Carceplex

Fig. 16. (a) Inclusion complex of a cryptophane and (b) a carceplex (carcerand inclusion complex). 

Carceplexes and hemicarceplexes, host-guest complexes in which carcerands and hemicarcerands, in particular those including heterocyclic fragments, are hosts 99CRV931. 

Along the same lines, there is a fuzzy boundary between hemicarceplexes and carceplexes, some hemicarceplexes having more carceplex-like traits than others. The schematic diagram illustrated in Figure 8 shows how the concepts of a pseudorotaxane and of a hemicarceplex may be explained using fuzzy sets. The sets of these species belong simulta-... 

Thus, the hemicarcerands differ161 from the related carce-rands, which are similar in shape and constitution, but from which, guests cannot escape without the breaking of covalent bonds. The mechanically bound complexes formed between carcerands and their guests are termed carceplexes. 

Scheme 6.111 Photolysis ofp-tolyldiazirine (552) within the enantiopure molecular container 547d giving rise to the diastereomeric carceplexes 547dO10.

The above observations and many other similar ones prompted Cram to define inside carceplex volume as a specific innerphase intermediate between the polar solvent and vacuum. 

Mechanically interlocked molecular compounds, including catenanes, rotax-anes, and carceplex, are constituted of molecules composed of two or more components that cannot be separated from each other [95-98]. The development of strategy for achieving controlled self-assembling systems by non-covalent interaction enables one to prepare such attractive compounds for applications in nanoscale molecular devices. The dithiafulvene derivatives are effective electron donors, which are good candidates to form those supramolecular systems with appropriate acceptors by virtue of intermolec-ular CT interactions. In this chapter, dithiafulvene polymers forming rotax-ane structures are especially described. 

Figure 6.47 Carceplexes formed in the preparation of 6.97 (denoted by grey oval).

Table 6.10 Template ratios for the formation of 6.98 (n = 1, R = CH2CH2Ph) by a variety of guest species, and relative stabilities of the resulting carceplexes in nitrobenzene

Figure 6.49 (a) X-ray crystal structure (stereoview) of the pyrazene carceplex of 6.98 (reprinted... 

A large carcerand has a cavity volume of 120 A3. If the molecular volume of methane is 28.5 A3, calculate the occupancy factor, p, for a 1 1 methane carceplex of this host. What host volume would result in an occupancy factor of 0.67, equivalent to solid methane Calculate the notional pressure of one molecule of methane in a cavity of this size. Do you think that such a carceplex is likely to form ... 

Fraser, J. R., Borecka, B., Trotter, J., Sherman, J. C., An asymmetric carceplex and new crystal-structure yield information regarding a 1-million-fold template effect. J. Org. Chem. 1995, 60, 1207-1213. 

Makeiff, D. A., Sherman, J. C., Template effect where 1-3 molecules drive formation of a trimer carceplex. Chem. Eur. J. 2003, 9, 3253-3262. 

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