Donor-Acceptor Tribenzotriquinacene-Based Molecular Wizard Hats Bearing Three ortho-Benzoquinone Units

Two π-extended bay-bridged tribenzotriquinacenes ("TBTQ wizard hats") 12 and 16 bearing three mutually conjugated, alternating veratrole-type and ortho-benzoquinone units were synthesized. The electronic properties of these complementarily arranged, nonplanar push-pull systems are affected by the fusion with the rigid, C₃ -symmetric TBTQ core to a different extent, as revealed by X-ray structural analysis, UV-vis spectroscopy and cyclovoltammetry. The combination of three quinone units within the original TBTQ core and three veratrole-type bay bridging units in 12 gives rise to a more efficiently π-conjugated chromophore, as reflected by the shallower shape of wizard hat and its absorption in the visible up to 750 nm in comparison to 16. Congener 12 contains an aromatic 18-π electron system in contrast to the cross-conjugated analog 16. X-ray structure analysis of the precursor dodecaether 15 revealed the formation of a cage-like supramolecular dimer, in which the peripheral dioxane-type ether groups interlace by twelve noncovalent C-H⋅⋅⋅⋅⋅O bonds.

A cylinder-shaped macrocycle formed via Friedel-Crafts reaction

By performing Friedel-Crafts reaction with a mixture of 1,3,5-tri(furan-2-yl) benzene (TFB) and acetone, we successfully synthesized a cylinder-shaped macrocycle. The isolated yield of 36% is relatively high, considering that twelve C-C bonds are formed simultaneously. The structure of this macrocycle was confirmed using 1H NMR spectroscopy, mass spectrometry and X-ray crystallography. This macrocycle is able to recognize a variety of cationic guests driven by cation-dipole and CH-π interactions.

Water-soluble host-guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

A sugar-functionalized water-soluble tribenzotriquinacene derivative bearing six glucose residues, TBTQ-(OG) 6 , was synthesized and its interaction with C60 and C70-fullerene in co-organic solvents and aqueous solution was investigated by fluorescence spectroscopy and ultraviolet-visible spectroscopy. The association stoichiometry of the complexes TBTQ-(OG) 6 with C60 and TBTQ-(OG) 6 with C70 was found to be 1:1 with binding constants of K a = (1.50 ± 0.10) × 105 M-1 and K a = (2.20 ± 0.16) × 105 M-1, respectively. The binding affinity between TBTQ-(OG) 6 and C60 was further verified by Raman spectroscopy. The geometry of the complex of TBTQ-(OG) 6 with C60 deduced from DFT calculations indicates that the driving force of the complexation is mainly due to the hydrophobic effect and to host-guest π-π interactions. Hydrophobic surface simulations showed that TBTQ-(OG) 6 and C60 forms an amphiphilic supramolecular host-guest complex, which further assembles to microspheres with diameters of 0.3-3.5 μm, as determined by scanning electron microscopy.