Noncovalent Interactions Impact Borrowing-Hydrogen Processes

  • Author: David Smith
  • Published Date: 27 October 2015
  • Source / Publisher: Chemistry – A European Journal/Wiley-VCH
  • Copyright: Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
thumbnail image: Noncovalent Interactions Impact Borrowing-Hydrogen Processes

Related Societies

Supramolecular interactions, such as H-bonding or π-stacking, can be exploited to tune catalytic reactions, usually by altering the reaction selectivity. For example, π-stacking between the ligands of catalysts and the substrate can effect asymmetric induction. However, noncovalent interactions can also affect the rates of catalytic reactions, as reported by Sheila Ruiz-Botella and Eduardo Peris of Universitat Jaume I, Castellón, Spain.


The team tested an iridium-NHC complex decorated with rigid aromatic pyrene groups (pictured) as a homogeneous catalyst for reduction of ketones by transfer hydrogenation and β-alkylation of secondary alcohols – two reactions proceeding by the borrowing hydrogen methodology. If aromatic substrates are used, the addition of π-stacking additives inhibited the reactions.


In the absence of additives, reactions with aromatic substrates follow zero-order dependence on substrate concentration, presumably owing to saturation of the catalyst by π-stacking with the substrate, whereas, with aliphatic substrates, the reaction exhibits second-order substrate dependence. The reactions follow a reaction order of <1 in the pyrene-containing catalyst, indicating that the catalyst self-associates. The pyrene tags were also used to immobilize the catalyst on a reduced graphene oxide surface, giving a recyclable catalyst for β-alkylation of secondary alcohols.


 

Article Views: 3305

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

1 Comments

Maoping Pu wrote:

supramolecular interactions tune catalytic reactions - clear evidence?

"Supramolecular interactions, such as H-bonding or π-stacking, can be exploited to tune catalytic reactions, usually by altering the reaction selectivity. For example, π-stacking between the ligands of catalysts and the substrate can effect asymmetric induction."

Hi David, you have clearly written what can be done for supramolecular interactions. As far as I know, this is not so clear at all so far. And I am going to propose in this direction for my postdoc. Can you send me the specific examples or post it here?

Sun Jan 03 16:27:46 UTC 2016

If you would like to reuse any content, in print or online, from ChemistryViews.org, please contact us first for permission and consult our permission guidance prior to making your request

Follow on Facebook Follow on Twitter Follow on YouTube Follow on LinkedIn Follow on Instagram RSS Sign up for newsletters

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