Mechanofluorochromic behaviours of functionalized carbazole‐based difluoroboron compounds with different aryl substituents moieties

Abstract

Abstract To better understand the relationship between molecular structure and mechanofluorochromic characteristics, three carbazole‐based N^O‐chelated difluoroboron compounds ( Cz‐S‐BF 2 , Cz‐PhNp‐S‐BF 2 , and Cz‐BNp‐S‐BF 2 ) with different aryl substituents moieties were designed and synthesized. The mechanofluorochromic behaviours of Cz‐S‐BF 2 (luminescence from bluish‐green to yellowish‐green, emission from 504 to 535 nm) without aryl substitution and Cz‐PhNp‐S‐BF 2 (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‐BF 2 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.