The photochemistry and photophysics of inter- and intra-molecular reactions of amines with styrenes and stilbenes will be studied in order to determine the mechanistic details of these reactions. The intramolecular addition reactions will also provide an attractive synthetic route to medium-ring nitrogen-containing heterocyclic molecules. The structure of the products in these reactions are dependent upon both the structure of the reactant(s) and the method of photochemical excitation (direct vs. electron-transfer sensitized irradiation). In order to understand the mechanism of these reactions, the reactants, intermediates, and products will be characterized by modern spectroscopic and computational methods. The study will include a characterization of styrene photoisomerization processes, intermolecular styrene-amine exciplexes, both styrene and stilbene intramolecular exciplexes, and electron-transfer sensitized intramolecular photoamination. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Frederick D. Lewis at Northwestern University. Amines, which are one of the important classes of nitrogen-containing organic molecules, undergo diverse reactions with compounds containing a carbon-carbon double bond by irradiation with ultraviolet light. This study will unravel the details of these reactions, where the amine is part of the molecule which contains the carbon-carbon double bond and where the amine is a separate molecule. In the former reaction, the potential for the synthesis of cyclic compounds containing nitrogen will be evaluated. There is considerable interest in these nitrogen heterocycles, since they are prevalent in biological systems and in plants.