Visualizing molecular diffusion direction and processes in the solid state via dichromatic fluorescent cocrystalization transformation

作者：Jialu Zheng, Xiwen Zhu, Wei Wang, Songrui Xie, Wenyi Ma, Shishi Shao, Hanbing Nie, Yan Jie Li, Zheng Zheng, Cheng Zhi Huang, Peng Fei Gao · 发表于：Nature Communications · 年份：2026 · DOI：10.1038/s41467-026-70152-5 · 研究领域：Crystallography and molecular interactions、Luminescence and Fluorescent Materials、X-ray Diffraction in Crystallography

Solid-state molecular motion (SSMM) plays a critical role in enriching material properties and functions, yet visualizing its detailed dynamics including direction, progression, and velocity to thoroughly elucidate its mechanism remains a great challenge. Herein, an intermolecular charge transfer (ICT)-mediated fluorescence strategy is developed to visualize and regulate SSMM in binary cocrystal systems, utilizing 6-methoxy-2-acetylnaphthalene (MA)/1,2,4,5-tetracyanobenzene (TCNB) as modeling platform. This approach leverages the reversible transformation between MA/TCNB = 1/1 (MT1, yellow emission) and MA/TCNB = 1/2 (MT2, green emission) crystalline phases, enabling real-time visualization of detailed SSMM information via localized dichromatic fluorescence signatures. It reveals an unexpected significant disparity in diffusion rates between electron donor MA and electron acceptor TCNB during the diffusion process at their interface, even exhibiting unidirectional diffusion from MA to TCNB within a restricted time. Applications demonstrated include pretreatment-free impurity analysis of MA (a key impurity in naproxen) down to 0.1% leveraging the fluorescence shift, and real-time monitoring of transesterification reactions based on the differing interaction capabilities of various naproxen esterification derivatives with TCNB. This study not only provides fundamental insights into SSMM and cocrystallization mechanisms but also demonstrates the potential of charge transfer cocr...