Fluorescence-enhanced organogelators with mesomorphic and piezofluorochromic properties based on tetraphenylethylene and gallic acid derivatives

• Two novel aggregation-induced emission compounds were synthesized.
• The compounds possess different gelation behavior in organic solvents.
• Their emission was reversibly changed with the gel–solution transition.
• The emission color of one compound could be switched by external stimuli.
• Both of them possessed mesomorphic properties.

Two novel aggregation-induced emission compounds derived from tetraphenylethylene and gallic acid were synthesized and characterized. Both of the emission compounds possessed mesomorphic properties and exhibited mesomorphic phases over a wide temperature range and the thermal-induced mesomorphic transition from metastable to stable phases accompanied by a change of the luminescent color. The mesomorphic transition may be ascribed to liquid crystalline phase transition. The emission compounds possess different gelation behavior in organic solvents. The emission intensities of the emission compounds can be reversibly changed with the gel–solution transition by alternate cooling and heating. Moreover, the color and emission of these organogelators can be repeatedly switched by various external stimuli including pressing, heating and solvent-fuming. These new compounds may offer potential as external stimuli-responsive materials.

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