Benzothiazole integrated into a cryptand for ESIPT-based selective chemosensor for Zn ions.

A novel benzothiazole-based cryptand was designed and synthesized, and it exhibited high fluorescence intensity in the presence of Zn ions based on the metal chelation inhibition of the excited state intramolecular proton transfer (ESIPT) process. The structure of the cryptand was confirmed by NMR, mass spectroscopy and X-ray crystallography. Importantly, this probe showed high selectivity over other biologically relevant metal ions and anions and a detection limit of 0.20 μM, which is acceptable within the EPA (US) limit.