Highly fluorescent response of 4-(2,5-dimethylthiophen-3-yl)-2- hydroxyphenylbenzothiazole toward BF3•Et2O and Zn2+.

In this contribution, the emission response of 4-(2,5-dimethylthiophen-3-yl)-2-(2-hydroxy- phenyl)benzothiazole (THBT) was investigated in detail. The experimental shows that Zn²⁺ could induce fluorescence increasing in tetrahydrofuran (THF). Especially, the quenched emission of THBT was significantly enhanced with 0.76 quantum yield. Due to the coordination of Zn²⁺, the excited state intramolecular proto transfer (ESIPT) was inhibited and leads to emission quenching correspondingly. The strong emission could ascribe to the Zn-THBT complex. As well, the addition of BF₃·Et₂O also could form fluorine-boron complex and inhibit ESIPT effect. Additionally, the BF complex is also a strong blue emitter. Therefore, strong blue emission upon BF₃·Et₂O addition to THBT in dioxane was found. The possible coordinating mechanisms of THBT coordinate with Zn²⁺ and BF₃·Et₂O were given. [ABSTRACT FROM AUTHOR]