Oxygen Evolution Catalyzed by a Mononuclear Ruthenium Complex Bearing Pendant SO3− Groups

分子研の正岡グループのお仕事です。活性点近傍に、酸化剤かつ、水の酸化をアシストすると言われているCe(IV)を捕まえる分子設計です。「アイディアを形にする」分子設計だと思います。

Angewandte Chemie International Edition by Masaki Yoshida, Mio Kondo, Sena Torii, Ken Sakai, Shigeyuki Masaoka  /  13d  //  keep unread  //  hide  //  preview

Abstract

Rational molecular design of catalytic systems capable of smooth OO bond formation is critical to the development of efficient catalysts for water oxidation. A new ruthenium complex was developed, which bears pendant SO₃⁻ groups in the secondary coordination sphere: [Ru(terpy)(bpyms)(OH₂)] (terpy=2,2′:6′,2′′-terpyridine, bpyms=2,2′-bipyridine-5,5′-bis(methanesulfonate)). Water oxidation driven by a Ce⁴⁺ oxidant is distinctly accelerated upon introduction of the pendant SO₃⁻ groups in comparisons to the parent catalyst, [Ru(terpy)(bpy)(OH₂)]²⁺ (bpy=2,2′-bipyridine). Spectroscopic, electrochemical, and crystallographic investigations concluded that the pendant SO₃⁻ groups promote the formation of an OO bond via the secondary coordination sphere on the catalyst, whereas the influence of the pendant SO₃⁻ groups on the electronic structure of the [Ru(terpy)(bpy)(OH₂)]²⁺ core is negligible. The results of this work indicate that modification of the secondary coordination sphere is a valuable strategy for the design of water oxidation catalysts.

Lucky pendant: Ce⁴⁺-driven water oxidation catalyzed by a mononuclear ruthenium complex was observed to be accelerated following the introduction of pendant SO₃⁻ groups to the catalyst, which are able to capture Ce⁴⁺ ions. The results of this work indicate that modification of the secondary coordination sphere is an effective strategy for the development of catalysts for water oxidation.

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