Assembly of calix[4]arene carboxylic acid derivatives by hydrogen bonding

Crystallisation of seven calix[4]arene derivatives leads to the formation of a “head-to-head” or “head-to-tail” dimer motif through hydrogen bonding.

Investigations into the assembly behaviour of a ‘rigidified’ p-carboxylatocalix[4]arene

A rigidified p-carboxylatocalix[4]arene has been synthesised and used in self- and metal-directed assembly, affording molecular capsules in both neutral and salt forms, as well as 1-D coordination polymers.

Two-Dimensional Calix[4]arene-based Metal-Organic Coordination Networks of Tunable Crystallinity

A flexible and versatile method to fabricate two-dimensional metal-organic coordination networks (MOCNs) by bottom-up self-assembly is described. 2D crystalline layers were formed at the air-water interface, coordinated by ions from the liquid phase, and transferred onto a solid substrate with their crystallinity preserved. By using an inherently three-dimensional amphiphile, namely 25,26,27,28-tetrapropoxycalix[4]arene-5,11,17,23-tetracarboxylic acid, and a copper metal node, large and monocrystalline dendritic MOCN domains were formed. The method described allows for the fabrication of monolayers of tunable crystallinity on liquid and solid substrates. It can be applied to a large range of differently functionalized organic building blocks, also beyond macrocycles, which can be interconnected by diverse metal nodes.

Selective recognition of the di/trimethylammonium motif by an artificial carboxycalixarene receptor

Chemical tools that recognise post-translational modifications have promising applications in biochemistry and in therapy. We report a simple carboxycalixarene that selectively binds molecules containing di/trimethylammonium moieties in isolation, in cell lysates and when incorporated in histone peptides. Our findings reveal the potential of using carboxycalixarene-based receptors to study epigenetic regulation.

‘Honeycomb’ nanotube assembly based on thiacalix[4]arene derivatives by weak interactions

Crystallisation of six thiacalix[4]arene derivatives from hexane–chloroform leads to ‘honeycomb’ nanotube architectures and each tubular stack is surrounded by six close tubular neighbours via weak interactions, such as S⋯π interactions, C–H⋯π interactions, and so on.

Different metal-ion-induced dimeric self-assembling cavities based on thiacalix[4]benzocrown-4 isomers

To construct the self-assembly of metal-ion-induced well-ordered architectures based on calixcrowns, isomeric thiacalix[4]benzocrowns-4 1 and 2 with rigid and small crown units were employed as the new scaffolds. They all show remarkable selectivity for Ag(+) and their complexation ability towards Ag(+) results in two novel dimeric aggregates of calixcrowns, which were first evidenced by ESI-MS, (1)H and DOSY-NMR spectra. Ultimately, X-ray diffraction experiments confirmed unambiguously the existence of the two metal-ion-induced dimers in lower rim/lower rim mode, and showed that dimerization of calixcrown 1 or 2 in the presence of Ag(+) could form dimeric supramolecular cavity with a small inner room. Moreover, the positional isomerism of their crown units (o-benzocrown unit for ligand 1 and m-benzocrown unit for 2) led to a dramatic change in the configuration of the two dimeric cavities 1·Ag(+) and 2·Ag(+). For dimeric cavity 1·Ag(+), two silver centers seamed two thiacalix[4]crown molecules together and resided at the edge of the dimeric self-assembling cavity; for dimeric cavity 2·Ag(+), one Ag(+) stitched two thiacalixcrowns together and was encapsulated in the center of the self-assembling cavity, while the other Ag(+) is tied down to one end of the dimer. Consequently, as a result of the different construction of dimeric cavities 1·Ag(+) and 2·Ag(+) the extended structures of the complexes are also different. The neighbour self-assembling cavities 1·Ag(+) are mutually oriented side-by-side and form a 1-D rectilineal polymeric chain. While, the neighbour self-assembling cavities 2·Ag(+) arrange themselves in a typical head-to-tail fashion to form a zig-zag polymeric chain.