Unidirectional Rotary Motion

Kelly TR, De Silva H, Silva RA (1999) Unidirectional rotary motion in a molecular system. Nature 401 150-152... 

R.A. van Delden, N. Koumura, N. Harada, B.L. Feringa, Unidirectional Rotary Motion in a Liquid Crystalline Environment Color Tuning by a Molecular Motor , Proc. Natl. Acad. Sci. USA, 99, 3945 (2002)... 

T.R. Kelly, H. de SUva, R.A. SUva, Unidirectional Rotary Motion in a Molecular System , Nature, 401,150 (1999)... 

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...

Photochemical E Z isomerization (Section 6.1.1) is responsible for continuous unidirectional rotary motion along a carbon carbon double bond of 433, a chiral helical alkene mounted on the surface of gold nanoparticles through two octanethiol linkers (Scheme 6.206).1245 Thanks to the considerable conformational flexibility of... 

In the previous sections, our main focus was on mechanical molecular switches based on mechanically interlocked structures pseudorotaxanes, rotaxanes, and cate-nanes. Molecular motors, rotors, and propellers based on single rotor molecules, as important molecular machines, have also attracted great attention during the last two decades. Molecular motors can be defined as molecules that are able to convert any energy input into controlled motion. Inspired by the unidirectional rotary motion of Fi-ATPase, much effort has been focused on systems that allow controlled molecular rotation and translation. 

Later, the same group developed a molecular system that could achieve a unidirectional rotary motion of 120° around a single bond (Figure 84). This molecule consists of an amino-substituted triptycene unit linked by a single bond... 

Although this molecular motor does not achieve continuous and fast rotation, the design principles may prove relevant for a better understanding of biological molecular motors producing unidirectional rotary motion. 

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... 

J. Vicario, M. Walko, A. Meetsma, B.L. Eeringa, Eine tuning of the rotary motion by stmctural modification in light-driven unidirectional molecular motors. J. Am. Chem. Soc. 128, 5127-5135 (2006)... 

The rotary motion of the molecular motor (28) could be controlled by a self-complexing [l]pseudorotaxane system under acid-base conditions. The surface-bound motors (29) on SAM underwent photochemical and thermal isomerizations consistent with unidirectional rotation. ... 

The time scales and number of reactions involved for unidirectional ring rotation in catenane 20 and in other similar catenanes [93] make their operation as rotary motors somewhat unpractical. Nevertheless, analysis of the thermodynamic and kinetic aspects of the operation mechanisms provides a fundamental insight on how energy inputs can be used to harness thermal fluctuations and drive unidirectional motion. 

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... 

Fig. 4 A chemically driven rotary molecular motor able to achieve a 360° unidirectional rotation (a) the sequence of chemical reactions (b) a stylized representation of the motion...

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