Metalloenzymes catalyze hydrolytic reactions of various functional groups such as amide bonds (proteases) and phosphate esters (phosphatases). A large number of these enzymes contain one or more metal ions at their active centers.[1] The hydrolysis of organic functional groups such as esters, amides, and nitriles are catalyzed by metalloenzymes in biological systems.[2] There has been particularly much interest in the synthesis and study of enzyme models that catalyze the hydrolysis of phosphate esters which are known to be kinetically stable. Environmentally, these compounds are of particular interest due to the use of phosphate ester compounds as herbicides and insecticides. Physiologically, the nucleoside units in DNA and RNA are bridged by phosphate esters. Phosphate ester can also be found in the hydrophilic head of phospholipids. The active sites of enzymes are modeled by metal complexes that enhance the rates of hydrolysis of esters. Cells possess highly evolved enzymatic catalytic mechanisms to make and break various bonds in high rate reactions, which are otherwise extremely slow reactions at physiological pH. In this work Zn(II), Cu(II), and Ni(II) complexes have been synthesized and studied for their catalytic properties. In addition, a series of Mn(II) complexes with varied functional groups were also studied for the hydrolysis of phosphate esters. The complexes have been studied in order to determine the features of the complexes that enhance the rates for the catalysis of hydrolysis of phosphate ester bonds. This report details the rates of catalysis by these complexes of chelating ligands with nitrogen donors in the hydrolysis of phosphate esters. [1.] Dominique Desbouisa, Ivan P. Troitskyb, Matthew J. Belousoffa, Leone Spicciaa*, Bim Grahamb**, (2012) Elsevier. Copper(II), zinc(II) and nickel(II) complexes as nuclease mimetics, Coordination Chemistry Reviews 256 (2012) 897–937 [2.] Roberts, S. M., Turner, N. J., Willetts, A. J. and Turner, M. K. (1996), Introduction to Biocatalysis, Using Enzymes and Microorganisms. Journal of Eukaryotic Microbiology, 43: 162. doi: 10.1111/j.1550-7408.1996.tb04500.x

Homogeneous catalysis of hydrolysis of phosphate esters by Schiff base transition metal complexes

254th National Meeting (2017)

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