A dual-channel chemosensor based on 2-hydroxy-5-methyl-1,3-benzenedialdehyde for fluorescence detection and colorimetric recognition of glutamic acid

Abstract

A colorimetric and fluorescent dual-channel glutamic acid (Glu) chemosensor 4-methyl-6-aldehyde-6′-methoxy-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol (AMS) bearing an aldehyde group has been designed and synthesized. This structurally simple chemosensor displays rapid response and high selectivity for Glu over other common amino acids in DMF/H2O (9: 1, v/v, buffered by 0.2 M Tris-phosphate buffer at pH = 7.0) solution. The chemosensor interacted with Glu to form intermolecular hydrogen bonds with significantly quenched fluorescence, switching from bright green fluorescence to no fluorescence. Moreover, AMS can also successfully detect glutamic acid by absorption spectroscopy, which exhibited an UV–vis spectrum change, while its color changed from pale yellow to colorless under natural light. The experimental results of the competitive amino acids revealed that chemosensor is highly selective for recognizing Glu without the interference of other amino acids. Job's plot indicates that the binding stoichiometry between the chemosensor AMS and the targeted amino acid Glu is 1:1. Hence, our experimental findings very strongly suggest that AMS can be used as chemosensor for detecting Glu in future.