Crystal Growth & Design · 2019 · 31 citations · 38 references
Natural SciencesChemistryMaterials ScienceCrystal StructureInorganic ChemistryOrganic ChemistryCoordination ChemistryCrystal ChemistryMolecular DynamicsPorous MaterialsSupramolecular MaterialsTransition Metal ComplexesMetal-organic FrameworksPorphyrin ComplexesPyridine ChemistryRotational DynamicsSingle-crystal DiffractionSingle-crystal X-ray DiffractionSolvent TreatmentsVariable-temperature Spectroscopy
Zinc(II) metal–organic framework (MOF) materials were prepared using a porphyrin-based tetracarboxylate linker and pyridine-terminated [2]rotaxane linkers as pillars. Two pillaring rotaxanes (R = H or CH3 at pyridine 2-position) were used to create two MOFs α-UWDM-6 and α-UWDM-7, and their structures were determined by single-crystal X-ray diffraction. Both MOFs undergo reversible phase transitions upon solvent removal to generate γ-UWDM-6 and β-UWDM-7. The dynamics of the 24-membered macrocycle ([24]crown-6) inside each MOF phase was studied using variable-temperature 2H solid-state NMR spectroscopy. Interestingly, only solvated α-UWDM-7 demonstrates unrestricted rotation of the macrocycle inside the MOF pores; studies on α-UWDM-7 with various solvents showed that the dynamics of the wheel is essentially independent of the solvent.
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