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

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.