The purchase of a modern electron paramagnetic resonance (EPR) spectrometer is proposed for routine acquisition and data storage, variable temperature operation down to liquid helium temperature, and the accessories necessary for proposed research. The instrument will be used in the School of Chemical Sciences Molecular Spectroscopy Laboratory to support the research of faculty, post-doctorates, and graduate students in biological chemistry, biochemistry, inorganic, and analytical chemistry at the University of Illinois. EPR analyses are planned on a large variety of problems of significance in biological chemistry. (See Section D.2 for details of these and other proposals.) Research areas where timely access to modern EPR equipment will be of great value include electron-transfer in mixed-valence metal complexes and binuclear and tetranuclear manganese complexes which serve as models of photosynthetic water oxidation centers, the examination of photolabeling experiments, the definition and study of the structure of genetically engineered metalloproteins, the structural characterization of the binuclear 02 binding-site of cytochrome c oxidase, the characterization of the electronic structure of highly oxidized single-atom bridged iron porphyrin dimers and of the unusual low-spin five coordinate Fe (III) hydrosulfido complexes. The proposed equipment would greatly improve the capability of the School instrumentation for EPR service.
