Anion Association and Macrocycle Encapsulation Tune the Fluorescence of <i>N</i>-Alkylpyridinium-Conjugated Push–Pull Thiazolothiazole Derivatives

The fluorescence properties of <i>N</i>-alkylpyridinium-conjugated thiazolothiazole (TTZ) fluorophores can be effectively modulated through counterion pairing and macrocyclic encapsulation. A distinct blue emission response to the iodide counterion offers potential applications in anion sensing. Host-guest complexation at the pyridinium site with macrocyclic receptors significantly perturbs the electronic environment of the TTZ core, enabling reversible dual-color emission.