Synthesis, crystal structure and spectroscopic study of novel benzimidazoles and benzimidazo[1,2-a]quinolines as potential chemosensors for different cations

In this manuscript the synthesis, crystal structure, spectroscopic characterization and titration with several metal chloride salts of novel E-3-phenyl-2-(1-phenylbenzimidazol-2-yl)acrylonitriles and 5-phenylbenzimidazo[1,2-a]quinoline derivatives are described. All compounds were characterized by means of 1H, 13C NMR, MS, UV/Vis and fluorescence spectroscopy. Crystal and molecular structures of E-3-(4-nitrophenyl)-2-(1-phenyl-benzimidazol-2-yl)acrylonitrile and 5-phenylbenzimidazo[1,2-a]quinoline-6-carbonitrile were determined by single-crystal X-ray diffractometry. The molecular assembly is characterized by the C–H···O and C–H···N intermolecular hydrogen bonds in E-3-(4-nitrophenyl)-2-(1-phenyl-benzimidazol-2-yl)acrylonitrile and 5-phenylbenzimidazo[1,2-a]quinoline-6-carbonitrile, respectively. Spectroscopic characterization of the prepared compounds was performed by using UV/Vis and fluorescence spectroscopy in ethanol. In order to determine a selectivity towards a variety of cations, to explore their use as potential chemosensors, the amino substituted 5-phenylbenzimidazo[1,2-a]quinoline-6-carbonitrile was chosen for a titration with metal chloride salts using fluorescence spectroscopy. The fluorescence intensity significantly increased upon addition of Zn2+ and Ag+ cations while decreased by addition of Mn2+, Co2+, Cu2+, Hg2+, Li+ and Fe3+ cations.