Structural, Spectroscopic Insights, And Antimicrobial Properties Of Mononuclear And Dinuclear Metal(Ii) Carboxylate Derivatives With Metronidazole

A dinuclear paddle-wheel complex [Cu-2(PTA)(4)(mnz)(2)] (1) and mononuclear [M(BBA)(2)(mnz)(2)(H2O)(2)] complexes, where PTA = p-methylbenzoate, BBA = 2-bromobenzoate, mnz = metronidazole and M = Cu (II) (2), Co(II) ( 3), Ni(II) (4), Zn(II) (5), Cd(II) (6) were prepared by adding metronidazole to the mixture of divalent metal nitrate salts and arylcarboxylate acid in alkaline aqueous solution under ambient conditions. The complexes were characterized by elemental analysis, spectroscopy (FTIR, UV-visible and NIR-Vis-UV), single crystal X-ray diffraction (SCXRD), Hirshfeld surface analysis and High-Field EPR. The asymmetry of the d - d bands observed in the electronic diffuse - reflectance spectra of cobalt(II) and nickel(II) complexes is due to the symmetry lowering from Oh to elongated D-4h in trans - [MN2O2O2'] chromophores. Large zero-field splitting was observed in the HF EPR spectra of the Ni(II) and Co(II) complexes which was modeled by using the CASSCF method. The antimicrobial activity was studied using the agar well diffusion method. The antimicrobial tests of these new compounds were carried out on Candida albicans and five bacterial strains (three Gram-negative and two Gram-positive), and were compared to their respective parent ligands. A broad antimicrobial spectrum was observed in some of the complexes. (C) 2020 Elsevier Ltd. All rights reserved.