Novel dithieno-benzo-imidazole-based Pb2+ sensors: substituent effects on sensitivity and reversibility.

Two novel dithieno-benzo-imidazole-based compounds (M2 and A2) showed remarkable sensitivities towards Pb2+ by 12-fold enhancement and 10-fold decay of fluorescence, respectively, in aqueous solutions. Substituent effects of different dithieno-benzo-imidazole-based moieties (M1, M2, A1 and A2) on the quantum yields, fluorescence lifetimes and sensitivities to Pb2+ along with the reversibilities by S2- were investigated.