Ru(ii)-Re(i) binuclear photocatalysts connected by -CH2XCH2- (X = O, S, CH2) for CO2 reduction

Eishiro Kato; Hiroyuki Takeda; Kazuhide Koike; Kei Ohkubo; Osamu Ishitani

doi:10.1039/c4sc03710c

Ru(ii)-Re(i) binuclear photocatalysts connected by -CH₂XCH₂- (X = O, S, CH₂) for CO₂ reduction

Chem Sci. 2015 May 1;6(5):3003-3012. doi: 10.1039/c4sc03710c. Epub 2015 Mar 2.

Authors

Eishiro Kato¹, Hiroyuki Takeda^{1

2}, Kazuhide Koike^{2

3}, Kei Ohkubo¹, Osamu Ishitani^{1

2}

Affiliations

¹ Department of Chemistry , Graduate School of Science and Engineering , Tokyo Institute of Technology , 2-12-1-NE1, O-okayama , Meguro-ku , Tokyo 152-8550 , Japan . Email: ishitani@chem.titech.ac.jp.
² CREST , Japan Science and Technology Agency , 4-1-8 Honcho , Kawaguchi-shi , Saitama 322-0012 , Japan.
³ National Institute of Advanced Industrial Science and Technology , 16-1 Onogawa , Tsukuba , Ibaraki 305-8569 , Japan.

Abstract

We developed Ru(ii)-Re(i) supramolecular photocatalysts in which each metal complex unit is connected by a -CH₂XCH₂- (X = O, S, CH₂) chain. The photocatalyst with X = O exhibited the best photocatalytic efficiency for CO₂ reduction in the reported systems using a NAD(P)H model compound as an electron donor because the introduced oxygen atom strengthened the oxidation power of the Ru photosensitizer unit in the excited state and accelerated electron transfer from the one-electron-reduced Ru photosensitizer unit to the Re catalyst unit. In contrast, the catalytic ability of the photocatalyst with X = S rapidly decreased during irradiation because the supramolecular structure split into mononuclear complexes. A detailed mechanism for the efficient photocatalytic reaction involving these supramolecular photocatalysts was investigated for the first time.