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Styrene oxidation catalyzed by Au11(PPh3)7Cl3 and [Au11(PPh3)8Cl2]Cl nanoclusters: Impacts of capping ligands, particle size and charge state
Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2018-03-08 , DOI: 10.1016/j.apcata.2018.03.001
Likai Wang , Jin Peng , Zhenghua Tang , Xiongwu Kang , Mingli Fu , Shaowei Chen

Structurally similar molecule-like Au11(PPh3)7Cl3 and [Au11(PPh3)8Cl2]Cl nanoclusters have been successfully synthesized and employed as catalysts for selective oxidation of styrene. The two clusters exhibited similar but slightly different well-defined optical absorbance, and the subtle structural difference is also reflected in proton nuclear magnetic resonance (1H NMR) studies. In electrochemical measurements, Au11(PPh3)7Cl3 and [Au11(PPh3)8Cl2]Cl show a large electrochemical band gap of 2.15 eV and 2.09 eV, respectively. Styrene oxidation has been employed as a model reaction to investigate the impacts of the ligand shell composition on the catalytic activity and selectivity of the two clusters. Interestingly, the main product is benzaldehyde when oxygen is employed as oxidant, and the catalytic activity of Au11(PPh3)7Cl3 is higher than that of [Au11(PPh3)8Cl2]Cl. Under the same conditions, the two Au11 clusters exhibit much higher catalytic activity than larger clusters (Au25, Au38 and Au144) capped with phenylethiolates, as a manifestation of both size influence and surface ligand impacts. In addition, the oxidation efficiency of styrene exhibit a sharp increase when tert-butyl hydroperoxide is utilized as the oxidant, where the catalytic activities of Au11(PPh3)7Cl3 and [Au11(PPh3)8Cl2]Cl are comparable with styrene epoxide being the major product. Finally, the twin clusters are either reduced or oxidized to probe the charge effects upon the catalytic reaction, and it was found that the conversion of styrene went up with the charge state from reduced to oxidized for both clusters.



中文翻译:

Au 11(PPh 37 Cl 3和[Au 11(PPh 38 Cl 2 ] Cl纳米簇催化的苯乙烯氧化:封端配体,粒径和电荷态的影响

结构相似的分子状Au 11(PPh 37 Cl 3和[Au 11(PPh 38 Cl 2 ] Cl纳米簇已成功合成,并用作苯乙烯选择性氧化的催化剂。这两个簇显示相似但略有不同的明确的吸光度,并且在质子核磁共振(1 H NMR)研究中也反映出微妙的结构差异。在电化学测量中,Au 11(PPh 37 Cl 3和[Au 11(PPh 38 Cl 2 ] Cl显示出分别为2.15eV和2.09eV的大电化学带隙。苯乙烯氧化已被用作模型反应来研究配体壳组成对两个簇的催化活性和选择性的影响。有趣的是,当使用氧气作为氧化剂时,主要产物是苯甲醛,Au 11(PPh 37 Cl 3的催化活性高于[Au 11(PPh 38 Cl 2 ] Cl的催化活性。在相同条件下,两个Au 11团簇的催化活性要比较大的团簇(Au 25,Au 38和Au 144)被苯硫醇封端,作为尺寸影响和表面配体影响的体现。此外,当使用叔丁基氢过氧化物作为氧化剂时,苯乙烯的氧化效率会急剧提高,其中Au 11(PPh 37 Cl 3和[Au 11(PPh 38 Cl 2] Cl与主要产品苯乙烯环氧化物相当。最后,双簇被还原或被氧化以探测催化反应中的电荷效应,并且发现对于两个簇,苯乙烯的转化率随着电荷状态从还原态到氧化态的上升而上升。

更新日期:2018-03-08
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