Simpler molecular structure as selective & sensitive ESIPT-based fluorescent probe for cysteine and Homocysteine detection with DFT studies

The undesired research results of triazole synthesis were successfully utilized as a simpler, sensitive and selective turn-on fluorescent probe 2 namely chloro-acetic acid 2-benzothiazol-2-yl-phenyl ester (HBT-AcCl) which was synthesized by simple chloroacylation of 2-hydroxyphenyl benzothiazole (HBT). Only one simple chloroacetate, a trigger unit as the reaction site of probe 2 makes it more simple, sensitive and selective for Cys and Hcy over other Amino Acids. The presented probe HBT-AcCl conserves simple structure, reduces the use of extra chloroacetate and improves %atom economy as compare to similar reported probes. Paper strip tests were carried out to explore the potential application for naked-eye detection of Cys under UV lamp. The selectivity of the HBT-AcCl probe for Cys and Hcy is supported by the results of absorbance and emission spectroscopy experiments and theoretical DFT calculations. A new simpler, sensitive, selective turn-on fluorescent probe chloro-acetic acid 2-benzothiazol-2-yl-phenyl ester (HBT-AcCl) was developed from the negative research results of some other scheme. The probe selectively detected Cys & Hcy from other amino acids. The presented probe considered as a green probe that conserves complexity, reduces use of extra chloroacetate and has improved %atom economy. [Display omitted] •A new simpler, sensitive, selective turn-on ESIPT-based fluorescent probe chloro-acetic acid 2-benzothiazol-2-yl-phenyl ester (HBT-AcCl) developed from the negative research results of some other scheme.•The HBT-AcCl probe was efficiently utilized for selective detection of Cys and Hcy over other Amino Acids.•The %atom economy of the presented probe was found better than other similar but complex reported probes.•Paper strip tests were carried out to explore the potenitial application for naked eye detection of Cys under UV lamp.•Selectivity of HBT-AcCl probe for Cys and Hcy is supported by theoritical DFT calculations.