Compound, Dianin

Many further cases of inclusion materials were discovered by happy accident during the next two centuries, for example, additional clathrate hydrates, the Hofmann clathrates, phenol inclusion compounds, Dianin s compound, urea tubulates, choleic acids, cyclodextrins, aud interpenetrated hydroquinone inclusion compounds. These substances remained problematic despite being the object of much painstaking scientific study. Mauy were unstable under ambient conditions and therefore it proved difficult to determine accurate ratios of their two components A and B. Furthermore, the substances did not follow the usual rules of covalent bonding, leading to their representation in the fonn (A)x (B)y. It was surmised that one component somehow trapped the other, but no experimental methods were available to analyze this phenomenon. 

Polar and coordinatively active functional groups are structural elements frequently found in the constitution of crystal inclusion hosts, mainly including conventional host molecules7 . Typical examples are urea (2), thiourea (5), hydroquinone (4), Dianin s compound (5), deoxycholic add (6) or simply water (Fig. 1). This was the reason to assume that functional groups play an important part in the construction of crystal inclusion compounds. 

Fig. 4. Inclusion cage of Dianin s compound (5). The matrix is constructed via a cyclic H-bonded hexagonal system of host molecules (on top and on bottom of the macrocage O atoms as bold dots, H-bonds as dotted lines) bulky parts of the host molecules interlock (equatorial of the cage). The cage can be filled with molecules of fitting size (e.g. one molecule of chloroform) (Adapted from Ref. 16)...

Clathration is the third sorption situation. Guests are incorporated during the growth of the host lattice. Their liberation occurs on heating or lowering the pressure with lattice breakdown. This situation is found for water, phenol, quinol, cresol, urea, and Dianin s compound. 

A number of crystals other than zeolites possess permanent intracrystalline porosity on a molecular scale. These include Dianin s compound, /3-Ni(or Co)(4-methylpyridine)4(NCS)2, and smectites in which the... 

Dianin s Compound. The unit cells of inclusion complexes in Dianin s compound and of the guest-free compound are almost the same, and there is no doubt that the guest-free lattice contains the same voids as those in which guests are present. 

Figure 3. The shape and size of the cavity/channel of Dianin s compound, (a) The cage formed by two sets of hexamers. (b) The top or bottom half of the cage, hexamers are held together by hydrogen bonds, (c) Schematic illustration of the cage/channel. The stacking is along the c axis. (Reproduced with permission from D. D. MacNicol in Inclusion Compounds, Vol. 2, J. L. Atwood, J. E. D. Davies, and D. D. MacNicol, Eds., Academic Press, New York, 1984, p. 1.)...

A similar study of Norrish II reactions has been conducted on complexes of aryl ketones in Dianin s compound 1 [295], a nonpolar host whose channels are effectively truncated at each 11A of length by a 2.8-A constriction from 6 hydrogen-bonding hydroxyl groups (see Figure 3) [296]. Table 13 summarizes the results from complexes with ketones expected to undergo primarily the Norrish II reactions [297]. As befits the rather large (and mostly) nonpolar reaction cavities, the E/C and t/c ratios in Table 13 provide evidence for relatively little control by the channels of Dianin s compound over the fate BRs. Even in the most selective case from 5-methyl-... 

TABLE 13 Photoproduct Ratios from Alkanophenones in Benzene and Complexes of Dianin s Compound 297]... 

Although no crystallographic studies of the tocopherols have been made, molecular dimensions have been calculated for both 2,2,5,7,8-pentamethylchroman-6-ol and a-tocopherol (81HC(36)63). These results are based on the agreement between the X-ray data for 4-(p-hydroxyphenyl)-2,2,4-trimethylchroman (Dianin s compound, 159) (70JA3749) and the computer-produced values for a strain-free model. 

Some phenolic compounds can form flat hexagonal structures with the aromatic rings facing outward, and linked by hydrogen bonds. The internal space thus formed contains solvent. Such compounds are called inclusion compounds or clathrates. An example is dianin (2.14), which can form clathrates in more than 50 different solvents. 

Hydroquinone, Phenol, Dianin s Compound and the Hexahost Strategy... 

Figure 7.21 (a) The structure of unsolvated Dianin s compound (front and back of the central cavity... 

Figure 7.23 The hexameric hydrogen bonding in the Dianin s complex of morpholinium cation (only the phenol residues of Dianin s compound shown for clarity).24...

Figure 7.43 (top) 129Xe CP-MAS NMR solid-state spectra for a the xenon clathrate of Dianin s compound obtained at 1 atmosphere pressure (bottom) the DQ filtered spectrum showing only the resonance due to the doubly occupied cavity. (Reproduced by permission of The Royal Society of Chemistry). 

Hydroquinone and phenol based clathrates including Dianin s compound are based upon cages made up of 6-membered hydrogen bonded rings of hydroquinone and are subject to considerable synthetic variation. 

Lloyd, G. 0., Bredenkamp, M. W., Barbour, L. J., Enclathration of morpholinium cations by Dianin s compound salt formation by partial host-to-guest proton transfer. Chem. Commun. 2005, 4053 4055. 

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