An efficient and versatile synthesis of 2, 2′-(alkanediyl)-bis-1H- benzimidazoles employing aqueous fluoroboric acid as catalyst: Density functional theory calculations and fluorescence studies

Abstract

2,2′-(Alkanediyl)-bis-1H-benzimidazoles (simple and mixed) with variable methylene spacers were synthesized in excellent yields with aqueous fluoroboric acid (45%) (0.1 ml) as catalyst under solvent-free conditions. Their optimized structures were obtained using DFT calculations where it was seen that the s-trans orientation of the two imidazole rings was preferred for all types of bis-benzimidazole systems. The X-ray crystal structure of one such bis-benzimidazole further corroborated this fact. Finally, photophysical studies were carried out to get insight into the fluorescence characteristics of the newly synthesized bis-1H-benzimidazoles. © ARKAT USA, Inc.