Highly Selective Turn‐On Fluorescent Chemodosimeter for Al^III Detection through Al^III‐Promoted Hydrolysis of C=N Double Bonds in the 8‐Hydroxyquinoline Aldehyde Schiff Base

Abstract

Fluorescent chemodosimeters based on small organic molecules are widely used in the detection of various analytes. However, chemodosimeters for metal ion detection are still limited to a few transition metals, such as Hg , Cu , Fe , Au , etc. In this work, a fluorescent chemodosimeter of 5-chloro-7-phenyliminomethyl-8-hydroxyquinoline (2) for the detection of Al is reported. Chemodosimeter 2 exhibits a turn-on fluorescence response to Al owing to an Al -promoted hydrolysis of carbon-nitrogen double bonds. This reaction yielded a 1-Al complex, which exhibited high fluorescence emission at 487 nm based on inhibition of excited-state intramolecular proton transfer (ESIPT). Because of the specific catalytic ability of Al , the selectivity of 2 to Al is excellent both in aqueous solutions and in solid matrix. The fluorescence enhancement was as high as 582-fold and the turn-on fluorescence can be observed even by the naked eye upon an irradiation with a UV lamp. The detection limit of 2 for Al sensing is 54 nmol L and the linear range is 0-50 μmol L . This work provides a new strategy for designing main-group-metal chemodosimeters based on small organic molecules.

Eu3+-Functionalized Covalent Organic Framework Hybrid Material as a Sensitive Turn-On Fluorescent Switch for Levofloxacin Monitoring in Serum and Urine

“…It is reported that excess consumption of levofloxacin may trigger severe adverse symptoms, such as anaphylactic shock, laryngeal edema, tendon rupture, peripheral nervous system damage, and so on. − Therefore, it is urgent to investigate a reliable method for detecting levofloxacin in the medical and clinical fields. In recent years, fluorescence-sensing methods have attracted widespread attention because of their quick response, high sensitivity, nondestructive emission signals, low cost, and capability of real-time detection. − Employing fluorescence analysis for the determination of levofloxacin is a reliable method.…”

8‐Hydroxyquinoline Fluorophore for Sensing of Metal Ions and Anions

“…Schiff‐base fluorescence 15 (Figure 13)at pH 5.0 in aqueous solution indicated two absorption spectra at the wavelengths of 314 and 456 nm [42] . With the incremental increase in the amount of Al 3+ ion, there is a gradual decrease in two absorption bands, accompanied by the appearance of a new absorption signal at 381 nm.…”

A Highly Selective Fluorescent Sensor for Detection of Trivalent Metal Ions Based on a Simple Schiff-Base

“…According to the literature, the imine group in the Schiff base could be destroyed by hydrolysis reactions in the acidic solvent. 34 The trivalent metal ion solutions were acidic which could generate acids in protic solvents. 35 Figure 5 clearly demonstrated that the intensity of the fluorescence signal of L in the acidic pH range was almost similar to that achieved in presence of the trivalent metal ions in ethanol.…”