Light-Induced Activation of a Molybdenum Oxotransferase Model within a Ru(II)-Mo(VI) Dyad.
Light-Induced Activation of a Molybdenum Oxotransferase Model within a Ru(II)-Mo(VI) Dyad.
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DOI：
10.1021/acs.inorgchem.6b01485
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发表时间：
2016-10
影响因子：
4.6
通讯作者：
Aurélien Ducrot;B. Coulson;R. Perutz;A. Duhme‐Klair
中科院分区：
文献类型：
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作者：
Aurélien Ducrot;B. Coulson;R. Perutz;A. Duhme‐Klair
大自然使用含氘的酶来催化氧原子从水转移到有机底物。在这些酶中，在反应过程中释放的两个电子被空间上分离的电子转移单元一次一个地快速移除。受此设计的启发，Ru（II）-Mo（VI）二联体的合成和表征，其目的是加速顺式-二氧代铼催化的OAT循环中的速率决定步骤，通过光氧化过程将氧代配体转移到三苯基膦。二联体由一个光活性的双（联吡啶）-菲咯啉钌部分，共价连接到一个bioinspired顺式-二氧代钼缩氨基硫脲复合物。测定了配合物[Ru（bpy）2（L2）MoO 2（solv）]2+的量子产率和发光寿命。在MeCN溶液中，发光衰减的主要成分（τ = 1149 ± 2 ns，67%）与激发态[Ru（bpy）2（phen-NH 2）]2+的寿命密切相关，而次要成分（τ = 320 ± 1 ns，31%）与激发态[Ru（bpy）2（H2-L2）]2+的寿命密切相关。此外，还研究了该体系的光谱电化学性质.催化实验表明，在可见光照射下，二元催化OAT从二甲基亚砜到三苯基膦的反应速度明显快于在黑暗中。甲基紫精在光氧化还原循环中充当介体，但它是再生的，因此仅需要相对于催化剂的化学计量的量，而不是牺牲量。有人提出，氧化淬灭的光激发的Ru单元，然后通过分子内电子转移，导致生产的反应性的单电子氧化催化剂，这是不能通过电化学方法访问。一个显着的，但不太明显，速率增强时，观察到一个类似的双分子系统进行了测试，表明光敏剂和催化中心之间的分子内电子转移是更有效的比分子间的电子转移之间的单独的组件。
Nature uses molybdenum-containing enzymes to catalyze oxygen atom transfer (OAT) from water to organic substrates. In these enzymes, the two electrons that are released during the reaction are rapidly removed, one at a time, by spatially separated electron transfer units. Inspired by this design, a Ru(II)-Mo(VI) dyad was synthesized and characterized, with the aim of accelerating the rate-determining step in the cis-dioxo molybdenum-catalyzed OAT cycle, the transfer of an oxo ligand to triphenyl phosphine, via a photo-oxidation process. The dyad consists of a photoactive bis(bipyridyl)-phenanthroline ruthenium moiety that is covalently linked to a bioinspired cis-dioxo molybdenum thiosemicarbazone complex. The quantum yield and luminescence lifetimes of the dyad [Ru(bpy)2(L2)MoO2(solv)]2+ were determined. The major component of the luminescence decay in MeCN solution (τ = 1149 ± 2 ns, 67%) corresponds closely to the lifetime of excited [Ru(bpy)2(phen-NH2)]2+, while the minor component (τ = 320 ± 1 ns, 31%) matches that of [Ru(bpy)2(H2-L2)]2+. In addition, the (spectro)electrochemical properties of the system were investigated. Catalytic tests showed that the dyad-catalyzed OAT from dimethyl sulfoxide to triphenyl phosphine proceeds significantly faster upon irradiation with visible light than in the dark. Methylviologen acts as a mediator in the photoredox cycle, but it is regenerated and hence only required in stoichiometric amounts with respect to the catalyst rather than sacrificial amounts. It is proposed that oxidative quenching of the photoexcited Ru unit, followed by intramolecular electron transfer, leads to the production of a reactive one-electron oxidized catalyst, which is not accessible by electrochemical methods. A significant, but less pronounced, rate enhancement was observed when an analogous bimolecular system was tested, indicating that intramolecular electron transfer between the photosensitizer and the catalytic center is more efficient than intermolecular electron transfer between the separate components.