Construction of a Luminogen Exhibiting High Contrast and Multicolored Emission Switching through Combination of a Bulky Conjugation Core and Tolyl Groups.

Stimuli-responsive luminogens may find application in highly sensitive sensors, memories and security inks. However, few examples exhibiting both high contrast and multi-colored emission switching have been reported due to the absence of a molecular design strategy. Through combination of large conjugation core and peripheral phenyl rings, we obtained ditolyldibenzofulvene (1). Luminogen 1 is AIE active and exhibits tetracolored emission depending on its morphology. Its three single crystals emit blue, yellow and dark orange light upon excitation, exhibiting a maximal emission of 461 nm, 545 nm and 586 nm, respectively, and its amorphous solid emits at 557 nm. All the four aggregates exhibit enhanced emission intensity at lower temperature, but only the orange-emissive crystals exhibit blue-shifted emission. The emission of 1 can be switched reversibly between any two of the four states through morphology tuning. Finally, the potential application of 1 in optical data storage was also investigated.