Long Synthetic Nanotubes from Calix[4]arenes

Triazolated calix[4]semitubes: assembling strategies towards long multicalixarene architectures

Cone and 1,3-alternate calix[4]arenes bearing pairs of 2-azidoethyl or propargyl groups, and 1,3-alternate calix[4]arenes having four 2-azidoethyl, four propargyl groups or pairs of 2-azidoethyl and silylated propargyl groups were explored...

Assembling triazolated calix[4]semitubes by means of copper(i)-catalyzed azide–alkyne cycloaddition

Calix[4]arene-based bis(alkynes) and bis(azides) react with each other under thoroughly tuned CuAAC conditions and produce diverse biscalixarene semitube assemblies linked by two triazole units, which are capable of binding transition metal cations.

Preparation and application of tubular assemblies based on amphiphilic tetramethoxyresorcinarenes

A silver nanoparticle/organic hybrid micro-tubular material was prepared by fabricating tetramethoxyresorcinarene tetraaminoamide-functionalized silver nanoparticles on templates of microtubular assemblies.

Synthesis of calixarene-based cavitands and nanotubes by click chemistry

The synthesis of a variety of calixarene-based cavitands (capped and functional calixarenes) and calix nanotubes is easily performed in good to high yields using "click chemistry" methodology through the Cu(I)-catalyzed ligation of adequate bis-alkyne and bis-azide derivatives.

Self-Assembly of a Double Calix[6]arene Pseudorotaxane in Oriented Channels

A synthetic study to disclose the more appropriate manner by which two calix[6]arene units could be connected for the construction of an extended tubular structure was undertaken. As a result, a head-to-tail double calix[6]arene having the structure of an oriented nanotube that is about 2.6 nm long and 1.6 nm wide was prepared and characterized. This molecule is able to act as a wheel-type host and forms a supramolecular complex with an axle-type molecule, derived from 4,4'-bipyridinium (viologen), through very efficient self-assembly in solution. The properties of such a pseudorotaxane-type complex, which is stabilized by a combination of noncovalent interactions, were investigated in solution by UV/Vis absorption spectroscopy and voltammetric methods. These observations provide a clue about the location of the bipyridinium unit along the nanotube. In the solid state, the complex undergoes a further stage of self-assembly, thereby initiating extended oriented tubular structures. Crystallographic studies revealed that the positioning of the viologen dication in this asymmetric wheel is addressed by a complicated pattern of cooperative noncovalent intermolecular interactions that involve only one half of the host, whereas the remaining (more polar) half of the host is exploited to create long-range structural order that leads to a "secondary" structure of extended supramolecular channels that, in turn, self-assemble in the lattice, thus giving rise to a "tertiary" structure of parallel sandwiches of nanotubes.

Emerging host–guest chemistry of synthetic nanotubes

Emerging host-guest chemistry of synthetic nanotubes is reviewed, including the preparation of their encapsulation complexes, guest dynamics, exchange and potential applications.