Molecular Vises for Precisely Positioning Ligands near Catalytic Metal Centers in Metal–Organic Frameworks

We report the construction of a molecular vise by pairing a tritopic phenylphosphorus(III) linker and a monotopic linker in opposite positions within a metal–organic framework. The angle between these linkers at metal sites is fixed upon changing the functionality in the monotopic linker, while the distance between them is precisely tuned. This distance within the molecular vise is accurately measured by 1 H– 31 P solid-state nuclear magnetic resonance spectroscopy. This unveils the impact of the distance on catalytic performance without interference from electrostatic effects or changes in the angle of the ligand, which is unprecedented in classic organometallic complexes.