In this study, synthesis and structural illumination of eight compounds that are expected to display antifungal and antibacterial activity in addition to interaction with DnA has been conducted. The syntheses were performed by heating o-phenylendiamine and derivatives with succinic acid and maIonic acid in 4N HCl. It has been observed that, the reactions with succinic acid formed bisbenzimidazole derivatives. On the other hand, the reactions with the malonic acid under the same conditions resulted in formation of benzimidazole derivatives instead of bisbenzimidazole derivatives. The structures of all synthesized compounds were analysed with spectroscopic methods (UV, IR, ¹H NMR, MS). Among the synthesized compounds, 1 and 5 which are nonsubstitue compounds, were selected so as to dispose the roles of electron acceptor or donor atoms in the activity and their interaction with DNA has been examined with respect to concentration and time. When these two compounds were compared, it 's seen that 1 requires higher concentrations and longer time to be able to interact with DNA. In addition, all compounds have been examined for antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, and for antifungal activities against Candida albicans. It was found that 7 was the most effective compound against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, 5 was the most effective compound against Enterococcus faecalis, 7 and 8 were effective equivalently against Candida albicans.

Keywords: Bisbenzimidazole, Benzimidazole, Antimicrobial activity, Electrochemical detection, The interaction with DNA