The synthesis, characterization and optical properties of novel pyrido[1,2-a]benzimidazole derivatives

A series of novel substituted pyrido[1 2-a]benzimidazole derivatives were synthesized using a novel tandem annulation reaction between 2-acylbenzimidazole derivatives and 4-bromobut-2-enoic esters under mild conditions The compounds were characterized using IR H-1 NMR C-13 NMR and HRMS the crystal structure of 2 7 8-trimethyl-3-ethoxycarbonyl-4-phenylpyrido[1 2-a]benzimidazole was determined as orthorhombic The absorbance and fluorescence spectra of the pyrido[1 2-a]benzimidazoles were measured in dichloromethane an intense absorption maxima was observed at 250 nm and emission maxima were noted at 460 nm The absorption spectra and fluorescence characteristics of the pyrido[1 2-a]benzimidazole derivatives revealed that a phenyl and a methyl group attached to the pyrido [1 2-a]benzimidazole ring markedly influenced maximum emission (C) 2010 Elsevier Ltd All rights reserved