ChemDigest

Molecular Transformer: A flexible π‐conjugated, all carbon‐based “figure‐eight” macrocycle (3) without a meso bridge was synthesized in one step. The supramolecular assembly behavior of 3 was investigated in this work; compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its larger ring size, which endows it with the ability to adjust its conformation according to changes in the external environment.

Abstract

Here, we report a facile method to synthesize a series of macrocycles with different conformations. The planar macrocycle dimer (1), twisted macrocycle trimer (2) and “figure‐eight” tetramer (3) are clearly elucidated by X‐ray single‐crystal analysis, in which the electron‐rich phenanthrene units offer the possibility of supramolecular assembly. As expected, in the solid state, 1 and 3 assemble into a columnar stack and an interlocking dimer, respectively, via π–π interactions between the phenanthrene units. Compared to the rigid conformation of dimer 1, the structure of tetramer 3 is more flexible due to its enlarged ring size. 3 can deform from a figure‐eight into a boat‐shaped geometry to host a planar electron‐deficient guest using its electron‐rich phenanthrene units. When assembled with spherical electron‐deficient C₆₀, interestingly, 3 further undergoes a conformational transformation from a figure‐eight to a belt shape in order to host C₆₀. These supramolecular assembly behaviors of 3 demonstrate that it is an adaptable macrocyclic host for both planar molecules and fullerenes.