Studies Of Fluorescent Switch Based On Selective Quenching Of Iron Ion And Its Applications

The article found that salicylate derivatives and aniline-type derivatives have high selectivity and sensitivity towards iron over other metal ions. We can design multi-control fluorescent switch based on selective recognition of different valence iron ion. A new method for the determination of citric acid in beverages has been proposed. The paper’s main work is summarized as follows:According to the fluorescence spectrum of the salicylate and aniline-type derivatives with different metal ions, we found that the fluorescence of salicylate derivatives and aniline-type derivatives can be quenched by Fe3-than by Zn2+、Cu2+、Ni2+、Co2+、Mn2+Cr3-、Ca2+、Fe2+and other metal ions. It is found that the p-π conjugation plays an important role in fluorescence quenching.A fluorescence probe (SSA) for the selective signaling of different valence metal ions has been studied. This system shows a sharp Fe(Ⅲ)-selective fluorescence decrease response to SSA. In addition, the fluorescent intensity of SSA can be recovered by adding EDTA for competitor or NH2OH·HCI for reducing agent. As a result, the fluorescence intensity of SSA could be reversibly turned by H+/OH-or Fe3+/EDTA or NH2OH·HCl/K2S2O8in aqueous solution. Hereby, starting with SSA system, a NOR logic gate was fabricated with Fe3+and H+as two chemical inputs. On the other hand, starting with SSA-Fe3+complex system, an OR logic gate and two INHIBIT logic gates were fabricated.A simple method for the determination of citric acid (CA) has been established based on the reversion of fluorescent quenching of sulfosalicylic acid (SSA) by iron (Ⅲ) ion. Citric acid forms stable complexes with Fe (Ⅲ), thus, reducing the effect of its fluorescence quenching on SSA. Under the optimized experimental conditions, the system exhibited a linear relationship between the enhanced fluorescence intensity and the concentration of CA. All recoveries were in the range98.5%～102.3%. The method was successfully applied to the determination of CA in beverages with satisfactory results.