Precise Spatial Arrangement and Interaction between Two Different Mobile Components in a Metal-Organic Framework

An H-shaped [2]rotaxane with a biphenyl axle and a 24-crown-8 (24C8) macrocycle was inserted into the tetrahedral cavities of the isostructural fcu MOFs PCN-57, UiO-68-d(4), and UWCM-10. The resulting rotaxane containing MOFs UWDM-8, UWDM-9-d(4), and UWDM-10 have precise spatial arrangements of two different mobile components-a rigid rotor (tetramethylphenyl, phenyl-d(4), or tetrazine) and a rotaxane macrocycle (24C8). The mobility of these units was characterized by variable-temperature (VT) solid-state nuclear magnetic resonance (SSNMR). VT C-13 SSNMR showed that the translational position of the macrocyclic wheel along the [2]rotaxane axle is dictated by the bulk and rotational orientation of the central rotor, while (VTH)-H-2 SSNMR demonstrated that the dynamics of the rotor are influenced by the presence of the macrocycle.

Automated summary

A study demonstrated that by inserting an H-shaped rotaxane with specific structure into different MOFs, rotaxane-containing MOFs with precise spatial arrangements of components can be formed. Through the use of VT solid-state nuclear magnetic resonance (SSNMR), it was found that the dynamics of the rotor are influenced by the presence of the macrocycle, while the translational position of the macrocyclic wheel along the rotaxane axle is dictated by the bulk and rotational orientation of the central rotor.