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.