Synthesis and piezochromic luminescence of aggregation-enhanced emission 9,10-bis(N-alkylcarbazol-2-yl-vinyl-2)anthracenes

• This new series of A2Cn all exhibits remarkable piezofluorochromism.
• These compounds all have aggregation-enhanced emission.
• The alkyl lengths do not affect significantly the fluorescence properties.

Aggregation-enhanced emission active 9,10-bis(N-alkylcarbazol-2-yl-vinyl-2)anthracenes with changed length of N-alkyl chains (methyl, propyl, pentyl, and dodecyl) have been synthesized and their piezofluorochromic properties investigated. The results show that these homologues all exhibit remarkable piezofluorochromism with the pressing-induced spectral shifts of 36–45 nm, but the alkyl lengths do not affect significantly the fluorescence properties. The fluorescence emission changes induced by pressing can be restored by heat-annealing or solvent-fuming and regenerated by repressing. Powder wide-angle X-ray diffraction and differential scanning calorimetric experiments reveal that the transformation between crystalline and amorphous states upon external stimuli is responsible for piezofluorochromic behavior.

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