Synthesis, Spectral Characterizations and Antimicrobial Activity of 5-methoxy-2-(5-H/Me/F/Cl/Br/NO2/OMe-1H-benzimidazol-2-yl)-phenols and Their ZnCl2 Complexes

Abstract

5-Methoxy-2-(5-H/Me/F/Cl/Br/NO2/OMe-1H-benzimidazol-2-yl)-phenols (HL1- HL7) and their complexes with ZnCl2 were synthesized. The structures of the ligands and the complexes were confirmed on the basis of elemental analysis and FT-IR, FT Raman, H-1-NMR and fluorescence spectroscopic techniques. In addition, molar conductivity was carried out for the ZnCl2 complexes. In the complexes, the ligands acted as bidentate, via the imine nitrogen and the phenolate oxygen atoms. Fluorescence characteristics of the compounds were observed in ethanol: The ligands fluoresce as dual or triple whereas the complexes give dual or single fluorescence and most of them blue shifted. In addition, fluorescence spectra of HL1 were investigated in various solvents. The compounds were screened for in vitro antimicrobial activities against S. aureus, E. faecalis, E. coli I, E. coli II, K pneumoniae, P. aeruginosa, A. baumannii and for antifungal activity against C. albicans. The compounds HL4, [Zn(HL4)(2)Cl-2]center dot 2H(2)O, HL5, HL6 and [Zn(HL6)(2)O-2]center dot 4H(2)O exhibit antibacterial and antifungal activity against S. aureus, E. faecalis and C. albicans. It is observed that the Cl, Br and NO2 groups increase the antimicrobial activity toward S. aureus, E. faecalis and C. albicans. These results can be considered as selective activity.