Honeycomb supramolecular frameworks of organic–inorganic hybrid cluster composed of cation radical and Keggin-type polyoxometalate

Abstract

Keggin-type phosphomolybdic acid (H₃PMo₁₂O₄₀) promoted the formation of a cation radical of tetra(thienylthio)-tetrathiafulvalene (TT-TTF), consequently resulting in a cation radical complex [(TT-TTF)^+•]₃[(PMo₁₂O₄₀)³⁻](CH₂Cl₂), which shows self-assembly in solution and forms microtubes. The molecular level structure of the microtube is evaluated by X-ray diffraction analysis, which reveals that the microtube is produced via various non-covalent interactions in the hierarchical assembly process: the electrostatic interactions between (TT-TTF)^+• and (PMo₁₂O₄₀)³⁻ afford an organic–inorganic hybrid triangular nanocluster [(TT-TTF)^+•]₃[(PMo₁₂O₄₀)³⁻] as the building block; the strong π–π interactions between (TT-TTF)^+• result in the cluster-based two-dimensional honeycomb nanosheet; the van der Waals forces between the nanosheets lead to the propagation along the third direction to form a three-dimensional supramolecular framework possessing nano-sized channels.