Enantioselective recognition of carboxylic acids by novel fluorescent triazine-based thiazoles

Chemistry of 2-(2'-Aminophenyl)benzothiazole Derivatives: Syntheses, Photophysical Properties and Applications

2-(2'-aminophenyl)benzothiazole is a readily tunable fluorescent core with widespread applications in coordination chemistry, sensing, light-emitting processes, medicinal chemistry, and catalysis. This review provides an overview of the synthetic methodologies to access 2-(2'-aminophenyl)benzothiazole and its organic derivatives, including various phosphorous and silane pincer ligands. The luminescent properties will be discussed, with a special focus on ESIPT and AIE processes. The coordination of transition metals and lanthanides is presented, as well as their influence on biological and light-emitting properties. 2-(2'-aminophenyl)benzothiazole derivatives have also been employed as sensors for a range of cations and anions due to their various binding modes, as well as for bioimaging purposes. Recently, the first application in photocatalysis has emerged, showing one of the many openings for these organic building blocks in the future.

Chiral Oxazoline-Triazole-Benzothiazole Molecular Triads: Photoactive Sensors for Enantioselective Carbohydrate Recognition in Solution

Understanding the mechanism of drug action in biological systems is facilitated by the interactions between small molecules and target chiral biomolecules. In this context, focusing on the enantiomeric recognition of carbohydrates in solution through steady-state fluorescence emission spectroscopy is noteworthy. To this end, we have developed a third generation of chiral optical sensors for carbohydrates, distinct from all of those previously presented, which interact with carbohydrates to form non-covalent probe-analyte interactions. The proposed sensor is based on 2-oxazolines bearing a fluorophoric benzothiazole unit. We evaluated their photophysical properties in the presence of enantiomeric pairs of arabinose, mannose, xylose, and glucose in solution. Our primary findings indicate that the compounds outlined in this study were able to distinguish between enantiomeric pairs in solution, demonstrating good to excellent enantioselectivity through simple intermolecular interactions. To achieve the best enantioselectivity results, theoretical calculations were performed to better understand the observed interactions between the sensors and the analytes.

Effective enantioselective recognition by steady-state fluorescence spectroscopy: Towards a paradigm shift to optical sensors with unusual chemical architecture

A series of amino acid-derived 1,2,3-triazoles presenting the amino acid residue and the benzazole fluorophore connected by a triazole-4-carboxylate spacer was studied for enantioselective recognition using only steady-state fluorescence spectroscopy in solution. In this investigation, the optical sensing was performed with D-(-) and L-(+)-Arabinose and (R)-(-) and (S)-(+)-Mandelic acid as chiral analytes. The optical sensors showed specific interactions with each pair of enantiomers, allowing photophysical responses, which were used for their enantioselective recognition. DFT calculations confirm the specific interaction between the fluorophores and the analytes corroborating the observed high enantioselectivity of these compounds with the studied enantiomers. Finally, this study investigated nontrivial sensors for chiral molecules by a mechanism different than turn-on fluorescence and has the potential to broad chiral compounds with fluorophoric units as optical sensors for enantioselective sensing.