Supramolecular Assemblies and Anticancer Activities of Aminopyidine-Based Polynuclear and Mononuclear Co(II) Benzoates: Experimental and Theoretical Studies

Two new Co(II) coordination compounds viz. [Co(H2O)(bz)2(μ-3-Ampy)2]n (1) and [Co(4-Mebz)2(2-Ampy)2] (2) (where; bz = benzoate, 4-Mebz = 4-Methylbenzoate and Ampy = Aminopyridine) were synthesized and characterized by elemental (CHN), electronic spectroscopy, FT-IR spectroscopy, and thermogravimetric analysis (TGA). The crystal structures were determined by single crystal X-ray diffraction analysis, inferring that compound 1 crystallizes as a 3-Ampy bridged Co(II) coordination polymer; whereas, compound 2 crystallizes as mononuclear Co(II) compound. Compound 1 unfolds the presence of N‒H∙∙∙O, C‒H∙∙∙O, O‒H∙∙∙O, C‒H∙∙∙N and aromatic π∙∙∙π interactions; while for compound 2, N‒H∙∙∙O, C‒H∙∙∙O, C‒H∙∙∙C and C‒H∙∙∙π interactions are observed. Both the compounds showcase scarcely reported chelate ring interactions involving the benzoate moiety (chelate ring∙∙∙π in 1 and N‒H∙∙∙chelate ring in 2). We have also carried out theoretical studies comprising of combined QTAIM/NCI plot analysis, DFT energy calculation and MEP surface analysis to analyze the non-covalent interactions present in the crystal structures. As per QTAIM parameters, the predominance of π-stacking interactions over hydrogen bonds in stabilizing the assembly in compound 1 is affirmed. Likewise, in compound 2, both hydrogen bonding (HBs) and C–H···π interactions are deemed pivotal in stabilizing the dimeric assemblies. The in vitro antiproliferative activity of compounds 1 and 2 were evaluated against Dalton’s lymphoma (DL) malignant cancer cell lines using cytotoxicity and apoptosis assays which showcases higher cytoxicity of compound 1 (IC50 = 28 μM) over compound 2 (IC50 = 34 μM). Additionally, molecular docking study investigates the structure activity relationship of these compounds and to understand the molecular behavior after treatment.