Benzimidazole quinoline derivatives — An effective green fluorescent dye for bacterial imaging

A one-pot synthesis of benzimidazoles by condensing naphthyl or quinoline aldehyde with benzene-1,2-diamine has been reported. IR, 1H and 13C NMR, mass spectral, and CHN analyses were used to elucidate the structures of the products. The molecular structural correlation in the optical properties of the quinoline and naphthalene benzimidazoles was explored. The fluorescence quantum yield ([Formula: see text]) and time-resolved fluorescent lifetime of the quinoline benzimidazoles derivatives were estimated. The influence of solvent polarity and pH on the optical property of quinoline derivatives was illustrated. To explore the bioanalytical applicability, the thermal stability by TG–DTA analysis and the cytogenetic analysis of 3-(1H-benzoimidazol-2-yl)-2-chloro-8-methyl-quinoline (1b) compound were carried out. The fluorescent staining ability of 1b was analyzed and also compared with the normal Gram staining in the bacterium.