Photosynthetic antenna-reaction-center mimicry

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Channa Aravinda Wijesinghe, W.M.
D'Souza, Francis

The research presented in this dissertation discusses the mimicry of primary events in natural photosynthesis via artificial molecular constructs. Photosynthesis involves two major steps, absorption of light by antenna pigments and transfer of the excitation energy to the reaction center where charge separated entities are formed via photoinduced electron transfer (PET). The synthesized artificial molecular systems are comprisedof porphyrin-fullerene, donor-acceptor entities due to their well studied photophysical properties which are essential to yield long-lived charge-separated states. Covalent and non covalent binding strategies have been employed in the design and synthesis of these novel artificial antenna-reaction centers. The synthesized molecular systems are characterized using standard spectroscopic techniques. Their properties and performances in terms of an artificial photosynthetic model are evaluated by electrochemical, computational, time resolved emission, and transient absorption spectral studies. The systems studied reveal their potential in transferring excitation energy and yielding long-lived charge separated states with fast charge separation and slow charge recombination. The photoelectrochemistry of some of the compounds reveal their ability to convert light into electricity. Some triads show better performance as dyes in dye sensitized solar cells giving around 12% IPCE, incident photon-to-photocurrent conversion efficiency.

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Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Chemistry