The arcuate and curved shape structures of AR-11 and ARO-11 were confirmed by single-crystal X-ray diffraction analysis (Figure ). Slow diffusion of acetone into a CDCl3/CS2 solution of AR-11 at room temperature resulted in the formation of AR-11 single crystals. The single crystals of ARO-11 were obtained by the slow diffusion of CH3OH into the CHCl3 solution. Single-crystal structure analysis indicated that the π-skeletons of AR-11 and ARO-11 are highly twisted along their longitudinal axes (Figure ). With the presence of bulky tert-butyl groups on the fjord edges of AR-11 and ARO-11, the benzenoid rings adopt an interlacing "up-down" conformation with dihedral angles ranging from 36° to 47° (also see Figure ). The end-to-end arc lengths for π-backbone of AR-11 and ARO-11 are 2.05 nm and 2.06 nm, respectively, which correspond with the DFT optimized structures (Scheme 1a). In the packing structures of AR-11 and ARO-11 (Figure and), every two identical molecules (shown in green and blue) surround each other in the form of face to edge, forming a dimer. This dimer presents a slip-stacked packing mode along the plane of the a-axis and c-axis. In the stacking structures of AR-11, the dimer with intermolecular π-π interactions with an interlayer distance as short as 3.3 Å (Figure and Figure ). In the crystal structure of ARO-11 are 3.0 Å distance of π-π interactions between the adjacent molecules. Besides, there are face-to-edge intermolecular C-H…O hydrogen bonding interactions (2.5 Å) and the arrangement is closer for ARO-11 (Figure and Figure ).