Host-guest properties neutral guests

We have defined the terms carcerand, carceplex, hemicarcerand, and hemicarceplex The formation of carcer-ands an carceplexes has led to some important information regarding templation by neutral molecules Similarly, the properties of hemicarcerands and hemicarceplexes has led to some interesting host-guest properties, including the storage of highly reactive species such as cyclobutadiene or benzyne... 

Fig. 6.10 Host-guest properties of XCA and XCAOEG toward neutral guests (G). Inset (a) X-ray diffraction structure of avidin-biotin complex (PDB accession 2AVI) (b) X-ray diffraction structure of complex XCADimi. H-bonds are indicated by dashed lines...

Fig. 6.11 Host-guest properties of Xtren and XtrenC toward neutral guests. Inset H NMR spectra (guest region, 300 MHz, CDCI3,260 K) of (a) 1 2 mixture of the two diastereomeric endo-complexes obtained upon the addition of ( )-Mimi (ca. 9 equiv.) to XtrenC.4H (b) 2 1 mixture of the two diastereomeric endo-complexes obtained upon the addition of ( )-PPD (ca. 17 equiv.) to XtrenC.4H (c) after the subsequent addition of / -(-)-PPD ca. 23 equiv.) to the previous mixture...

A summary of the complexing properties of hosts 38 and 40 in (CDC12)2 towards neutral guest species is given in Fig. 13, where the experimental free energy of association AG°a(= — RT In Ka) at 300 K has been plotted as a function of the guest van der Waals volumes [35],... 

The present chapter will concentrate on these two types, including more or less close modifications of their structure, while cyclic oligomers derived from pyrocatechol which are [l ]orthocyclophanes and various other cyclooligomers for which meanwhile the prefix calix is used will be excluded. The main emphasis will be also on the synthesis and the chemical modification of calixarenes and some basic properties, such as their conformational behaviour. Their host properties towards cations, anions or neutral guests... 

---