Ferrocene in the metal–organic framework MOF-5 studied by homo- and heteronuclear correlation NMR and MD simulation

• Ferrocene in MOF-5 investigated by 2D NMR and computer simulations.
• Host–guest interaction detected via intermolecular 1H–1H spin diffusion.
• C–C distances between ferrocene and bdc linkers measured by MD simulation.
• Intermolecular distances estimated by 1H–1H correlation spectroscopy.

Advanced solid-state 2D NMR spectroscopy and molecular dynamics computation are employed to investigate the interaction between adsorbed ferrocene molecules and the MOF-5 lattice. Relayed 13C–1H heteronuclear correlation (HETCOR) 2D NMR spectra clearly indicate short-distance contacts between the ferrocene guests and the benzene-1,4-dicarboxylic-acid linkers, mediated via intermolecular 1 H spin diffusion. By use of 2D 1H–1H correlation spectroscopy the distances between 1H nuclei in the guests and the linkers are estimated to be shorter than 0.5 nm. MD computer simulations support the interpretation of the 2D solid state NMR studies. Moreover, they suggest a wide distribution of intermolecular distances in this host–guest system with the shortest intermolecular hydrogen–hydrogen distances of 0.15 nm.

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