The design of multifunctional fluorescent probe for detecting Zn2+/ ClO−/H2O and application in high-security level information encryption

In this article, a Schiff base-structured compound (TNB) was synthesized using 3-hydroxy-2-naphthaldehyde hydrazone and 2-hydroxy-5-tert-butylbenzaldehyde as starting materials. The structure of TNB was characterized using NMR spectroscopy, high-resolution MS, and IR spectroscopy. Studies showed that TNB can selectively recognize Zn2+/ClO− in solvent system of H2O/DMSO. Fluorescence and UV–vis spectrophotometry were used to investigate the spectral properties of TNB. TNB displayed a significant fluorescence enhancement effect when bound to Zn2+, while binding to ClO− resulted in fluorescence quenching. Job’s plot and NMR titration were used to study the binding mechanism of TNB with Zn2+/ClO−. Linear standard curves were fitted for different Zn2+/ClO− concentrations corresponding to fluorescence intensity, and detection limits (LOD) were determined as 5.0300 × 10−9 mol/L (Zn2+) and 3.1700 × 10−9 mol/L (ClO−). Furthermore, TNB was used to determine trace water in organic solvents. The fluorescence intensity changes with water content were measured in three organic solvents (THF, DMSO, and acetone). Detection limits (LOD) were calculated as 1.4 × 10−4 % (THF), 8.3 × 10−4 % (DMSO), and 1.2 × 10−3 % (acetone). Using the characteristic reactions of TNB with Zn2+, a two-dimensional code information encryption technology was developed and can be used for high-security information encryption and transmission.