A compact fluorescence/circular dichroism dual-modality probe for detection, differentiation, and detoxification of multiple heavy metal ions via bond-cleavage cascade reactions

Selective detection of multiple analytes in a compact design with dual-modality and theranostic features presents great challenges. Herein, we wish to report a coumarin-thiazolidine masked D-penicillamine based dual-modality fluorescent probe COU-DPA-1 for selective detection, differentiation, and detoxification of multiple heavy metal ions(Ag^(+), Hg^(2+), Cu^(2+)). The probe shows divergent fluorescence(FL)/circular dichroism(CD) responses via divergent bond-cleavage cascade reactions(metal ion promoted C-S cleavage and hydrolysis at two distinctive cleavage sites): FL “turn-off” and CD “turn-on” for Ag+(no hydrolysis), FL “turn-on” and CD “turn-off” for Hg^(+)(imine hydrolysis), and FL “self-threshold ratiometric” and CD “turn-off” for excess Cu^(2+)(lactone and imine hydrolysis), providing the first example of a fluorescence/CD dual-modality probe for multiple species with complimentary responses. Moreover, the bond-cleavage cascade reactions also lead to the formation of D-penicillamine heavy metal ion complexes for potential detoxification treatments.