Two Cu21 clusters with pseudo-D3 symmetry derived from the D-saccharate pentaanion, C6H5O8(5-)

The combination of Cu(NO₃)₂, potassium hydrogen saccharate (KC₆H₉O₈) and 1,10‐phenanthroline (phen) yields a pair of chiral cluster compounds, each with composition Cu₂₁(C₆H₅O₈)₆(phen)₁₂(NO₃)₁₂?solvate. One of the compounds forms as orthorhombic crystals, while the other forms cubic crystals. Each of the clusters has D₃ or approximate D₃ symmetry, but the arrangement of the saccharate ion in the clusters is quite different in the two cases. The clusters in the cubic form interact with neighbouring clusters through face‐to‐face π interactions involving the phen ligands, an association that leads to the generation of very large solvent‐filled spaces in the crystal structure. In contrast the clusters in the orthorhombic form are much more densely packed. At the centre of each cluster that crystallises in the orthorhombic form is a nitrate anion that binds to six Cu^II centres. ESI mass spectral studies indicate that the Cu₂₁ clusters exist in solution. Solid‐state magnetic studies of the cubic form of Cu₂₁ show that antiferromagnetic coupling occurs to leave a non‐zero‐spin ground state, and comparisons are made to the magnetic data for other large Cu^II clusters.     

Multifunctional Tricarbazolo Triazolophane Macrocycles: One‐Pot Preparation,Anion Binding,and Hierarchical Self‐Organization of Multilayers

Programming the synthesis and self‐assembly of molecules is a compelling strategy for the bottom‐up fabrication of ordered materials. To this end, shape‐persistent macrocycles were designed with alternating carbazoles and triazoles to program a one‐pot synthesis and to bind large anions. The macrocycles bind anions that were once considered too weak to be coordinated, such as PF₆^?, with surprisingly high affinities (β₂=10¹¹ M ^?2 in 80:20 chloroform/methanol) and positive cooperativity, α=(4 K₂/K₁)=1200. We also discovered that the macrocycles assemble into ultrathin films of hierarchically ordered tubes on graphite surfaces. The remarkable surface‐templated self‐assembly properties, as was observed by using scanning tunneling microscopy, are attributed to the complementary pairing of alternating triazoles and carbazoles inscribed into both the co‐facial and edge‐sharing seams that exist between shape‐persistent macrocycles. The multilayer assembly is also consistent with the high degree of molecular self‐association observed in solution, with self‐association constants of K=300 000 M ^?1 (chloroform/methanol 80:20). Scanning tunneling microscopy data also showed that surface assemblies readily sequester iodide anions from solution, modulating their assembly. This multifunctional macrocycle provides a foundation for materials composed of hierarchically organized and nanotubular self‐assemblies.     

Crystal engineering: Supramolecular structures by cocrystallization ofMeso-1,2-diphenyl-1,2-ethanediol and bisimines,simple cases of molecular recognition

The crystal structures of molecular complexes betweenmeso- 1,2-diphenyl-1,2-ethanediol and two bisimines (N,N-(dibenzylidene)-ethylenediamine and glyoxylidene-bis(2,4-dimethyl-3-pentyl-amine) are reported at different temperatures. The structure-determining motif of the cocrystalline arrangement is one single O-H . N hydrogen bond resulting in infinite ladderlike polymers. The supramolecular structure is formed by recognition of fitting species: Thed- orl-isomers do not arrange in such structures.¹H NMR experiments show that no prearrangements take place by forming complexes in solution.     

Solvent exchange in thermally stable resorcinarene nanotubes

The assembly of C-methyl resorcinarene into a tubular supramolecular solid-state structure, its thermal stability, and its hosting properties are reported. Careful control of the crystallisation conditions of C-methyl resorcinarene and 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane (1,4-dimethyl DABCO) dibromide leads to a formation of two crystallographically different, but structurally very similar, solid-state nanotube structures. These structures undergo a remarkable variety of supramolecular interactions, which lead to the formation of 0.5 nm diameter nonpolar tubes through the crystal lattice. The formation of these tubes is templated by suitably sized small alcohols, namely, n-propanol, 2-propanol, or n-butanol. The self-assembly involves close pi...pi interactions between the adjacent resorcinarenes, and C--H...pi and cation...pi interactions between the resorcinarenes and the guest 1,4-dimethyl DABCO dications. The crystals of these supramolecular tube structures are thermally very stable and the included solvent alcohol can be removed from the tubes without breaking the single-crystalline structure of the assembly. After removal of the solvent molecules the tubes can be filled with other small, less polar solvent molecules such as dichloromethane.     

Construction of hydrogen-bonded ternary organic crystals derived from L-tartaric acid and their application to enantioseparation of secondary alcohols

Ternary organic crystals consisting of an L-tartaric acid-derived dicarboxylic acid, a commercially available achiral diamine, and a chiral secondary alcohol have been developed and characterized by X-ray crystallography. 1D, 2D, and 3D hydrogen-bonded supramolecular networks were constructed, depending on the structure of the diamine used. Benzylic and aliphatic secondary alcohols were enantioselectively incorporated into the crystal and were successfully enantioseparated with up to 86 and 79% enantiomeric excess (ee), respectively. Selective incorporation of one enantiomer of 2-butanol, which is a small chiral aliphatic alcohol, was achieved by the cooperative effects of hydrogen bonds, CH···π interactions, and van der Waals interactions between the guest and host molecules, with the aid of two water molecules. The high host potential of the binary supramolecular system is mainly attributed to the skewed conformation of two rigid aromatic groups of tartaric acid derivatives, which prevents dense packing of the molecules and enhances the formation of multicomponent inclusion crystals.     

Triple hydrogen bonds direct crystal engineering of metal-assembled complexes: the effect of a novel organic-inorganic module on supramolecular structure

Novel triply hydrogen bonded suprastructures based on [M(tdpd)2(L)2]2- (H2tdpd=1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, L=solvent) and melamine-analogous cations have been synthesized and characterized. The use of anions containing two AAA sets from [M(tdpd)2(L)2]2- together with cations containing one DDD set (A=hydrogen-bond acceptor, D=hydrogen-bond donor) leads to the formation of complementary triply hydrogen bonded modules in the solid state. In all cases, the building module is further extended via additional hydrogen-bonding interactions to produce a tape, and tapes are assembled into sheets. These results show that a hydrogen-bonded module consisting of different kinds of building blocks, one of which is a metal complex that includes hydrogen-bond acceptor sites and the other is a hydrogen-bond donor molecule, will be attractive for constructing metal-containing supramolecular systems by the self-assembly technique.