title: Pigment-acceptor-catalyst triads for photochemical hydrogen evolution.
abstract: In order to solve the problems of global warming and shortage of fossil fuels, researchers have been endeavoring to achieve artificial photosynthesis: splitting water into H2 and O2 under solar light illumination. Our group has recently invented a unique system that drives photoinduced water reduction through "Z-scheme" photosynthetic pathways. Nevertheless, that system still suffered from a low turnover number (TON) of the photocatalytic cycle (TON=4.1). We have now found and describe herein a new methodology to make significant improvements in the TON, up to around TON=14-27. For the new model systems reported herein, the quantum efficiency of the second photoinduced step in the Z-scheme photosynthesis is dramatically improved by introducing multiviologen tethers to temporarily collect the high-energy electron generated in the first photoinduced step. These are unique examples of "pigment-acceptor-catalyst triads", which demonstrate a new effective type of artificial photosynthesis.
authors.affiliation: Department of Chemistry, Faculty of Sciences, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka, 812-8581 (Japan); International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University (Japan).
authors.forename: Kyoji
authors.initials: K
authors.lastname: Kitamoto
authors.forename: Ken
authors.initials: K
authors.lastname: Sakai
keywords: artificial photosynthesis; hydrogen; photochemistry; pigments; platinum