Enclathration of Mn(II)(H2O)6 guests and unusual Cu⋯O bonding contacts in supramolecular assemblies of Mn(II) Co-crystal hydrate and Cu(II) Pyridinedicarboxylate: Antiproliferative evaluation and theoretical studies

Abstract

Two new coordination compounds of Mn(II) and Cu(II) involving 2,6-pyridinedicarboxylate viz. [Mn3(2,6-PDC)4(H2O)4][Mn(H2O)6]·8H2O (1) and [Cu(2,6-PDC)(H2O)(4-CNpy)]·H2O (2) (2,6-PDC = 2,6-pyridinedicarboxylate, 4-CNpy = 4-cyanopyridine) have been synthesized at room temperature. Compound 1 crystallizes as a co-crystal hydrate of Mn(II); whereas compound 2 is a mononuclear compound of Cu(II). Crystal structure analysis of 1 unfolds the presence of Mn(II)(H2O)6 guests within the supramolecular host cavities formed by anionic complex moieties and lattice water molecules. The lattice water molecules of the compounds 1 and 2 are involved in the formation of (H2O)2 cores which are enclathrated in the supramolecular host cavities. Furthermore, the unconventional anion⋯π, antiparallel CN⋯CN, CO⋯CO, CR⋯CR (CR: chelate ring) and Cu⋯O bonding interactions observed in compound 2 play crucial role to the stability of the crystal structure. Theoretical calculations confirm that the H-bonding network in 1 and anion-π, unconventional Cu···O bonds, antiparallel CO···CO along with CR···CR interactions in 2 play crucial roles in the solid state stability of the compounds. In vitro anticancer activities of the compounds considering cell viability and apoptosis assays against Dalton's lymphoma (DL) cancer cell lines reveal that the compounds induce considerable cytotoxicity in DL cells with negligible cytotoxicity in normal PBMC cells. Lactate dehydrogenase (LDH) leakage assay also unfolds the release of LDH from DL cells to extracellular space suggesting the irreversible cell death with cell membrane damage. The molecular docking simulations of the compounds further demonstrate the structure activity relationships involving the active sites of some important antiapoptotic proteins.