An intermolecular (H2O)10 cluster in a solid-state supramolecular complex

Chemical self-assembly is the process by which 'programmed' molecular subunits spontaneously form complex supramolecular frameworks. This approach has been applied to many model systems, in which hydrogen bonds, metal- ligand coordination or other non-covalent interactions typically control the self-assembly process. In biology, self-assembly is generally dynamic and depends on the cooperation of many such non-covalent interactions. Water can play an important role in these biological self-assembly processes, for example by stabilizing the native conformation of biopolymers. Hydrogen- bonded (H2O) clusters can play an important role in stabilizing some supra- molecular species, both natural and synthetic, in aqueous solution. Here we report the preparation and crystal structure of a self-assembled, three- dimensional supramolecular complex that is stabilized by an intricate array of non-covalent interactions involving contributions from solvent water clusters, most notably a water decamer ((H2O)10) with a ice-like molecular arrangement. These findings show that the degree of structuring that can be imposed on water by its surroundings, and vice versa, can be profound.; Chemical self-assembly is the process by which 'programmed' molecular subunits spontaneously form complex supramolecular frameworks. This approach has been applied to many model systems, in which hydrogen bonds, metal-ligand coordination or other non-covalent interactions typically control the self-assembly process. In biology, self-assembly is generally dynamic and depends on the cooperation of many such non-covalent interactions. Water can play an important role in these biological self-assembly processes, for example by stabilizing the native conformation of biopolymers. Hydrogen-bonded (H2O)n clusters can play an important role in stabilizing some supramolecular species, both natural and synthetic, in aqueous solution. Here we report the preparation and crystal structure of a self-assembled, three-dimensional supramolecular complex that is stabilized by an intricate array of non-covalent interactions involving contributions from solvent water clusters, most notably a water decamer ((H2O)10) with an ice-like molecular arrangement. These findings show that the degree of structuring that can be imposed on water by its surroundings, and vice versa, can be profound.</p

Supramolecular assembly of well-separated, linear columns of closely-spaced C60 molecules facilitated by dipole induction

Co-crystallization of C60 with p-bromocalix[4]arene propyl ether results in a remarkably well packed structure; the calixarene molecules pack with their dipole moments aligned unidirectionally and the unusually close van der Waals contact between the C60 molecules is most likely a result of an opposing induced dipole.</p

Controlling molecular self-organization: Formation of nanometer-scale spheres and tubules

Amphiphilic polyhedron-shaped p-sulfonatocalix[4]arene building blocks, which have been previously shown to assemble into bilayers in an antiparallel fashion, have been assembled in a parallel alignment into spherical and helical tubular structures by the addition of pyridine N-oxide and lanthanide ions. Crystallographic studies revealed how metal ion coordination and substrate recognition direct the formation of these supramolecular assemblies. The addition of greater amounts of pyridine N-oxide changed the curvature of the assembling surface and resulted in the formation of extended tubules.</p

Characterization of a well resolved supramolecular ice-like (H2O)10 cluster in the solid state

The conformation of a previously observed ice-like water cluster in the solid state proves to be robust to geometric changes in its surroundings and the hydrogen bonded arrangement is finally revealed in detail.</p

Supramolecular intercalation of C60 into a calixarene bilayer - A well-ordered solid-state structure dominated by van der Waals contacts

C60 co-crystallizes with p-iodocalix[4]arene benzyl ether to form a layered structure in which the C60 molecule is ordered without the presence of appreciably strong intermolecular interactions.</p

Structure of the p-sulfonatocalix[4]arene complex with tetramethylammonium ions, [NMe4]5[p-sulfonatocalix[4]arene].4H2O

Treatment of p-calix[4]arene sulfonic acid with excess tetramethylammonium hydroxide yields [NMe4]5[p-sulfonato-calixarene]-4H20. The compound crystallizes from aqueous solution in the triclinic space group PI with a = 13.125(3), b = 14.881(3), c = 16.320(4) A, a = 77.19(1), β = 77.30(1), y = 72.30(1)°, and Dc = 1.35 g cm3 for Z = 2 (C48H87O20N5S4). Refinement based on 5044 observed reflections yielded a final R value of 0.084. The overall structure consists of bilayers of calix[4]arenes separated by regions which contain the cations and water molecules. One of the tetramethylammonium ions is bound within the hydrophobic calix[4Jarene cavity. © 1995, Taylor & Francis Group, LLC. All rights reserved.</p