RUI: Determination of Magnetic Exchange Coupling in Carboxylate-Bridged Binuclear Co(II) by Magnetic Circular Dochroism

Middlebury College, Middlebury VT

Investigators

Abstract

Dr. James Larrabee, Chemistry Department, Middlebury College, is supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division to determine the magnetic exchange coupling, J, in a series of carboxylate bridged binuclear Co(II) complexes using variable-field, variable temperature magnetic circular dichroism (VTVH MCD). The ultimate goal is to develop VTVH MCD as a tool to monitor changes in the active sites of binuclear Co(II) enzymes that occur when they interact with substrates, substrate analogs and/or inhibitors. A series of binuclear Co(II) model compounds will be investigated to determine the factors that determine the magnitude of J. The enzymes methionyl aminopeptidase from E. coli, Co(II)-substituted hemerythrin, and Co(II)-substituted aminopeptidase, each of which contains a carboxylatebridged binuclear Co(II) site, will then be examined. Ultimately, correlations between the model complexes and the enzymes will be attempted in order to ascertain if the magnitude of J plays a role in the function of the enzyme and if changes in J can be used to probe enzyme function. The carboxylatebridged dimetallic active site is a common structural motif in proteins and enzymes. This investigation aims to develop a new tool, VTVH MCD, to investigate how these metal sites function in biological systems. In addition, it will deepen the understanding of factors that affect the strength of the interactions between Co(II) ions, which can have relevance to molecular magnetism. The research will be conducted at a predominantly undergraduate institution, Middlebury College, with undergraduate students. This type of research experience will encourage undergraduates to pursue careers in science.