This investigation will deal with spectroscopic and kinetic evaluation of the generation of arylnitrenium ions. Although the initial phase of the project will involve the photolysis of anthranilium salts, it is expected that several new photochemical methods for the general production of arylnitrenium ions will eventually emerge. The study will center on the use of nanosecond laser flash photolysis, low temperature ESR spectroscopy, and molecular orbital calculations to provide unequivocal identification of arylnitrenium ions. A highlight of the work will be to define the spin-multiplicity of the nitrenium ions generated and the products formed from each spin state. The question of the existence of a singlet-triplet equilibrium will be answered and the consequences for final product distribution will be delineated. The role of arylnitrenium ions in DNA damaging reactions will also be investigated by trapping of arylnitrenium ions with guanine to simulate carcinogenetic reactivity. %%% This new grant from the Organic Dynamics Program supports the work of Professor Daniel A. Falvey at the University of Maryland. The investigation will seek to analyze the reactivity of very short lived molecules called nitrenium ions. Nitrenium ions, which possess a nitrogen with a positive charge, have received little attention and yet represent a potential class of reactive species with widespread utility in chemical processes induced by light. By using an instrument designed to take snap-shot ultraviolet absorption "pictures" of transient chemical species which live a few billionths of a second, it will be possible to confirm the existence of arylnitrenium ions which have been implicated as the primary entities involved in the DNA damaging process of arylamines.
