Multimodal metal cation sensing with bis(macrocyclic) dye

The synthesis, electrochemical, optical, and cation sensing properties of a bis(macrocyclic) dye 1, in which the benzo-15-crown-5 and phenylazathia-15-crown-5 subunits are linked through a styryl pyridinium moiety, are reported. In this new ditopic receptor, the benzo-15-crown-5 macrocycle acts as a highly selective binding site for alkaline earth metal cations (Mg(II) and Ba(II)), whereas the phenylazathia-15-crown-5 displays a strong binding affinity towards soft heavy-metal cations (Hg(II) and Ag(I)). The pronounced changes of the absorption and fluorescence spectra of this bichromophoric dye observed upon different metal cation addition make the dye suitable for dual-wavelength analysis and offer an enticing potential for multitasking sensors.