Unidirectional rotary motion in a liquid crystalline environment: Color tuning by a molecular motor

Abstract

Life could not exist without motion induced by a variety of molecular motors. The construction of artificial motors by chemical synthesis, which can power motions that lead to macroscopic detectable effects in a system, is a major endeavor in contemporary science. To move toward this goal, a host-guest system, composed of a nematic liquid crystal film doped with a chiral light-driven molecular motor, is assembled. Irradiation of the film results in unidirectional rotary motion of the molecular motor, which induces a motion of the mesogenic molecules leading to a molecular reorganization and, as a consequence, a change in the color of the film. In this way, by control of the rotary motion at the molecular level, color tuning over the entire visible spectrum is achieved. These findings demonstrate that a molecular motor can exert a visually observable macroscopic change in a material.

Optimizing rotary processes in synthetic molecular motors

“…In fact, an internal, 360°rotation was induced in one specific direction (i.e., clockwise or counterclockwise) upon input of photons and thermal energy. On the road toward applications, it was shown that the phase of liquid crystals can be controlled when doped with small portions of optically enriched molecular motor, and micro objects can be moved (18)(19)(20). In addition, molecular motors were recently grafted on gold (21) and quartz surfaces (22).…”

Profile of Jean-Pierre Sauvage, Sir J. Fraser Stoddart, and Bernard L. Feringa, 2016 Nobel Laureates in Chemistry

“…3A) could be added at ∼2-6 wt% in a liquid-crystal (LC) matrix and still undergo unidirectional rotary motion that induced color changes in the reorganized LC material (24). Improving on this feat, Feringa's group demonstrated in 2006 that a newly designed molecular motor 17 (Fig.…”

Well-Tempered Metadynamics as a Tool for Characterizing Multi-Component, Crystalline Molecular Machines

“…Of particular interest to the study described here is the class of crystalline molecular machines, 14,15 which are rigid systems of individual functional molecules that can either interact with one another in a well-defined way, much like a conventional machine, or act collectively to affect the macroscopic properties of the bulk. Examples of the latter have already been demonstrated in the liquid crystal phase, where properties of the constituent molecules have been modified to react to external stimuli, changing bulk properties such as the color 16 or helicity. 17 The alternative approach of constructing systems of molecules that mimic macroscopic mechanical machines presents a significant challenge in crystal engineering, as welldefined multicomponent systems are needed in which the functions of the individual molecules can be correlated with one another.…”