A novel turn-on fluorescent probe for the multi-channel detection of Zn2+ and Bi3+ with different action mechanisms.

A novel multifunctional sensing material, RSPT, incorporating rhodamine B hydrazide, a Schiff base, and a phenolic hydroxyl group into triazine, was identified and prepared. After the molecular structure was characterized by FTIR, 1H NMR, mass spectra and element analysis, it was notably found that there were multichannel turn-on fluorescent responses to Zn2+ and Bi3+, i.e., a strong fluorescence emission at 481 nm in DMF-water (99/1, v/v) for Zn2+ with a color change from colorless to light yellow-green, while an increased fluorescence emission at 580 nm in CH3CN-water (99/1, v/v) for Bi3+ with a color change from colorless to red. Their different action mechanisms for the RSPT-Zn2+ and RSPT-Bi3+ complexes were investigated and confirmed by means of fluorescent titration, binding constant, Job's plot curve, 1H NMR titration, and theoretical simulation. RSPT would be a promising turn-on fluorescent chemo-dosimeter for multichannel detection of Zn2+ and Bi3+ with a detection limit of 3.0 nM for Zn2+ and 8.6 nM for Bi3+.