Engineering Nanobelt Structure via Sulphur and Oxygen Doping: Synthesis, Structural Characterization, and...

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.