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

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.