Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction Journal Article In: JOURNAL OF ORGANIC CHEMISTRY, 80 (13), pp. 6922–6929, 2015, ISSN: 0022-3263. @article{richmond_ligand_2015, title = {Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction}, author = {Richmond, Edward and Moran, Joseph}, doi = {10.1021/acs.joc.5b01047}, issn = {0022-3263}, year = {2015}, date = {2015-07-01}, journal = {JOURNAL OF ORGANIC CHEMISTRY}, volume = {80}, number = {13}, pages = {6922--6929}, abstract = {A nickel-catalyzed transfer hydrogenative alkyne semireduction protocol that can be applied to bath internal and terminal alkynes using formic acid, and Zn as the terminal reductants has been developed. In the case of internal alkynes, the (E)- or (Z)-olefin isomer can be accessed selectively under the same reaction conditions by judicious inclusion of a triphos ligand.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A nickel-catalyzed transfer hydrogenative alkyne semireduction protocol that can be applied to bath internal and terminal alkynes using formic acid, and Zn as the terminal reductants has been developed. In the case of internal alkynes, the (E)- or (Z)-olefin isomer can be accessed selectively under the same reaction conditions by judicious inclusion of a triphos ligand. |
Dalmonte, M; Lechner, W; Cai, Zi ; Mattioli, M; Laeuchli, A M; Pupillo, G Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model Journal Article In: PHYSICAL REVIEW B, 92 (4), 2015, ISSN: 2469-9950. @article{dalmonte_cluster_2015, title = {Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model}, author = {Dalmonte, M. and Lechner, W. and Cai, Zi and Mattioli, M. and Laeuchli, A. M. and Pupillo, G.}, doi = {10.1103/PhysRevB.92.045106}, issn = {2469-9950}, year = {2015}, date = {2015-07-01}, journal = {PHYSICAL REVIEW B}, volume = {92}, number = {4}, abstract = {We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge c = 1, where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix renormalization-group methods, we demonstrate that the CLL phase [first predicted in M. Mattioli et al., Phys. Rev. Lett. 111, 165302 (2013)] is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge c = 3/2. The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly dressed Rydberg atoms confined to optical lattices. Using quantum Monte Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate the quantum phases of hard-core bosonic atoms in an extended Hubbard model where particles interact via soft-shoulder potentials in one dimension. Using a combination of field-theoretical methods and strong-coupling perturbation theory, we demonstrate that the low-energy phase can be a conformal cluster Luttinger liquid (CLL) phase with central charge c = 1, where the microscopic degrees of freedom correspond to mesoscopic ensembles of particles. Using numerical density-matrix renormalization-group methods, we demonstrate that the CLL phase [first predicted in M. Mattioli et al., Phys. Rev. Lett. 111, 165302 (2013)] is separated from a conventional Tomonaga-Luttinger liquid by an exotic critical point with central charge c = 3/2. The latter is expression of an emergent conformal supersymmetry, which is not present in the original Hamiltonian. We discuss the observability of the CLL phase in realistic experimental settings with weakly dressed Rydberg atoms confined to optical lattices. Using quantum Monte Carlo simulations, we show that the typical features of CLLs are stable up to comparatively high temperatures. Using exact diagonalizations and quantum trajectory methods, we provide a protocol for adiabatic state preparation as well as quantitative estimates on the effects of particle losses. |
Xu, Jialiang ; Semin, Sergey ; Cremers, Jonathan ; Wang, Linjun ; Savoini, Matteo ; Fron, Eduard ; Coutino, Eduardo ; Chervy, Thibault ; Wang, Chunliang ; Li, Yongjun ; Liu, Huibiao ; Li, Yuliang ; Tinnemans, Paul ; Kouwer, Paul H J; Ebbesen, Thomas W; Hofkens, Johan ; Beljonne, David ; Rowan, Alan E; Rasing, Theo Controlling Microsized Polymorphic Architectures with Distinct Linear and Nonlinear Optical Properties Journal Article In: ADVANCED OPTICAL MATERIALS, 3 (7), pp. 948–956, 2015, ISSN: 2195-1071. @article{xu_controlling_2015, title = {Controlling Microsized Polymorphic Architectures with Distinct Linear and Nonlinear Optical Properties}, author = {Xu, Jialiang and Semin, Sergey and Cremers, Jonathan and Wang, Linjun and Savoini, Matteo and Fron, Eduard and Coutino, Eduardo and Chervy, Thibault and Wang, Chunliang and Li, Yongjun and Liu, Huibiao and Li, Yuliang and Tinnemans, Paul and Kouwer, Paul H. J. and Ebbesen, Thomas W. and Hofkens, Johan and Beljonne, David and Rowan, Alan E. and Rasing, Theo}, doi = {10.1002/adom.201400637}, issn = {2195-1071}, year = {2015}, date = {2015-07-01}, journal = {ADVANCED OPTICAL MATERIALS}, volume = {3}, number = {7}, pages = {948--956}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
El Garah, Mohamed ; Marets, Nicolas ; Mauro, Matteo ; Aliprandi, Alessandro ; Bonacchi, Sara ; De Cola, Luisa ; Ciesielski, Artur ; Bulach, Veronique ; Hosseini, Mir Wais ; Samori, Paolo Nanopatterning of Surfaces with Monometallic and Heterobimetallic 1D Coordination Polymers: A Molecular Tectonics Approach at the Solid/Liquid Interface Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (26), pp. 8450–8459, 2015, ISSN: 0002-7863. @article{el_garah_nanopatterning_2015, title = {Nanopatterning of Surfaces with Monometallic and Heterobimetallic 1D Coordination Polymers: A Molecular Tectonics Approach at the Solid/Liquid Interface}, author = {El Garah, Mohamed and Marets, Nicolas and Mauro, Matteo and Aliprandi, Alessandro and Bonacchi, Sara and De Cola, Luisa and Ciesielski, Artur and Bulach, Veronique and Hosseini, Mir Wais and Samori, Paolo}, doi = {10.1021/jacs.5b02283}, issn = {0002-7863}, year = {2015}, date = {2015-07-01}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {137}, number = {26}, pages = {8450--8459}, abstract = {The self-assembly of multiple molecular components into complex supramolecular architectures is ubiquitous in nature and constitutes one of the most powerful strategies to fabricate multifunctional nanomaterials making use of the bottom-up approach. When spatial confinement in two dimensions on a solid substrate is employed, this approach can be exploited to generate periodically ordered structures from suitably designed molecular tectons. In this study we demonstrate that physisorbed directional periodic arrays of monometallic or heterobimetallic coordination polymers can be generated on a highly oriented pyrolitic graphite surface by combinations of a suitably designed directional organic tecton or metallatecton based on a porphyrin or nickel(II) metalloporphyrin backbone bearing both a pyridyl unit and a terpyridyl unit acting as coordinating sites for CoCl2. The periodic. architectures were visualized at the solid/liquid interface with a submolecular resolution by scanning tunneling microscopy and corroborated by combined density functional and time-dependent density functional theory calculations. The capacity to nanopattern the surface for the first time with two distinct metallic centers exhibiting different electronic and optical properties is a key step toward the bottom-up construction of robust multicomponent and, thus, multifunctional molecular nanostructures and nano devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The self-assembly of multiple molecular components into complex supramolecular architectures is ubiquitous in nature and constitutes one of the most powerful strategies to fabricate multifunctional nanomaterials making use of the bottom-up approach. When spatial confinement in two dimensions on a solid substrate is employed, this approach can be exploited to generate periodically ordered structures from suitably designed molecular tectons. In this study we demonstrate that physisorbed directional periodic arrays of monometallic or heterobimetallic coordination polymers can be generated on a highly oriented pyrolitic graphite surface by combinations of a suitably designed directional organic tecton or metallatecton based on a porphyrin or nickel(II) metalloporphyrin backbone bearing both a pyridyl unit and a terpyridyl unit acting as coordinating sites for CoCl2. The periodic. architectures were visualized at the solid/liquid interface with a submolecular resolution by scanning tunneling microscopy and corroborated by combined density functional and time-dependent density functional theory calculations. The capacity to nanopattern the surface for the first time with two distinct metallic centers exhibiting different electronic and optical properties is a key step toward the bottom-up construction of robust multicomponent and, thus, multifunctional molecular nanostructures and nano devices. |
