Metal-Promoted Hydrolysis of Polymeric Chelating Agents: Chelators on Demand
The feasibility of designing polymer-chelator conjugates from which release of the chelator is triggered reversibly by the appearance of the target (toxic) metal in the circulatory system was tested by synthesis and measurement of the rates of metal-catalysis hydrolysis of the ester of poly(vinyl alcohol) and quinaldic acid at pH 7.5. Hydrolysis in 50% aqueous ethanol solution in the presence of the four metals, Cu(II), Ni(II), Co(II) and Zn(II) at pH 7.5 was first order, with half lives of 67, 71, 172 and 476 min., respectively. The rate of hydrolysis in the absence of metals was not measurable. A double reciprocal plot of kobs vs. [M] for Ni(II) exhibited the expected linearity. For films of the ester, the deviation from first order kinetics was consistent with a contributing diffusion process.
KeywordsVinyl Alcohol Double Reciprocal Plot Aqueous Ethanol Solution Amino Acid Ester Polymeric Metal Complex
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