ChemInform Abstract X-ray absorption edge and EXAFS data for the binary form of the Cu-ZnO methanol synthesis catalysts show four phases to be present in the reduced catalyst. First, bulk metallic Cu and Cu2O, which are not believed to be active in methanol synthesis, are observed. In addition, the dispersed phase in the catalyst, which corresponds to 50% of the Cu, is shown to consist of small Cu microclusters and Cu(I) doped into the ZnO lattice.
X-ray absorption edge studies of C~(I) complexes with different coordination number and covalency reveal that the 8983-8984 eV feature (assigned as the Is-tQp transition) can be correlated with ligation and site geometry. These Cu(1) features have been qualitatively interpreted using a Ligand Field model, and this has been applied to analyze the polarized single crystal, pH dependent edge spectra of reduced plastocyanin. In addition, normalized difference X-ray absorption edge analysis has been used to quantitatively determine the percent of Cu(I) in several derivatives of the multicopper oxidase, laccase.
The iron coordination structures of the oxygenated cytochrome P-450-CAM and chloroperoxidase and of a number of penta- and hexa-coordinate ferrous porphyrin complexes containing biologically relevant, sulfur axial ligands have been investigatied by EXAFS spectroscopy. The two oxygenated enzymes have both been found to contain a sulfur atom located 2.37 Å from the central heme iron. In the CO-ligated series of model complexes, two distinct categories of Fe-Sax distances have been observed that correlate with thiolate and non-thiolate ligation (~2.33 and ~2.41 Å, respectively) . The data for these model ferrous-CO ccomplexes, together with previously reported Fe-S distance in oxygenated heme iron model complexes ; allows the sulfur atoms in oxygenated P-450-CAM and chloroperoxidase to be identified as a thiolate sulfur
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