Although heteropolyacids are excellent homogeneous polyoxometalate catalysts, recovering these molecules at the end of a reaction is often tricky and can have an impact on their application. By inserting the polyoxometalate into the cavity of a metal-organic framework, scientists in Belgium have developed a way of releasing and re-trapping the catalyst at will.
The key to the system is to take advantage of the solvent-dependent solubility of the metal-organic framework. The team, led by Johan Martens from the University of Leuven, dissolved the caged catalyst, triggering the collapse of the metal-organic framework and releasing the heteropolyacid. They then used hexane to re-assemble the catalyst and metal-organic framework, producing a blue solid that could be removed easily by centrifugation.
Recovery and reuse of a homogeneous catalyst through reversible encapsulation in a metal-organic framework
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Link to journal article
Recovery and reuse of heteropolyacid catalyst in liquid reaction medium through reversible encapsulation in Cu3(BTC)2 metal–organic framework
Nikki Janssens , Lik H. Wee , Sneha Bajpe , Eric Breynaert , Christine E. A. Kirschhock and Johan A. Martens
Chem. Sci., 2012, Advance Article, DOI: 10.1039/C2SC01102F
