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

Abstract

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.

Enabling Light Work in Helical Self-Assembly for Dynamic Amplification of Chirality with Photoreversibility

“…Particularly, perylene bisimides 18,19 and naphthalene diimides 20,21 are exploited as fluorescent building blocks in construction of these thermodynamically helical nanostructures. Photochromic diarylethenes (DAEs) have also attracted much attention since their chemical and physical properties are reversibly controllable with photo-irradiation [22][23][24] , especially for their functional switching characteristics [25][26][27][28][29][30][31] , such as the photoresponsive helical gel 13,32 and light-driven self-assembly 33,34 . However, the dynamic photoreversibility with modulation of amplified chirality, morphology as well as fluorescence between two thermally stable states are still remaining challenges.…”

Molecular photoswitches mediating the strain-driven disassembly of supramolecular tubules

“…Light constitutes an ideal source of energy that can be supplied continuously to an isolated system to obtain structural switching-as opposed to previously employed external environmental triggers that do not modify the structure of the building blocks [i.e., salinity (23) and temperature (24)]. Notwithstanding the tubular shape, a number of pioneering reports on supramolecular fibers (25,26) have demonstrated strategies to achieve out-of-equilibrium operation (27)(28)(29)(30). The mechanism of assembly of supramolecular polymers, mostly fiber-like objects, has attracted much attention (31,32), but much less is known about the mechanism by which these fibers disassemble (29).…”

Improving Photocatalytic Activity: Versatile Polyelectrolyte – Photosensitizer Assemblies for Methyl Viologen Reduction

“…On‐off switching of the self‐assembled dendrimer‐dye structures was possible by changing between acidic and basic conditions . This type of electrostatic self‐assembly has further led to the formation of light‐switchable and pH‐triggerable nanostructures . Besides electrostatic interactions being the major structure directing force for charged building blocks, also hydrogen bonding plays an important role in binding small molecules to dendrimer macroions, acting as encapsulating agents …”