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 C(60) and C(70)-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 C(60) and TBTQ-(OG)(6) with C(70) was found to be 1:1 with binding constants of K(a) = (1.50 ± 0.10) × 10(5) M(−1) and K(a) = (2.20 ± 0.16) × 10(5) M(−1), respectively. The binding affinity between TBTQ-(OG)(6) and C(60) was further verified by Raman spectroscopy. The geometry of the complex of TBTQ-(OG)(6) with C(60) 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 C(60) 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.