Naphthalimide-based luminogens with bright aggregative-state emission: High-contrast blue-shift mechanofluorochromism and application in ink-free secure information storage

In recent decades, with the advancement of the field of organic luminescent materials, mechanofluorochromic materials with aggregation-induced emission (AIE) properties have become a pioneering research hotspot due to their excellent photophysical properties and wide range of applications. Herein, a series of carbazole-naphthalamide (CN-R) type derivatives containing different benzene ring substituents and their isomers were designed and synthesized. The fluorescence of the donor–acceptor type derivatives could be modulated through the introduction of diverse benzene ring substituents. CN_me-OCH₃ demonstrated excellent AIE activity and a remarkable 74 nm force-induced fluorescence blue shift. Other compounds exhibited AIE or aggregation-induced emission enhancement (AIEE) properties. This innovative structural regulation strategy enables the design of organic materials with multiple photophysical properties. Moreover, the application of CN_me-OCH₃ in ink-free security information storage provides a new way to curb the increasingly serious counterfeiting phenomenon.