Co(II) complexes derived from (1-methyl-1H-imidazol-2-yl)methanol: Synthesis, characterization, spectroscopic study, DFT/TD-DFT calculations and biological evaluation

Abstract

We report in this paper, a combined experimental and theoretical study of two new Co(II) complexes [Co(OAc)2(L)2 (1) and CoCl2(L)2 (2)] based on (1-methyl-1H-imidazol-2-yl)methanol (L). The synthetized complexes were characterized by single-crystal X-ray diffraction, FT-IR and UV–Vis. spectroscopy. In complex 1, two molecules of L are coordinated to the Co(II) ion in bidentate mode through the nitrogen and oxygen atoms, displaying a hexa-coordinated compound in a distorted octahedral geometry, while in complex 2, L is ligated to the metal ion in monodentate fashion through the nitrogen atom exhibiting a distorted tetrahedron. The molecular geometries, electronic transitions and vibrational frequencies of the two complexes and L in the ground state were calculated using the global hybrid (B3LYP) and the range separated hybrid (CAM-B3LYP) density functional. The theoretical calculations are in good agreement with the experimental values. The ligand and its Co(II) complexes have been screened and evaluated for their potential as DPPH radical scavengers as well as antimicrobial agents against five pathogenic microorganisms such as Gram-positive and Gram-negative bacteria, a yeast and a fungus. The SAR study revealed that complex 1 exhibited the best antimicrobial effects and higher antioxidant activity than complex 2 and L.