Novel AIE-active ratiometric fluorescent probes for mercury(ii) based on the Hg2+-promoted deprotection of thioketal, and good mechanochromic properties

Abstract

Novel AIE-active ratiometric fluorescent probes for Hg²⁺ were synthesized, which combined the advantages of the excellent luminescence properties of AIEgens in the solid state and the high selectivity of the Hg²⁺-promoted deprotection reaction. Upon testing with mercury ions, the luminescent color changed from sky blue to yellow-green almost immediately, while other metal ions (Ag⁺, Fe³⁺, Cu²⁺, Pb²⁺, Co²⁺, Cr³⁺, Al³⁺, Cd²⁺, Mg²⁺, Mn²⁺, Ba²⁺, Fe²⁺, Ca²⁺, Ni²⁺, Zn²⁺, Li⁺, K⁺, and Na⁺) caused no disturbance to the sensing process. Furthermore, the fabricated test strips reported the presence of Hg²⁺ ions with the detection limit as low as 1 × 10⁻⁵ M. Moreover, the synthesized AIEgens showed reversible mechanochromic properties with high color contrast, suggesting that they could have additional promising applications in optoelectronic devices.