Metal – organic frameworks (MOFs) hold much promise for separation technology. However, the nucleation and growth techniques currently employed result in polydisperse mixtures that are unsuitable for good column packing.

Dirk De Vos and colleagues, Universiteit Leuven, Belgium, report a new synthesis method for the common MOF, [Cu₃(BTC)₂] where coordinatively unsaturated Cu²⁺ ions are connected by 1,3,5-benzenetricarboxylate (BTC) ligands. The new synthesis forms [Cu₃(BTC)₂] directly within the pores of silica spheres used as the stationary phase in HPLC.

In a HPLC test case, no separation was seen with the unmodified silica spheres while pure [Cu₃(BTC)₂] gave poorly resolved, broad peaks. The modified silica-MOF material gave good separation under the same conditions with narrow peaks and good resolution as a result of the free Cu²⁺ sites.

• Silica–MOF Composites as a Stationary Phase in Liquid Chromatography
  R. Ameloot, A. Liekens, L. Alaerts, M. Maes, A. Galarneau, B. Coq, G. Desmet, B. F. Sels, J. F. M. Denayer, D. E. De Vos,
  Eur. J. Inorg. Chem. 2010, 24, 3735–3738.
  DOI: 10.1002/ejic.201000494