Structure‐Dependent Fluorescent Behavior of Heterotetraarylene‐Quinolones: The Critical Role of Chemical Bond Linkages

Altering the manner in which groups are connected could offer a straightforward approach to achieving different functionality. Herein, heterotetraarylene molecules with varying bond‐linked quinoline moieties are synthesized and designed to investigate their differential performances. The heterotetraarylene with carbon‐carbon double bonded quinolines exhibits multifunctional properties: 1) all‐visible light‐induced photochromism, 2) acidochromism, and 3) acid–base gated photoswitch. Simultaneously, it achieves dual‐mode fluorescence modulation through both photoexcitation and acid/base stimuli. However, the heterotetraarylene and quinoline connected by carbon carbon single bonds exhibit divergent properties, including light‐induced emission enhancement and solvent‐dependent fluorescence emission. This bond‐selective functional divergence enables precise customization of stimulus‐responsive fluorescence through simple connectivity control, establishing a novel design paradigm for smart molecular systems. Furthermore, the heterotetraarylene‐linked quinolines with carbon carbon double bonds exhibit many properties, thus allowing for the construction of a new dual‐responsive encryption system.