2026/04/29 by Haifei Wen, Ziqi Meng, Ximing Chen +12 · 1 voice
Chemistry · Engineering · Materials Science · #Luminescence and Fluorescent Materials #Metal-Organic Frameworks: Synthesis and Applications #Nanoplatforms for cancer theranostics
paper · doi:10.1002/agt2.70327
openalex created_date 2025/11/13 · openalex publication_date 2026/04/29 · openalex updated_date 2026/07/22
ABSTRACT High molar absorption coefficients (ε) in the near‐infrared (NIR) region are critical for maximizing light‐harvesting efficiency, enabling deep‐tissue penetration, and enhancing reactive oxygen species (ROS) generation in phototheranostics. However, strong absorptivity at NIR wavelengths is challenging for organic luminogens due to intrinsically diminished oscillator strengths. We report a symmetry‐guided molecular engineering approach to construct octupolar aggregation‐induced emission luminogens (AIEgens) that overcome this limitation. Incorporating fused tetrahydroxanthylium (THX) acceptors into a D(A) 3 framework yields a four‐fold enhancement in ε (5.47 × 10 4 M −1 cm −1 ) at 670 nm compared to dipolar analogs (D–A), while achieving bright NIR‐II emission at 963 nm. Femtosecond transient absorption spectroscopy reveals stronger ground‐state bleaching and additional excited‐state absorption in octupolar systems, correlating with enhanced light‐harvesting. Density functional theory calculations demonstrate that symmetry‐enabled dipole coupling activates additional S 0 →S 2 transitions, explaining the high absorptivity. The octupolar architecture also reduces Δ E ST and introduces low‐lying excited states, promoting intersystem crossing and boosting ROS generation. This symmetry‐driven design combines twisted conformations with AIE features to create a robust platform for bright NIR‐II emission and advanced phototheranostic applications.