Synthesis of a benzothiazole-based structure as a selective colorimetric-fluorogenic cyanate chemosensor

Abstract In this study, a new heterocyclic compound incorporating a benzothiazole moiety was specifically designed for the detection of cyanate anions, employing a hydrogen bonding mechanism. Through strategic integration of triazine and phenylenediamine cyclic groups into the compound’s structure, intramolecular hydrogen bonding interactions between the donor and acceptor sites were enhanced, leading to exceptional sensitivity towards cyanate anions. Utilizing the amino-type excited-state intramolecular proton transfer phenomenon, this new compound exhibited dual signals and achieved a significant Stokes’ shift via proton transfer, coupled with aggregation-induced emission properties. This unique combination resulted in visible color changes and an impressive fluorescence response, offering a promising solution for the sensitive detection of cyanate ions in critical environmental matrices. Cyanate detection at low concentrations by this as-synthesized compound (L1), accompanied by a distinct color change and a gradual fluorescence increase upon incremental cyanate addition demonstrated L1’s selectivity, as confirmed in the presence of various competing anions F − , Cl − , Br − , I − , ClO 3 − {\text{ClO}}_{3}^{-} , ClO 4 − {\text{ClO}}_{4}^{-} , NO 3 − {\text{NO}}_{3}^{-} , BrO 3 − {\text{BrO}}_{3}^{-} , CN − and CNO − . Spectrofluorometric investigations demonstrated that L1 shows significant potential as a selective cyanate anion detection candidate.