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.

Graphical Abstract

Keywords:

• Copper(II)–hydrazone complex
• Crystal structure
• DNA binding
• Electrochemistry
• EPR

Acknowledgements

M. Nandy gratefully acknowledges the Council of Scientific and Industrial Research (CSIR), New Delhi, Government of India, for awarding Senior Research Fellowship (SRF) to him [CSIR Sanction No. 09/096(0598)/2009–EMR–I]. Thanks are also extended to the University Grants Commission, New Delhi, for financial assistance to Dr. S. Mitra as emeritus fellow [F.6-6/EMERITUS-2013-14-GEN-2214/(SA-II)] to carry out this work. Thanks are also extended to Dr. S. Das, Assistant Professor, Department of Chemistry, J.U., for the helpful discussion about DNA interaction studies.