Highly selective and sensitive fluorometric probe for Cd2+ ions based on 4-(quinolin-2-ylmethylene)aminoanisole Schiff base

Herein, we report a reversible and easy assembled fluorometric probe (4-(quinolin-2-ylmethylene)aminoanisole, QMAA ) for the highly selective and sensitive detection of cadmium ion (Cd 2+ ) in DMF solution with PBS buffer (0.01 M, pH = 7.30). The strong fluorescence response of QMAA to Cd 2+ along with a bright blue fluorescence was mainly ascribed to the formation of the complex QMAA–CdCl 2 . The results show that the complexation can inhibit the C N isomerisation and photo–induced electron transfer (PET), and further lead to the occurrence of chelation fluorescence enhancement. The 1:1 stoichiometry of the complex between QMAA and cadmium ion was studied by fluorescence titration, Job’s plot analysis, 1 H NMR, FT–IR, and ESI–MS data, and was further confirmed by the single crystal structure of the complex QMAA–CdCl 2 . Density functional theory (DFT) calculations have verified the mechanism of fluorescence enhancement. In addition, the limit of detection of QMAA for Cd 2+ was as low as 0.1547 µM (at 10 –7 M level), which was lower than the acceptable limit of Cd 2+ level in drinking water defined by World Health Organization. The analog experiments about nature contamination of Cd 2+ in real samples were finished.