Studies of the Effect of Electron Exchange Coupling on the Photophysics and Photochemistry of Transition Metal Complexes: Discrete Molecules to Magneto-Optical Polymers

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James McCuskerCHE-9729003Title: Studies of the Effect of Electron Exchange Coupling on the Photophysics and Photochemistry of Transition Metal Complexes: Discrete Molecules to Magneto-Optical PolymersAbstractDr. McCusker is supported by the Inorganic Bioinorganic and Organometallic Chemistry Program to examine how the presence of exchange coupling affects photo-induced excited-state properties of metal complexes. McCusker has proposed to study intramolecular exchange coupling, between the radical ligand and the metal ion, via the systematic variation of semiquinone ligands coordinated to paramagnetic metal centers. Having demonstrated the effect of electron exchange on ground-state characteristics of chromium-semiquinone complexes, effects upon the excited-state will be examined using low-temperature time-resolved adsorption and time-resolved resonance Raman spectroscopy. Additional goals of the proposed work are to 1) measure the effect of exchange coupling upon inter-ligand electron-exchange dynamics and 2) examine the wavelength dependence of photoredox activity. Extension studies will include the synthesis and characterization of magneto-optical dimers.While the impact of spin coupling of paramagnetic centers on the physical properties of molecules has received considerable attention, there is a paucity of information on how the photophysical characteristics of molecules are affected by this phenomenon. An increased understanding of exchange coupling may lead to the development of molecular-based magneto-optical materials.