Electrocatalytic oxidation of formate with nickel diphosphine dipeptide complexes: Effect of ligands modified with amino acids

Brandon R. Galan, Matthew L. Reback, Avijita Jain, Aaron M. Appel, Wendy J. Shaw

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

A series of nickel bis(diphosphine) complexes with dipeptides appended to the ligands were investigated for the catalytic oxidation of formate to carbon dioxide, a proton, and two electrons. Typical rates of approximately 7 s -1 were found, similar to that for the parent complex (ca. 8 s -1), with amino acid size and positioning contributing very little to the rate or operating potential. Hydroxy functionalities did result in lower rates, which were recovered by protecting the hydroxy group. The results suggest that the overall dielectric properties introduced by the dipeptides do not play an important role in catalysis, but free hydroxy groups do influence activity, implying contributions from intra- or intermolecular interactions. These observations are important in developing a fundamental understanding of the effect that an enzyme-like outer coordination sphere can have upon molecular catalysts. Electrocatalysts Ni(PR2N R′2)2 substituted with dipeptides were used for the oxidation of formate. Polar substituents resulted in a significant loss in activity, which was recovered upon protection of these groups. This work adds to our growing understanding of the role of the outer coordination sphere in molecular electrocatalysis.

Original languageEnglish
Pages (from-to)5366-5371
Number of pages6
JournalEuropean Journal of Inorganic Chemistry
Issue number30
DOIs
Publication statusPublished - Oct 1 2013

Keywords

  • Biocatalysts
  • Bioinorganic chemistry
  • Electrocatalysts
  • Formate
  • Nickel
  • Outer coordination sphere
  • Oxidation
  • Peptide catalysts

ASJC Scopus subject areas

  • Inorganic Chemistry

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