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Molecular Rotors in a Metal-Organic Framework: Muons on a Hyper-Fast Carousel.

Giacomo PrandoJacopo PeregoMattia NegroniMauro RiccòSilvia BraccoAngiolina ComottiPiero SozzaniPietro Carretta
Published in: Nano letters (2020)
Using muon-spin spectroscopy, we study the exceptional dynamical properties of rotating molecular struts engineered within a Zn-based metal-organic framework at cryogenic temperatures, where the internal motions of almost any other organic substance are quenched. Muon-spin spectroscopy is particularly suited for this aim, as the experimental evidence suggests several implantation sites for the muons, among which at least one directly onto the rotating moiety. The dynamics of the molecular rotors are characterized by the exceptionally low activation energy EA ∼ 30 cal mol-1. At the same time, we evidence a highly unusual temperature dependence of the dipolar interaction of muons with nuclear magnetic moments on the rotors, suggesting a complex influence of the rotations on the muon implantation and diffusion.
Keyphrases
  • metal organic framework
  • single molecule
  • density functional theory
  • high resolution
  • room temperature
  • risk assessment
  • solid state
  • molecular dynamics