Unlocking Advanced Information Encryption Through Dual‐Responsive Donor–Acceptor Derived Salicylaldimines

ABSTRACT Exploring multiple functionalities plays a crucial role in smart materials. This study presents an innovative strategy by integrating a triphenylamine‐naphthalimide (TPA‐NPI) donor‐acceptor (D‐A) structure with salicylaldimines, resulting in intriguing solvatochromism and mechanochromism. The target compounds TN‐BUT , TN‐PHE , TN‐BN exhibit distinct solvatochromism, with fluorescence finely tuned from blue to nearly red upon increasing solvent polarity, attributed to intramolecular charge transfer driven by the D–A structure. Importantly, they display pronounced mechanochromism in the solid state, particularly in TN‐BN , transitioning from yellow to orange fluorescence upon mechanical grinding. Single crystal analysis of TN‐BN reveals a highly twisted Z‐shaped conformation with loose packing that is altered upon mechanical grinding, leading to an in‐plane arrangement and a redshift in fluorescence. It is worth noting that all three compounds demonstrate prominent solvato‐ and mechano‐chromism, highlighting the versatility of such a molecular engineering strategy. Given the distinctive solvato‐ and mechano‐chromism, they hold significant potential for applications in information encryption and ink‐free writing. This research provides valuable insights into the design of multi‐stimuli responsive luminescent materials.