Synthesis and fluorescent properties of 2-(1H-benzimidazol-2-yl)-phenol derivatives

Abstract

A high yield one pot synthesis of 2-(2-hydroxyaryl)-1H-benzimidazole derivatives by 2-hydroxy aromatic aldehydes with aromatic 1,2-diamines in the presence of manganese(III) acetate at room temperature was developed. Nine fluorescencers 2-(2-hydroxyaryl)-1H-benzimidazoles with substituent(s) X (X = H, CH3, CH3O, Cl) and two fluorescencers 2-(2-hydroxyaryl)-1H-naphth[2,3-d]imidazoles with substituent of H or Cl were prepared in 38-87% yield and the ultraviolet absorption and fluorescent spectra of the eleven compounds synthesized were measured in methanol. The fluorescent characteristics of the 2-(2-hydroxyaryl)benzimidazole derivatives prepared were investigated on the basis of excited-state intramolecular proton transfer mechanism, Stokes' shift, quantum yield, and the relationship between fluorescent intensity and the substituents were derived.