Reusable Nanowire Photocatalyst for Radical Couplings

  • Author:
  • Published: 03 July 2020
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
  • Source / Publisher: Chemical Science/Royal Society of Chemistry
  • Associated Societies: Royal Society of Chemistry (RSC), UK
thumbnail image: Reusable Nanowire Photocatalyst for Radical Couplings

New methods to create C–C bonds are always interesting for organic synthesis. Photocatalysis can be used for radical couplings, for example, for the pinacol coupling reaction (pictured) in which aldehydes or ketones are coupled at the carbonyl C atoms. Most often, homogeneous photocatalysts such as Ru or Ir complexes are used. However, they are expensive and difficult to recycle and reuse. Heterogeneous photocatalysts could solve these problems.

Zetian Mi, University of Michigan, Ann Arbor, USA, and McGill University, Montreal, Canada, Chao-Jun Li, McGill University, and colleagues have used gallium nitride nanowires (GaN NWs) on a silicon wafer as a reusable, heterogeneous photocatalyst system for pinacol coupling reactions. The team used plasma-assisted molecular beam epitaxy (PAMBE) under nitrogen-rich conditions to grow GaN NWs on an Si(111) wafer. As shown by scanning electron microscopy (SEM), the nanowires form a forest-like, vertical array on the silicon surface. The electronic properties of the GaNWs could be tuned to give either an n-type or a p-type semiconductor by doping with either a group 4 element (such as Ge) or a group 2 element (such as Mg), respectively.

The researchers used p-type GaN NWs to catalyze pinacol coupling reactions under a black light bulb in methanol at room temperature. The reaction gave the desired diols in excellent yields for a wide range of ketones. Aldehydes could also be coupled, but at lower yields due to the formation of hydrogenated side products. Both ketones and aldehydes can also be cross-coupled with formaldehyde when an excess of formaldehyde is used. The catalyst can be easily reused for many reactions.



Article Views: 885

Sign in Area

Please sign in below

Additional Sign In options

Please note that to comment on an article you must be registered and logged in.
Registration is for free, you may already be registered to receive, e.g., the newsletter. When you register on this website, please ensure you view our terms and conditions. All comments are subject to moderation.

Article Comments - To add a comment please sign in

Bookmark and Share

If you would like to reuse any content, in print or online, from, please contact us first for permission. more

CONNECT: on Facebook on Twitter on YouTube on LinkedIn Sign up for our free newsletter

Magazine of Chemistry Europe (16 European Chemical Societies)published by Wiley-VCH