Crystal structures, lariat ethers

H O and N-H- - -O types. Based upon crystal structure data of lariat and crown ethers, another group [85] found evidence that aryl CH- - -O bonds help to define the conformation and binding character of their complexes. Supra-molecular self-assembly is another area where these bonds display some influence [86-88] and they seem to help with formation of inorganic channel structure [89, 90]. 

Figure 11 (a) X-ray crystal structures of cation-jr interactions between Na+ and indole of a lariat crown ether and (b) five-component... 

Figure 18 X-Ray crystal structures of some lariat ether complexes (a) [(K+ - lV-(allyl)aza-15-crown-5)PF6 ]2 (b) Pb + N-(allyl)aza-15-crown-5 (c) K+ N-(ethylbenzene)aza-18-crown-6 (d) K+ N,lV -di(but-l-enyl)diaza-18-crown-6 (e) K+ N-(methoxyethy l)aza-18-crown-6. ...

Earlier in this chapter we noted the selectivity of 18-crown-6 for K relative to other crown ethers of different sizes. Shown below is a diaza-18-crown-6 receptor possessing phenol groups as arms (lariats). This crown has a similar selectivity for K, but also binds this cation with some degree of a cation-ir effect. The accompanying crystal structure (selected portions) shows that the phenyl rings stack above and below the plane formed by the... 

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