Photochemical and photophysical properties of molecules which react from delocalized and/or multiple excited states will be studied, with a particular emphasis on evaluating the relative roles of through-bond and through-space interactions. In solution, polyfunctional substrates will be studied, utilizing antenna chromophores or delocalized excitation to activate distal groups which are transparent or weakly absorbent in the ultraviolet or are absorbent but may be selectively activated through the antenna. Special attention will be given to: (1) charge transfer transmission through the steroid frame-work, (2) energy transfer in trifunctional steroids, and (3) the potential role of sigma bonded relay mechanisms to facilitate virtual orbital mixing. In the gas-phase, studies will emphasize the newly discovered Norrish Type II chemistry of thioketones. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Morrison at Purdue University. Functional groups in molecules will be excited by light absorption and the mechanism by which this energy is transferred to other functional groups in molecules will be studied. A particular concern will be to determine if the energy is transferred through bonds or through space. In another phase of the research, unique photochemical and photophysical properties sulfur containing compounds will be investigated.
