1,1,6,6-tetraphenylhexa-2,4-diyne-1,6-diol inclusion compounds

However, in an inclusion crystal of chalcone 70a with 1,1,6,6-tetraphenylhexa-2,4-diyne-l,6-diol host compound 91, the 70a molecules aggregate in close posi-... 

In 1968, we found that l,l,6,6-tetraphenylhexa-2,4-diyne-l,6-diol la) and 1,1,4,4-tetraphenylbut-2-yne-l,4-diol lb) form crystal inclusions with a wide variety of guest compounds, as shown in Table 1 In most cases, la and lb include guest species in 1 2 and 1 1 ratios, respectively. The vOH absorption band of all inclusion compounds appears at lower frequencies than those of uncomplexed la and Ib -. This suggests the presence of strong hydrogen bonding between host and guest (inclusion complexes ). 

Figure 1 Molecular structures of some organic molecules that form the host structures in solid inclusion compounds (these specific host structures are encountered freqnently in this chapter) urea, thiourea, tri-orfto-thymotide (TOT), perhydrotriphenylene (PHTP), deoxycholic acid (DCA) and varions molecules related to deoxycholic acid, host A (l,l,6,6-tetraphenylhexa-2,4-diyne-l,6-diol), host B (frans-2,3-bis(hydroxydiphenylmethyl)-l,4-dioxaspiro[5.4]decane), and host C (irans-2,3-bis(hydroxydiphenylmethyl)-l,4-dioxaspiro[5.4]nonane).

The wheel-and-axle design as source for host-guest compounds was originally proposed by Toda and Hart in 1981 for hosts containing hydroxyl functions 481 (see Ch. 3, Sect. 2.1 of Vol. 140). The l,l,6,6-tetraphenylhexa-2,4-diyne-l,6-diol (24) provides a representative compound. It forms 1 2 crystalline inclusion complexes with a large number of small guest molecules, including a variety of ketones, amines, amides and a sulfoxide 48). 

In 1986, we have found that l,l,6,6-tetraphenylhexa-2,4-diyne-l,6-diol (1) includes various guest molecules in a stoichiometrical ratio and forms crystalline inclusion complexes.1 X-ray analysis of a 1 2 inclusion complex of 1 and acetone showed that the guest molecules are accommodated in inclusion crystalline cavity by the formation of hydrogen bond with the hydroxyl groups of l.2 It was also found that inclusion complexation with 1 occurs selectively, and a mixture of isomers can be separated by the selective inclusion process.3 This suggests that racemic guest compound can be separated into enantiomers by inclusion... 

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