Sulfone-functionalized stereoisomeric [3]radialene displays guest induced modulation of porous frameworks and critical crystallization-induced near-infrared emission.

Luminescence-responsive porous organic materials have garnered significant interest due to their chemical versatility, adaptability and potential applications in smart sensors and optoelectronic devices. In this study, we introduce a novel class of sulfone-functionalized stereoisomeric [3]radialenes TTRO with quasi-C 3 symmetry, which demonstrate flexible structural configurations and the ability to form diverse crystalline frameworks with tunable porosity ranging from 0% to 31.2%. These assembled frameworks are characterized by distinct stereochemical configurations of TTRO, which influence their dipole moment vectors and molecular packing parameters, especially the geometry of the exo-cyclic radialene ring. The stability of these structures is further enhanced by sulfone-embedded aromatics and guest solvent molecules, establishing a network of multivalent molecular interactions. Remarkably, TTRO-based materials exhibit crystallization-induced emission in the near-infrared (NIR) region (650-1000 nm), transitioning from non-emissive amorphous powders to exhibiting strong photoluminescence (up to 24.1%) in guest-involved porous crystalline frameworks. Time-resolved fluorescence and computational analyses reveal that the dynamic stacking geometry of TTRO units, combined with multivalent sulfone-based intermolecular interactions with guest molecules, modulates the reorganization energy within the frameworks, thereby tuning solid-state emission. These findings provide new insights and strategies for designing NIR luminophores through crystalline engineering of [3]radialene materials.