Synthesis, spectral and crystallographic study, DNA binding and molecular docking studies of homo dinuclear Co(II) and Ni(II) complexes M. Shahnawaz Khan a , Mohd Khalid a, * , M. Shahwaz Ahmad a , Musheer Ahmad b , Mo Ashafaq a , Rahisuddin c , Rizwan Arif c , M. Shahid a a Department of Chemistry, Aligarh Muslim University, Aligarh, 202002, India b Department of Applied Chemistry, Aligarh Muslim University, Aligarh, 202002, India c Department of Chemistry, Jamia Millia Islamia, New Delhi, India article info Article history: Received 27 July 2018 Received in revised form 13 August 2018 Accepted 16 August 2018 Available online 17 August 2018 Keywords: Homodinuclear complexes Crystal structure DNA binding Molecular docking abstract Two homo dinuclear metal complexes with composition [M 2 (pda) 2 (H 2 O) 5 ]$2H 2 O (M ¼ Ni 2þ and Co 2þ ) have been synthesized and characterized by elemental, spectral and thermal analysis (UVevis, FT-IR, Fluorescence, EPR, and TGA). The structures of complexes 1 and 2 have been determined by single crystal X-ray diffraction studies and the geometry around M(II) ion was elongated distorted octahedral. Binding studies of the complexes 1 and 2 with Ct-DNA was investigated by absorption, fluorescence and viscosity measurements. The experimental results of DNA binding studies were supported by theoretical (molecular docking analysis). DNA binding results reveal that complexes 1 and 2 bind to the minor groove of DNA and are stabilized through hydrogen bonding interactions. © 2018 Published by Elsevier B.V. 1. Introduction Coordination compound has always been a choice of study because of their great applications in wide-ranging areas from material sciences to biological sciences [1]. Especially, 3 d metal complexes are very well-known to stimulate the drug action since the efficacy of an organic drug increased upon coordination with a metal ion [2]. The nature of metal ion, as well as the type of ligand, played a crucial role in the pharmacological activity because of different metal and ligand exhibit different biological property [3]. From a bioinorganic chemist point of view, the coordination chemistry of functionalized carboxylate species has been a fasci- nating field due to glutamate and aspartate which contain car- boxylic function [4]. These glutamate and aspartate work as supporting ligand for the metal of various metalloproteinase [5]. Recent researches have revealed that the carboxylate group plays an important role in structural holding and proton transfer via hydrogen bonding interaction [6]. Chemistry of carboxylate group has been the most attractive synthetic target in recent time because the bimetallic core is the common structural motif for various O 2 metabolic non-heme Mn and Fe protein [7 ,8]. For example, all kind of pyridine dicarboxylic acid derivative (2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-) are very good choices for construction of simple coordination complex as well as metal-organic framework due to their trustable planer pyridine ring and carboxylate group, which is very rich in their coordination sites [9e15]. Among the pyridine dicarboxylic derivatives, pyridinee2,6edicarboxylic acid (H 2 pda) which is also known as dipicolinic acid is cheap versatile commercially available and water-soluble N, O, O donor ligand has played an essential role to participate in unusual coordination chemistry. H 2 pda forms stable chelates with simple metal ions and oxometal cations and can demonstrate wide varying coordination behavior, functioning as a multidentate ligand [15e20]. The reason for this interest is because H 2 pda is a planer ligand with rigid 120  angle between the central pyridine ring and the two carboxylate groups and hence could conceivably provide different coordination modes to form both discrete and consecutive metal complexes under appropriate synthesis conditions [20e24]. The binding of two or more car- boxylic groups in different angles allows the formulation of 1D (long chain), 2D (sheet) or 3D (cage) structure [25]. Furthermore, metal complexes of H 2 pda have also been used as electron carriers * Corresponding author. E-mail address: khalid215@gmail.com (M. Khalid). Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: http://www.elsevier.com/locate/molstruc https://doi.org/10.1016/j.molstruc.2018.08.048 0022-2860/© 2018 Published by Elsevier B.V. Journal of Molecular Structure 1175 (2019) 889e899