To better understand the relationship between molecular structure and mechanofluorochromic characteristics, three carbazole‐based N^O‐chelated difluoroboron compounds (Cz‐S‐BF2, Cz‐PhNp‐S‐BF2, and Cz‐BNp‐S‐BF2) with different aryl substituents moieties were designed and synthesized. The mechanofluorochromic behaviours of Cz‐S‐BF2 (luminescence from bluish‐green to yellowish‐green, emission from 504 to 535 nm) without aryl substitution and Cz‐PhNp‐S‐BF2 (luminescence from green and yellow, emission from 521 to 557 nm) with a phenyl‐naphthalene group underwent reversible conversion using the grinding–fuming process. For Cz‐BNp‐S‐BF2 this was not apparent due to the well coplanarity of the binaphthalene moiety. Mechanofluorochromic properties were demonstrated through XRD patterns measurement. We envisage that this study will provide a practicable reference to acquire organic molecules with mechanofluorochromic characteristics.

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