Molecular motor light controlled

Pijper D, Feringa BL. Molecular transmission controlling the twist sense of a helical polymer with a single light-driven molecular motor. Angew. Chem. Int. Ed. 2007 46 3693-3696. 

Furthermore, just as photochemistry is a clean way to cause a reaction, it may offer a clean way to cause a movement in a macroscopic object. As a matter of fact, this is an issue rarely adopted by natme, where direct conversion of light into mechanical energy is limited to a few cases in bacteria [16]. This does not preclude adopting this principle for artificial system. As an example, one may think of controlling and directing the Brownian motion of molecules in solution and to induce directional translational and rotary motion of molecules or of nano-objects. In other words, rotary and translational motors may be devised and used to power future nanodevices. For example, rotary molecular motors allow the transmission of motion in multicomponent systems as well as reaching out-of-equilibrium assemblies (see Fig. 11.5) [18]. 

Lubbe AS, Ruangsupapichat N, Caroli G, Feringa BL (2011) Control of rotor function in light-driven molecular motors. J Org Chem 76 8599-8610... 

So far, several example of the chemically and electrochemically controlled switching of bistable linear molecular machines have been presented. The final section of this chapter will be dedicated to illustrating how such molecular switches and motors, when designed ingenuously, can also be powered by nature s most abundant and powerful energy source - light. 

The basic epoxy resin most often used with concrete is a light, amber-colored liquid, about the viscosity of a heavy motor oil. Liquid epoxy resins are generally made by the same process as that used to make solid epoxy resins. The ratio of epichlorhydrin to bis-phenol controls the type of resin produced. The higher the ratio of epichlorhydrin to bis-phenol, the lower the viscosity of the final resin, and the lower its molecular weight. 

Other types of rotary motors can be constructed using catenanes, that is, species minimally composed of two mechanically interlocked macrocycles. In appropriately designed systems, the rotation of one ring around the other can be achieved by external stimulation. If suitable control elements are introduced in the structure, such a rotation can be performed unidirectionally. This concept was cleverly realized with benzylic amide catenanes by exploiting the isomerization of fumaramide to maleamide caused by UV light. Chiral C=N compounds such as imines also fulfill the criteria of two-step light-driven unidirectional molecular... 

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