Blue copper proteins (Type I) exhibit unusual spectral and chemical properties such as higher reduction potentials and small hyperfine coupling constants A|| in the EPR spectrum in comparison with other copper(II) complexes. Such unusual properties are justified partly by the tetralhedral geometry around the copper(II) site and partly by the CuN2S2 chromophores in which the soft S atoms coordin...

A mutant form of Klebsiella aerogenes urease possessing Ala instead of His at position 134 (H134A) is inactive and binds approximately half the normal complement of nickel (Park, I.-S., and Hausinger, R. P.(1993) Protein Sci. 2, 1034-1041). The crystal structure of the H134A protein was obtained at 2.0-A resolution, and it confirms that only Ni-1 of the two nickel ions found in the native enzym...

Flash photolysis and K-edge x-ray absorption spectroscopy (XAS) were used to investigate the functional and structural effects of pH on the oxygen affinity of three homologous arthropod hemocyanins (Hcs). Flash photolysis measurements showed that the well-characterized pH dependence of oxygen affinity (Bohr effect) is attributable to changes in the oxygen binding rate constant, k(on), rather th...

The electrochemical splitting of water into hydrogen and oxygen has been proposed as an alternative means to store electrical energy. The limiting aspect of this reaction is the oxygen forming reaction, which can be catalyzed by transition metal species with varying degrees of efficiency. This thesis examines the characteristics of oxygen bonding that complicate the 0-0 bond formation reaction,...

Extended coordination frameworks containing the pyrimidin-4-olate ligand (4-pymo) and Zn(II) and Ni(II) metal ions have been obtained by solid state reactions and have been fully characterized by spectroscopic, thermal, and magnetic measurements and by ab initio XRPD. The reaction of ZnO and 4-Hpymo at 140 degrees C gives a solid microcrystalline phase, Zn(4-pymo)(2) (1). Its 3D framework conta...

A ditopic benzobis(carbene) ligand precursor was prepared that contained a chelating pyridyl moiety to ensure co-planarity of the carbene ligand and the coordination plane of a bound octahedral metal center. Bimetallic ruthenium complexes comprising this ditopic ligand [L4Ru-C,N-bbi-C,N-RuL4] were obtained by a transmetalation methodology (C,N-bbi-C,N=benzobis(N-pyridyl-N'-methyl-imidazolyliden...

One of the most important chemical concepts is defining how one molecule recognizes and controls the properties of another molecule or ion. Nowhere is this issue more significant than in the field of biomolecular recognition. Metalloproteins efficiently control the geometry and coordination number of metal ions as well as the types of ligands bound to them. Incorporation of metals in the correc...

One of the most important chemical concepts is defining how one molecule recognizes and controls the properties of another molecule or ion. Nowhere is this issue more significant than in the field of biomolecular recognition. Metalloproteins efficiently control the geometry and coordination number of metal ions as well as the types of ligands bound to them. Incorporation of metals in the correc...

We recently reported the synthesis, characterization, and reactivities of molybdenum bispyrrolyl complexes of the type Mo(NR)(CHR′)(pyrrolyl)2 where pyrrolyl is either the parent pyrrolyl1 or 2,5-dimethylpyrrolyl (Me2Pyr). We are interested primarily in the use of bispyrrolyl species as precursors to bisalkoxide catalysts3 of the type Mo(NR)(CHR′)(OR)2 or Mo(NR)(CHR′)(diolate) through addition ...