Development of a multi-responsive fluorescence switch system based on a pyrimidine functionalized tetrarylethylene compound

Abstract

The pyrimidine-functionalized tetrarylethylene derivatives, BTPT-2-PAo and TPT-2-PAo, were designed, synthesized and characterized. Both compounds exhibit distinct responses to various external stimuli including solvents, acids, light, and metal ions. Remarkable acidichromism and “turn-off” fluorescence are induced by protonation effects, while significant enhancement in photoluminescence resulted from photocyclization reactions. Additionally, the emission intensity of BTPT-2-PAo and TPT-2-PAo can be significantly attenuated upon interaction with Cr³⁺, Al³⁺, and Fe³⁺ accompanied by a color change from colorless to yellow. Job's plots confirmed the 1 : 1 stoichiometry of complex formation between them and Cr³⁺, Al³⁺, and Fe³⁺, respectively. Moreover, the limit of detection for these trivalent metal ions reached a magnitude of 10⁻⁷ mol L⁻¹. Finally, we successfully demonstrated that BTPT-2-PAo and TPT-2-PAo can be utilized in test paper strips for rapid “naked-eye” detection of acid as well as M³⁺ (M: Cr, Al, and Fe). Therefore, the multi-response performance along with the ease of preparation endows BTPT-2-PAo and TPT-2-PAo with potential applications in fluorescence sensing of acid/metal ions and security ink.