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(organic chemistry)
A compound with two or more independent portions not bonded to each other but linked by a linear portion threaded through a ring and maintained in this position by bulky end groups.



any of a group of chemical compounds composed of a linear molecular chain passing through a chainlike molecular ring. The compound is so arranged that the bulky end groups of the linear chain prevent the ring from slipping off.

Figure 1

The structural representation of a rotaxane molecule is shown in Figure 1, where R and R’ are radicals and the ring is a cyclic macromolecule.

The simplest type of rotaxane structure is shown in Figure 2, where η = 25–29. (This type of linear molecule will not fit within a smaller ring, that is, where η < 25; where n > 29, the stability of the rotaxane molecule is limited and the ring slips off the linear molecule.) The entities that form rotaxanes, that is, the linear and cyclic molecules, are bonded mechanically rather than chemically in what is called a topological bond.

Figure 2

Chemical compounds with topological bonding also include catenanes, wherein the cyclic macromolecules are joined in a fashion suggesting chain links. Figure 3 shows the structure of one of the synthesized catenanes. Rotaxanes and catenanes are obtained either by random formation in accordance with statistical laws (statistical synthesis) or by directed synthesis. The first statistical synthesis of rotaxanes was carried out by I. Harrison and S. Harrison (1967, United States); directed synthesis was first achieved by G. Schill and H. Zollenkopf (1969,

Figure 3

Federal Republic of Germany). Molecules of compounds constructed without chemical bonds occur in both organic and inorganic nature. Rotaxane and catenane forms of deoxyribonucleic acid (DNA) have been discovered.


Schill, G., E. Logemann, and W. Vetter. “Ozonolytischer Abbau eines Catensins” Augewandte Chemie, 1972, vol. 84, no. 23, p. 1144.
Schill, G. Katenany, rotaksany i uzly. Moscow, 1973. (Translated from English.)
Kostianovskii, R. G. Katenany iklatraty. Moscow, 1966.


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Over the past few decades, mechanically interlocked molecules [44-48], such as rotaxanes and catenanes, have become typical candidates in the design of artificial molecular machines.
Stephen Loeb's group in Windsor's Department of Chemistry specializes in rotaxanes, a type of mechanically interlocked molecule where a cyclical 'wheel' freely rotates around a straight 'axle.' Large functional groups on either end of the axle prevent the wheel from slipping off.
Heath's and Kuekes' teams said the rotaxane molecules, sandwiched between metal electrodes, functioned as logic gates.
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Stoddart received recognition for his 1991 development of "rotaxane," a structure in which a molecular ring is threaded onto a thin molecular axle, and for demonstrating that the ring could move along the axle.
Chapters cover modification reactions of cyclodextrins and the chemistry of modified cyclodextrins, polymers involving cyclodextrin moieties, cyclodextrin catalysis, chromatographic studies of molecular and chiral recognition, application of cyclodextrins for enantioseparations, crystallographic study of cyclodextrins and their inclusion complexes, microcalorimetry, NMR (nuclear magnetic resonance) of cyclodextrins and their complexes, other physiochemical methods, modeling of cyclodextrins and their complexes, rotaxane and catenane structures involving cyclodextrins, large-ring cyclodextrins, pharmaceutical applications, cyclodextrins in dispersed systems, and non-pharmaceutical applications.
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We are especially proud to recognize the work of Northwestern University's Fraser Stoddart, whose efforts to develop rotaxane -- a molecular structure that represents a revolutionary step in the miniaturization of technology -- our agency helped fund.
"So, there's a great deal of skepticism as to whether or not these things do what the researchers claim they do." To weigh in on this controversy, Blanco and his team modeled a rotaxane atom by atom.
Dr Steve Goldup, Associate Professor of Supramolecular Chemistry, and his team have developed a catalyst with significantly enhanced properties based on a rotaxane, in which a gold catalyst is embedded in the cavity formed by threading a ring shaped molecule around a dumbell shaped axle.
Kuekes of Hewlett-Packard Laboratories in Pale Alto, Calif., who is one of the experimenters, explains that in these prototypes, electrodes sprawl across several million rotaxane molecules.