Carbohydrate triazole tethered 2-pyridyl-benzimidazole ligands: Synthesis of their palladium (II) complexes and antimicrobial activities

• This article illustrates the synthetic route for tagging biomolecules to benzimidazole moiety.
• The palladium (II) complexes were prepared with modified benzimidazole ligands.
• Few ligands and metal complexes have shown high antibacterial activity compared to streptomycin.

A series of carbohydrate-tethered 1-triazolyl-2-pyridyl-benzimidazole ligands have been prepared and the antimicrobial activity of their Pd(II) complexes has been studied. The alkyne, 1-propargyl-2-pyridyl-benzimidazole (2) was synthesized by the reaction of 2-pyridyl-benzimidazole and propargyl bromide in the presence of sodium hydride. The carbohydrate triazoles (4a-e) were synthesized by the Huisgen 1,3-dipolar cycloaddition reaction of alkyne (2) and different carbohydrate azides (3a-e). For comparative studies, benzyl triazole ligand (4f) was also synthesized. The palladium complexes (5a-f and 6), obtained from the reaction of the ligands (4a-f and 2 respectively) and Pd(COD)Cl2 (1:1 ratio) in dichloromethane solution, were characterized by NMR, mass and elemental analysis. All the ligands and metal complexes were tested for the antibacterial activity against Gram positive and Gram negative bacterial strains. In this study, the ligands have displayed superior antimicrobial activity as compared to their corresponding metal complexes.

In this article, we report the synthesis of a series of palladium (II) complexes of carbohydrate triazoles derived form 2-pyridyl-benzimidazole. The ligands and metal complexes were characterized by spectroscopic means and they were screened for the antimicrobial activity.Figure optionsDownload as PowerPoint slide