Mechanically interlocked molecule

Kim, K., Mechanically interlocked molecules incorporating cucurbituril and their supramolecular assemblies. Chem. Soc. Rev. 2002, 31, 96-107. 

Mechanically Interlocked Molecules as Artificial Molecular Machines 297... 

Mechanically interlocked molecules, such as bistable catenanes [13] and [2]rotax-anes [14], constitute some of the most appropriate candidates to serve as nanoscale switches and machines in the rapidly developing fields of nanoelectronics [15] and nanoelectromechanical systems (NEMS) [16]. The advantages of using mechanically interlocked molecules in the fields of molecular electronics and... 

Fig. 2 Timescales for different intermolecular interactions mechanically interlocked molecules, encapsulated species and solvated encounters...

The inability of bis-, tris-, or tetraloop compounds to form homodimers and the general tendency of tetra-urea calix[4]arenes to dimerize can be further exploited for the synthesis of mechanically interlocked molecules. A 1 1 mixture of tetra-ureas 5 or 6 with bis- or tetraloop compounds 8 or 9 (in practice the non-reactive loop component is added in a small excess) contains exclusively heterodimers (e.g., 5-8, 5-9, or 6-9), since this is the only possibility, to have all the urea functions involved in the favorable hydrogen-bonded belt.5 Again this is easily evidenced by the complete absence of peaks for the homodimer 5-5, or 6-6 in the H NMR spectra (for an example see Figure 5.11). 

Fig. 2 Graphical representations of the structures of mechanically interlocked molecules (MIMs) a catenane (left) and a rotaxane (right)...

A special issue devoted to molecular machines appeared in Accounts of Chemical Research in 2001. It reflects the current interest for this field in which ruthenium complexes act as important tools. Molecular machines are characterized by a mobile part and a stationary part. Photochemical and electrochemical inputs can make a machine work, offering the advantage of being switched on and off easily and rapidly. Mechanically interlocked molecules, such as rotaxanes and catenanes, are suitable candidates. Crown ethers, cyclophanes, and calixarenes are representative families of the cyclic... 

Alternatively, the use of reversible, thermodynamically-controlled synthetic methods - similar to those used to make the supramolecular polymers discussed in Figure 1 - can be used to assemble mechanically interlocked molecules in near quantitative yields (Figure 7)." However, imlike the supramolecular systems, once formed (after removal of the catalyst) the mechanically interlocked structures are robust and cannot be destroyed without breaking a (strong) covalent bond ... 

Mechanically interlocked molecules incorporating cucurbituril and their supramolecular assemblies 02CSR96. 

One of the potential applications of mechanically interlocked molecules is construction of molecular-scale devices such as molecular machines and switches. [2J(Pseudo)rotaxanes containing CB 6] were studied along... 

Fig. 1 Different topologies cf mechanically interlocked molecules (a) catenane, (b) rotaxane. (c) pseudorotaxane,(d) oligocatenane, (e) [3]rotaxane, and (t) pretzelane.

Kim. K. Mechanically interlocked molecules incorporating cucurbituril and their supramolecular assemblies. Chem. Soc. Rev. 2002. 31. 96-107 and references therein. Amabilino, D.B. Ashton, P.R. Reder, A. Spencer, N. Stoddart, F.J. Olympiadane. Tkngew. Chem., Int. Ed. Engl. 1994. 33. 1286-1290. 

---