A Fluorescent Probe Based on the Hydrazone Schiff Base for the Detection of Zn²⁺ and its Application on Test Strips

A novel fluorescent probe SHK for Zn²⁺ detection was designed based on the hydrazone Schiff base, successfully synthesized by Suzuki coupling and condensation reactions. The probe SHK in DMSO/H₂O showed extremely weak fluorescence. However, the solution exhibited an intensive yellow-green emission with the introduction of Zn²⁺. In contrast, negligible fluorescence change was observed when other metal ions were added, suggesting a high selectivity of SHK for Zn²⁺ detection. The Job's Plot analysis revealed that a 1:1 stoichiometric adduct SHK-Zn²⁺ formed during the Zn²⁺ sensing. The binding constant of the complex was determined to be 184 M^- 1, and the detection limit for Zn²⁺ was calculated to be 112 µM. Moreover, the probe SHK achieved selective fluorescence sensing for Zn²⁺ on test strips, which guaranteed its practical application prospect.