Translational dynamics of a non-degenerate molecular shuttle imbedded in a zirconium metal-organic framework

Abstract

A new [2]rotaxane molecular shuttle linker based on the binding of a 24-crown-8 ether macrocycle at a benzimidazole recognition site was synthesised. The shuttling dynamics of the linker were studied in solution and the structure confirmed by X-ray crystallography. A multivariate Zr(iv) MOF,UWDM-11, containing the new MIM linker and primary linker tetramethylterphenyldicarboxylate was synthesised and the translational motion of the molecular shuttle studied in the solid state. The use of a13C enriched MIM linker allowed the dynamics of both activated and mesitylene-solvatedUWDM-11to be elucidated by VT13C CPMAS SSNMR. The incorporation of mesitylene into the pores ofUWDM-11resulted in a significant increase in the barrier for thermally driven translation of the macrocycle.