Three Salicylaldehyde Schiff Base Fluorescent Probes: Synthesis and Recognition of Zn2+

Three novel Schiff-base fluorescent probes, 2-((2-hydroxybenzylidene)amino)-2-(hydroxymethyl)propane-1,3-diol (L1), 2-((5-chloro-2- hydro. xybenzylidene)amino). 2-(hydroxymethyl). propane. 1,3-diol (L2), and 2-((2-hydroxy-4-methoxy-benzylidene)amino)-2-(hydroxymethyl)propane-1,3-diol (L3), were designed and synthesized, and characterized by H-1 NMR, C-13 NMR, elemental analysis, and HRMS. The results of the spectral analysis showed that probe L2 was more selective and sensitive to Zn2+ than probes L1 and L3. The detection limit of L2 was found to be 11.96 nmol center dot L-1, which was far lower than the limit value of Zn2+ in drinking water, 1.0 mg center dot L-1 (about 15 mu mol center dot L-1), stipulated in the national standard GB5749-2006. There was a good linear relationship between the fluorescence intensity of probe L2 and the concentration of Zn2+ in a range of 0 to 10 mu mol center dot L-1. Meanwhile, the singlecrystal structure of complex [Zn(C11H13ClNO4)(2)] (L2-Zn2+) and the Job's plot revealed a 2:1 L2-Zn2+ identification. Moreover, probe L2 could detect Zn2+ in actual water samples. CCDC: 2121021, L2-Zn2+.