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.     

Supramolecular cobalt cages and coordination polymers templated by anion guests: self-assembly, structures, and magnetic properties

We report the anion-templated syntheses of a variety of supramolecular assemblies of Co(II). Remarkably in the presence of a weakly coordinating ion such as BF(4) (-), a discrete three-dimensional cage [BF(4) subset(BF(4))(2)Co(2)(L(1))(4)][BF(4)] (2) is formed with three coordinated BF(4) (-) ions, a rare example in supramolecular chemistry (L(1)=di(benzimidazole)-1,4-phenylene). Switching to stronger coordinating ions, such as NO(3) (-) or Cl(-), a one-dimensional coordination polymer [[Co(L(1))(NO(3))(2)](n)] (3) and a metallomacrocycle [Co(2)(L(1))(2)(Cl)(4)] (5) were formed, respectively. These results illustrate the powerful effect of the anion-templating chemistry. Finally the magnetic properties of these assemblies 1 b, 2, 3, and 5 are presented and discussed.     

Host-guest-driven copolymerization of tetraphosphonate cavitands

The outstanding complexing properties of tetraphosphonate cavitands towards N‐methylpyridinium salts were exploited to realise a new class of linear and cyclic AABB supramolecular polymers through host–guest interactions. The effectiveness of the selected self‐association processes was tested by ¹H NMR studies, whereas microcalorimetric analyses clarified the binding thermodynamics and revealed the possibility of tuning entropic contributions by acting on the flexibility of the guest linker. Although the formation of linear polymeric chains for a rigid system was demonstrated by X‐ray analysis, the presence of a concentration‐dependent ring–chain equilibrium was indicated by solution viscosity measurements in the case of a very flexible ditopic BB guest co‐monomer.