Investigating the Role of the Outer-Coordination Sphere in [Ni(PPh2NPh-R2)2]2+ Hydrogenase Mimics
A series of dipeptide substituted nickel complexes with the general formula, [Ni(PPh2NNNA-amino acid/ester2)2](BF4)2, have been synthesized and characterized (P2N2 = 1,5-diaza-3,7-diphosphacyclooctane, and the dipeptide consists of the non-natural amino acid, 3-(4-aminophenyl)propionic acid (NNA), coupled to amino acid/esters = glutamic acid, alanine, lysine, and aspartic acid). Each of these complexes is an active electrocatalyst for H2 production. The effects of the outer-coordination sphere on the catalytic activity for the production of H2 were investigated; specifically, the impact of sterics, the ability of the side chain or backbone to protonate and the pKa values of the amino acid side chains were studied by varying the amino acids in the dipeptide. The catalytic rates of the different dipeptide substituted nickel complexes varied by over an order of magnitude. The amino acid derivatives display the fastest rates, while esterification of the terminal carboxylic acids and side chains resulted in a ...
Avijita Jain; Matthew L. Reback; Mary Lou Lindstrom; Colleen E. Thogerson; Monte L. Helm; Aaron M. Appel; Wendy J. Shaw
In this article we have investigated intermolecular excited-state proton transfer (ESPT) of firefly’s chromophore D-luciferin in DMSO–water binary mixtures using steady-state and time-resolved fluorescence spectroscopy. The unusual behavior of DMSO–water binary mixture as reported by Bagchi ... more
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The aryl hydrocarbon receptor (AhR) is a nuclear receptor regulating a wide range of biological and toxicological effects. Metabolites of l-tryptophan are able to bind and activate AhR, providing a link between tryptophan catabolism and a novel mechanism of protective tolerance, referred to ... more
Rohm and Haas Powder Coatings is delighted to announce that its Reading, Pennsylvania, facility is the first site in the world to receive the RCMS® Site Certification awarded by the American Chemical Council (ACC).
When Raj Gupta, Chairman and CEO of Rohm and Haas Company, became Chairman ... more