Kovaricek, Petr ; Lehn, Jean-Marie Directional Dynamic Covalent Motion of a Carbonyl Walker on a Polyamine Track Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (26), pp. 9380–9384, 2015, ISSN: 0947-6539. @article{kovaricek_directional_2015, title = {Directional Dynamic Covalent Motion of a Carbonyl Walker on a Polyamine Track}, author = {Kovaricek, Petr and Lehn, Jean-Marie}, doi = {10.1002/chem.201500987}, issn = {0947-6539}, year = {2015}, date = {2015-06-01}, journal = {CHEMISTRY-A EUROPEAN JOURNAL}, volume = {21}, number = {26}, pages = {9380--9384}, abstract = {Controlled directional displacement of a molecular group has been achieved based on dynamic covalent motions implementing the reactional features of the imine bond. ortho-Carboxybenzaldehyde derivatives are able to form stable adducts with both primary and secondary amines as imines or as amino lactones, respectively, depending on the acidity of the medium. They may thus perform pH-driven intramolecular walking along a non-symmetric polyamine chain, in which an imine serves as the terminus under basic conditions on one end of the chain and a lactone formed on a secondary hydroxylamine nitrogen on the other end serves as the terminal site upon addition of acid. The displacement between the termini occurs stochastically through reversible change in valency at the carbon site of the carbonyl group between imine, aminal, iminium and amino lactone form. On the other hand, the directionality results from the stabilisation of the terminal products under given pH conditions. By its ability to undergo interconversion between CN and O-C-N moieties, the ortho-carboxybenzaldehyde group extends the realm of dynamic covalent chemistry of imines to secondary amines and opens new perspectives in this field. Kovalentne-dynamicky character iminove vazby umonil vyvoj smerove oritentovaneho pohybu na molekulove urovni. Derivaty 2-karboxybenzaldehydu mohou vytvaet stabilni adukty jak s primarnimi, tak sekundarnimi aminy a tvoit odpovidajici iminy i amino-laktony v zavisloti na kyselosti prostedi. Tyto derivaty jsou diky tomu schopny pH-izeneho intramolekularniho achozeni na nesymetrickych polyaminovych drahach, piem v basickem prostedi je stabilni iminova forma na jednom konci drahy, zatimco v kyselem prostedi je stabilizovan lakton utvoeny na sekundarnim dusiku hydroxylaminove skupiny na opanem konci. Pesun mezi opanymi konci drahy probiha diky valenni flexibilite karbonylove skupiny, je reversibilne pechazi mezi formami iminu, aminalu, iminia a amino-laktonu. Pestoe jednotlive kroky probihaji stochasticky, smerove izeni je dano rozdilnou stabilitou aduktu utvoenych na koncich drahy pi danem pH. Samotna schopnost 2-karboxybenzaldehydu reversibilne pechazet mezi CN a O-C-N formami pedstavuje duleite rozieni v oblasti dynamicke kovalentni chemie iminu, jeliko umouje zakomponovat rovne sekundarni aminy a tim otevira nove monosti v teto perspektivni oblasti.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Controlled directional displacement of a molecular group has been achieved based on dynamic covalent motions implementing the reactional features of the imine bond. ortho-Carboxybenzaldehyde derivatives are able to form stable adducts with both primary and secondary amines as imines or as amino lactones, respectively, depending on the acidity of the medium. They may thus perform pH-driven intramolecular walking along a non-symmetric polyamine chain, in which an imine serves as the terminus under basic conditions on one end of the chain and a lactone formed on a secondary hydroxylamine nitrogen on the other end serves as the terminal site upon addition of acid. The displacement between the termini occurs stochastically through reversible change in valency at the carbon site of the carbonyl group between imine, aminal, iminium and amino lactone form. On the other hand, the directionality results from the stabilisation of the terminal products under given pH conditions. By its ability to undergo interconversion between CN and O-C-N moieties, the ortho-carboxybenzaldehyde group extends the realm of dynamic covalent chemistry of imines to secondary amines and opens new perspectives in this field. Kovalentne-dynamicky character iminove vazby umonil vyvoj smerove oritentovaneho pohybu na molekulove urovni. Derivaty 2-karboxybenzaldehydu mohou vytvaet stabilni adukty jak s primarnimi, tak sekundarnimi aminy a tvoit odpovidajici iminy i amino-laktony v zavisloti na kyselosti prostedi. Tyto derivaty jsou diky tomu schopny pH-izeneho intramolekularniho achozeni na nesymetrickych polyaminovych drahach, piem v basickem prostedi je stabilni iminova forma na jednom konci drahy, zatimco v kyselem prostedi je stabilizovan lakton utvoeny na sekundarnim dusiku hydroxylaminove skupiny na opanem konci. Pesun mezi opanymi konci drahy probiha diky valenni flexibilite karbonylove skupiny, je reversibilne pechazi mezi formami iminu, aminalu, iminia a amino-laktonu. Pestoe jednotlive kroky probihaji stochasticky, smerove izeni je dano rozdilnou stabilitou aduktu utvoenych na koncich drahy pi danem pH. Samotna schopnost 2-karboxybenzaldehydu reversibilne pechazet mezi CN a O-C-N formami pedstavuje duleite rozieni v oblasti dynamicke kovalentni chemie iminu, jeliko umouje zakomponovat rovne sekundarni aminy a tim otevira nove monosti v teto perspektivni oblasti. |
Shalabney, Atef ; George, Jino ; Hiura, Hidefumi ; Hutchison, James A; Genet, Cyriaque ; Hellwig, Petra ; Ebbesen, Thomas W Enhanced Raman Scattering from Vibro-Polariton Hybrid States Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (27), pp. 7971–7975, 2015, ISSN: 1433-7851. @article{shalabney_enhanced_2015, title = {Enhanced Raman Scattering from Vibro-Polariton Hybrid States}, author = {Shalabney, Atef and George, Jino and Hiura, Hidefumi and Hutchison, James A. and Genet, Cyriaque and Hellwig, Petra and Ebbesen, Thomas W.}, doi = {10.1002/anie.201502979}, issn = {1433-7851}, year = {2015}, date = {2015-06-01}, journal = {ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, volume = {54}, number = {27}, pages = {7971--7975}, abstract = {Ground-state molecular vibrations can be hybridized through strong coupling with the vacuum field of a cavity optical mode in the infrared region, leading to the formation of two new coherent vibro-polariton states. The spontaneous Raman scattering from such hybridized light-matter states was studied, showing that the collective Rabi splitting occurs at the level of a single selected bond. Moreover, the coherent nature of the vibro-polariton states boosts the Raman scattering cross-section by two to three orders of magnitude, revealing a new enhancement mechanism as a result of vibrational strong coupling. This observation has fundamental consequences for the understanding of light-molecule strong coupling and for molecular science.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Ground-state molecular vibrations can be hybridized through strong coupling with the vacuum field of a cavity optical mode in the infrared region, leading to the formation of two new coherent vibro-polariton states. The spontaneous Raman scattering from such hybridized light-matter states was studied, showing that the collective Rabi splitting occurs at the level of a single selected bond. Moreover, the coherent nature of the vibro-polariton states boosts the Raman scattering cross-section by two to three orders of magnitude, revealing a new enhancement mechanism as a result of vibrational strong coupling. This observation has fundamental consequences for the understanding of light-molecule strong coupling and for molecular science. |
