Synthesis, characterization, crystal structure, and DNA binding of two copper(II)–hydrazone complexes

Abstract

Two new Cu(II)–hydrazone complexes, [Cu(L)(Hbpe)ClO4]·ClO4·[Cu(L)Cl] (1) and [Cu(HL)2]·1.5ClO4·0.5OH (2) (where HL = (E)-N′-(1-(pyridine-2-yl)ethylidene)benzohydrazide and bpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene), have been synthesized and characterized by physicochemical methods. The structures of the complexes have been established by single-crystal X-ray diffraction direct methods, which reveal that the metal ions have distorted square-pyramidal and square-planar geometries in 1, and a distorted octahedral geometry in 2. DNA binding of HL, 1, and 2, performed by UV–vis titration in tris-buffer medium, yielded binding constants, which are 9.5 × 103, 1.88 × 104, and 4.66 × 104 M−1, respectively. Viscosity measurements suggest a surface or groove-binding mode of interaction between CT-DNA with HL, 1, and 2.