Abstract
An inorganic–organic hybrid constructed from a Zn-cluster with a polyoxometalate {[Zn3Na2(μ-OH)2(bpdo)6(H2O)16][PW12O40]2}·(bpdo)3·C2H5OH·2H2O (bpdo = 4,4′-bis(pyridine-N-oxide)) (1) has been synthesized by hydrothermal reaction and characterized by elemental analyses, IR spectra, and single crystal X-ray diffraction. The structural analysis indicates that 1 is an S-like complex constructed by [Zn3Na2(μ-OH)2(bpdo)6(H2O)16]6− with two PW12O40 3− with water occupying several coordination sites and have the potential to act as labile ligands, allowing for substrate and nucleophile binding. Kinetic experiments for hydrolytic cleavage of the DNA-model phosphodiester bis(p-nitropheny1)phosphate (BNPP) were followed spectrophotometrically for absorbance increase at 400 nm in 4-(2-hydroxyethyl)piperazine-1–propane sulfonic acid (EPPS) buffer solution due to the formation of p-nitrophenoxide with 1 at pH 4.0 and 50 °C. UV spectroscopy indicates cleavage of the phosphodiester bond proceeds with pseudo-first-order rate constant 6.7(±0.2) × 10−7 s−1, giving an inorganic phosphate and p-nitrophenol as the final products of hydrolysis. The results demonstrate that 1 exhibits good catalytic activity and reusability for hydrolytic cleavage of BNPP.
Acknowledgment
This work was supported by the Foundation of Education Department of Henan Province (No. 2009A150003).