Molecular Approaches to Investigating and Developing Polymers, Organogels, and Ionic Liquids through Photochemistry, Photophysics, and Structure

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With this renewal award the Organic and Macromolecular Chemistry Program supports the work of Dr. Richard G. Weiss of the Department of Chemistry at Georgetown University in Washington, D.C. The work involves a broad program of research in the area of liquid crystals, organogels, and polymers, including the use of phosphonium salts for carrying out selective photochemical reactions and as NMR solvents, the study of the photo-Fries reaction of optically active substrates in polymer matrices, the use of polymer films as reaction media for promoting diastereoselective photoreactions, intramolecular photocyclizations, the preparation of high energy intermediates, and the use of high energy particles to induce selective chemical reactions normally caused by photons. A variety of experimental techniques will be used, including single-crystal and powder x-ray diffraction, differential scanning calorimetry, polarizing optical microscopy, static fluorescence and phosphorescence, time-correlated single photon counting, and dipolar nuclear magnetic resonance spectroscopy.Dr. Weiss' work covers a variety of subjects at the interface of organic chemistry and materials science, with the unifying theme of static and dynamic molecular interactions in anisotropic environments, i.e. in environments where the material has different properties in different directions, such as in an oriented liquid crystal or a stretched polyethylene film. The new devices and materials which might result include sensors, membranes which separate molecules on the basis of size and shape, and ordered ionic liquids that may be useful as 'green solvents' for selective organic reactions, or permit 3D structures of solutes to be determined by nuclear magnetic resonance spectroscopy. The work is expected to provide excellent training for the students, each one of whom is assigned a research project rather than a technique, and who may participate in a number of international collaborations.