Catalytic and Surface-Electrocatalytic Water Oxidation by Redox Mediator-Catalyst Assemblies
Catalytic and Surface-Electrocatalytic Water Oxidation by Redox Mediator-Catalyst Assemblies
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DOI：
10.1002/anie.200901279
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发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Meyer, Thomas J.
中科院分区：
文献类型：
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作者：
Concepcion, Javier J.;Jurss, Jonah W.;Meyer, Thomas J.
我们最近描述了用于水氧化的单中心催化剂，其通过明确的机制进行操作，涉及逐步三电子氧化为高氧化态氧配合物 [RuV (tpy)(bpm)(O)] 3+ 和 [RuV (tpy)(bpz)(O)] 3+(tpy= 2, 2': 6', 2''-三联吡啶；bpm= 2, 2'-联嘧啶； bpz= 2, 2’-联吡嗪）。[1] Thummel 等人还发现了其他单中心钌催化剂。可以利用相关机制。[2]这些反应似乎是通过关键的 OΣΣ O 键形成步骤和过氧化物中间体发生的，这让人想起光系统 II (PSII)[3, 4] 的析氧复合物 (OEC) 中提出的水氧化机制以及蓝色钌二聚体 cis, cis-[(bpy) 2 (H2O) RuIIIORuIII (OH2)-(bpy) 2] 4+(bpy= 2, 2'-联吡啶）。[5]我们还报道，通过添加氧化还原介体 [Ru (bpy) 2 (LL)] 2+(LL= bpy、bpm 或 bpz) 和 [Ru-(bpm) 3] 2+，蓝色二聚体的铈 (IV) 催化水氧化速率大大提高。 [6]在此，我们提出了基于溶液中含有两种功能的组件的稳定、强大的水氧化催化，特别是在电极表面的亚甲基膦酸酯衍生物中，其转换次数已超过 28 000。组件可以分两步合成：1) [RuII (bpy) 2Cl2]Σ 2H2O 与 [RuII (LLL)(bpm) Cl]+[7, 8] 在 1:1 EtOH 中反应： H2O (LLL= tpy 或 Mebimpy: 2, 6-双(1-甲基苯并咪唑-2-基)吡啶；结构见图 1a)； 2) 通过与纯 HOTf (OTf¿= 三氟甲磺酸盐) 反应，去除所得配体桥联组件中的氯配体和氯抗衡离子 [(bpy) 2RuII-(bpm) RuII (LLL) Cl] Cl3，然后在水中置换 OTf¿，得到 [(bpy) 2RuII (bpm) RuII (tpy)(OH2)] 4+(1) 或 [(bpy) 2RuII (bpm) RuII (Mebimpy)(OH2)] 4+(2)。通过使用水作为洗脱液的柱色谱法(Sephadex LH-20)实现纯化。采用类似策略，用[{[4, 4’-(EtO) 2OPCH2] 2-bpy} 2RuIICl2]代替[RuII (bpy) 2Cl2]Σ 2H2O，制备了相应的亚甲基膦酸乙酯衍生物。 [9]亚甲基膦酸酯的水解
We recently described single-site catalysts for water oxidation that operate by a well-defined mechanism involving stepwise three-electron oxidation to high-oxidation-state oxo complexes [RuV (tpy)(bpm)(O)] 3+ and [RuV (tpy)(bpz)(O)] 3+(tpy= 2, 2’: 6’, 2’’-terpyridine; bpm= 2, 2’-bipyrimidine; bpz= 2, 2’-bipyrazine).[1] Additional single-site ruthenium catalysts have been identified by Thummel et al. that may utilize a related mechanism.[2] These reactions appear to occur through key O∑∑∑ O bond forming steps and peroxido intermediates that are reminiscent of the proposed water oxidation mechanism in the oxygen evolving complex (OEC) of photosystem II (PSII)[3, 4] and water oxidation by the blue ruthenium dimer cis, cis-[(bpy) 2 (H2O) RuIIIORuIII (OH2)-(bpy) 2] 4+(bpy= 2, 2’-bipyridine).[5] We also reported that rates of cerium (IV)-catalyzed water oxidation by the blue dimer are greatly enhanced by added redox mediators,[Ru (bpy) 2 (LL)] 2+(LL= bpy, bpm, or bpz) and [Ru-(bpm) 3] 2+.[6] Herein, we present stable, robust water oxidation catalysis based on assemblies containing both functions in solution, and notably in methylenephosphonate derivatives on electrode surfaces, for which turnovers of more than 28 000 have been achieved.The assemblies can be synthesized in two steps: 1) Reaction of [RuII (bpy) 2Cl2]∑ 2H2O with [RuII (LLL)(bpm) Cl]+[7, 8] in 1: 1 EtOH: H2O (LLL= tpy or Mebimpy: 2, 6-bis (1-methylbenzimidazol-2-yl) pyridine; structures in Figure 1 a); 2) removal of the chloro ligand and chloride counter ions in the resulting ligand-bridged assemblies [(bpy) 2RuII-(bpm) RuII (LLL) Cl] Cl3 by reaction with neat HOTf (OTf¿= trifluoromethanesulfonate) followed by displacement of OTf¿ in water to give [(bpy) 2RuII (bpm) RuII (tpy)(OH2)] 4+(1) or [(bpy) 2RuII (bpm) RuII (Mebimpy)(OH2)] 4+(2). Purification was achieved by column chromatography (Sephadex LH-20) by using water as the eluant. The corresponding methylenephosphonate ethyl esther derivatives were prepared by similar strategies by replacing [RuII (bpy) 2Cl2]∑ 2H2O with[{[4, 4’-(EtO) 2OPCH2] 2-bpy} 2RuIICl2].[9] Hydrolysis of the methylenephosphonate