Karan, Sujoy ; Hamann, Christian ; Tang, Hao ; Stefankiewicz, Artur R; Lehn, Jean-Marie ; Berndt, Richard Surface Trapping and STM Observation of Conformational Isomers of a Bis(Terpyridine) Ligand from Metallosupramolecular Grids Journal Article In: CHEMPHYSCHEM, 16 (7), pp. 1370–1373, 2015, ISSN: 1439-4235. @article{karan_surface_2015, title = {Surface Trapping and STM Observation of Conformational Isomers of a Bis(Terpyridine) Ligand from Metallosupramolecular Grids}, author = {Karan, Sujoy and Hamann, Christian and Tang, Hao and Stefankiewicz, Artur R. and Lehn, Jean-Marie and Berndt, Richard}, doi = {10.1002/cphc.201500100}, issn = {1439-4235}, year = {2015}, date = {2015-05-01}, journal = {CHEMPHYSCHEM}, volume = {16}, number = {7}, pages = {1370--1373}, abstract = {Tetranuclear Co-grid complexes incorporating bis-tridentate ligands, namely 4,6-bis(2,2-bipyrid-6-yl)-2-phenylpyrimidine, were electrosprayed onto a Au(111) substrate under an ultrahigh vacuum. Fragmentation occurs leaving the ligands in four different conformations. Most ligands are found to form H-bonded dimers. The most abundant conformer of the ligand on the Au surface is an asymmetric form, which has not been observed before. The present results indicate that the fragmentation of coordination compounds during the deposition process, in principle, allows for surface trapping, identification, and investigation of high energy, out-of-equilibrium conformations of the ligand molecules at low temperatures, which otherwise would not be observable.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Tetranuclear Co-grid complexes incorporating bis-tridentate ligands, namely 4,6-bis(2,2-bipyrid-6-yl)-2-phenylpyrimidine, were electrosprayed onto a Au(111) substrate under an ultrahigh vacuum. Fragmentation occurs leaving the ligands in four different conformations. Most ligands are found to form H-bonded dimers. The most abundant conformer of the ligand on the Au surface is an asymmetric form, which has not been observed before. The present results indicate that the fragmentation of coordination compounds during the deposition process, in principle, allows for surface trapping, identification, and investigation of high energy, out-of-equilibrium conformations of the ligand molecules at low temperatures, which otherwise would not be observable. |
Limani, P; Linecker, M; Kachaylo, E; Tschuor, C; Schlegel, A; Jang, J -H; Georgioupolou, S; Lehn, J -M; Graf, R; Humar, B; Clavien, P -A Inositol trispyrophosphate (ITPP) and its anti-hypoxic potential in colorectal metastases of the liver Journal Article In: BRITISH JOURNAL OF SURGERY, 102 (6), pp. 17, 2015, ISSN: 0007-1323. @article{limani_inositol_2015, title = {Inositol trispyrophosphate (ITPP) and its anti-hypoxic potential in colorectal metastases of the liver}, author = {Limani, P. and Linecker, M. and Kachaylo, E. and Tschuor, C. and Schlegel, A. and Jang, J. -H. and Georgioupolou, S. and Lehn, J. -M. and Graf, R. and Humar, B. and Clavien, P. -A.}, issn = {0007-1323}, year = {2015}, date = {2015-05-01}, journal = {BRITISH JOURNAL OF SURGERY}, volume = {102}, number = {6}, pages = {17}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Schachenmayer, Johannes ; Genes, Claudiu ; Tignone, Edoardo ; Pupillo, Guido Cavity-Enhanced Transport of Excitons Journal Article In: PHYSICAL REVIEW LETTERS, 114 (19), 2015, ISSN: 0031-9007. @article{schachenmayer_cavity-enhanced_2015, title = {Cavity-Enhanced Transport of Excitons}, author = {Schachenmayer, Johannes and Genes, Claudiu and Tignone, Edoardo and Pupillo, Guido}, doi = {10.1103/PhysRevLett.114.196403}, issn = {0031-9007}, year = {2015}, date = {2015-05-01}, journal = {PHYSICAL REVIEW LETTERS}, volume = {114}, number = {19}, abstract = {We show that exciton-type transport in certain materials can be dramatically modified by their inclusion in an optical cavity: the modification of the electromagnetic vacuum mode structure introduced by the cavity leads to transport via delocalized polariton modes rather than through tunneling processes in the material itself. This can help overcome exponential suppression of transmission properties as a function of the system size in the case of disorder and other imperfections. We exemplify massive improvement of transmission for excitonic wave packets through a cavity, as well as enhancement of steady-state exciton currents under incoherent pumping. These results may have implications for experiments of exciton transport in disordered organic materials. We propose that the basic phenomena can be observed in quantum simulators made of Rydberg atoms, cold molecules in optical lattices, as well as in experiments with trapped ions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We show that exciton-type transport in certain materials can be dramatically modified by their inclusion in an optical cavity: the modification of the electromagnetic vacuum mode structure introduced by the cavity leads to transport via delocalized polariton modes rather than through tunneling processes in the material itself. This can help overcome exponential suppression of transmission properties as a function of the system size in the case of disorder and other imperfections. We exemplify massive improvement of transmission for excitonic wave packets through a cavity, as well as enhancement of steady-state exciton currents under incoherent pumping. These results may have implications for experiments of exciton transport in disordered organic materials. We propose that the basic phenomena can be observed in quantum simulators made of Rydberg atoms, cold molecules in optical lattices, as well as in experiments with trapped ions. |
Squillaci, Marco A; Ferlauto, Laura ; Zagranyarski, Yulian ; Milita, Silvia ; Muellen, Klaus ; Samori, Paolo Self-Assembly of an Amphiphilic pi-Conjugated Dyad into Fibers: Ultrafast and Ultrasensitive Humidity Sensor Journal Article In: ADVANCED MATERIALS, 27 (20), pp. 3170–3174, 2015, ISSN: 0935-9648. @article{squillaci_self-assembly_2015, title = {Self-Assembly of an Amphiphilic pi-Conjugated Dyad into Fibers: Ultrafast and Ultrasensitive Humidity Sensor}, author = {Squillaci, Marco A. and Ferlauto, Laura and Zagranyarski, Yulian and Milita, Silvia and Muellen, Klaus and Samori, Paolo}, doi = {10.1002/adma.201500940}, issn = {0935-9648}, year = {2015}, date = {2015-05-01}, journal = {ADVANCED MATERIALS}, volume = {27}, number = {20}, pages = {3170--3174}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Musumeci, Chiara ; Salzmann, Ingo ; Bonacchi, Sara ; Roethel, Christian ; Duhm, Steffen ; Koch, Norbert ; Samori, Paolo The Relationship between Structural and Electrical Characteristics in Perylenecarboxydiimide-Based Nanoarchitectures Journal Article In: ADVANCED FUNCTIONAL MATERIALS, 25 (17), pp. 2501–2510, 2015, ISSN: 1616-301X. @article{musumeci_relationship_2015, title = {The Relationship between Structural and Electrical Characteristics in Perylenecarboxydiimide-Based Nanoarchitectures}, author = {Musumeci, Chiara and Salzmann, Ingo and Bonacchi, Sara and Roethel, Christian and Duhm, Steffen and Koch, Norbert and Samori, Paolo}, doi = {10.1002/adfm.201403773}, issn = {1616-301X}, year = {2015}, date = {2015-05-01}, journal = {ADVANCED