Photo-induced ring-expansion reactions mediated by B12-TiO2 hybrid catalyst
Photo-induced ring-expansion reactions mediated by B12-TiO2 hybrid catalyst
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DOI：
10.1039/b921802e
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发表时间：
2010-01-01
影响因子：
4
通讯作者：
Hisaeda, Yoshio
中科院分区：
文献类型：
--
作者：
Izumi, Shin-ichiro;Shimakoshi, Hisashi;Hisaeda, Yoshio
用多种光谱方法阐明了维生素B-12-二氧化钛多相杂化催化剂(B-12-二氧化钛)催化的扩环反应及其反应机理。漫反射UV/Vis(DR-UV/VIS)研究表明，在紫外光照射下，B-12-TiO2光催化剂被活化，形成了B-12的超亲核Co(I)物种。然后，DR-UV/VIS和电子自旋共振(ESR)研究阐明了光敏中间体在非均相表面的形成。光激发的B-12-TiO2光催化扩环反应是高效、环保的。这种催化效率强烈地依赖于溶剂的种类。溶剂在纳米二氧化钛表面的空穴氧化反应在整个催化反应中起着至关重要的作用。
Vitamin B-12-TiO2 heterogeneous hybrid catalyst (B-12-TiO2) mediated ring-expansion reactions and their reaction mechanism were clarified by various spectroscopic methods. Diffuse reflectance UV/VIS (DR-UV/VIS) studies showed that B-12-TiO2 was activated to form the supernucleophilic Co(I) species of B-12 by irradiation with ultraviolet light. DR-UV/VIS and electron spin resonance (ESR) studies then elucidated the formation of the photo-sensitive intermediate on heterogeneous surfaces. The photo-excited B-12-TiO2 catalyzed ring-expansion reactions were efficient and eco-friendly. This catalytic efficiency was strongly dependent on the kind of solvent. The oxidation reaction of the solvent by holes at TiO2 nanoparticle surfaces had a crucial role in the overall catalytic reaction.