Turn-on fluorescent chemosensor for selective detection of Zn^{2 +} in an aqueous solution: Experimental and theoretical studies

A new simple receptor 1 based on the combination of julolidine and 2-(aminomethyl)benzenamine groups was prepared. It exhibited a 'turn-on fluorescence type' mode with high selectivity in the presence of Zn^{2 +}. Noticeably, receptor 1 could clearly distinguish Zn^{2 +} from Cd^{2 +}. The mechanism of fluorescence enhancement of 1 for zinc was explained by theoretical calculations. Moreover, sensor 1 had a sufficiently low detection limit (10.9 μM), which is below than the WHO recommendation level (76 μM) for drinking water. Therefore, 1 can serve as a practical chemosensor for zinc ion in an aqueous solution.