A Metal-Organic Tetrahedron as a Redox Vehicle to Encapsulate Organic Dyes for Photocatalytic Proton Reduction
A Metal-Organic Tetrahedron as a Redox Vehicle to Encapsulate Organic Dyes for Photocatalytic Proton Reduction
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DOI：
10.1021/jacs.5b00832
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发表时间：
2015-03-25
影响因子：
15
通讯作者：
Duan, Chunying
中科院分区：
文献类型：
--
作者：
Jing, Xu;He, Cheng;Duan, Chunying
设计模仿高度进化和精细调节的自然光合系统的人工系统是深入研究的主题。我们在此报告了一种新的方法来构建超分子系统的光催化制氢从水通过封装的有机染料分子到口袋中的氧化还原活性的金属有机多面体。组装的中性Co 4L 4四面体由以交替方式连接在一起的四个配体和四个钴离子组成。钴离子由三种缩氨基硫脲NS螯合剂配位，并表现出适合于电化学质子还原的氧化还原电位。氧化还原位点和包封在口袋中的光敏剂之间的紧密接近使得能够通过强大的伪分子内途径将光诱导的电子从光敏剂的激发态转移到钴基催化位点。改性的超分子系统表现出TON值与相关的钴/荧光素系统报道的最高值相当。对照实验的基础上，一个较小的四面体类似物的车辆与填充口袋和单核化合物类似的钴角的四面体的酶动力学行为。新的，充分阐明的反应途径和在有限空间内的反应的摩尔浓度的增加使得这些超分子系统优于其他相关系统上级。
The design of artificial systems that mimic highly evolved and finely tuned natural photosynthetic systems is a subject of intensive research. We report herein a new approach to constructing supramolecular systems for the photocatalytic generation of hydrogen from water by encapsulating an organic dye molecule into the pocket of a redox-active metal organic polyhedron. The assembled neutral Co4L4 tetrahedron consists of four ligands and four cobalt ions that connect together in alternating fashion. The cobalt ions are coordinated by three thiosemicarbazone NS chelators and exhibit a redox potential suitable for electrochemical proton reduction. The close proximity between the redox site and the photosensitizer encapsulated in the pocket enables photoinduced electron transfer from the excited state of the photosensitizer to the cobalt-based catalytic sites via a powerful pseudo-intramolecular pathway. The modified supramolecular system exhibits TON values comparable to the highest values reported for related cobalt/fluorescein systems. Control experiments based on a smaller tetrahedral analogue of the vehicle with a filled pocket and a mononuclear compound resembling the cobalt corner of the tetrahedron suggest an enzymatic dynamics behavior. The new, well-elucidated reaction pathways and the increased molarity of the reaction within the confined space render these supramolecular systems superior to other relevant systems.