FUNCTIONAL MATERIALS}, volume = {25}, number = {17}, pages = {2501--2510}, abstract = {The controlled assembly of the prototypical n-type organic semiconductor N, N'-1H, 1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) into ordered nanoarchitectures and the multiscale analysis of the correlation between their structural and their electrical properties is reported. By making use of the Langmuir-Blodgett (LB) technique, monolayers of PDIF-CN2 arranged in upright standing molecular packing on different substrates are formed. Postdeposition thermal treatment makes it possible to trigger a reorganization into layered ultrathin crystalline nanostructures, exhibiting structural and photophysical properties similar to those of microscopic crystals obtained by solvent-induced precipitation. The controlled engineering of these molecular architectures on surfaces enables us to identify both a dependence of the monolayer resistance on the molecular tilt angle in vertical junctions and a pronounced charge-transport anisotropy with enhanced transport along the pi-pi stacking direction of the PDI core. While a charge carrier mobility for electrons as high as 10(-2) cm(2) V-1 s(-1) is determined in monolayer field-effect transistors for the in-plane direction, being the highest yet reported value for a n-type LB monolayer, the out-of-plane mobility measured by conductive atomic force microscopy in multilayered structures is found to be one order of magnitude lower.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The controlled assembly of the prototypical n-type organic semiconductor N, N'-1H, 1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) into ordered nanoarchitectures and the multiscale analysis of the correlation between their structural and their electrical properties is reported. By making use of the Langmuir-Blodgett (LB) technique, monolayers of PDIF-CN2 arranged in upright standing molecular packing on different substrates are formed. Postdeposition thermal treatment makes it possible to trigger a reorganization into layered ultrathin crystalline nanostructures, exhibiting structural and photophysical properties similar to those of microscopic crystals obtained by solvent-induced precipitation. The controlled engineering of these molecular architectures on surfaces enables us to identify both a dependence of the monolayer resistance on the molecular tilt angle in vertical junctions and a pronounced charge-transport anisotropy with enhanced transport along the pi-pi stacking direction of the PDI core. While a charge carrier mobility for electrons as high as 10(-2) cm(2) V-1 s(-1) is determined in monolayer field-effect transistors for the in-plane direction, being the highest yet reported value for a n-type LB monolayer, the out-of-plane mobility measured by conductive atomic force microscopy in multilayered structures is found to be one order of magnitude lower. |
Esque, Jeremy ; Cecchini, Marco Accurate Calculation of Conformational Free Energy Differences in Explicit Water: The Confinement-Solvation Free Energy Approach Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY B, 119 (16), pp. 5194–5207, 2015, ISSN: 1520-6106. @article{esque_accurate_2015, title = {Accurate Calculation of Conformational Free Energy Differences in Explicit Water: The Confinement-Solvation Free Energy Approach}, author = {Esque, Jeremy and Cecchini, Marco}, doi = {10.1021/acs.jpcb.5b01632}, issn = {1520-6106}, year = {2015}, date = {2015-04-01}, journal = {JOURNAL OF PHYSICAL CHEMISTRY B}, volume = {119}, number = {16}, pages = {5194--5207}, abstract = {The calculation of the free energy of conformation is key to understanding the function of biomolecules and has attracted significant interest in recent years. Here, we present an improvement of the confinement method that was designed for use in the context of explicit Solvent MD simulations. The development involves an additional step in which the solvation free energy of the harmonically restrained conformers is accurately determined by multistage free energy perturbation simulations. AS a test-case application, the newly introduced confinement/solvation free energy (CSF) approach was used to compute differences in free energy between conformers of the alanine dipeptide in explicit water. The results are in excellent agreement with reference calculations based on both converged molecular dynamics and umbrella sampling. To illustrate the general applicability of the method, conformational equilibria of met-enkephalin (5 aa) and deca-alanine (10 aa) in solution wire also analyzed. In both cases, smoothly converged free-energy results were obtained in agreement with equilibrium sampling or literature calculations. These results demonstrate that the CSF method may provide conformational free-energy differences of,biomolecules with small statistical errors (below 0.5 kcal/mol) and at a moderate computational cost even with a full representation of the solvent.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The calculation of the free energy of conformation is key to understanding the function of biomolecules and has attracted significant interest in recent years. Here, we present an improvement of the confinement method that was designed for use in the context of explicit Solvent MD simulations. The development involves an additional step in which the solvation free energy of the harmonically restrained conformers is accurately determined by multistage free energy perturbation simulations. AS a test-case application, the newly introduced confinement/solvation free energy (CSF) approach was used to compute differences in free energy between conformers of the alanine dipeptide in explicit water. The results are in excellent agreement with reference calculations based on both converged molecular dynamics and umbrella sampling. To illustrate the general applicability of the method, conformational equilibria of met-enkephalin (5 aa) and deca-alanine (10 aa) in solution wire also analyzed. In both cases, smoothly converged free-energy results were obtained in agreement with equilibrium sampling or literature calculations. These results demonstrate that the CSF method may provide conformational free-energy differences of,biomolecules with small statistical errors (below 0.5 kcal/mol) and at a moderate computational cost even with a full representation of the solvent. |
Bonacchi, Sara ; El Garah, Mohamed ; Ciesielski, Artur ; Herder, Martin ; Conti, Simone ; Cecchini, Marco ; Hecht, Stefan ; Samori, Paolo Surface-Induced Selection During In Situ Photoswitching at the Solid/Liquid Interface Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (16), pp. 4865–4869, 2015, ISSN: 1433-7851. @article{bonacchi_surface-induced_2015, title = {Surface-Induced Selection During In Situ Photoswitching at the Solid/Liquid Interface}, author = {Bonacchi, Sara and El Garah, Mohamed and Ciesielski, Artur and Herder, Martin and Conti, Simone and Cecchini, Marco and Hecht, Stefan and Samori, Paolo}, doi = {10.1002/anie.201412215}, issn = {1433-7851}, year = {2015}, date = {2015-04-01}, journal = {ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, volume = {54}, number = {16}, pages = {4865--4869}, abstract = {Here we report for the first time a submolecularly resolved scanning tunneling microscopy (STM) study at the solid/liquid interface of the insitu reversible interconversion between two isomers of a diarylethene photoswitch, that is, open and closed form, self-assembled on a graphite surface. Prolonged irradiation with UV light led to the insitu irreversible formation of another isomer as by-product of the reaction, which due to its preferential physisorption accumulates at the surface. By making use of a simple yet powerful thermodynamic model we provide a quantitative description for the observed surface-induced selection of one isomeric form.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Here we report for the first time a submolecularly resolved scanning tunneling microscopy (STM) study at the solid/liquid interface of the insitu reversible interconversion between two isomers of a diarylethene photoswitch, that is, open and closed form, self-assembled on a graphite surface. Prolonged irradiation with UV light led to the insitu irreversible formation of another isomer as by-product of the reaction, which due to its preferential physisorption accumulates at the surface. By making use of a simple yet powerful thermodynamic model we provide a quantitative description for the observed surface-induced selection of one isomeric form. |
