Multiscale Structural Analysis of Aggregation-Induced Emission Nanocrystals by Combining Electron and Confocal Microscopy

Aggregation-induced emission (AIE) materials have attracted intense interest due to their remarkable luminescent properties and potential applications in biological and medical fields. A comprehensive structural analysis from atomic-level to micrometer-scale is essential for rationally designing AIE materials and understanding their structure-property relationships. However, this remains a challenge due to the lack of proper methods. Herein, we present a strategy for multiscale structural analysis of AIE materials through a combination of electron and confocal microscopy. One mechanically induced fluorescent AIE material consisting of a chiral Au(I) complex was prepared and studied. The correlation of scanning electron and optical microscope images reveals that the fluorescence is closely related to the anisotropy of nanocrystals with strong signals on fracture {110} facets. Furthermore, instead of growing large single crystals, atomic-level crystal structures of individual nanocrystals were directly resolved using three-dimensional electron diffraction (3D ED), highlighting the changes in molecular arrangement before and after mechanical treatment. The results provide experimental evidence for the previously proposed mechanically induced Restriction of Intramolecular Rotation (RIR) mechanism.