Red‐Emitting Ratiometric Fluorescence Chemodosimeter for the Discriminative Detection of Aromatic and Aliphatic Amines

Abstract

AbstractA NIR‐emitting fluorescent probe using phenothiazine and 1,3‐dimethylbarbituric acid (PMB) connected through methylene bridge was developed in a two‐step simple chemical reaction. The fluorescent probes were highly reactive towards various primary amines and the reaction was accompanied by the changes in the optical and fluorescent properties of the PMB characteristic to the amine and thereby can have the potential to be used as a sensor for amines. In addition to the ratiometric changes in the fluorescence intensity corresponding to the PMB before and after reaction with an amine, the emission spectral maximum is specific to the analyte. For, example 1,4‐diaminobenzene, 4‐methoxyaniline, aniline, hydrazine, ethylamine, ethylenediamine respectively shows the maximum at 532, 546, 555, 484, 497, and 488 nm and this unique feature originated due to the involvement of the analyte in the extended π‐conjugation with the probe. Sensor strips prepared using PMB coated filter paper were able to sense the volatile amine gases with shorter response time. Analysis of the strips using the CIELAB 1976 color coordinates provides different signals for hydrazine, aniline, propylamine, and ethylamine gases. The applicability of the sensor was further ascertained by monitoring the decomposition of skin used for leather processing and also proteins engineered with an amino‐functionalized unnatural amino acid.