Geometric Evolution of Perylene-Based Intermolecular π-π Dimers Toward Static and Dynamic Multicolor Emission.

Controllably achieving multicolor emission from single-molecule-based organic solids is of great significance, yet it remains a challenge because of the inherent complexity of molecular packing motifs. Herein, multicolor emission is governed by tailoring the geometries of π-π dimers. Using perylene (PE) as a planar π-fluorophore, we strategically design a compound, 3-(4-(1,2,2-triphenylvinyl)phenyl)perylene (pTPE-PE), which integrates a tetraphenyl ethylene (TPE) substituent with multiple rotatable phenyl rings to modulate the PE-based π-π dimer formation. On the one hand, pTPE-PE crystallization produces four polymorphs exhibiting green, yellow, orange, and red emission color, which are static presentations of the dimer model. This static multicolor emission is directly linked to π-π interactions within the dimers: a smaller interplanar distance and a larger overlap ratio between π-π PE units result in more strengthened interactions and more red-shifted emission. On the other hand, the observed multicolor transitions under pressure (yellow → orange → red) via dimer compression and thermal stimuli (sky-blue → green → orange) through dimer (dis)assembly provide dynamic presentation of the dimer model. Consequently, polymorphism/piezochromism/thermochromism not only provides direct experimental evidence for exciton modulation from the perspective of the simplest supramolecular dimer model, but also offers insights for designing intelligent optical materials.