Molecular design and synthesis of benzimidazole heterocycle : a model molecule for a hydrogen bonded proton transfer network

Abstract

A series of difunctional benzimidazole-based compound, i.e., l,4-di (1H- benzo[d]imidazol-2-yl) benzene, 1, and 3,5-di(1H-benzo[d]imidazol-2- yl)benzenamine, 2 are designed as model compounds for the proton transferring pathway in water free system. The model compound 1 is developed by cyclizing terephthaloyl chloride and 1,2-phenylenediamine via amidation and ring closure reactions. In the same pathway, 5-aminoisophthalic acid and 1,2-phenylenediamine as the starting materials for 2 is also proposed. The work also shows how the reaction is effective if the amino group of 5-aminoisophthalic acid is protected during the reaction. The structures of the compounds are characterized by using FT-IR, 1H- NMR, MALDI-TOF and EA techniques.