Supramolecular assemblies in fumarato and succinato based Mn(II) and Ni(II) coordination solids involving pyridine and phenanthroline: Anticancer activities and theoretical studies

Two new coordination compounds [Mn(3-Mepy)₂(µ-fum)(H₂O)₂]_n (1) and [Ni(phen)(succH_0.5)(H₂O)₃](NO₃)_0.5·2H₂O (2) (3-Mepy = 3-Methylpyridine, phen = 1,10-phenanthroline, fum = fumarate, succH = monoanion of succinic acid) were synthesized and characterized by SCXRD technique, electronic, FT-IR spectroscopy and thermogravimetric analysis (TGA). Polymer compound 1 exhibits two distinct polymeric chains with identical coordination environment, slightly differing in bond distances and bond angles surrounding the Mn(II) metal centres. The polymeric chains are interconnected via various hydrogen-bonding and π-stacking interactions forming the 2D supramolecular layered architecture. Crystal structure analysis of 2, a Ni(II) monomer, reveals the enclathration of dual guest water molecules and nitrate anions in Ni(II) supramolecular host cavities. DFT (Density Functional Theory) was used to analyze the important non-covalent interactions present in the crystal structures of the compounds. Moreover, MEP (Molecular Electrostatic Potential) surface calculations, QTAIM (Quantum Theory of Atoms In Molecules), and NCI (Non-Covalent Interaction) plot analyses were also employed to rationalize and characterize these interactions. Computational studies confirm the strong stabilizing role of the network of H-bonds and π-stacking interactions in extending the polymeric chains into 2D supramolecular architectures in compound 1. Similarly, for compound 2, the QTAIM/NCI plot analysis of the H-bonded self-assembled dimer, reveals the contribution of O–H···O and C–H···O H-bonds. The in vitro cytotoxicity of compounds 1 and 2 were evaluated against Dalton’s lymphoma (DL) cancer cell line supported by Trypan blue assay and LDH (Lactate Dehydrogenase) leakage parameters. Apoptosis was investigated through dual fluorochrome staining and mitochondrial membrane potential (MMP) studies. Results demonstrated that both the compounds induced cytotoxicity and apoptosis in DL cells, highlighting their potential as therapeutic agents for further study.