title: Dinuclear manganese complexes for water oxidation: evaluation of electronic effects and catalytic activity.
abstract: During recent years significant progress has been made towards the realization of a sustainable and carbon-neutral energy economy. One promising approach is photochemical splitting of H2O into O2 and solar fuels, such as H2. However, the bottleneck in such artificial photosynthetic schemes is the H2O oxidation half reaction where more efficient catalysts are required that lower the kinetic barrier for this process. In particular catalysts based on earth-abundant metals are highly attractive compared to catalysts comprised of noble metals. We have now synthesized a library of dinuclear Mn2(II,III) catalysts for H2O oxidation and studied how the incorporation of different substituents affected the electronics and catalytic efficiency. It was found that the incorporation of a distal carboxyl group into the ligand scaffold resulted in a catalyst with increased catalytic activity, most likely because of the fact that the distal group is able to promote proton-coupled electron transfer (PCET) from the high-valent Mn species, thus facilitating O-O bond formation.
authors.affiliation: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden. bjorn.akermark@organ.su.se.
authors.forename: Wael A A
authors.initials: WA
authors.lastname: Arafa
authors.forename: Markus D
authors.initials: MD
authors.lastname: Kärkäs
authors.forename: Bao-Lin
authors.initials: BL
authors.lastname: Lee
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Åkermark
authors.forename: Rong-Zhen
authors.initials: RZ
authors.lastname: Liao
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Berends
authors.forename: Johannes
authors.initials: J
authors.lastname: Messinger
authors.forename: Per E M
authors.initials: PE
authors.lastname: Siegbahn
authors.forename: Björn
authors.initials: B
authors.lastname: Åkermark
mesh_terms: D002384:Catalysis; D004578:Electron Spin Resonance Spectroscopy; D009682:Magnetic Resonance Spectroscopy; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D008345:Manganese