New turn-on fluorescence sensors for Co2+ based on conjugated carbazole Schiff base

Two novel conjugated Schiff bases were prepared and characterized by IR, 1H NMR, and elementary analysis. Their fluorescence measurements indicated that both compounds have excellent performance on fluorescence emission, and the intensity of fluorescence emissions was enhanced sharply by adding Co2+. These compounds can be used as highly sensitive fluorescence turn-on sensors for Co2+ with the detection limit below 10−14 M.