Haar, Sebastien ; Ciesielski, Artur ; Clough, Joseph ; Yang, Huafeng ; Mazzaro, Raffaello ; Richard, Fanny ; Conti, Simone ; Merstorf, Nicolas ; Cecchini, Marco ; Morandi, Vittorio ; Casiraghi, Cinzia ; Samori, Paolo A Supramolecular Strategy to Leverage the Liquid-Phase Exfoliation of Graphene in the Presence of Surfactants: Unraveling the Role of the Length of Fatty Acids Journal Article In: SMALL, 11 (14), pp. 1691–1702, 2015, ISSN: 1613-6810. @article{haar_supramolecular_2015, title = {A Supramolecular Strategy to Leverage the Liquid-Phase Exfoliation of Graphene in the Presence of Surfactants: Unraveling the Role of the Length of Fatty Acids}, author = {Haar, Sebastien and Ciesielski, Artur and Clough, Joseph and Yang, Huafeng and Mazzaro, Raffaello and Richard, Fanny and Conti, Simone and Merstorf, Nicolas and Cecchini, Marco and Morandi, Vittorio and Casiraghi, Cinzia and Samori, Paolo}, doi = {10.1002/smll.201402745}, issn = {1613-6810}, year = {2015}, date = {2015-04-01}, journal = {SMALL}, volume = {11}, number = {14}, pages = {1691--1702}, abstract = {Achieving the full control over the production as well as processability of high-quality graphene represents a major challenge with potential interest in the field of fabrication of multifunctional devices. The outstanding effort dedicated to tackle this challenge in the last decade revealed that certain organic molecules are capable of leveraging the exfoliation of graphite with different efficiencies. Here, a fundamental understanding on a straightforward supramolecular approach for producing homogenous dispersions of unfunctionalized and non-oxidized graphene nanosheets in four different solvents is attained, namely N-methyl-2-pyrrolidinone, N,N-dimethylformamide, ortho-dichlorobenzene, and 1,2,4-trichlorobenzene. In particular, a comparative study on the liquid-phase exfoliation of graphene in the presence of linear alkanes of different lengths terminated by a carboxylic-acid head group is performed. These molecules act as graphene dispersion-stabilizing agents during the exfoliation process. The efficiency of the exfoliation in terms of concentration of exfoliated graphene is found to be proportional to the length of the employed fatty acid. Importantly, a high percentage of single-layer graphene flakes is revealed by high-resolution transmission electron microscopy and Raman spectroscopy analyses. A simple yet effective thermodynamic model is developed to interpret the chain-length dependence of the exfoliation yield. This approach relying on the synergistic effect of a ad-hoc solvent and molecules to promote the exfoliation of graphene in liquid media represents a promising and modular strategy towards the rational design of improved dispersion-stabilizing agents.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Achieving the full control over the production as well as processability of high-quality graphene represents a major challenge with potential interest in the field of fabrication of multifunctional devices. The outstanding effort dedicated to tackle this challenge in the last decade revealed that certain organic molecules are capable of leveraging the exfoliation of graphite with different efficiencies. Here, a fundamental understanding on a straightforward supramolecular approach for producing homogenous dispersions of unfunctionalized and non-oxidized graphene nanosheets in four different solvents is attained, namely N-methyl-2-pyrrolidinone, N,N-dimethylformamide, ortho-dichlorobenzene, and 1,2,4-trichlorobenzene. In particular, a comparative study on the liquid-phase exfoliation of graphene in the presence of linear alkanes of different lengths terminated by a carboxylic-acid head group is performed. These molecules act as graphene dispersion-stabilizing agents during the exfoliation process. The efficiency of the exfoliation in terms of concentration of exfoliated graphene is found to be proportional to the length of the employed fatty acid. Importantly, a high percentage of single-layer graphene flakes is revealed by high-resolution transmission electron microscopy and Raman spectroscopy analyses. A simple yet effective thermodynamic model is developed to interpret the chain-length dependence of the exfoliation yield. This approach relying on the synergistic effect of a ad-hoc solvent and molecules to promote the exfoliation of graphene in liquid media represents a promising and modular strategy towards the rational design of improved dispersion-stabilizing agents. |
Hermans, Thomas M; Stewart, Peter S; Grzybowski, Bartosz A pH Oscillator Stretched in Space but Frozen in Time Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6 (5), pp. 760–766, 2015, ISSN: 1948-7185. @article{hermans_ph_2015, title = {pH Oscillator Stretched in Space but Frozen in Time}, author = {Hermans, Thomas M. and Stewart, Peter S. and Grzybowski, Bartosz A.}, doi = {10.1021/jz502711c}, issn = {1948-7185}, year = {2015}, date = {2015-03-01}, journal = {JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, volume = {6}, number = {5}, pages = {760--766}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Mydlak, Mathias ; Yang, Cheng-Han ; Polo, Federico ; Galstyan, Anzhela ; Daniliuc, Constantin G; Felicetti, Michael ; Leonhardt, Jens ; Strassert, Cristian A; De Cola, Luisa Sterically Hindered Luminescent Pt-II-Phosphite Complexes for Electroluminescent Devices Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (13), pp. 5161–5172, 2015, ISSN: 0947-6539. @article{mydlak_sterically_2015, title = {Sterically Hindered Luminescent Pt-II-Phosphite Complexes for Electroluminescent Devices}, author = {Mydlak, Mathias and Yang, Cheng-Han and Polo, Federico and Galstyan, Anzhela and Daniliuc, Constantin G. and Felicetti, Michael and Leonhardt, Jens and Strassert, Cristian A. and De Cola, Luisa}, doi = {10.1002/chem.201405839}, issn = {0947-6539}, year = {2015}, date = {2015-03-01}, journal = {CHEMISTRY-A EUROPEAN JOURNAL}, volume = {21}, number = {13}, pages = {5161--5172}, abstract = {Pt-II complexes with one bulky, sterically demanding, tertiary phosphite ancillary ligand and a coordinating chromophore are herein presented. The phosphite ligand, tris(2,4-di-tert-butylphenyl) acts as a bidentate ligand coordinating the platinum ion through the central phosphorus atom and a cyclometalating carbon atom of one of the substituents. The two free phenoxy moieties lie above and below the coordination plane, leading to steric hindrance that avoids aggregation and provides solubility in organic solvents. The other two coordination sites on the central metal ion are occupied by a chromophoric ligand, which is responsible for the energy of the luminescent excited state. This separation of functions, on the two coordinated ligands, allows the use of a wider range of luminophores with good luminescent properties, maintaining the control of the intermolecular interactions with the non-chromophoric ligand. Based on this approach we were able to achieve a bright deep blue emission (lambda= 444 nm, Phi(em)= 0.38) from a complex with a tailored ligand, which was then used for the fabrication of an electroluminescent device. In addition commercially available luminophores were also employed to synthesize green emitters.