A dual-model and on-off fluorescent Al3+/Cu2+- chemosensor and the detection of F-/Al3+ with 'in situ' prepared Al3+/Cu2+ complexes

A multifunctional fluorescent chemosensor for Al3+ and Cu2+ has been developed, which displays a dual-model and on-off fluorescence response upon addition of Al3+ and Cu2+ respectively. The fluorescence signals of the chemosensor can be restored with F- and ethylenediaminetetraacetic acid (EDTA) disodium for Al3+ and Cu2+, showing that the binding of the chemosensor and Al3+/Cu2+ is chemically reversible. The 'in situ' prepared Al3+ complex (1 center dot Al) showed high selectivity toward F-, which can be applied to distinguish F- from Cl-, Br- and I-. Moreover, the fluorescence emission intensity of the 'in situ' prepared Cu2+ complex (1 center dot Cu) is increased with the addition of Al3+, demonstrating that 1 center dot Cu could be a good off-on Al3+ sensor candidate.