Design and evaluation of dansyl-derived chemosensors for disulfide-cleavage-triggered detection: photophysical, metal sensing, and thermometric applications†

In this work, two new dansyl-derived chemosensors have been designed with the aim of developing a disulfide-cleavage-triggered probe. These stable new ligands, containing a thioether (L1) and a disulfide bridge (L2), have been synthesized and evaluated for their photophysical properties in both solution and the solid state. Different fluorescence emission responses have been observed for both compounds due to the self-quenching nature of the disulfide bond in L2 compared to L1, with the latter reaching quantum yields close to 50%. Efforts to characterize solute–solvent interactions through Kamlet–Taft studies have revealed a positive solvatofluorochromic response for both compounds. Furthermore, the aggregation-induced emission phenomenon was demonstrated at increasing water fractions. The presence of free thiol groups enhances the complexation ability, making L1 particularly beneficial for sensing Cu²⁺ and Hg²⁺ ions, achieving detection limits as low as 2 μM in the case of mercury. Finally, incorporating L1 into polymer-doped films demonstrated promising results as molecular thermometers, while the response of L2 to sodium dithionite underscores its potential for disulfide-cleavage-triggered applications.