Effective Heterogeneous Hydrolysis of Phosphodiester by Pyridine-Containing Metallopolymers
Ahmed I. Hanafy, Vasiliki Lykourinou-Tibbs, Kirpal S. Bisht,* and Li-June Ming*
Inorg. Chim. Acta. 2005, 358, 1247–1252

Abstract: The copper(II) complex of a simple pyridine- and amide-containing copolymer serves as an effective catalyst for heterogeneous hydrolysis of the prototypical phosphodiester substrate bis(p-nitrophenyl)phosphate at pH 8.0 and 25 °C.  The catalysis has a first-order rate constant of kcat = 8.3 × 10–6 s–1, corresponding to a catalytic proficiency of 75-thousand folds relative to the uncatalyzed hydrolysis with a rate constant of ko = 1.1 × 10–10 s–1 at pH 8.0.  This observation suggests that polymers can be designed to include various functional groups feasible for effective metal-centered catalysis of phosphodiester hydrolysis.

Concluding remarks
Cu2+ is unique among first-row transition metal ions in hydrolytic chemistry, wherein it can activate a few hydrolases (including serralysin and astacin) to a great extent while show negligible activation toward some other hydrolases such as carboxypeptidase A and carbonic anhydrase. To gain further understanding of metal-centered hydrolysis and design more effective hydrolytic catalysts, it is essential to solve the puzzle about why and why not Cu2+ can activate these enzyme systems for hydrolysis. We present in this communication the investigation of the Cu2+ complex of a simple pyridine- and amide-containing copolymer family that exhibits a significant activity toward phosphodiester hydrolysis, which provides another model system for
further investigation of Cu2+ -centered hydrolytic chemistry. The simplicity in the preparation of this 4VpAc copolymer and the high hydrolytic activity of its Cu2+ complex suggest potential application of this family of metallopolymers in hydrolytic chemistry. Moreover, since Cu2+ is a redox-active ion, Cu2+-polymer systems may also serve as oxidative catalysts for further investigation of Cu-centered oxidation and oxygenation chemistry.

This research on hydrolytic chemistry of phosphoesters is partially supported by the Petroleum Research Funds administrated by the American Chemical Society (ACS-PRF #35313AC3). A.I.H acknowledges the Egyptian Government for a scholarship to perform research overseas. Aswini Komarla, Anupama Kotha, Kara Brown and Jane Zhu from the USF Summer Program for High School Students are acknowledged for their contribution to the preliminary studies.

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