Co(II), Ni(II) and Cu(II) ternary complexes with sulfadiazine and dimethylformamide: Synthesis, spectroscopic characterization, crystallographic study and antibacterial activity

Abstract

Sulfadiazine Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized. The crystal structure of the cobalt(II) complex, for short [Co(SDZ)2(DMF)2], was determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P2 1/c with Z= 2 molecules per unit cell. The complex is centre-symmetric with the metal at the centre of a rectangular bi-pyramid environment (CoN4O2 core), coordinated at the bi-pyramid base to two SDZ molecules and at the apices to two DMF solvent molecules. The crystal structure determination was combined with Hirshfeld surface analysis to obtain detailed information on the intermolecular interactions that stabilizes the crystal packing. The nature and strength of the Co-N and Co-O bonds were investigated by the natural bond orbital (NBO) analysis and the atoms in molecules (AIM) approach. Based on NBO and AIM analysis, the shorter Co-N4 bonds are more covalent in nature than Co-O bonds. The antibacterial assays of the metal complexes revealed lower activity than the free ligand, probably due to their low solubility in water. However, their low toxicity as compared with SDZ makes them potential alternatives against other microorganisms, and/or biological targets.