Interlocked molecules

Arico F, Badjic JD, Cantrill SJ, Flood AH, Leung KCF, Liu Y, Stoddart JF (2005) Templated synthesis of interlocked molecules. Top Curr Chem 249 203-259... 

Ceo-TTF molecules, interlocked molecules (catenanes, rotaxanes), donor-acceptor macrocycles, cage molecules, etc. (Jeppesen et al, 2004). It is beyond the scope of this book to review such developments and I appeal to the curiosity of researchers really not familiar with such macromolecules to see how big the molecules can become. 

Summing up, it can be said that interwoven and interlocked molecules open up enormous possibilities not only to chemists but also to interdisciplinary researchers. Non-ionic templated syntheses and the newly established non-template strategy are powerful tools for further rapid and unprecedented developments in this field. 

HOW TO THREAD A STRING THROUGH THE EYE OF A MOLECULAR NEEDLE TEMPLATE SYNTHESIS OF INTERLOCKED MOLECULES... 

This brief summary on template effects for the syntheses of interlocked molecules not only shows that a broad variety of different non-covalent interactions mediate the threading step in their preparations, it also intends to demonstrate how many different structural types of such molecules exist, each of which has its own properties and special characteristics. However, regardless of the different structures and varying features of these molecules, the common motif among all of them is the presence of a mechanical bond. 

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

Combination of 10.41 with crown ether derivative 10.48 and Ag0) gives a trimetallic sheathed rack in which a rack of Ag(I) ions is threaded through the cavities of three heterocrowns (Figure 10.42). This complex is an example of a pseudorotaxane (stricdy a [4] pseudorotaxane because there are four components - three loops and an axel) and we will return to these kinds of assemblies, which are precursors for the synthesis of complex interlocked molecules by postmodification techniques, in Section 10.7. 

The versatility of this approach to interlocked molecules make it very attractive as a means towards nanoscale molecular machines in which the motions of the individual components are beginning to be translated into molecular logic operations and mechanical switches. We will return to this subject in the next chapter. 

The existence of interlocked molecules such as 10.95 can be established by a variety of spectroscopic techniques. Most importantly, mass spectrometry provides very characteristic patterns for catenanes. The mass spectra for catenated species are very different from those of covalently linked precursors (such as 10.94) but are more than the sum of their two individual components. Catenane mass spectra are characterised by the appearance of peaks at high mlz corresponding to the parent species as well as fragments corresponding to the transfer of hydrogen atoms from one macrocycle to the functional... 

---