-Tetrazine-Bridged Photochromic Aromatic Framework Material.

Integrating fluorescent chromophores in aromatic frameworks could not only prevent aggregation-induced quenching caused by the π-π stacking interaction between the chromophore components but also confer new fluorescence properties. Herein, we report the fabrication of -tetrazine-bridged aromatic frameworks by the incorporation of the smallest aromatic fluorophore, -tetrazine (), into the skeleton of a tetrahedrally connected lattice of aromatic frameworks. The thin films of coated on silica gel plates were found to exhibit reversible photoswitching fluorescence characteristics under alternate UV and visible-light irradiations with excellent fluorescence stability and high on/off contrast. The repeatable "on/off"fluorescence photoswitchability of the thin films was mechanistically attributed to light-induced reversible transformation between 's neutral and radical states.