ABSTRACT
The Schiff base ligands in their deprotonated forms have been utilized to synthesize thermodynamically and kinetically stabilized Cobalt(II) complexes. In the complexes, cobalt ion present is in distorted octahedral arrangement and is coordinated by four tridentate ligands in complexes. The synthesized Schiff base ligands coordinate with Cobalt (II) ion through four azomethine nitrogen atoms and two sulfur atoms developing a 6- membered chelate ring. Synthesized Cobalt(II) complexes via hexadentate ligands have been characterized thoroughly through various spectroscopic techniques like FT-IR, UV-Vis, 1HNMR, TGA, TEM, SEM, Particle size, Elemental analysis (C, H, N, Co, S) and conductivity measurements. All Cobalt(II) complexes have been evaluated for in vitro antimicrobial activity against isolated bacterial strains of E. coli (MTCC-1687), E. faecalis (MTCC-439), S. aureus (MTCC-737) and MR S. aureus (Indigenous). All Cobalt complexes show mild to moderate antibacterial activity. The MIC ranged from 50 µg/ mL to 3.125 µg/ mL. All Cobalt(II) complexes displayed in-vitro antibacterial activity against both gram-positive and gram-negative bacterial strains. It may be proved that the antibacterial activity of the complexes is related to the cell wall structure of the tested bacteria. In-vitro toxicity tests explained the Cobalt complexes were less cytotoxic than the Vancomycin drug on A431 cancer cell lines and the results explain that synthesized Cobalt complexes can act as potent antimicrobial agents and can be considered as a good drug candidate for medicinal chemistry researchers.
ABSTRACT
The title Zn (II) complex was synthesized by reacting the compound Bis-[(E)-3{2-(1-4-chlorophenyl) ethylidiene}hydrazinyl]-N-(4-methylphenyl)-3-oxo propanamide with Zn (II) chloride dihydrate in alkaline dimethylsulphoxide and ethanol solution under reflexing condition for 8 h. The resultant compound was filtered and recrystallized from ethanol. The hydrazone Schiff base ligand and its Zn (II) complex were characterized by using UV-Vis spectroscopy and XRD, TEM and SEM analysis. The antibacterial activities of ligand and its Zn complex were examined using disc diffusion method. The spectra results showed that the hydrazone ligand undergoes keto-enoltautomerism forming a bidentated ligand (N,N) towards Zn+2 (II) ion. It is very interesting that on sides of the two hydrazone ligands which coordinate to the Zn+2 ions, an additional two thiosemicarbazine moiety were also coordinated with Zn+2 ions in the crystalline powder, resulting in a hexa coordinated octahedral Zn (II) complex. Both hydrazone Schiff base ligand and its Zn (II) complex were found to exhibit good antibacterial activity even when the concentrations were high. Molecular docking analysis also deciphered that Zinc complex and carbohydrazone ligand both were found to be fitted into the active sites of molecular targets and Zn complex showed better binding affinities towards macromolecules compared to ligand.
ABSTRACT
New complexes of Co(II), Ni(II), Cu(II), Cd (II), Pt(II),and Pd(II) with 4-(trifluoro-4-ylidene) hydrazine carbothioamide have been synthesized. All the new compounds were characterized by elemental analysis, molar conductance measurements, magnetic susceptibility measurements, LC-MS. H1NMR, FTIR and electronic spectral studies. Based on the molar conductance measurements in DMF the complexes may be formulated as [Ni(L)2Cl2] and [M(L)2]X2 (where M = Co (II), Cu (II), Cd (II), Pt (II) and Pd(II) and X = Cl - , CH3COO - due to their non electrolytic nature respectively. The antimicrobial activities of the ligand and their complexes have been studied by screening the compounds against the bacteria E. coli and S. aureus and also the fungi Asperillius niger and candida albicans and results have been compared with standard drug streptomycin and fluconazole. The data indicate that the metal complexes have higher antimicrobial activity than the free ligand and the standard drug. The DNA cleavage experiments, performed using gel electrophoresis with the corresponding metal complexes in the presence of H2O2 showed that all the complexes afford a pronounced discernible DNA cleavage evidenced by the disappearance of form I (supercoiled) of DNA and the production of formII (Linear).