Iron(III) Complexes of Metal-Binding Copolymers as Proficient Catalysts for Acid Hydrolysis of Phosphodiester and Oxidative DNA Cleavage
—Insight into Rational Design of Functional Metallopolymers
Vasiliki Lykourinou,[a] Ahmed I. Hanafy,[a,b] Kirpal Bisht,[a] Alexander Angerhofer,[c] and Li-June Ming*[a]
[a] Department of Chemistry, University of South Florida, 4202 Fowler Avenue, CHE205, Tampa, Florida 33620-5250
[b] Department of Chemistry, Faculty of science, Al-Azhar University, Nasr City, Cairo, Egypt
[c] Department of Chemistry, University of Florida, Gainesville, Florida 32611
Fe3+ complexes of pyridine-containing copolymers are found to be efficient and selective catalyst toward phosphodiester hydrolysis and show significant activity toward oxidative DNA cleavage. The catalysis toward bis-(p-nitrophenyl)phosphate (BNPP) hydrolysis exhibits enzyme-like pre-equilibrium kinetics with maximum activities in the range of ~pH 6–8 and a first-order catalytic proficiency (kcat/ko) of 4.2 × 107-fold at the acidic pH = 5.3 (i.e., pKa of the coordinated nucleophilic water) and 25 °C, entitling this Fe3+-copolymer an acid phosphodiester catalyst. This catalyst also shows significant selectivity toward BNPP hydrolysis relative to the hydrolyses of p-nitrophenyl phenylphosphonate and p-nitro-phenylphosphate monoester, with a ratio of 4250:16:1 in terms of their first-order catalytic proficiencies at pH 8.0 and 25 °C. Fe3+ complexes of a few pyridine-containing copolymers show different hydrolytic activities which points a direction for rational design of catalytic metallopolymers.