Molecular photo-charge-separators enabling single-pigment-driven multi-electron transfer and storage leading to H2 evolution from water

Kyoji Kitamoto, Makoto Ogawa, Gopalakrishnan Ajayakumar, Shigeyuki Masaoka, Heinz Bernhard Kraatz, Ken Sakai

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

Single-chromophore-driven single-electron-pumping processes leading to multi-electron transfer and storage are effectively promoted in natural photosynthesis, generating photocurrent at the molecular level. Moreover, these single-electron-pumping events are converted into double-electron-pumping events by releasing multiple plastoquinol molecules without releasing reactive semiquinone radicals, thereby enabling storage of two-electron-reduced molecules within the lipid bilayer constructing the thylakoid membrane. Here we report new unimolecular architectures that enable these highly sophisticated light-driven multi-electron transfer and storage processes. The photo-charge-separators (PCSs) reported herein possess a single Ru(bpy)3 2+ fragment with each bpy derivatized with four dicationic viologen acceptors, abbreviated as [RuII(bpy)3 2+-(MV2+)12]26+ (MV2+ is a viologen unit). These highly positively charged PCSs form stable ion pairs with anionic electron donors, enabling consecutive multi-electron transfer processes from the donors to the pendant viologen acceptors. The multiple transferred electrons are collected over twelve pendant viologen acceptors, leading to storage of 7-8 electrons per molecule. The resulting organic radicals show a strong preference to form diamagnetic π-dimers, which suppress reactive radical formation. These reducing equivalents can then be efficiently consumed in catalytic H2 evolution from water in the presence of a colloidal platinum catalyst.

Original languageEnglish
Pages (from-to)671-680
Number of pages10
JournalInorganic Chemistry Frontiers
Volume3
Issue number5
DOIs
Publication statusPublished - May 2016

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All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

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