Synthesis, characterization, X-ray Crystallography, Photoluminescence property and DNA binding activity of Co(II) and Ni(II) complexes of a pyrazole-containing Schiff-base ligand

Two new complexes, [Co(MPAFA)(3)](ClO4)(2) (1) and [Ni(MPAFA)(3)](NO3)(2)<middle dot>2H(2)O (2), of an 'NN' bidentate Schiff-base ligand, N-(furan-2-ylmethyl)-1-(5-methyl-1H-pyrazol-3-yl)methanimine (MPAFA), have been synthesized and characterized by physicochemical and spectral methods such as elemental analyses, conductance, IR, UV-Vis, and emission spectra. In both complexes, three ligands coordinate with a metal ion to form 1:3 complexes. Both 1 and 2 are distorted octahedral and cationic, behaving as 1:2 electrolytes. IR spectra showed that each of the ligands coordinates via the pyrazolyl tertiary nitrogen and the azomethine nitrogen atoms. Single crystal X-ray studies confirmed CoN6 and NiN6 coordination for 1 and 2, respectively, and showed that both complexes exhibit pi & mldr;pi stacking and various hydrogen bonding interactions. Both 1 and 2 are fluorescent and participate in DNA binding with calf thymus DNA (CT-DNA) via groove binding.