A simple Schiff-base fluorescence probe for the simultaneous detection of Ga³⁺and Zn²⁺

A new Schiff-base sensor 1, based on fluorene and salicylaldehyde, has been prepared for the fluorescent detection of Ga³⁺and Zn²⁺by different emissions. The sensing behaviors of 1 with Ga³⁺and Zn²⁺were studied by using photophysical experiments, NMR titration, and ESI-mass spectrometry analysis. Moreover, turn-on fluorescence of 1 toward Ga³⁺and Zn²⁺caused by photo-induced electron transfer (PET) was explained by density functional theory (DFT) calculations. In particular, the detection limit of 1 for Ga³⁺was down to nano-molar concentration (10 nM), which is the lowest one among those previously reported for organic-probes for sensing Ga³⁺by fluorescence.