Construction of metal – organic frameworks (MOFs) of various pore structures and porosities is possible due to the availability of linkers of differing lengths. The pore-size-exclusion effect has permitted these to be applied to gas separation and sorption.

Dongyuan Zhao, Fudan University, China, and Banglin Chen, University of Texas at San Antonio, USA, have developed an MOF with immobilized OH groups on the pores. The MOF is demonstrated to have moderate pore volume and narrow pore sizes.

In selectivity studies, the selectivity of C₂H₂/CH₄ was 6.7 and the selectivity of CO₂/CH₄ was 9.3, much higher than the equivalent values for the well studied MOF-508. The increased selectivities are attributed to the molecular sieving effect and the narrow pores amplifying the difference in interaction of the gases with the host material.

• A Microporous Metal–Organic Framework with Immobilized –OH Functional Groups within the Pore Surfaces for Selective Gas Sorption
  Z. Chen, S. Xiang, H. D. Arman, P. Li, S. Tidrow, D. Zhao, B. Chen,
  Eur. J. Inorg. Chem. 2010, 24, 3745–3749.
  DOI: 10.1002/ejic.201000349