Synthesis, X-ray crystal structure and optical properties of novel 2-aryl-3-ethoxycarbonyl-4-phenylpyrido[1,2-a]benzimidazoles

A series of novel 2‐aryl‐3‐ethoxycarbonyl‐4‐phenylpyrido1,2‐a]benzimidazole derivatives were synthesized by the tandem reaction of 2‐benzoyl benzimidazole and (Z)‐ethyl 4‐bromo‐3‐arylbut‐2‐enoate in the presence of potassium carbonate. The compounds were characterized using IR, ¹H‐NMR, ¹³C‐NMR, HRMS and the structure of 6f was further determined by X‐ray crystallography. Both absorption and fluorescence spectra characteristics of the compounds were investigated in acetonitrile and dichloromethane. The results showed that the absorption maxima of the compounds varied from 220 to 284 nm, depending on the structure of 2‐aryl group. The fluorescence results revealed that these compounds exhibited blue‐green fluorescence (463–475 nm) in dilute solutions and showed acceptable fluorescence quantum yields (Ф_PL = 0.13–0.73) in dichloromethane. Copyright © 2011 John Wiley & Sons, Ltd.