Guiyan Liu and Jianhui Wang report the use of light to switch a metathesis catalyst between a polar and a nonpolar phase, plus they show that the catalyst can be recycled – a feature that offers exciting prospects and that may lead to industrial interest.

The team from Tianjin University, China, used a Grubbs-Hoveyda-type catalyst tagged with a UV-active group and the photoreaction resulted in drastic changes in the polarity and solubility of the catalyst. This tagged complex had significant catalytic activity in ring-closing metathesis reactions and was recycled several times. Features of the process include: the uses light as the driving force, no temperature changes, no need for expensive supporting media.

• Recycling a Homogeneous Catalyst through a Light-Controlled Phase Tag
  G. Liu, J. Wang
   Angew. Chem. 2010, Early View