Current Research Projects

1. Communication between molecules via photocontroled ions

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The goal of this project is to establish a strategy whereby functional molecular devices (e.g. photo-/electroactive) can communicate with one another in solution and in organized, self-assembled media (biotic and abiotic). Despite intense research, no single strategy has been shown to satisfactorily connect artificial molecular components in networks. This is perhaps the greatest hurdle to overcome if implementation of artificial molecular devices and sophisticated molecule-based arrays are to become a reality. In this project, communication between distant sites / molecules will be based on the use of photoejected ions in solution and organized media (membranes, thin films, nanostructured hosts, micellar nanodomains).
Ultimately this will lead to coded information transfer through ion movement, signalled by fluorescent reporter groups and induced by photomodulated receptor groups in small photoactive molecules. Integrated photonic and ionic processes operate efficiently in the biological world for the transfer of information and multiplexing distinct functional systems. Application in small artificial systems, combining “light-in, ion-out” (photoejection of an ion) and “ion-in, light-out” processes (ion-induced fluorescence), has great potential in a bottom-up approach to nanoscopic components and sensors and understanding and implementing logic operations in biological systems. Fast processes of photoejection and migration of ions will be studied in real-time (using time-resolved photophysical techniques) with high spatial resolution (using fluorescence confocal microscopy techniques) allowing evaluation of the versatility of this strategy in the treatment and transfer of information and incorporation into devices. Additionally, an understanding of the fundamental events implicated during the process of photoejection / decomplexion of coordinated ions and ion-exchange processes at membrane surfaces will be obtained.

2. Photoactive nanomaterials and reversible electronic energy transfer processes

 

As well as in-house devlopped novel nanomaterials, through diverse collaborations we are studying different photophysical processes in a range of nanomaterials and functional molecules. One aspect of fundamental importance is the management of energy following light absorption for the development of efficient optoelectronic devices, charge separation and ultimately energy storage (as chemical energy). This is exemplified in natural photosynthetic systems where a structurally complex multiporphyrin architecture can absorb light energy before subsequently transferring it in a unidirectional fashion to drive a charge transfer process at a distant site, ultimately transforming light energy into chemical energy, via multi-electron processes. Recent research efforts in the direction of artificial photosynthesis are largely directed at developing multichromophoric antenna systems, which efficiently absorb light energy and transfer it in a unidirectional fashion to a specific site following a downhill energy gradient. Close to 100% efficiency in energy transfer can now be routinely obtained. In our approach we are using fully reversible electronic energy transfer as a means to govern properties, resulting from the effect of this energy shuttling.
We are principally harnessing reversible energy transfer process in multicomponent systems for the purpose of charge separation and to improve the photophysical properties of a diversity of molecules such as light harvesting pigments, notably low-cost metal complexes.

Copyright 2010 © Nathan McClenaghan, Institut des Sciences Moléculaires - UMR 5255 CNRS/Université Bordeaux 1