Synthesis and Optical Properties of Novel Fluorescence‐Traced Benzimidazolium Bromides

Seven novel fluorescence-traced 1-aryl-2-substituted-3-allyl-1H-benzimidazolium bromides (5a, 5b, 5c, 5d, 5e, 5f, 5g) were synthesized by alkylation and quaternization of compounds 1-aryl-2-substituted-1H-benzimidazoles (4a, 4b, 4c, 4d, 4e, 4f, 4g) with excess allyl bromide in acetonitrile at refluxing temperature. Their structures were characterized by 1H-NMR, MS, and elemental analysis. They emit violet-blue light (Emmax=386-438nm) with fluorescence quantum yields of 0.54 to 0.75 in aqueous solution.