C-H•••S Hydrogen Bond Assisted Supramolecular Encapsulation of Fullerenes with Nanobelts

Hydrogen-bonded capsules have been widely employed as supramolecular hosts for organic molecular guests. Encapsulation of fullerenes by capsules is relatively scarce, especially those that utilize sulfur atoms as hydrogen-bond acceptors. Herein, we describe, in both solution and solid state, a bowl-shaped nanobelt [8]cyclophenoxathiin la and its tetra-methylated derivative lb that can form C-H center dot center dot center dot S hydrogen-bonded capsules induced by complexation with suitable fullerenes. la strongly encapsulates C-60, C-70, or 6,6-phenyl-C-61-butyric acid methyl ester (PC61BM) to form a 2:1 ternary complex featuring 16 equatorial (sp(2))C-H center dot center dot center dot S hydrogen bonds. A pseudorotaxane structure was further obtained for the complex of la with PC61BM. Conversely, a 1:1 inclusion complex was observed for binding C-60 or PC61BM with lb indicating the reduced tendency to form capsules by introducing methyl groups into the belt. Surprisingly, the capsule-like structure was retained for the 1:2 complex of C(70 )with lb as observed by the presence of multiple (sp(3))C-H center dot center dot center dot S hydrogen bonds. The strong binding affinity and tailorable complexation mode enable further applications of nanobelts in fullerene chemistry. [GRAPHICS] .