Conor F. Hogan

 Dept. of Chemistry & Physics, La Trobe Institute for Molecular Science,
La Trobe University, Melbourne, Victoria, Australia

e-mail: c.hogan@latrobe.edu.au

Our research seeks to control electrochemiluminescence (ECL) processes in a number of ways:  1) By tuning the characteristic emission wavelength and redox potentials through systematic structural changes to the molecule during synthesis.  2) By making the colour of the ECL emission sensitive to the chemical environment of the molecule and 3) By making the colour of the ECL emission sensitive to the applied potential.

In this presentation it will be discussed how insight into the design of ECL emitters is gained by seeking to understanding the complex interplay of photophysical and electrochemical properties which dictate such characteristics. We have used this understanding to inform the design of new electrochemiluminophores with varying oxidation potentials and emission wavelengths for potential sensing applications.[1-2]

The modulation of photoluminescent and ECL emission colour as a function of pH, where electrochemiluminescent complexes containing ligands which can be protonated, are shown to be pH sensitive with respect to their emission wavelength.  The ability to control emission wavelength by selectively exciting luminescent species from mixtures or eliciting potential dependant changes to the luminophores will be discussed. Moreover, we will describe a new method to continuously vary the emission colour by scanning the electrode potential, producing 3D-ECL excitation emission matrixes. The prospects for enhanced selectivity or multiplexed ECL detection by exploiting both the potential and wavelength axes will be demonstrated. [3-5]

The application of the above concepts to low-cost sensing strategies based on paper microfluidics, where a mobile phone is co-opted to act as both a luminescence detector and a potentiostat will also be discussed.

References

[1] Gregory J. Barbante, E. H. D., Emily Kerr, Timothy U. Connell, Paul S. Donnelly, Jonathan M. White, Thais Lópes, Sarah Laird, David J. D. Wilson, Peter J. Barnard, Conor F. Hogan and Paul S. Francis, Understanding Electrogenerated Chemiluminescence Efficiency in Blue-Shifted Iridium(III)-Complexes: An Experimental and Theoretical Study. Chemistry – A European Journal 2014.

[2] Reid, E. F.; Cook, V. C.; Wilson, D. J. D.; Hogan, C. F., Facile Tuning of Luminescent Platinum(II) Schiff Base Complexes from Yellow to Near-Infrared: Photophysics, Electrochemistry, Electrochemiluminescence and Theoretical Calculations. Chemistry-a European Journal 2013, 19 (47): 15907-15917.

[3] Doeven, E. H.; Zammit, E. M.; Barbante, G. J.; Francis, P. S.; Barnett, N. W.; Hogan, C. F., A potential-controlled switch on/off mechanism for selective excitation in mixed electrochemiluminescent systems. Chemical Science 2013, 4 (3): 977-982.

[4] Doeven, E. H.; Zammit, E. M.; Barbante, G. J.; Hogan, C. F.; Barnett, N. W.; Francis, P. S., Selective Excitation of Concomitant Electrochemiluminophores: Tuning Emission Color by Electrode Potential. Angewandte Chemie-International Edition 2012, 51 (18): 4354-4357.

[5] Egan H. Doeven, G. J. B., Emily Kerr, Conor F. Hogan, John A. Endler, Paul S. Francis, Red-Green-Blue Electrogenerated Chemiluminescence Utilizing a Digital Camera as Detector. Analytical Chemistry 2014 86 (5) 2727.