Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants
Visible-Light-Induced Olefin Activation Using 3D Aromatic Boron-Rich Cluster Photooxidants
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DOI：
10.1021/jacs.6b03568
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发表时间：
2016-06-08
影响因子：
15
通讯作者：
Spokoyny, Alexander M.
中科院分区：
文献类型：
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作者：
Messina, Marco S.;Axtell, Jonathan C.;Spokoyny, Alexander M.
我们报告了一项发现，B-12型（OCH2Ar）（12） （Ar = Ph或C6F5）功能化二十面体十二硼酸盐粉尘可以在可见光下进行光激发，从而产生了一类新的无金属光氧化剂。这些物质的激发是由于位于苄基取代基上的低轨道和整个硼团簇核心的未占据轨道之间的电荷转移而发生的。在这里，我们展示了这些物质是如何在蓝色LED光源的光激发下，表现出高达3v的激发态还原电位，并且可以参与广泛的苯乙烯单体的电子转移过程，引发它们的聚合。在簇载低至0.005 mol%时，富电子和缺电子的苯乙烯单体都发生了引发反应。此外，B-12(OCH2-C6F5)（12）在活性较低的烯烃（如异丁烯）存在下的光激发可以产生高支化的聚异丁烯。这项工作介绍了一类新的空气稳定，无金属的光氧化还原试剂：能够介导化学转化的试剂。
We report a discovery that perfunction-alized icosahedral dodecaborate dusters of the, type B-12(OCH2Ar)(12) (Ar = Ph or C6F5) can undergo photoexcitation with visible light, leading to a new class of metal free photooxidants. Excitation in these species occurs as a result of the charge transfer between low-lying orbitals located on the-benzyl substituents and an unoccupied orbital delocalized throughout the boron cluster core. Here we show how these species, photo-excited with a benchtop blue LED source, can exhibit excited-state reduction potentials as high as 3 V,and can participate in electron transfer processes with a broad range of styrene monomers, initiating their polymerization. Initiation is observed in cases of both electron-rich and electron deficient styrene monomers at cluster loadings as low as 0.005 mol%. Furthermore, photo-excitation of B-12(OCH2-C6F5)(12) in the presence of a less activated olefin such as isobutylene result's in the production of highly branched poly(isobutylene). This work introduces a new class of air stable, metal-free photo-redox: reagents capable of mediating chemical transformations.