Guest-free structures

Fig. 10a-f Examples of the structural motifs of p-ferf-butylcalix[4] arene derivatives a guest-free structure b 1 1 complex c 2 1 host-guest complex d hydrogen-bonded structure with an amine guest e self-inclusion structure f 1 1 host-guest clay mimic structure. (Adopted from [44] with permission)... 

An opposite effect, that is, shrinkage of the framework on desolvation occurs in a neutral, microporous MOF [22] with a double-pillared-layer structure, where offset stacking of the layers generate channels. These channels are occupied by water molecules, which can be exchanged with MeOH or EtOH solvents at room temperature in SC-SC mode. The solvent molecules of the mother crystals can also be removed either by heating or under vacuum to produce the desolvated framework as stable crystals. While the guest-free structure experiences shrinkage, the unit-cell... 

Fig. 21 a and b. Stereoviews of a the 1 1 16 (R = Ph3C) toluene clathrate (the disordered guest methyl is not shown), and b the crystal structure of the uncomplexed host (it represents one of a very few examples of a guest-free lattice which could be obtained from this type of compounds) 21)... 

Figure 7.44 X-ray crystal structure of the host portion of p I bulylcalix 4 arene (A) guest-free crystal showing a, b, c, d... repeating layers and (B) after exposure to vinyl bromide showing an a, b, a, b... repeat pattern arising from a shift of ca. 6A between layers b and c (reprinted with permission from AAAS from [55]).

Figure 2 Crystal structures of (a) DCA with acetone, (b) CA with y-valerolactone, (c) hexagonal crystal of CDCA, (d) guest-free crystal of LCA, (e) DCAM with 1-propanol, (f) CAM with m-cresol, (g) CDCAM with water, (h) LCAM with 2-hexanol, (i) DCAtriol with p-xylene, (j) guest-free crystal of CAtetraol, (k) CDCAtriol with ethanol, and (1) LCAdiol with dichloromethane.

It is interesting to note that the solvents which form complexes with rac-131 do not form complexes with optically active 131 and vice versa. For example, the powdered (+)-131 obtained by the evaporation of THF from the (+)-130-THF complex turns to guest-free crystals by recrystallization from solvents indicated in Table 8. The big difference of the role between the solvents shown in Tables 8 and 9 is interesting. X-ray crystal structural analysis of a 1 1 complex of (S)-(-)-131 and 1,2-dichloroethane showed that the latter is accommodated in the cavity of the inclusion complex as a form of nearly eclipsed chiral rotamer, but no any significant interaction between the host and guest molecules is present.59... 

Another class of inclusion complexes containing phosphorus in the host structure are cyclophosphazenes. Sozzani and co-workers have reported 31P CP/MAS studies of two organic derivatives tris(o-phenylene-dioxy)cyclotriphosphazene (TPP) and tris(2,3-naphtalene-dioxy)cyclotri-phosphazene (TNP). In the cited works, SS NMR technique was employed to recognise guest-free TNP matrix and of ICs with guests, for example benzene, tetrahydrofuran and p-xylene. The 31P NMR spectra were particularly informative regarding the symmetry of the phos-phazene ring. 

It seems that LCA will not include any organic guests, as can be seen from the fact that only structures of guest-free... 

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