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pt-II complexes with one bulky, sterically demanding, tertiary phosphite ancillary ligand and a coordinating chromophore are herein presented. The phosphite ligand, tris(2,4-di-tert-butylphenyl) acts as a bidentate ligand coordinating the platinum ion through the central phosphorus atom and a cyclometalating carbon atom of one of the substituents. The two free phenoxy moieties lie above and below the coordination plane, leading to steric hindrance that avoids aggregation and provides solubility in organic solvents. The other two coordination sites on the central metal ion are occupied by a chromophoric ligand, which is responsible for the energy of the luminescent excited state. This separation of functions, on the two coordinated ligands, allows the use of a wider range of luminophores with good luminescent properties, maintaining the control of the intermolecular interactions with the non-chromophoric ligand. Based on this approach we were able to achieve a bright deep blue emission (lambda= 444 nm, Phi(em)= 0.38) from a complex with a tailored ligand, which was then used for the fabrication of an electroluminescent device. In addition commercially available luminophores were also employed to synthesize green emitters. |
George, Jino ; Shalabney, Atef ; Hutchison, James A; Genet, Cyriaque ; Ebbesen, Thomas W Liquid-Phase Vibrational Strong Coupling Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6 (6), pp. 1027–1031, 2015, ISSN: 1948-7185. @article{george_liquid-phase_2015, title = {Liquid-Phase Vibrational Strong Coupling}, author = {George, Jino and Shalabney, Atef and Hutchison, James A. and Genet, Cyriaque and Ebbesen, Thomas W.}, doi = {10.1021/acs.jpclett.5b00204}, issn = {1948-7185}, year = {2015}, date = {2015-03-01}, journal = {JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, volume = {6}, number = {6}, pages = {1027--1031}, abstract = {Light-matter strong coupling involving ground-state molecular vibrations is investigated for the first time in the liquid phase for a set of molecules placed in microcavities. By tuning the cavities, one or more vibrational modes can be coupled in parallel or in series, inducing a change in the vibrational frequencies of the bonds. These findings are of fundamental importance to fully develop light matter strong coupling for applications in molecular and material sciences.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Light-matter strong coupling involving ground-state molecular vibrations is investigated for the first time in the liquid phase for a set of molecules placed in microcavities. By tuning the cavities, one or more vibrational modes can be coupled in parallel or in series, inducing a change in the vibrational frequencies of the bonds. These findings are of fundamental importance to fully develop light matter strong coupling for applications in molecular and material sciences. |
El Gemayel, Mirella ; Borjesson, Karl ; Herder, Martin ; Duong, Duc T; Hutchison, James A; Ruzie, Christian ; Schweicher, Guillaume ; Salleo, Alberto ; Geerts, Yves ; Hecht, Stefan ; Orgiu, Emanuele ; Samori, Paolo Optically switchable transistors by simple incorporation of photochromic systems into small-molecule semiconducting matrices Journal Article In: NATURE COMMUNICATIONS, 6 , 2015, ISSN: 2041-1723. @article{el_gemayel_optically_2015, title = {Optically switchable transistors by simple incorporation of photochromic systems into small-molecule semiconducting matrices}, author = {El Gemayel, Mirella and Borjesson, Karl and Herder, Martin and Duong, Duc T. and Hutchison, James A. and Ruzie, Christian and Schweicher, Guillaume and Salleo, Alberto and Geerts, Yves and Hecht, Stefan and Orgiu, Emanuele and Samori, Paolo}, doi = {10.1038/ncomms7330}, issn = {2041-1723}, year = {2015}, date = {2015-03-01}, journal = {NATURE COMMUNICATIONS}, volume = {6}, abstract = {The fabrication of multifunctional high-performance organic thin-film transistors as key elements in future logic circuits is a major research challenge. Here we demonstrate that a photoresponsive bi-functional field-effect transistor with carrier mobilities exceeding 0.2 cm(2)V(-1) s(-1) can be developed by incorporating photochromic molecules into an organic semiconductor matrix via a single-step solution processing deposition of a two components blend. Tuning the interactions between the photochromic diarylethene system and the organic semiconductor is achieved via ad-hoc side functionalization of the diarylethene. Thereby, a large-scale phase-segregation can be avoided and superior miscibility is provided, while retaining optimal p-p stacking to warrant efficient charge transport and to attenuate the effect of photoinduced switching on the extent of current modulation. This leads to enhanced electrical performance of transistors incorporating small conjugated molecules as compared with polymeric semiconductors. These findings are of interest for the development of high-performing optically gated electronic devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The fabrication of multifunctional high-performance organic thin-film transistors as key elements in future logic circuits is a major research challenge. Here we demonstrate that a photoresponsive bi-functional field-effect transistor with carrier mobilities exceeding 0.2 cm(2)V(-1) s(-1) can be developed by incorporating photochromic molecules into an organic semiconductor matrix via a single-step solution processing deposition of a two components blend. Tuning the interactions between the photochromic diarylethene system and the organic semiconductor is achieved via ad-hoc side functionalization of the diarylethene. Thereby, a large-scale phase-segregation can be avoided and superior miscibility is provided, while retaining optimal p-p stacking to warrant efficient charge transport and to attenuate the effect of photoinduced switching on the extent of current modulation. This leads to enhanced electrical performance of transistors incorporating small conjugated molecules as compared with polymeric semiconductors. These findings are of interest for the development of high-performing optically gated electronic devices. |
Mosciatti, Thomas ; Haar, Sebastien ; Liscio, Fabiola ; Ciesielski, Artur ; Orgiu, Emanuele ; Samori, Paolo A Multifunctional Polymer-Graphene Thin-Film Transistor with Tunable Transport Regimes Journal Article In: ACS NANO, 9 (3), pp. 2357–2367, 2015, ISSN: 1936-0851. @article{mosciatti_multifunctional_2015, title = {A Multifunctional Polymer-Graphene Thin-Film Transistor with Tunable Transport Regimes}, author = {Mosciatti, Thomas and Haar, Sebastien and Liscio, Fabiola and Ciesielski, Artur and Orgiu, Emanuele and Samori, Paolo}, doi = {10.1021/acsnano.5b00050}, issn = {1936-0851}, year = {2015}, date = {2015-03-01}, journal = {ACS NANO}, volume = {9}, number = {3}, pages = {2357--2367}, abstract = {Here we describe a strategy to fabricate multifunctional graphene-polymer hybrid thin-film transistors (PG-TFT) whose transport properties are tunable by varying the deposition conditions of liquid-phase exfoliated graphene (LPE-G) dispersions onto a dielectric surface and via thermal annealing post-treatments. In particular, the ionization energy (IE) of the LPE-G drop-cast on SiO2 can be finely adjusted prior to polymer deposition via thermal annealing in air environment, exhibiting values gradually changing from 4.8 eV up to 5.7 eV. Such a tunable graphene's IE determines dramatically different electronic interactions between the LPE-G and the semiconducting polymer (p- or n-type) sitting on its top, leading to devices where the output current of the PG-TFT can be operated from being completely turned off up to inodulable. In fact upon increasing the surface coverage of graphene nanoflakes on the SiO2 the charge transport properties within the top polymer layer are modified from being semiconducting up to truly conductive (graphite-like). Significantly, when the IE of LPE-G is outside the polymer band gap, the PG-TFT can operate as a multifunctional three terminal switch (transistor) and/or memory device featuring high number of erase-write cycles. Our PG-TFT, based on a fine energy level engineering, represents a memory device operating without the need of a dielectric layer separating a floating gate from the active channel.