Artificial synthetic Mn^IVCa–oxido complexes mimic the oxygen-evolving complex in photosystem II

Abstract

A novel family of heteronuclear Mn(IV)Ca-oxido complexes containing Mn(IV)Ca-oxido cuboidal moieties and reactive water molecules on Ca(2+) have been synthesized and characterized to mimic the oxygen-evolving complex (OEC) of photosystem II (PSII) in nature.

Mimicking the Catalytic Center for the Water-Splitting Reaction in Photosystem II

“…The key feature of this mechanism is that the O-O bond is formed by a nucleophilic attack of a calcium ligated hydroxyl group onto an electrophilic oxo of Mn V ≡O or Mn IV -O • , derived from the deprotonation of the second substrate water molecule. Similar proposals have been suggested by other groups [80,82,83]. However, this proposal was not supported by a recent theoretical calculation reported by Siegbahn [84].…”

From Enzymes to Functional Materials—Towards Activation of Small Molecules

“…The binding of af ifth metal is herein influenced by the presence of the redoxi nactive Ca 2+ centera nd leads to significant stabilization of the oxidized Mn clusters. [65,71,72] Although sharing the same structuralm otif, the synthetic complexes revealed only low potentialtowards OER.…”

“…Furthermore, it has been suggested that an exchange of coordinated water molecules plays ak ey role in the proton-transfer during water oxidation and Ca 2+ is required to stabilize the high oxidation state of the Mn ion. [71] The importance of Ca 2+ was also highlighted through the investigation of structural analogues with a Mn 3 CaO 4 core bearing the 1,3,5-triphenylbenzene-based ligand 1 (Figure 3). [67,70] The MnÀMn and MnÀCa bond lengths therein are close to that of the naturalc luster.…”

From natural photosynthesis to artificial photosynthesis

“…(3) Ca离子如何发挥作用 [39] ? (4) 哪些水分子是 底物水分子 [59] [76] 、难以在高价Mn簇中引入生物配体 [55] 的合 成难题. 最近, 受生物OEC组装规律的启示 [77] , 本课题 组 [70,78] 借助高活性的单核Mn 3+ 化合物与Mn3CaO4立方 烷原位加成反应, 成功合成出不对称的Mn4Ca-簇合物…”