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45374-AC7
Chiral and Prochiral Singlet Biradical Pairs as Probes of Reaction Cages in Polymer Films

Richard G. Weiss, Georgetown University

During this period, a great deal of the preliminary work associated with developing protocols, defining the characteristics of materials, etc. has been performed.

1-Naphthyl 2-phenylbutanoate has been synthesized and irraditated in ethyl acetate. The photoproducts have been identified and separated by HPLC and the response factor of each has been determined. Thus, quantification of product yields as a function of the conversion of the starting ester is now possible. In collaboration with Drs. Steven Pas and Anita Hill at the CSIRO in Clayton, Australia, we have determined the mean hole free volumes (directly proportional to ortho-positron lifetimes) for the first 4 poly(alkyl methacrylate) films we intend to employ over temperature ranges spanning the glass transition temperatures . The glass transition temperatures have been measured independently by differential scanning calorimetry. Additional studies of the photophysics from pyrene (i.e., both the steady-state spectra and temporal decay of fluorescence) embedded in the polymers as a function of temperature are ongoing.

Attempts to synthesize enantiomerically pure phenyl ester derivatives of naproxen with long alkoxy chains in place of the methyl group have been frustrated by racemization that attends the replacement of the methyl. To overcome this problem, we intend to perform the needed chemical steps and then to separate the enantiomers of the racemic mixture by making diastereomeric salts.

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