ID Infinite Hydrogen Bonding Nanotubes

Guichard and coworkers [72] applied an enantiopure cyclic tetraurea 34 to form a square-shaped nanotube (Fig. 3.16a). The four walls are all formed by 3-centered 

The formation of organic nanotubes from acyclic molecules is relatively rare. They are usually bent molecules that can curl up to give the required curvature. Chen and coworkers [78] reported a novel organic tubular structure from a bisdentate 

A beautiful tubular structure has been reported by Durka and coworkers [80] very recently from simple 1,2-phenylenediboronic acid 40 (Fig. 3.21). The dibo-ronic moieties form an alternating hexameric ring, and the rings are further connected laterally to a tube. The tubes may host interesting water clusters, but the incorporated water molecules are interacting weakly with the boronic framework, thus are not responsible for templating the self-assembly. 

As expected, molecule 42 assembled into 2D undulated hcb nets with large cavities through synthons 1 and 3 respectively, without or in the presence of methanol solvent (Fig. 3.23a). Three such nets are further interpenetrated through multiple C-H---71 interactions in a Borromean way that none of them are catenated but altogether they are not separable (Fig. 3.23b). One particular feature of the structure obtained from methanol is that it contains both the two different Borromean weaves shown in Fig. 3.23b with a 2 1 ratio within the same structure. 

3 24 a The pseudohexagonal nets of 42 with phenazine 44 and bipy 45. b One Borromean weave consisting of three hcb nets, c Topological view of 2D 3D polycatenated Boiromean-linked network the thick Borromean weave and the thin one are further interlocked by sixfold phenyl embrace interactions around the circles [82] 

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