Engineering Nanobelt Structure via Sulphur and Oxygen Doping: Synthesis, Structural Characterization, and Complexation with Fullerenes

This study explores the synthesis, structural characterization, and host‐guest interactions of heteroatom bridged nanobelts, focusing on a cyclothianthrene nanobelt and a fused nanobelt incorporating thianthrene and phenoxathiin. Utilizing a cyclization‐followed‐by‐bridging synthetic approach, both molecular belts were successfully synthesized, and their structures confirmed through NMR and MALDI‐TOF‐MS analysis. Crystallographic studies revealed that the cyclothianthrene nanobelt adopts an octagonal column‐like conformation, while the hybrid belt forms an oval tub‐shaped shape, both exhibiting distinct assembly motifs. The host‐guest chemistry of these nanobelts was investigated with fullerenes (C60, C70, and PC61BM). The cyclothianthrene belt showed no interaction with these fullerenes, whereas the other belt demonstrated adaptive binding capabilities, forming stable complexes with C60 and C70 through π−π interactions and C‒H∙∙∙S hydrogen bonds. The binding constants indicated that the hybrid belt has a stronger affinity for C70 due to better size complementarity. Additionally, its interaction with PC61BM showcased a specific 1:1 binding mode despite exhibiting a smaller binding constant. This study underscores the impact of heteroatom incorporation on the structural and functional properties of nanobelts, offering insights for future molecular design strategies.