Unidirectional rotors

Scheme 5 Feringa s unidirectional rotor [32], The 360° unidirectional rotation is achieved in a four-step process involving alternative photo-isomerization of the double bond and thermal interconversion of helicity...

Strambi A, Durbeej B, Ferre N, OUvucci M (2010) Anabaena sensory rhodopsin is a Ught-driven unidirectional rotor. Proc Natl Acad Sci USA 107 21322-21326... 

Fig. 5 A chemically driven unidirectional rotor. Reprinted with permission from Ref. [16]. Copyright 2000 by American Chemical Society.

The seal unit located at each end of the multistage compressor rotor is installed as a cartridge. The cartridge has positive locating features to permit proper placement on installation. It normally includes a provision to ensure that cartridges are not interchanged from the intended end. This is to prevent reverse rotation on the unidirectional configurations. 

Applications. Boron fibers are used as unidirectional reinforcement for epoxy composites in the form of preimpregnated tape. The material is used extensively, mostly in fixed and rotary wing military aircrafts for horizontal and vertical stabilizers, mdders, longerons, wing doublers, and rotors. They are also used in sporting goods. Another application is as reinforcement for metal matrix composites, in the form of an array of fibers pressed between metal foils, the metal being aluminum in most applications. 

Scheme 23 Light-driven unidirectional molecular rotor 35.

Light-driven unidirectional molecular rotary motors based on photoisomerization around a C=C bond51 have been successfully immobilized on nanoparticle gold surfaces by two thiol-functionalized legs to yield an azimuthal rotary motor (compound 1 in Fig. 17.2).52 Repetitive and unidirectional 360-degree rotary motion of the rotor moiety with respect to the surface-immobilized stator part was observed to occur on... 

Lactones have been used by Flechter, Dumur, Pollard, and Feringa [35] to conceive and set up a rotary motor that uses subsequent chemical reactions to achieve a 360° unidirectional rotation (Fig. 4). The stator is a naphthalene-derived unit connected in position 1 to a phenyl ring and bearing at position 2 a group that is transformed during the motions. The rotor is a 1,3-diphenol unit connected at position 2 to the stator. In the initial station 11 of the motor, one phenol group is... 

If this equation is satisfied, a unidirectional rotation occurs when the kinetic energy of the rotor is greater than maxg V(0). A given atom of the molecule shown in Fig. 1 will follow an x(t) = dcos(0(f) andy(f) = dsin(0(f)) motion in a Cartesian frame. 

To construct, on a single-molecule basis, an (x(t), y t)) motion of rotation in the classical sense, the only solution is to find a superposition of / (()) rotor eigenstates for (9(t)), which is almost a solution of Eq. (2) in the time interval of interest. Furthermore, (0(f)) cannot be an exact solution of Eq. (2) for all times. This is again a manifestation that a classical motion such as a unidirectional rotation is not a natural movement for an isolated quantum object. Only a simple quantum harmonic oscillator is able to perform classical motion when correctly prepared [17]. 

Fig. 8. Schematic of a molecular motor activated by intramolecular vibration energy relaxation of manifold A towards the rotor part of the motor. The rotor is positioned on an axis connected to reservoir 1 kept at a temperature T. Vibration manifold A is represented here by a simple molecular spring that can be excited by light or by the inelastic effect of a tunneling current passing through the molecular spring. Without such an excitation, manifold A is statistically populated by reservoir 1. A specific choice of a molecular structure equivalent to the spring may avoid its complete thermalization, for example by filtering the thermal noise giving rise to a unidirectional rotary motion...

On a single-molecule basis, a unidirectional molecular rotation requires careful preparation of the non-stationary quantum state of the rotor. The motive power of such rotating wave-packet states is weak and requires... 

Whilst oversimplified, these rheological relationships help to understand how the rotor speed and the nip width directly affect the shear rate in the unidirectional flow region. This corresponds well to the empirical experience that the higher the rotor speed, the lower the effective mixing time. In addition, equation (I) explains why rotors wearing decreases the shear rate (since e increases) and therefore affects the mixer efficiency. 

B. L. Light-driven molecular rotor Unidirectional rotation controlled by a single stereogenic center. J. Am. Chem. Soc. 2000. 122 (48). 12005-12006. 

E-glass - unidirectional/epoxy tapes Higher strength application rotor blades, wing components for smaller aircraft. 

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