Porous metal-organic polyhedra: Morphology, porosity, and guest binding

Research output: Contribution to journalArticlepeer-review

Authors

  • Stephen P. Argent
  • Ivan Da Silva
  • Alex Greenaway
  • Mathew Savage
  • Jack Humby
  • Andrew J. Davies
  • Harriott Nowell
  • William Lewis
  • Pascal Manuel
  • Chiu C. Tang
  • Alexander J. Blake
  • Michael W. George
  • Alexander V. Markevich
  • Elena Besley
  • Sihai Yang
  • Martin Schröder

Colleges, School and Institutes

External organisations

  • University of Nottingham
  • ISIS Facility
  • Rutherford Appleton Laboratory
  • University of Manchester
  • Diamond Light Source
  • University of Vienna

Abstract

Designing porous materials which can selectively adsorb CO2 or CH4 is an important environmental and industrial goal which requires an understanding of the host-guest interactions involved at the atomic scale. Metal-organic polyhedra (MOPs) showing permanent porosity upon desolvation are rarely observed. We report a family of MOPs (Cu-1a, Cu-1b, Cu-2), which derive their permanent porosity from cavities between packed cages rather than from within the polyhedra. Thus, for Cu-1a, the void fraction outside the cages totals 56% with only 2% within. The relative stabilities of these MOP structures are rationalized by considering their weak nondirectional packing interactions using Hirshfeld surface analyses. The exceptional stability of Cu-1a enables a detailed structural investigation into the adsorption of CO2 and CH4 using in situ X-ray and neutron diffraction, coupled with DFT calculations. The primary binding sites for adsorbed CO2 and CH4 in Cu-1a are found to be the open metal sites and pockets defined by the faces of phenyl rings. More importantly, the structural analysis of a hydrated sample of Cu-1a reveals a strong hydrogen bond between the adsorbed CO2 molecule and the Cu(II)-bound water molecule, shedding light on previous empirical and theoretical observations that partial hydration of metal-organic framework (MOF) materials containing open metal sites increases their uptake of CO2. The results of the crystallographic study on MOP-gas binding have been rationalized using DFT calculations, yielding individual binding energies for the various pore environments of Cu-1a.

Bibliographic note

Funding Information: We thank the Universities of Nottingham and Manchester, General Motors, EPSRC (award numbers EP/K038869, EP/I011870 and EP/S002995/1 to E.B., S.Y., N.R.C., and M.S.) for funding. This project has received funding to M.S. from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 742401, NANOCHEM). N.R.C. acknowledges the receipt of a Royal Society Wolfson Merit Award. We thank Diamond Light Source for access to beamlines I19 and I11. We thank the STFC/ISIS Neutron Facility for access to the WISH beamline. We thank the ALS Facility for access to the beamline 11.3.1. Funding Information: We thank the Universities of Nottingham and Manchester, General Motors, EPSRC (award numbers EP/K038869, EP/ I011870 and EP/S002995/1 to E.B., S.Y., N.R.C., and M.S.) for funding. This project has received funding to M.S. from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 742401, NANOCHEM). N.R.C. acknowledges the receipt of a Royal Society Wolfson Merit Award. We thank Diamond Light Source for access to beamlines I19 and I11. We thank the STFC/ISIS Neutron Facility for access to the WISH beamline. We thank the ALS Facility for access to the beamline 11.3.1. Publisher Copyright: © 2020 American Chemical Society.

Details

Original languageEnglish
Pages (from-to)15646-15658
Number of pages13
JournalInorganic Chemistry
Volume59
Issue number21
Publication statusPublished - 2 Nov 2020