A Highly Selective and Sensitive Sequential Recognition Probe Zn2+ and H2PO4− Based on Chiral Thiourea Schiff Base

Abstract

A series of novel chiral thiourea fluorescent probes HL1–HL6 were designed and synthesized from (1R,2R)-1,2-diphenylethylenediamine, phenyl isothiocyanate, and different substituted salicylic aldehydes. All of the compounds were confirmed by 1H NMR, 13C NMR, and HRMS. They exhibit high selectivity and sensitivity to Zn2+ in the presence of nitrate ions with the detection limit of 2.3 × 10−8 M (HL5). Meanwhile, their zinc (II) complexes (L-ZnNO3) showed continuous response to H2PO4− in acetonitrile solution. The identification processes could further be verified by supramolecular chemistry data analysis, X-ray single-crystal diffraction analysis, and theoretical study. The research provides reliable evidence for an explanation of the mechanism of action of thiourea involved in coordination, which is important for the application of thiourea fluorescent probes. In short, the sensors HL1–HL6 based on chiral thiourea Schiff base will be promising detection devices for Zn2+ and H2PO4−.