Synthesis of π-Expanded Azole-Fused Imidazo[1,2-a]pyridine Derivatives and their Photophysical Properties

Abstract

Structurally diverse imidazo[1,2-a]pyrido[2',1':2,3]imidazo[4,5-c]quinoline derivatives and benzo[4,5]imidazo[1,2-a]pyrido[2',1':2,3]-imidazo[4,5-c]-quinoline derivatives have been prepared from 2-(2-bromophenyl)-imidazo[1,2-a]pyridine-3-carbaldehyde in a one-pot, two-step method in good to excellent (50–85 %) yields. Photophysical properties (absorption and emission) and solvatochromism of these π-expanded compounds have been evelauted. The azole-fused imidazo[1,2-a]pyridines showed a high fluorescence emission with moderate to good quantum yields.