The synthesis of proton tranfer salts of some benzimidazole derivatives and their metal complexes, and investigation of their applications

In this study, a novel proton transfer salts have been prepared between 1H-benzimidazole, 2-aminobenzimidazole and 2-methylbenzimidazole and 2,6-pyridinedicarboxylic acid (DPC) and their twelve metal complexes have also been synthesized. After recrystallization, five metal complexes have yielded proper crystal for single X-ray diffraction studies. The structures of amorphous proton transfer salts (HBIDPC, HABIDPC, and HMBIDPC) have been characterized by 1H-NMR, 13C-NMR, FT-IR, UV-Vis methods and elemental analysis methods while the structures of metal complexes (FeDPC, FeHABIDPC, CoHABIDPC, NiHMBIDPC and CuHMBI) have been characterized by means of single crystal X-ray diffraction, magnetic susceptibility and molar conductivity methods, FT-IR, UV-Vis, elementary analaysis and ICP-OES techniques. The structures for amorphous metal complexes as CoHBIDPC, NiHBIDPC, CuHBIDPC, NiHABIDPC, CuHABIDPC, FeHMBIDPC and CoHMBIDPC have been proposed by using the above techniques except single crystal X-ray diffraction method. Besides, the antimicrobial activities of the starting materials, salts and their complexes was investigated in vitro against to gram positive bacteria Staphylococcus aureus (ATCC 29213) and gram negative bacteria Escherichia coli (ATCC 25922). MIC (minimum inhibitory consantration) values of the investigated compounds were found in the range of 600 and 1600 µg/mL for Staphylococcus aureus bacteria and in the range 500 and 1500 µg/mL for Escherichia coli bacteria.