A novel benzimidazole based cadmium (II) dinuclear complex as bioactive material with different coordination number and their interactions with BSA and HSA: Synthesis, characterization and docking studies

A novel dinuclear cadmium (II) complex [Cd-2(H4PDTB)(eta (Schenk et al., 2012 [1])-NO3)(2)(eta (Mitic et al., 2006 [2])-NO3)(2)H2O]center dot 3H(2)O having symmetrical ligand N,N,N',N'-tetrakis-(1H-benzimidazol-2ylmethyl)propane-1,3-diamine (H4PDTB) having N-6 donor set was synthesized. It was thoroughly characterized by different spectroscopic and elemental analysis. Single crystals of the dinuclear metal complex were grown and the structure of the complex was authenticated by X-ray crystal structure determination. The structural investigations revealed that the two metal centres rest in remarkably different coordination environments. The dinuclear complex comprised of two crystallographically unique metal centres exhibiting coordination number asymmetry despite symmetric nature of the H4PDTB ligand. The ancillary nitrato-ligand also exhibited dual binding behaviour towards cadmium (II) centres. It coordinated to the first metal centre (Cd1) only in monodentate fashion whereas it exhibited only bidentate binding mode with second metal centre (Cd2). The dinuclear cadmium (II) complex presented in this report sets the first example of coordination number asymmetric metal complex bearing symmetric ligand without any endogenous bridge to date. Photoluminescence properties of the ligand and the dinuclear metal complex were investigated in the solution state and enhancement in emission intensity was observed after complexation. Furthermore, binding of the synthesized complex to bovine serum albumin (BSA) and human serum albumin (HSA) was studied using computational tools. (C) 2021 Elsevier B.V. All rights reserved.