Hydrolytic cleavage of a DNA-model phosphodiester: a new inorganic–organic hybrid constructed from a Zn-cluster with a polyoxometalate

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) × 10⁻⁷s⁻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.

Keywords:

• Polyoxometalate
• Hybrid
• Hydrolytic cleavage
• Heterogeneous catalyst

Acknowledgment

This work was supported by the Foundation of Education Department of Henan Province (No. 2009A150003).