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.

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.

For creation of autonomous microrobots, which are able to move under conditions of a constant environment and a constant energy supply, a mechanism for maintenance of mechanical motion with a capacity for self‐control is required. This requirement, known as self‐organisation, represents the ability of a system to evade equilibrium through formation of a spatio‐temporal pattern. Following our previous finding of a self‐oscillatory flipping motion of an azobenzene‐containing co‐crystal, we present here regulation of the flipping motion by a light‐receiving sensor molecule in relation to the alignment and role of azobenzene molecules in crystals. In the anisotropic structure, a specific azobenzene molecule acts as a reaction centre for the conversion of light to a mechanical function process, whereas the other molecules act as modulators for spatio‐pattern regulation. The present results demonstrate that autonomously drivable molecular materials can exhibit information‐responsive, self‐sustainable motion by incorporating stimulus‐responsive sensors.

A key goal in developing molecular microrobots that mimic real‐world animal dynamic behavior is to understand better the self‐continuous progressive motion resulting from collective molecular transformation. This study reports, for the first time, the experimental realization of directional swimming of a microcrystal that exhibits self‐continuous reciprocating motion in a 2D water tank. Although the reciprocal flip motion of the crystals is like that of a fish wagging its tail fin, many of the crystals swam in the opposite direction to which a fish would swim. Here the directionality generation mechanism and physical features of the swimming behavior is explored by constructing a mathematical model for the crystalline flapper. The results show that a tiny crystal with a less‐deformable part in its flip fin exhibits a pull‐type stroke swimming, while a crystal with a fin that uniformly deforms exhibits push‐type kicking motion.

<p>To create autonomous microrobots which move in the presence of a constant energy source, their mechanical motion must have a capacity for self-control. This is realized when a structural change occurs with conversion of energy facilitated by cofactors, with a self-regulation component to prevent reaching a static state. Here, we present a single crystal structure analysis of azobenene derivatives which reveals a mille-feuille-like layered structure of sparse and dense layers of six independent azobenzene moieties. In this anisotropic structure, a specific azobenzene molecule acts as a reaction center for a light-to-mechanical function process. The other molecules in the crystal act as modulators. Moreover, depending on the photoisomerisation process activated by a polarized light source, different cyclic motions are observed. We clarify the mechanism by which the self-organized mechanical behavior of these azobenzene molecules is achieved at the molecular level. Thus, the present results demonstrate that autonomously driven molecular materials can exhibit information-responsive and self-sustainable motion by incorporating stimulus-responsive sensors. </p>