Supplementary material from "Arene guest selectivity and pore flexibility in a metal-organic framework with semi-fluorinated channel walls"

  • Rebecca Smith (Contributor)
  • Inigo Vitorica-Yrezabal (Contributor)
  • Adrian Hill (Contributor)
  • Lee Brammer (Contributor)



    A metal-organic framework (MOF) with one-dimensional channels of approximately hexagonal cross-section [Ag<sub>2</sub>(O<sub>2</sub>CCF<sub>2</sub>CF<sub>2</sub>CO<sub>2</sub>)(TMP)] <b>1</b> (TMP = 2,3,5,6-tetramethylpyrazine) has been synthesized with MeOH filling the channels in its as-synthesized form as [Ag<sub>2</sub>(O<sub>2</sub>CCF<sub>2</sub>CF<sub>2</sub>CO<sub>2</sub>)(TMP)]·<i>n</i>(MeOH) <b>1-MeOH</b> (<i>n</i> = 1.625 by X-ray crystallography). The two types of ligand connect columns of Ag(I) centres in an alternating manner, both around the channels and along their length, leading to an alternating arrangement of hydrocarbon (C-H) and fluorocarbon (C-F) groups lining the channel walls, with the former groups projecting further into the channel than the latter. MeOH solvent in the channels can be exchanged for a variety of arene guests, ranging from xylenes to tetrafluorobenzene, as confirmed by GC, <sup>1</sup>H NMR spectroscopy, TGA and <sup>13</sup>C CP-MAS NMR spectroscopy. Alkane and perfluoroalkane guests, however, do not enter the channels. Although exhibiting some stability under a nitrogen atmosphere, sufficient to enable crystal structure determination, the evacuated MOF <b>1</b> is unstable for more than periods of minutes under ambient conditions or upon heating, whereupon it undergoes an irreversible solid-state transformation to a non-porous polymorph <b>2</b>, which comprises Ag<sub>2</sub>(O<sub>2</sub>CCF<sub>2</sub>CF<sub>2</sub>CO<sub>2</sub>) coordination layers that are pillared by TMP ligands. This transformation has been followed <i>in situ</i> by powder X-ray powder diffraction and shown to proceed via a crystalline intermediate.
    Date made available17 Nov 2016

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