Synthesis, crystal structure, DFT analysis, and DNA studies of a binuclear copper(II) complex with 2,2′-bipyridine and 4-aminobenzoate

Abstract

A complex containing two discrete molecules, [Cu₂(bpy)₂(4-Ab)₂(NO₃)(H₂O)] and [Cu₂(bpy)₂(4-Ab)₂(H₂O)₂] and the lattice including three NO₃ anions, one 4-Ab, and three H₂O molecules (bpy = 2,2′-bipyridine, 4-Ab = 4-aminobenzoate), was prepared and structurally determined using elemental analyses, IR, EPR, UV-visible, and single-crystal X-ray crystallography. X-ray single-crystal structural studies indicated that the [Cu₂(bpy)₂(4-Ab)₂] unit was present in both the crystallographic units. The complex crystallized in an orthorhombic crystal system with space group Pna2₁, a = 35.004(3) Å, b = 18.4134(16) Å and c = 12.8659(12) Å. In both crystallographic units, the geometry of the Cu(II) ions is distorted square-pyramidal, where both nitrogen atoms from one bpy and two oxygen atoms from two different p-aminobenzoate ions constitute the square plane and the apical positions are occupied by solvent or nitrate oxygen atoms. The geometry optimization of both units of the binuclear complex was carried out by taking the coordinates of the respective X-ray structures using DFT. The binding studies of the copper(II) complex with calf thymus DNA (CT-DNA) were explored by UV-Vis absorption, fluorescence spectroscopic, and cyclic voltammetric techniques. Also, the cleavage of pBR322 DNA with the binuclear copper(II) complex was studied using the gel electrophoresis method.

Graphical Abstract

Keywords:

• Copper complex
• X-ray crystal structure
• DNA cleavage
• DFT computation

Supplementary data

CCDC 2064717 contains the supplementary crystallographic data for [Cu₂(bpy)₂(4-Ab)₂(H₂O)(NO₃)][Cu₂(bpy)₂(4-Ab)₂(H₂O)₂](NO₃)₃(4-Ab)·3H₂O. This data can be obtained free of charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: [phone]; or E-mail: [email protected].

Acknowledgements

We are grateful to IIT-Madras, Chennai, for providing instrumental facilities such as IR, spectroscopy, X-ray crystallography, and Emission spectroscopy. The authors are also highly thankful to Dr Ahmad Husain and Dr Rudi Seidel for their timely assistance.

Disclosure statement

In the present paper, we have mentioned each and everything about the studies carried out at different places and each author have contributed their part of interest. No potential conflict of interest was reported by the authors.