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首页> 外文期刊>Catalysis science & technology >Light-activated Ullmann homocoupling of aryl halides catalyzed using gold nanoparticle-functionalized potassium niobium oxides
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Light-activated Ullmann homocoupling of aryl halides catalyzed using gold nanoparticle-functionalized potassium niobium oxides

机译：激活Ullmann homocoupling芳基卤化物催化使用黄金nanoparticle-functionalized钾铌氧化物

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Lamellar, or layered, potassium niobium oxide perovskites are a class of underdeveloped semiconductors in organic photocatalysis that offer the inherent advantages of larger particle size and ease of recoverability as compared to traditional semiconductor materials. Using photochemical methodologies, gold nanoparticle-functionalized potassium niobium oxides are synthesized. Nanocomposite characterization using UV-visible spectroscopy, X-ray diffraction and TEM confirms nanoparticle deposition on the perovskite surface, with an average nanoparticle diameter of 17 nm. High resolution imaging and X-ray diffraction also confirmed the crystallinity of the niobium oxide support with an estimated interlayer spacing of 10 angstrom. Given the importance of carbon-carbon bond formation in organic synthesis, the Ullmann homocoupling of aryl halides is examined as a probe reaction for the application of this new class of nanocomposites. The influence of nanoparticle dopant, semiconductor support, reaction solvent, reaction time and aryl substitution are examined and shows that UVA-activation of gold nanoparticle/potassium niobium oxides promotes carbon-carbon bond formation in as little as 1 hour with yields as high as 98%, with high recyclability of the catalyst. The experimental methodology shows good versatility for a series of substituted iodobenzenes. The suggested mechanism involves a single electron transfer from the nanoparticle to facilitate aryl-halide bond activation to drive adsorption of the aryl halide starting material onto the gold nanoparticle surface. The positive results obtained with this lamellar nanocomposite may prove useful as a more cost-effective alternative in future carbon-carbon couplings.
机译：层状或分层,钾氧化铌钙钛矿是不发达的一个类在有机半导体光催化提供更大的粒子的固有优势大小和可恢复性相比传统的半导体材料。光化学方法、金nanoparticle-functionalized钾铌氧化物合成。使用紫外可见光谱表征,x射线衍射和透射电镜证实了纳米颗粒钙钛矿表面的沉积,纳米颗粒平均直径17海里。分辨率成像和x射线衍射证实了氧化铌的结晶度支持,估计层间间距10埃。在有机碳碳键的形成的乌尔曼homocoupling合成芳基卤化物作为探针反应的检查这种新型的纳米复合材料的应用。纳米掺杂剂的影响,半导体的支持,反应溶剂、反应时间和芳基取代是检查和显示UVA-activation的黄金纳米粒子/钾铌氧化物促进碳碳键的形成在1小时收益率高达98%,高再循环能力的催化剂。方法展示了一系列良好的通用性碘代苯取代。包括一个电子转移机制从纳米颗粒促进aryl-halide芳基的键激活驱动吸附卤化物起始物料到黄金纳米粒子表面。获得这种层状纳米复合材料证明有用的作为一个更划算的选择在未来碳碳耦合。

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