High-Resolution Crystallographic Studies Using Synchrotron Radiation

Suny At Buffalo, Amherst NY

Investigators

Abstract

The Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division supports Professor Philip Coppens, Chemistry Department, State University of New York at Buffalo, for high-resolution crystallographic studies using synchrotron radiation. The geometry of light-induced metastable states and highly reactive transient species will be probed using both steady-state and time-resolved crystallography. The work will contribute to the understanding of the nature of photoinduced molecular excited states and to elucidating geometry changes that occur during electron transfer in transition metal complexes. A second component of the research is the experimental mapping of charge density distribution in solids and the interpretation of these data in terms of chemical bonding within and between molecules. The high-brightness of the Advanced Photon Source at Argonne National Laboratory will be combined with area detectors to allow rapid X-ray data collection on small crystallites of dimensions of 50 micron and less. Very low-temperature single crystal techniques are to be applied for data collection in each stage of the project. The experimental work is to be complemented by extensive theoretical calculations on both molecules and solids, using supercomputer facilities available to the project, and by spectroscopic measurement of the absorption and emission spectra of the systems under investigation. X-ray diffraction is well-known as the sine qua non of structure-determining tools, capable of measuring extremely small changes in molecular geometry. However, this technique only measures stable structures. This work exploits innovations that allow x-ray crystallography to determine structural changes in molecules that occur on fast timescales. Knowledge that is gained about the interaction of radiation with matter in the solid state will underpin future applications in materials science and technology. This work involves much collaboration and provides a unique training ground for young scientists. An international collaboration with the Slovak University of Technology will benefit the efforts of both countries to advance research in this area. To aid in the utilization of the techniques used in this study, software will be developed and made available to the wider scientific community.