Photocontrol Over Self‐Assembled Nanostructures of π–π Stacked Dyes Supported by the Parallel Conformer of Diarylethene

Diarylethenes (DAEs) have rarely been used in the design of photoresponsive supramolecular assemblies with a well‐defined morphology transition owing to rather small structural changes upon photoisomerization. A supramolecular design based on the parallel conformation of DAEs enables the construction of photoresponsive dye assemblies that undergo remarkable nanomorphology transitions. The cooperative stacking of perylene bisimide (PBI) dyes was used to stabilize the parallel conformer of DAE through complementary hydrogen bonds. Atomic force microscopy, UV/Vis spectroscopy, and molecular modeling revealed that our DAE and PBI building blocks coassembled in nonpolar solvent to form well‐defined helical nanofibers featuring J‐type dimers of PBI dyes. Upon irradiating the coassembly solution with UV and visible light in turn, a reversible morphology change between nanofibers and nanoparticles was observed. This system involves the generation of a new self‐assembly pathway by means of photocontrol.