Metal-based Antimicrobial Agents: Synthesis, Characterization and Biological Studies of Mannich Base Derivatives of Benzimidazole and Their Metal Complexes

Abstract

Novel Mannich base derivatives of Benzimidazole were prepared through the condensation reaction of benzimidazole derivative with formaldehyde and primary and/ secondary amine. Zinc(II), copper(II), nickel(II) and cobalt(II) complexes of Mannich bases have also been synthesized. All the compounds were fully characterized by, elemental analyses, magnetic moment determination, molar conductivity measurement, thermogravimetric analysis, spectral and analytical data. Experimental results showed that metal complexes act as bi-dentate ligands towards divalent metal ions via azomethine-N and deprotonated-O while suggesting an octahedral geometry. All the compounds were screened for in-vitro antibacterial and antifungal activity against various bacterial and fungal strains. Almost all the compounds showed good potent activity against microorganisms. It was also seen that compounds with complexed form were more active as compared to un-complexed form. The prepared compounds were also screened for their cytotoxicity and results showed that only Ni(II) complexes exhibit some cytotoxicity while all other compounds were almost inactive.

Synthesis, structural and photo-physical studies of transition metal complexes with Mannich bases derived from 2-mercaptobenzimidazole

“…The comparison of IR spectral data of ligands and metal complexes also revealed the coordination through nitrogen (N) and sulfur (S). The results are in agreement with [23][24][25].…”

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“…Absorbance in the UV-Visible region was recorded in DMF solution using UV-Visible spectrometer. The 1 H & 13 C NMR of the Ligand was recorded on a Bruker instrument employing TMS as an internal reference and DMSO -DMF as solvent. The mass spectral study of the Ligand was carried out using LC mass spectrometer.…”

Synthesis and characterization complexes of bis (2-mercaptobenzimidazole) mercury (II) with transition metal (Ni (II), Pd (II), and Pt (II))

“…The spectra of the ligand exhibited band at 1514 cm -1 due to the V(C=N) group of the ligand and when the complexes were formed this spectra were shifted to higher or lower frequency in the range (1622-1490)cm -1 which indicate that the ligand was bonded to the metal ion through N atom of V(C=N)group (Kennedy et al, 1972, Mohammed et al, 2013, Anandarajagopal et al, 2010, Ganesh et al, 2011, Akira et al, 1970, Rehman et al, 2013, also the ligand showed band at (736)cm -1 due to the V(C-S) group of the ligand and this band was shifted to higher or lower frequency in the range (742-725)cm -1 during the complexes which indicate that the ligand was bonded to the metal ion through sulphur atom (Zora et al, 2002, Butrus et al, 2012, Irshad et al,2010, Khullar et al,1975 .The infrared spectra of the prepared complexes show band in the range (451-412) cm -1 , which are attributed to V (M-N) . On the other hand, it has been observed that in the spectra of all compounds, the bands at (310-290) cm -1 were assigned to V (Hg-S) (Carlo et al, 1977, Musa, 1998, Awaz, 2015.…”