Supramolecular assembly, -coordinated arene

The elaboration of organometallic networks and supramolecular assemblies, assembled via directional dirhodium-x-arene interactions [72,153], is important due to the relevance of alkene coordination to the dirhodium core in cyclopropanation reactions, and thus their applications in catalysis. Also, they are relevant to the Issues of x-arene interactions encountered in fullerene and carbon nanotubes [154], in hydrogen storage and fuel cell technology. 

Keywords Cavitand Metal coordination Resorcin[4]arene Self-assembly Supramolecular chemistry Terpyridine ligand... 

Very appealing supramolecular structures have been obtained289 with the three-component system consisting of the p-sulfonatocalix[4]arene 143290 (used as its pentasodium salt), pyridine N-oxide and La(N03)3-6H20. If these components are mixed in a 2 2 1 molar ratio 12 calixarene pentaanions, shaped like a truncated pyramid, form spherical supramolecules with the phenolic OH functions inside and the sulfonato groups outside. Coordination of the sulfonato groups and of pyridine N-oxide included in the calixarene cavity to the La3+ stabilizes this assembly. Each sphere is in contact with six other spheres via C-shaped dimers, as shown in Figure 41. 

The construction of self-assembled capsules based on ionic interactions to be tested as supramolecular hosts in polar solvents such as alcohols or water is a timely goal that, compared to hydrogen-bonded capsules, is still in its infancy even though important steps have been taken. Few examples have been reported regarding ionic capsules between cationic fiat tetrapyridinium-Zn(II)-porphyrinate and anionic tetrasulfonate-calix[4]arenes that form a hemispherical entropy-driven capsule that displayed high stability in the presence of water or competing salts. Apart from solvent molecules, such capsules showed encapsulation of small guests like 1-methylimidazole or 4-methylpyridine via coordination to the Zn(II) metal... 

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