Work

Tunable Stimuli‐Responsive Luminescence From Covalent Organic Frameworks Displaying Vibration‐Induced Emission

Year: 2026

Type: article

Abstract: ABSTRACT Introducing dynamic components that couple molecular motion with optical output offers a promising strategy for developing stimuli‐responsive luminescent covalent organic frameworks (COFs). Vibration‐induced emission (VIE) molecules are particularly attractive dynamic luminophores, as their excited‐state bent‐to‐planar conformational evolution enables dual emission, large Stokes shifts, and environment‐regulated fluorescence. However, VIE‐based COFs have not yet been reported. Herein, we report two VIE‐based three‐dimensional COFs, JUC‐735 and JUC‐736, constructed from a symmetric N,N’‐diphenyl‐dihydrodibenzo[a,c]phenazine (DPAC)‐derived building block with a saddle‐shaped conformation. Both COFs exhibit high crystallinity, thermal stability, and well‐defined porosity. Photophysical studies reveal that the excited‐state conformational evolution of DPAC remains operative in these crystalline environments, leading to dual emission with exceptionally large Stokes shifts in solution (> 300 nm; 14526 cm − 1 for JUC‐735 and 14272 cm − 1 for JUC‐736). This dynamic emission behavior further enables tunable luminescence responses to aggregation, viscosity, and pressure. Notably, JUC‐736 shows more pronounced dual‐emission modulation under aggregation, near‐white‐light emission tuning, and reversible multicolor piezofluorochromism, whereas JUC‐735 mainly exhibits long‐wavelength emission modulation with higher intensity sensitivity. These results highlight the important role of the local framework environment in regulating the stimuli‐responsive emission behavior of dynamic chromophores, providing a working strategy for designing multi‐stimuli‐responsive luminescent COF materials.

Source: Angewandte Chemie International Edition

DOI: 10.1002/anie.8220560