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Here we describe a strategy to fabricate multifunctional graphene-polymer hybrid thin-film transistors (PG-TFT) whose transport properties are tunable by varying the deposition conditions of liquid-phase exfoliated graphene (LPE-G) dispersions onto a dielectric surface and via thermal annealing post-treatments. In particular, the ionization energy (IE) of the LPE-G drop-cast on SiO2 can be finely adjusted prior to polymer deposition via thermal annealing in air environment, exhibiting values gradually changing from 4.8 eV up to 5.7 eV. Such a tunable graphene's IE determines dramatically different electronic interactions between the LPE-G and the semiconducting polymer (p- or n-type) sitting on its top, leading to devices where the output current of the PG-TFT can be operated from being completely turned off up to inodulable. In fact upon increasing the surface coverage of graphene nanoflakes on the SiO2 the charge transport properties within the top polymer layer are modified from being semiconducting up to truly conductive (graphite-like). Significantly, when the IE of LPE-G is outside the polymer band gap, the PG-TFT can operate as a multifunctional three terminal switch (transistor) and/or memory device featuring high number of erase-write cycles. Our PG-TFT, based on a fine energy level engineering, represents a memory device operating without the need of a dielectric layer separating a floating gate from the active channel. |
Roy, Nabarun ; Bruchmann, Bernd ; Lehn, Jean-Marie DYNAMERS: dynamic polymers as self-healing materials Journal Article In: CHEMICAL SOCIETY REVIEWS, 44 (11), pp. 3786–3807, 2015, ISSN: 0306-0012. @article{roy_dynamers:_2015, title = {DYNAMERS: dynamic polymers as self-healing materials}, author = {Roy, Nabarun and Bruchmann, Bernd and Lehn, Jean-Marie}, doi = {10.1039/c5cs00194c}, issn = {0306-0012}, year = {2015}, date = {2015-01-01}, journal = {CHEMICAL SOCIETY REVIEWS}, volume = {44}, number = {11}, pages = {3786--3807}, abstract = {Importing self-repair or self-healing features into inert materials is of great relevance to material scientists, since it is expected to eliminate the necessity of replenishing a damaged material. Be it material chemistry or more specifically polymer chemistry, such materials have attracted the imagination of both material scientists and chemists. A stroll down the memory lane 70 years back, this might have sounded utopian. However with the current progress in supramolecular chemistry and the emergence of dynamic covalent and non-covalent chemistries, novel perspectives have been opened up to materials science towards the development of dynamic materials (DYNAMATS) and in particular dynamic polymers (DYNAMERS), with the ability to produce such species by custom made designs. Chemistry took giant strides to gain control over the structure and features of materials and, besides basic progress, to apply it for tailor-making matter for applications in our daily life. In that applied perspective, materials science plays a paramount role in shaping our present and in contributing to a sustainable future. The goal is to develop materials, which would be dynamic enough to carry out certain functions as effectively as in biological systems with, however, the freedom to recruit the powers of chemistry on a wider scale, without the limitation imposed by life. Material scientists and in particular polymer chemists may build on chemistry, physics and biology for bridging the gap to develop dynamic materials presenting a wide range of novel functionalities and to convert dreams into reality. In this current review we will focus on developments in the area of dynamic polymers, as a class of dynamic materials presenting self-healing features and, more generally, the ability to undergo adaptation under the effect of physical and/or chemical agents, and thus function as adaptive polymers or ADAPTAMERS.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Importing self-repair or self-healing features into inert materials is of great relevance to material scientists, since it is expected to eliminate the necessity of replenishing a damaged material. Be it material chemistry or more specifically polymer chemistry, such materials have attracted the imagination of both material scientists and chemists. A stroll down the memory lane 70 years back, this might have sounded utopian. However with the current progress in supramolecular chemistry and the emergence of dynamic covalent and non-covalent chemistries, novel perspectives have been opened up to materials science towards the development of dynamic materials (DYNAMATS) and in particular dynamic polymers (DYNAMERS), with the ability to produce such species by custom made designs. Chemistry took giant strides to gain control over the structure and features of materials and, besides basic progress, to apply it for tailor-making matter for applications in our daily life. In that applied perspective, materials science plays a paramount role in shaping our present and in contributing to a sustainable future. The goal is to develop materials, which would be dynamic enough to carry out certain functions as effectively as in biological systems with, however, the freedom to recruit the powers of chemistry on a wider scale, without the limitation imposed by life. Material scientists and in particular polymer chemists may build on chemistry, physics and biology for bridging the gap to develop dynamic materials presenting a wide range of novel functionalities and to convert dreams into reality. In this current review we will focus on developments in the area of dynamic polymers, as a class of dynamic materials presenting self-healing features and, more generally, the ability to undergo adaptation under the effect of physical and/or chemical agents, and thus function as adaptive polymers or ADAPTAMERS. |
Publications
2016 |
Influence of the supramolecular order on the electrical properties of 1D coordination polymers based materials Journal Article In: NANOSCALE, 8 (4), pp. 2386–2394, 2016, ISSN: 2040-3364. |
On symplectic hypersurfaces Inproceedings In: {Kollar, J; Fujino, O; Mukai, S; Nakayama, N} (Ed.): Minimal Models and Extreme Rays (Kyoto, 2011), pp. 277–298, Kyoto Univ, Res Inst Math Sci, 2016, ISBN: 978-4-86497-036-5. |
Supramolecular reactions of metallo-architectures: Ag-2-double-helicate/Zn-4-grid, Pb-4-grid/Zn-4-grid interconversions, and Ag-2-double-helicate fusion Journal Article In: CHEMICAL SCIENCE, 7 (6), pp. 3689–3693, 2016, ISSN: 2041-6520. |
Competition-driven selection in covalent dynamic networks and implementation in organic reactional selectivity Journal Article In: CHEMICAL SCIENCE, 7 (5), pp. 3215–3226, 2016, ISSN: 2041-6520. |
Self-assembly of supramolecular triarylamine nanowires in mesoporous silica and biocompatible electrodes thereof Journal Article In: NANOSCALE, 8 (10), pp. 5605–5611, 2016, ISSN: 2040-3364. |
2015 |
Long-range Ising and Kitaev models: phases, correlations and edge modes Journal Article In: NEW JOURNAL OF PHYSICS, 18 , 2015, ISSN: 1367-2630. |
Correlating the Structural and Photophysical Features of Pincer Luminophores and Monodentate Ancillary Ligands in Pt-II Phosphors Journal Article In: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, (36), pp. 5822–5831, 2015, ISSN: 1434-1948. |
