Search

The synthesis of a [2]rotaxane, comprising a calix[6]arene-wheel and a dibenzyl-ammonium axle, is here reported. By virtue of its inherent directionality, the calix-wheel makes non-degenerate two equivalent stations of the symmetrical axle. In this way, the neutral rotaxane shows two co-conformations, named endo-alkyl and endo-benzyl, in which an alkyl or benzyl moiety of the axle are included inside the calix-cavity, respectively. NMR and DFT studies showed that the co-conformation preferred by the neutral mechanomolecule is the ‘endo-alkyl’ one, which is more stabilized by C-H···π interactions between the included alkyl chain and the aromatic wall of the calix-cavity. [ABSTRACT FROM AUTHOR]

The solid state structure of the co-crystal between proximal p-tert-butylcalix[4]dihydroquinone, ethylacetate and 4,4’-bipyridine shows an interesting interplay of H-bond and van der Waals interactions that allow to rationalise the assembly possibilities of the calixarene compound under study. [ABSTRACT FROM AUTHOR]

Polyoxomolybdate-based organic−inorganic hybrid architectures were synthesised and characterised by X-ray crystallography. The supramolecular assemblies present rows of metallic clusters H-bonded by ammonium cations, with a 1:2 molybdate/ammonium ratio. The organic moieties of the ammonium cations establish hydrophobic contact among them such as van der Waals, C–H⋯πandπ⋯πinteractions that stabilise the supramolecular architectures. In particular, for compound5then-alkyl tails pack closely together giving a lipid-like bilayer. In compound6, the aromatic phenyl rings of the organic cation allow the stabilisation of the supramolecular architecture by C–H⋯πandπ⋯πinteractions. Regarding the X-ray structure of the compound11,the tetraanionic octa-molybdate [Mo8O26]4−cluster is surrounded by four ethyl-triphenyl-phosphonium cations. Running along theb-axis open channels are occupied by DMF solvent molecules. Interestingly, a soaking experiment inn-pentane with the corresponding crystals of compound11afforded to a crystal structure very different from the native one. Van der Waals, C–H⋯πandπ⋯πinteractions between large organic moieties are fundamental in the stabilization of hybrid organic-inorganic POM architectures. [ABSTRACT FROM AUTHOR]

The solid state structure of the co-crystal between proximal p-tert-butylcalix[4]dihydroquinone, ethylacetate and 4,4’-bipyridine shows an interesting interplay of H-bond and van der Waals interactions that allow to rationalise the assembly possibilities of the calixarene compound under study. [ABSTRACT FROM AUTHOR]