Dissipative and Autonomous Square‐Wave Self‐Oscillation of a Macroscopic Hybrid Self‐Assembly under Continuous Light Irradiation

Abstract

Building a bottom-up supramolecular system to perform continuously autonomous motions will pave the way for the next generation of biomimetic mechanical systems. In biological systems, hierarchical molecular synchronization underlies the generation of spatio-temporal patterns with dissipative structures. However, it remains difficult to build such self-organized working objects via artificial techniques. Herein, we show the first example of a square-wave limit-cycle self-oscillatory motion of a noncovalent assembly of oleic acid and an azobenzene derivative. The assembly steadily flips under continuous blue-light irradiation. Mechanical self-oscillation is established by successively alternating photoisomerization processes and multi-stable phase transitions. These results offer a fundamental strategy for creating a supramolecular motor that works progressively under the operation of molecule-based machines.

Light-induced dynamic shaping and self-division of multipodal polyelectrolyte-surfactant microarchitectures via azobenzene photomechanics

“…Moreover, growth of the filaments occurred after a delay time (δ blue ) of ~0.2–2 s. Since 1/δ blue was proportional to the applied light intensity (Supplementary Fig. 11b), the delay time was attributed to a one-photon azoTAB photo-isomerisation process, consistent with previous reports on azobenzene photo-isomerisation1239. In contrast, the inverse of the time constants (1/τ blue ) associated with filament growth increased exponentially with light intensity, rather than linearly (Supplementary Fig.…”

“…Photochromic materials based on azobenzene derivatives are particularly attractive for the implementation of photo-mechanical responses owing to their robust and reversible trans-cis light-induced isomerisation that affects both the molecular volume and orientation of the transition dipole moment34567. Shape deformations involving bending, twisting, expansion-contraction, swelling, melting or oscillations have been observed in crystalline molecular assemblies89101112, microgel particles13, azobenzene-containing polymer films14151617 and liquid crystal azobenzene-containing elastomeric polymers181920212223. Repeatable deformations are usually achieved in these materials by the sequential use of ultraviolet (UV) and blue light irradiations to induce alternative trans - cis followed by reverse cis - trans isomerisation of the azobenzene moieties.…”

“…Activation to the trans/cis photostationary state has recently been applied to the design of dissipative supramolecular motors30, and induction of autonomous or chaotic oscillations in thin crystalline assemblies12 or liquid crystalline polymer films28, respectively. Long-distance mass transport is usually inhibited in these systems because of immobilization of the azobenzene molecules into crystalline arrays or via covalent attachment to crosslinked polymer chains31, which in turn limit the extent of light-induced shape transformations.…”

Phototransformative Supramolecular Assembly of Amphiphilic Diarylethenes Realized by a Combination of Photochromism and Lower Critical Solution Temperature Behavior

“…Not only the hydrophobic interaction, but also hydrogen bonding and metal coordination contribute to determining the structure . Among several directions of study, macroscopic transformation of the assembly in response to external stimuli is currently under intensive investigation …”

Anisotropic Diffusion of Microbeads Surrounded by an Anisotropically Elongated Supramolecular Diarylethene Architecture under Linearly Polarized Light

“…[6] Supramolecular architectures, which are assembled by noncovalentbonds such as hydrophobic interactions, hydrogen bonds, and p-p interactions, are also used to amplify the molecular structural change. [7][8][9][10][11][12][13][14][15][16][17][18] Linearly polarizedl ight is also used to achieve macroscopic anisotropic movement. Ap olymer film containing azobenzene, which gives al iquid-crystalline structure and dichroism to the polymer,s howed photoinducedb ending perpendicular to the directiono fp olarization.…”