Synthesis, structure, DNA interaction, and hydrolytic function toward bis(p-nitrophenyl) phosphate of a heterobinuclear macrocyclic complex

Abstract

An asymmetrical bis-pyridine pendant-armed macrocyclic heterobinuclear complex, [ZnNiL](ClO4)2·CH3CN (H2L was derived from the condensation between 3,3′-((ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))bis(methylene))bis(2-hydroxy-5-methylbenzaldehyde) and 1.3-diaminopropane), has been synthesized and characterized by physico-chemical and spectroscopic methods. The asymmetric unit contains two complete macrocyclic complexes that are nevertheless quite similar to one another. The Zn–Ni separations, bridged by the two phenoxides, are 3.107 and 3.141 Ǻ, respectively. The phosphate hydrolysis catalyzed by the complex was investigated using bis(4-nitrophenyl)phosphate (BNPP) as the substrate. The catalytic rate constant (kcat) is 1.64 × 10−3 s−1 at pH 7.4 and 25 °C, which is 108-fold higher than that of the corresponding uncatalyzed reaction. The interaction between the complex and calf thymus (CT) DNA was investigated by UV–vis absorption, viscosity experiments, and cyclic voltammetry. The complex shows good binding propensity to calf thymus DNA via intercalation with a binding constant of 5 × 104 M−1. The agarose gel electrophoresis studies show that the complex has a concentration-dependent DNA cleavage activity.