Abstract: The design and synthesis of functionalized receptors for the development of potential chemosensors is an increasingly topical field in anion recognition chemistry. The incorporation of chromophores into the receptor, which are sensitive to the interactions between the host and guest molecules, has recently gained considerable attention due to their low detection limit. In this article a benzimidazole-based anion receptor 1 was designed and synthesized. The structure of compound 1 was confirmed through single crystal X-ray diffraction analysis. Anion binding studies carried out by using ¹H NMR and UV-Visible reveal that this compound exhibited the recognition towards AcO^-, H₂PO₄^-, OH^- in DMSO solutions. Receptor 1 showed dramatic color changes from light-yellow to red in the presence of AcO^-, H₂PO₄^-, OH^-. The intermolecular interactions between compound 1 and anions could be easily monitored by anion complexation-induced changes in UV-Vis absorption and by the “naked eye”.

Key words: 5,6-Dinitrobenzimidazole derivatives , Synthesis, Crystal structure, Anions recognition