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Article: Water oxidation catalysed by iron complex of N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. Spectroscopy of iron-oxo intermediates and density functional theory calculations

TitleWater oxidation catalysed by iron complex of N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. Spectroscopy of iron-oxo intermediates and density functional theory calculations
Authors
Issue Date2015
Citation
Chemical Science, 2015, v. 6, n. 10, p. 5891-5903 How to Cite?
Abstract© The Royal Society of Chemistry 2015. The macrocyclic [FeIII(L1)Cl2]+(1, L1 = N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane) complex is an active catalyst for the oxidation of water to oxygen using [NH4]2[CeIV(NO3)6] (CAN), NaIO4, or Oxone as the oxidant. The mechanism of 1-catalysed water oxidation was examined by spectroscopic methods and by18O-labelling experiments, revealing that FeIVO and/or FeVO species are likely to be involved in the reaction. The redox behaviour of 1 and these high-valent FeO species of L1 has been examined by both cyclic voltammetry and density functional theory (DFT) calculations. In aqueous solutions, the cyclic voltammograms of 1 at different pH show a pH-dependent reversible couple (E1/2= +0.46 V vs. SCE at pH 1) and an irreversible anodic wave (Epa= +1.18 V vs. SCE at pH 1) assigned to the FeIII/FeIIcouple and the FeIIIto FeIVoxidation, respectively. DFT calculations showed that the E value of the half reaction involving [FeV(L1)(O)(OH)]2+/[FeIV(L1)(O)(OH2)]2+is +1.42 V vs. SCE at pH 1. Using CAN as the oxidant at pH 1, the formation of an FeIVO reaction intermediate was suggested by ESI-MS and UV-vis absorption spectroscopic measurements, and the rate of oxygen evolution was linearly dependent on the concentrations of both 1 and CAN. Using NaIO4or Oxone as the oxidant at pH 1, the rate of oxygen evolution was linearly dependent on the concentration of 1, and a reactive FeVO species with formula [FeV(L1)(O)2]+generated by oxidation with NaIO4or Oxone was suggested by ESI-MS measurements. DFT calculations revealed that [FeV(L1)(O)2]+is capable of oxidizing water to oxygen with a reaction barrier of 15.7 kcal mol-1.
Persistent Identifierhttp://hdl.handle.net/10722/218704
ISSN
2017 Impact Factor: 9.063
2015 SCImago Journal Rankings: 4.974

 

DC FieldValueLanguage
dc.contributor.authorTo, WP-
dc.contributor.authorChow, WS-
dc.contributor.authorTSE, CW-
dc.contributor.authorGuan, X-
dc.contributor.authorHuang, JS-
dc.contributor.authorChe, CM-
dc.date.accessioned2015-09-18T06:50:58Z-
dc.date.available2015-09-18T06:50:58Z-
dc.date.issued2015-
dc.identifier.citationChemical Science, 2015, v. 6, n. 10, p. 5891-5903-
dc.identifier.issn2041-6520-
dc.identifier.urihttp://hdl.handle.net/10722/218704-
dc.description.abstract© The Royal Society of Chemistry 2015. The macrocyclic [FeIII(L1)Cl2]+(1, L1 = N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane) complex is an active catalyst for the oxidation of water to oxygen using [NH4]2[CeIV(NO3)6] (CAN), NaIO4, or Oxone as the oxidant. The mechanism of 1-catalysed water oxidation was examined by spectroscopic methods and by18O-labelling experiments, revealing that FeIVO and/or FeVO species are likely to be involved in the reaction. The redox behaviour of 1 and these high-valent FeO species of L1 has been examined by both cyclic voltammetry and density functional theory (DFT) calculations. In aqueous solutions, the cyclic voltammograms of 1 at different pH show a pH-dependent reversible couple (E1/2= +0.46 V vs. SCE at pH 1) and an irreversible anodic wave (Epa= +1.18 V vs. SCE at pH 1) assigned to the FeIII/FeIIcouple and the FeIIIto FeIVoxidation, respectively. DFT calculations showed that the E value of the half reaction involving [FeV(L1)(O)(OH)]2+/[FeIV(L1)(O)(OH2)]2+is +1.42 V vs. SCE at pH 1. Using CAN as the oxidant at pH 1, the formation of an FeIVO reaction intermediate was suggested by ESI-MS and UV-vis absorption spectroscopic measurements, and the rate of oxygen evolution was linearly dependent on the concentrations of both 1 and CAN. Using NaIO4or Oxone as the oxidant at pH 1, the rate of oxygen evolution was linearly dependent on the concentration of 1, and a reactive FeVO species with formula [FeV(L1)(O)2]+generated by oxidation with NaIO4or Oxone was suggested by ESI-MS measurements. DFT calculations revealed that [FeV(L1)(O)2]+is capable of oxidizing water to oxygen with a reaction barrier of 15.7 kcal mol-1.-
dc.languageeng-
dc.relation.ispartofChemical Science-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.titleWater oxidation catalysed by iron complex of N,N′-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. Spectroscopy of iron-oxo intermediates and density functional theory calculations-
dc.typeArticle-
dc.identifier.emailTo, WP: kevintwp@hku.hk-
dc.identifier.emailGuan, X: xgguan@hku.hk-
dc.identifier.emailHuang, JS: jshuang@hku.hk-
dc.identifier.emailChe, CM: cmche@hku.hk-
dc.identifier.authorityHuang, JS=rp00709-
dc.identifier.authorityChe, CM=rp00670-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1039/C5SC01680K-
dc.identifier.scopuseid_2-s2.0-84982693880-
dc.identifier.hkuros252957-
dc.identifier.volume6-

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