Multi-stimuli-responsive luminescence in a pyrimidine-functionalized tetraphenylethylene derivative: AIE, trivalent ions (Cr3+/Al3+/Fe3+) sensing, and applications

We present a multi-stimulus responsive AIE fluorophore, BTPE-PA, incorporating dual tetraphenylethylene units. This probe demonstrates distinct optical responses to acidic environments and trivalent metal ions (Cr³⁺, Al³⁺, and Fe³⁺), which are characterized by instantaneous chromogenic and fluorogenic switching. Acidic stimulation induces a rapid color transition from blue to yellow, accompanied by fluorescence activation and an exceptionally large Stokes shift of 245 nm. The high-contrast color and emission changes, combined with operational simplicity, render BTPE-PA highly effective for anti-counterfeiting applications through acidity modulation. Concomitantly, BTPE-PA exhibits selective recognition of Cr³⁺, Al³⁺, and Fe³⁺ via dual-modal signaling: a bathochromic absorption shift (colorless → yellow) and fluorescence transition from blue to orange. The 1:1 binding stoichiometry with these trivalent ions, confirmed by Job’s plot analysis, enables sensitive detection with a limit approximately 10⁻⁷ mol L⁻¹ order. Furthermore, we successfully demonstrated BTPE-PA’s utility in test paper strips for rapid naked-eye detection of acid and Cr³⁺/Al³⁺/Fe³⁺. Therefore, the exceptional multi-stimulus responsive performance of BTPE-PA holds significant potential for developing multi-signal fluorescence probes targeting acid and trivalent metal ions detection.