Electron spectroscopy

The electronic spectrum of Cu(II)(L-His)2 has been measured in the visible-near IR and UV regions. By assigning ligand field bands and by fitting the band maxima with calculated energies using angular overlap model, the structure of the complex has been deduced to be five-coordinate C4v1 The observed bands in the UV spectrum have been assigned as due to ligand-to-metal charge transfer transitions. Electronic spectra of Cu(II)(diphenylcarbazide)2 and Cr(II)(diphenylcarbazone)(H2O)4 complexes have also been measured. By interpretation of the ligand field bands in these spectra, tentative structures of these complexes in solution have been proposed.

In an effort to gain detailed insight into the mechanism of electron transport in the respiratory chain, the synthesis of a reaction model approximating the first step of the sequence was attempted. The desired molecule should contain the isoalloxazine ring system, the reactive center of flavin adenine dinucleotide, and the nicotinamide ring, the reactive moiety of nicotinamide adenine dinucleotide, joined by a trimethylene bridge. The successful synthesis and characterization of many intermediate confirms that the procedure being used is viable. Attainment of the actual reaction model, based on the work described herein, should occur in the near future.

Most living organisms transduce electron transport chains in order to obtain energy. Flavin adenine dinucleotide (FAD) is a common electron transfer cofactor found in electron transport proteins referred to as flavoproteins. In this study, the different ionization and oxidation states of this cofactor found in cytochrome b5 reductase were identified spectroscopically and quantified as a function of solution potential and pH. The large data sets obtained from these experiments were analyzed and the acid dissociation constant for reduced cytochrome b5 reductase was determined.

Most living organisms utilize electron transport chains in order to obtain energy. Riboflavin, commonly known as vitamin B2, is the central component of the redox coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN). These cofactors serve as a prosthetic group to flavoproteins and function as the energy-carrying molecules in electron transfer reactions. In this study, the different ionization and oxidation states of riboflavin were identified and quantified as a function of solution potential and pH. To accomplish this task, spectroelectrochemical reductions of riboflavin at different pH were performed. Spectroscopic data offer clues concerning the identity of underlying species, such as oxidation/ionization states and the controlling equilibria. The large data sets obtained from these experiments were analyzed and the acid dissociation constant for reduced riboflavin was determined.