Synthesis, spectroscopy and structural elucidation of two new Co^II and Ni^II complexes of pyrazole derived heterocyclic Schiff base ligand as potential anticancer and photocatalytic agents

Two new complexes I and II of general composition, [ML₃]X₂.nH₂O (where, M = Co^II and Ni^II for I and II, respectively, L = MPAFA, X = Br and n = 2) were synthesized from a pyrazolyl Schiff base ligand, MPAFA (L). I and II were characterised through several physico-chemical and spectroscopic techniques, viz., C, H, N analyses, estimation of metal contents, conductance and magnetic susceptibility measurements, IR, electronic and fluorescence spectral studies. Both the reported coordination complexes were cationic in nature and behaved as 1:2 electrolytes. According to IR spectra, each of the MPAFA molecule coordinated to the metal centres via the azomethine nitrogen and the pyrazolyl tertiary nitrogen atoms. Single crystal X-ray diffraction studies of I and II had established a N6 donor set with a distorted octahedral structure for both the cases. Both the complexes exhibited some non-covalent interactions, like π…π stacking, H-bonding contacts etc. L, I and II had also been found to possess fluorescence property. Anticancer activities of L, I and II had been investigated and it was found that both the complexes I and II were stronger cytotoxic agents against the breast cancer cell line MCF7 than the primary ligand system; while all of them (L, I and II) were less toxic against a non-cancerous cell line HEK293. All the compounds had shown potential photocatalytic activity in degrading methylene-blue (MB).