Molecular knot

Of particular importance are oligopyridine ligands such as 2,2 6, 2",2" 6", 2""-pentapyridine. These molecules allow synthesis of helical, inter-finked and knotted molecular arrays.1 7 Similar species with interlocking rings are the catenands and torands.m Some examples of oligopyridines are (9-XVIII) and (9-XIX). Other nitrogen heterocycles are the following ... 

T. Schlick and W. K. Olson. Trefoil knotting revealed by molecular dynamics simulations of supercoiled DNA. Science, 257 1110-1115, 1992. 

Molecular knots, such as 37, are another variation of these molecules. The... 

Sauvage, J.-P. Dietrich-Buchecker, C. O. Chambron, J.-C. Transition metals as assembling and templating species synthesis of catenanes and molecular knots. In Comprehensive Supramolecular Chemistry, Sauvage, J.-P. Hosseini, M.W., Ed., Publisher Elsevier, Oxford, UK 1996 Vol. 2, p 43. 

Fujita, M. Transition metal-incorporating catenanes. In Molecular Catenanes, Rotaxanes and Knots Sauvage, J.-P., Dietrich-Buchecker, C., Eds. Wiley-VCH Verlag Weinheim, Germany, 1999, pp 57-76. 

Hugall, A., Stanton, J. and Moritz, C. (1997) Evolution of the AT-rich mitochondrial DNA of the root-knot nematode, Meloidogyne hapla. Molecular Biology and... 

Bird, D.M. and Wilson, M.A. (1994) DNA sequence and expression analysis of root-knot nematode elicited giant cell transcripts. Molecular Plant-Microbe Interactions 7, 419-424. 

Rosso, M.N., Favery, B., Piotte, C., Arthaud, L., de Boer, J.M., Hussey, R.S., Bakker, J., Baum, T.J. and Abad, P. (1999) Isolation of a cDNA encoding a beta-1,4-endoglucanase in the root-knot nematode Meloidogyne incognita and expression analysis during plant parasitism. Molecular Plantr-Microbe Interactions 12, 585-591. 

Sauvage, J.-P. Dietrich-Buchecker, G. Molecular Catenanes and Rotaxanes and Knots-, Wiley-VCH Weinheim, 1999. 

Some racemates (Figure 3.23) are more efficiently resolved on the bonded-type CSP than the coated-type CSP by using chloroform as a component of the eluent. On the bonded-type CSP of 24n, topologically interesting catenanes and molecular knots are successfully resolved using a hexane-chloroform-2-propanol mixture.185 The first direct HPLC resolution of the smallest chiral... 

Figure 3.23 Structures of dendrocatenanes, molecular knot, and C76 resolved on chemically bonded-type CSP of 24n.

A useful summary of the various and numerous types of rotaxanes, catenanes, and knots can be found in a review of template routes to interlocked molecular structures 468). Inorganic chemistry is centrally involved in the templating involved in self-assembly and in controlled synthesis of such species. 

The term rotamne derives (G. Schill, Histoiy , In Catenaries, Rotaxanes, and Knots, Academic, New York, 1971, pp. 1-4) from the Latin words rota, meaning wheel, and axis, meaning axle. In these molecular compounds, several wheel and axle components are constrained to be bound to one another mechanically, Le., without the aid of any valence forces, since the axle(s) is/are endowed with bulky stopper groups that prevent the extrusion of the wheel(s). 

Molecular Catenaries, Rotaxanes and Knots (Eds. J.-P. Sauv-age, C.O. Dietrich-Buckecher), VCH-Wiley, Weinheim, 1999. 

The principles were refined by Meyer in a second paper (70). In it he proposed that the micelles occurred at regular intervals. He also included an explanation of the elasticity of rubber based on the assumption that the molecular chains tended to roll together in knots in unstretched rubber, but line up when stretched. This explanation was especially elucidating since it agreed well with Katz s discovery (53) that amorphous rubber crystallizes when stretched. 

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