Supramolecular assemblies involving biologically relevant antiparallel π-stacking and unconventional solvent driven structural topology in maleato and fumarato bridged Zn(II) coordination polymers: antiproliferative evaluation and theoretical studies

Two new coordination polymers of Zn(ii), viz. {[Zn(Hdmpz)(2)(mu-male)]center dot(MeOH)(H2O)}(n) (1) and [Zn(3-AMpy)(2)(mu-fum)(H2O)(2)](n) (2) (where Hdmpz = 3,5-dimethylpyrazole, male = maleate, fum = fumarate, and 3-AMpy = 3-aminopyridine), have been synthesized and characterized using elemental analysis, TGA, spectroscopic and single crystal X-ray diffraction techniques. The 1D polymeric chains of the polymers self-assemble into 2D supramolecular architectures via several non-covalent interactions. Differences in the structural topologies have been observed with the change of solvent from the methanol-water mixture in compound 1 to de-ionized water in compound 2. Unconventional enclathration of the solvent molecules, viz. MeOH, and the water in the crystal structure of 1 results in an interesting layered assembly. The influences of the metal coordination on the strength of the pi-stacking interactions have been explored theoretically for compound 2, which confirms that the coordination of 3-AMpy to the Zn(II) centre strongly polarizes the pi-cloud and increases the local dipole of 3-AMpy, thereby enhancing the strength of pi-stacking interactions. The in vitro anticancer activities of the compounds have been explored in Dalton's lymphoma cancer cell lines considering cell cytotoxicity and apoptosis, and the results were compared with those observed for cisplatin (reference drug) under the same experimental conditions. The in silico molecular docking studies and the pharmacophore features further corroborate the cytotoxicity and apoptosis inducing ability of the compounds.

Automated summary

Two new coordination polymers of Zn(ii) have been synthesized and characterized, forming different structural topologies influenced by solvents. Metal coordination has been found to enhance the strength of pi-stacking interactions theoretically. The compounds exhibited in vitro anticancer activities and apoptosis-inducing abilities.