Construction of a tetraphenylethene derivative exhibiting high contrast and multicolored emission switching

Stimuli responsive luminogens with high contrast in both emission color and intensity in the solid state have seldom been reported, despite their underlying application in highly sensitive sensors, security papers and high density optical storage. Through cross-coupling of 4,4'-dibutoxylbenzophenone and benzophenone, we obtained a tetraphenylethene (TPE) derivative (1) with low symmetry exhibiting aggregation-induced emission (AIE). Compound 1 can form deep blue (1CA, 420 nm, Phi(F) = 50.4%) and sky blue (1CB, 460 nm, Phi(F) = 8.3%) emissive crystals and a green emissive amorphous solid (1Am, 496 nm, Phi(F) = 7.6%) with high contrast in both emission color and efficiency. The sharp contrast may be caused by the variation in their conformation and intermolecular interaction. The emission of compound 1 could be switched reversibly among deep blue, sky blue and green with high contrast in both emission color and efficiency through tuning the morphology of 1 by heating, solvent fuming and mechanical stimuli. The high contrast stimuli responsive luminescence of 1 affords its potential application in optical recording, sensors, and so on.