A Fluorescence Probe Based on Self-Absorption for Ni2+/Co2+ Detection and Information Encryption

Abstract

A compound 3-hydroxy-(2-hydroxy-3,5-diclorobenzylidene)-2-naphthohydrazide (HDN) with schiff base structure was synthesized from 3-hydroxy-2-naphthoylhydrazide and 3,5-dichlorosalicylialdehyde. The structure of HDN was characterized by NMR, HR-MS, and IR. Study the spectral properties of probe HDN using fluorescence spectrophotometer and UV-vis spectrophotometer. This indicates that in solvent system of PBS: DMF=4:6 (PBS: pH=7.5 phosphate buffer solution), Ni2+ and Co2+ have a significant “turn-off” effect on probe HDN, and are almost unaffected by other metal ions. The binding mechanism was studied using Job's curve and 1HNMR spectroscopy titration. The results indicate that self-absorption effect generated by the coordination of probe HDN with Ni2+/Co2+ causes fluorescence quenching. Linear equations were fitted for the fluorescence intensity corresponding to different concentrations of Ni2+/Co2+, and the detection limits (LOD) were calculated to be 5.6331×10-8 mol/L (Ni2+) and 5.5709×10-8 mol/L(Co2+) respectively. Application studies have shown that probe HDN can be applied to two-dimensional code information encryption technology.

Keywords: Schiff base, fluorescence probe, Ni2+/Co2+, self-absorption, Information encryption