2D and 3D metal-organic frameworks constructed with a mechanically rigidified [3]rotaxane ligand

A mechanically interlocked [3]rotaxane was newly designed, synthesized, and employed as a ligand for constructing metal-organic frameworks (MOFs). The nano-confinement by macrocycles forces the soft bis-isophthalate axle into a pseudo-rigid conformation and coordinates to zinc(ii) ions, affording a two- or three-dimensional MOF under controlled conditions. The 2D MOF exhibits a neutral framework with a periodic puckering sheet structure, while an anionic framework with a pts topology was observed for the 3D MOF. The phase purity of both bulk materials was confirmed by powder X-ray diffraction. Thermogravimetric analysis reveals that both materials are stable up to 250 degrees C. The success of applying mechanical bonds to rigidify flexible ligands provides new insights for the design of metal-organic frameworks.

Automated summary

A mechanically interlocked [3]rotaxane was designed, synthesized, and used as a ligand for constructing metal-organic frameworks (MOFs). The nano-confinement effect of macrocycles rigidifies the flexible ligand and coordinates it to zinc(ii) ions, resulting in the formation of two- or three-dimensional MOFs under controlled conditions.