Ratchetaxis: Long-Range Directed Cell Migration by Local Cues Journal Article In: TRENDS IN CELL BIOLOGY, 25 (12, SI), pp. 815–827, 2015, ISSN: 0962-8924. |
Two-dimensional soft supramolecular networks Journal Article In: CHEMICAL COMMUNICATIONS, 51 (97), pp. 17297–17300, 2015, ISSN: 1359-7345. |
Dynamic Covalent Chemistry of Nucleophilic Substitution Component Exchange of Quaternary Ammonium Salts Journal Article In: CHEMISTRY-AN ASIAN JOURNAL, 10 (11), pp. 2484–2496, 2015, ISSN: 1861-4728. |
Tunable defect interactions and supersolidity in dipolar quantum gases on a lattice potential Journal Article In: PHYSICAL REVIEW A, 92 (5), 2015, ISSN: 1050-2947. |
Monodisperse cluster crystals: Classical and quantum dynamics Journal Article In: PHYSICAL REVIEW E, 92 (5), 2015, ISSN: 1539-3755. |
Combined Delivery of Temozolomide and Anti-miR221 PNA Using Mesoporous Silica Nanoparticles Induces Apoptosis in Resistant Glioma Cells Journal Article In: SMALL, 11 (42), pp. 5687–5695, 2015, ISSN: 1613-6810. |
Theoretical study of actin layers attachment and separation Journal Article In: EUROPEAN PHYSICAL JOURNAL E, 38 (11), 2015, ISSN: 1292-8941. |
Enhancing the Liquid-Phase Exfoliation of Graphene in Organic Solvents upon Addition of n-Octylbenzene Journal Article In: SCIENTIFIC REPORTS, 5 , 2015, ISSN: 2045-2322. |
Organic Radical-Assisted Electrochemical Exfoliation for the Scalable Production of High-Quality Graphene Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (43), pp. 13927–13932, 2015, ISSN: 0002-7863. |
Conductivity in organic semiconductors hybridized with the vacuum field Journal Article In: NATURE MATERIALS, 14 (11), pp. 1123+, 2015, ISSN: 1476-1122. |
Synthetic Molecular Motors: Thermal N Inversion and Directional Photoinduced C=N Bond Rotation of Camphorquinone Imines Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (48), pp. 14345–14348, 2015, ISSN: 1433-7851. |
Contractile and Extensible Molecular Figures-of-Eight Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (41), pp. 14393–14400, 2015, ISSN: 0947-6539. |
Ultrahigh magnetoresistance at room temperature in molecular wires (Retraction of vol 341, pg 257, 2013) Journal Article In: SCIENCE, 350 (6257), pp. 170, 2015, ISSN: 0036-8075. |
A novel miR-371a-5p-mediated pathway, leading to BAG3 upregulation in cardiomyocytes in response to epinephrine, is lost in Takotsubo cardiomyopathy Journal Article In: CELL DEATH & DISEASE, 6 , 2015, ISSN: 2041-4889. |
The cell ratchet: Interplay between efficient protrusions and adhesion determines cell motion Journal Article In: CELL ADHESION & MIGRATION, 9 (5), pp. 327–334, 2015, ISSN: 1933-6918. |
Quantum Corrections to the Free Energy Difference between Peptides and Proteins Conformers Journal Article In: JOURNAL OF CHEMICAL THEORY AND COMPUTATION, 11 (9), pp. 4011–4022, 2015, ISSN: 1549-9618. |
The nicotinic acetylcholine receptor and its prokaryotic homologues: Structure, conformational transitions & allosteric modulation Journal Article In: NEUROPHARMACOLOGY, 96 (B, SI), pp. 137–149, 2015, ISSN: 0028-3908. |
Recent Advances in Phosphorescent Pt(II) Complexes Featuring Metallophilic Interactions: Properties and Applications Journal Article In: CHEMISTRY LETTERS, 44 (9), pp. 1152–1169, 2015, ISSN: 0366-7022. |
Diagnostic Implementation of Fast and Selective Integrin-Mediated Adhesion of Cancer Cells on Functionalized Zeolite L Monolayers Journal Article In: BIOCONJUGATE CHEMISTRY, 26 (9), pp. 1873–1878, 2015, ISSN: 1043-1802. |
Graphene-based nanocomposites for structural and functional applications: using 2-dimensional materials in a 3-dimensional world Journal Article In: 2D MATERIALS, 2 (3), 2015, ISSN: 2053-1583. |
Nitro-Assisted Bronsted Acid Catalysis: Application to a Challenging Catalytic Azidation Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (30), pp. 9555–9558, 2015, ISSN: 0002-7863. |
Dispersibility-Dependent Biodegradation of Graphene Oxide by Myeloperoxidase Journal Article In: SMALL, 11 (32), pp. 3985–3994, 2015, ISSN: 1613-6810. |
Strain-Induced Reactivity in the Dynamic Covalent Chemistry of Macrocyclic Imines Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (28), pp. 10070–10081, 2015, ISSN: 0947-6539. |
Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction Journal Article In: JOURNAL OF ORGANIC CHEMISTRY, 80 (13), pp. 6922–6929, 2015, ISSN: 0022-3263. |
Cluster Luttinger liquids and emergent supersymmetric conformal critical points in the one-dimensional soft-shoulder Hubbard model Journal Article In: PHYSICAL REVIEW B, 92 (4), 2015, ISSN: 2469-9950. |
Controlling Microsized Polymorphic Architectures with Distinct Linear and Nonlinear Optical Properties Journal Article In: ADVANCED OPTICAL MATERIALS, 3 (7), pp. 948–956, 2015, ISSN: 2195-1071. |
Nanopatterning of Surfaces with Monometallic and Heterobimetallic 1D Coordination Polymers: A Molecular Tectonics Approach at the Solid/Liquid Interface Journal Article In: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 137 (26), pp. 8450–8459, 2015, ISSN: 0002-7863. |
Directional Dynamic Covalent Motion of a Carbonyl Walker on a Polyamine Track Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (26), pp. 9380–9384, 2015, ISSN: 0947-6539. |
Enhanced Raman Scattering from Vibro-Polariton Hybrid States Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (27), pp. 7971–7975, 2015, ISSN: 1433-7851. |
Surface Trapping and STM Observation of Conformational Isomers of a Bis(Terpyridine) Ligand from Metallosupramolecular Grids Journal Article In: CHEMPHYSCHEM, 16 (7), pp. 1370–1373, 2015, ISSN: 1439-4235. |
Inositol trispyrophosphate (ITPP) and its anti-hypoxic potential in colorectal metastases of the liver Journal Article In: BRITISH JOURNAL OF SURGERY, 102 (6), pp. 17, 2015, ISSN: 0007-1323. |
Cavity-Enhanced Transport of Excitons Journal Article In: PHYSICAL REVIEW LETTERS, 114 (19), 2015, ISSN: 0031-9007. |
Self-Assembly of an Amphiphilic pi-Conjugated Dyad into Fibers: Ultrafast and Ultrasensitive Humidity Sensor Journal Article In: ADVANCED MATERIALS, 27 (20), pp. 3170–3174, 2015, ISSN: 0935-9648. |
The Relationship between Structural and Electrical Characteristics in Perylenecarboxydiimide-Based Nanoarchitectures Journal Article In: ADVANCED FUNCTIONAL MATERIALS, 25 (17), pp. 2501–2510, 2015, ISSN: 1616-301X. |
Accurate Calculation of Conformational Free Energy Differences in Explicit Water: The Confinement-Solvation Free Energy Approach Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY B, 119 (16), pp. 5194–5207, 2015, ISSN: 1520-6106. |
Surface-Induced Selection During In Situ Photoswitching at the Solid/Liquid Interface Journal Article In: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 54 (16), pp. 4865–4869, 2015, ISSN: 1433-7851. |
A Supramolecular Strategy to Leverage the Liquid-Phase Exfoliation of Graphene in the Presence of Surfactants: Unraveling the Role of the Length of Fatty Acids Journal Article In: SMALL, 11 (14), pp. 1691–1702, 2015, ISSN: 1613-6810. |
pH Oscillator Stretched in Space but Frozen in Time Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6 (5), pp. 760–766, 2015, ISSN: 1948-7185. |
Sterically Hindered Luminescent Pt-II-Phosphite Complexes for Electroluminescent Devices Journal Article In: CHEMISTRY-A EUROPEAN JOURNAL, 21 (13), pp. 5161–5172, 2015, ISSN: 0947-6539. |
Liquid-Phase Vibrational Strong Coupling Journal Article In: JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 6 (6), pp. 1027–1031, 2015, ISSN: 1948-7185. |
Optically switchable transistors by simple incorporation of photochromic systems into small-molecule semiconducting matrices Journal Article In: NATURE COMMUNICATIONS, 6 , 2015, ISSN: 2041-1723. |
A Multifunctional Polymer-Graphene Thin-Film Transistor with Tunable Transport Regimes Journal Article In: ACS NANO, 9 (3), pp. 2357–2367, 2015, ISSN: 1936-0851. |
DYNAMERS: dynamic polymers as self-healing materials Journal Article In: CHEMICAL SOCIETY REVIEWS, 44 (11), pp. 3786–3807, 2015, ISSN: 0306-0012. |