Sustained water oxidation by [Mn 4O 4] 7+ core complexes inspired by oxygenic photosynthesis

Robin Brimblecombe, Derrick R.J. Kolling, Alan M. Bond, G. Charles Dismukes, Gerhard F. Swiegers, Leone Spiccia

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77 Citations (Scopus)

Abstract

The bioinspired Mn-oxo cubane complex, [Mn 4O 4L 6] + 1b + (L = (p-MeO-Ph) 2P0 2), is a model of the photosynthetic O 2-evolving complex. It is able to electro-oxidize water at 1.00 V (vs Ag/AgCl) under illumination by UV-visible light when suspended in a proton-conducting membrane (Nation) coated onto a conducting electrode. Electrochemical measurements, and UV-visible, NMR, and EPR spectroscopies are interpreted to indicate that 1b + is the dominant electro-active species in the Nation, both before and after catalytic cycling, and thus correlates closely with activity. The observation of a possible intermediate and free phosphinate ligand within the Nation suggests a catalytic mechanism involving photolytic disruption of a phosphinate ligand, followed by O 2 formation, and subsequent reassembly of the cubane structure. Several factors that influence catalytic turnover such as the applied potential, illumination wavelength, and energy have been examined in respect of attaining optimum catalytic activity. Catalytic turnover frequencies of 20-270 molecules O 2 h -1 catalyst -1 at an overpotential of 0.38 V plus light (275-750 nm) and turnovers numbers >1000 molecules O 2 catalyst -1 are observed. The 1b +-Nafion system is among the most active and durable molecular water oxidation catalysts known.

Original languageEnglish
Pages (from-to)7269-7279
Number of pages11
JournalInorganic Chemistry
Volume48
Issue number15
DOIs
Publication statusPublished - Aug 3 2009

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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    Brimblecombe, R., Kolling, D. R. J., Bond, A. M., Dismukes, G. C., Swiegers, G. F., & Spiccia, L. (2009). Sustained water oxidation by [Mn 4O 4] 7+ core complexes inspired by oxygenic photosynthesis. Inorganic Chemistry, 48(15), 7269-7279. https://doi.org/10.1021/ic9006982