Schiff base metal complexes of 4-methyl-1H-indol-3-carbaldehyde derivative as a series of potential antioxidants and antimicrobial: Synthesis, spectroscopic characterization and 3D molecular modeling

• Published in: Journal of molecular structure 2019-11, Vol.1195, p.220-230
• Main Authors: EL-Gammal, Ohyla A., Alshater, Heba, El-Boraey, Hanaa A.
• Format: Article
• Language: English
• Subjects: Antimicrobial activity; Antioxidants; IC50; Modeling; Mono and binuclear metal complexes; Spectroscopic studies
• ISSN: 0022-2860; 1872-8014
• DOI: 10.1016/j.molstruc.2019.05.101

Novel mononuclear Fe(III), Cu(II), Cd(II), Sn(IV) and binuclear Ni(II) and Hg(II) complexes with the Schiff base ligand: (E)-N'-((4-methyl-1H-indol-3-yl)methylene) nicotinohydrazide were synthesized. The elucidation of the structure of the prepared compounds were performed by elemental analyses, magnetic measurements, thermogravimetry, 3D molecular modeling, molar conductance techniques and by various spectroscopic (IR, 1H NMR, UV–Visible, EPR) tools. Antioxidant activity in vitro by DPPH scanning of the ligand and its metal complexes was studied. The results indicated that all test compounds are excellent antioxidants and better than the standard (Ascorbic acid).[Sn(HL)Cl2(OH)2]·2H2O complex (5) showed the highest antioxidant activity. Moreover, the ligand and its metal complexes were screened against the sensitive organisms Staphylococcus aureus as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and two strains of fungi (Aspergillus flavus and Candida albicans). The results showed that all metal complexes have higher antimicrobial activity than the metal free ligand and the binuclear [Hg2(HL)Cl4]·EtOH complex (6) possessed excellent antibacterial activity better than the standard drug Ampicillin (antibacterial agent) and showed excellent antifungal activity against Aspergillus flavus, better than Amphotericin B (antifungal agent). •Mononuclear and binuclear metal complexes were synthesized and characterized.•Analytical, spectral, thermal and molecular modeling data confirmed their structure.•All compounds showed excellent DPPH scavenging activity better than ascorbic acid.•All complexes have higher antimicrobial activity than that of the free ligand.•Hg(II) complex (6) possessed antimicrobial activity better than that of the standard drugs.