Spectroscopic studies, structural characterization and electrochemical studies of two cobalt (III) complexes with tridentate hydrazone Schiff base ligands: Evaluation of antibacterial activities, DNA‐binding, BSA interaction and molecular docking

Abstract

Co(III) complexes of tridentate Schiff base ligands derived from N‐(2‐hydroxybenzylideneamino)benzamide (H2L1) and 2‐(2‐hydroxybenzylidene)hydrazine‐1‐carboxamide (H2L2) were synthesized and characterized using IR, Raman, 1H–NMR and UV–Vis spectroscopies. X‐ray single crystal structures of complexes 1 and 2 have also been determined, and it was indicated that these Co(III) complexes are in a distorted octahedral geometry. The cyclic voltammetry (CV) of the complexes indicates an irreversible redox behavior for both complexes 1 and 2. The antibacterial effects of the synthesized compounds have been tested by minimum inhibitory concentration and minimum bactericidal concentration methods, which suggested that the metal complexes exhibit better antibacterial effects than the ligands against Gram‐positive bacteria. The effects of the drug (drug = ligands and complexes) on bovine serum albumin (BSA) were examined using circular dichroism (CD) spectropolarimetry, and it was revealed that the BSA (BSA, as a carrier protein) secondary structure changed in the presence of the drug. Interaction of the drug with calf‐thymus DNA (CT‐DNA) was investigated by UV–Vis absorption, fluorescence emission, CV and CD spectroscopy. Binding constants were determined using UV–Vis absorption. The results indicated that the studied Schiff bases bind to DNA, with the hyperchromic effect and non‐intercalative mode in which the metal complexes are more effective than ligands. Furthermore, molecular docking simulation was used to obtain the energetic and binding sites for the interaction of the complexes with Mycobacterium tuberculosis enoyl‐acyl carrier protein reductase (InhA), and results showed that complex 1 has more binding energy.

Experimental and theoretical studies of new Co(III) complexes of hydrazide derivatives proposed as multi‐target inhibitors of SARS‐CoV‐2

“…The spectra of complex electron transitions relative to the ligands showed bands in the higher regions, which include absorption bands in the regions of 335, 349, 400, and 427 nm (for complex ( 1 )), 328, 346, 392, and 415 nm (for complex ( 2 )), and 336, 412, and 434 nm (for complex ( 3 )), which correspond to the intra‐ligand transitions of the azomethine group and the metal‐to‐ligand charge transfer (MLCT) transitions. [ 63‐65 ] These absorption bands at a high wavelength confirm the coordination of the cobalt(III) ion to the azomethine group (CN). Also, the wide shoulders observed in the 545, 614, and 668 nm regions are assigned to d → d transitions in cobalt complexes ( 1–3 ), respectively.…”

“…Also, these results prove the coordination of the (O) 2‐hydroxy benzaldehyde ring of the ligand to the cobalt(III) ion. [ 63–65 ]…”

“…Also, the wide shoulders observed in the 545, 614, and 668 nm regions are assigned to d → d transitions in cobalt complexes ( 1–3 ), respectively. [ 64 ]…”

“…According to the results obtained from the redox process, the potential observed in the cathodic range of À0.71 V to reduce Co (III) /Co (II) and in the range of À0.54 V is also related to the oxidation process of Co (II) /Co (III) . [64] 3.6 | Computational chemistry and DFT calculations…”

Combined Alkylating Agents as a Resolution for Highly Selective N-Alkylation of 2-Hydroxybenzaldehyde Acylhydrazones

“…7 As such, these complexes might be potentially useful for the treatment of cancer, 8,9 Alzheimer's disease, 10 inflammation, 11 or diseases caused by Gram-positive bacteria. 12 Previous studies have shown that the introduction of a methyl group onto the acylated nitrogen atom of acylhydrazones can lead to distinct biological responses. 3,[13][14][15] Although N-alkylation is of great interest, only limited range of N-alkyl derivatives of acylhydrazones are Scheme 1 N-Alkylation of 2-hydroxybenzaldehyde acylhydrazones known.…”