Tailoring the Electronic and Catalytic Properties of Au25 Nanoclusters via Ligand Engineering
Tailoring the Electronic and Catalytic Properties of Au25 Nanoclusters via Ligand Engineering
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DOI：
10.1021/acsnano.6b03964
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发表时间：
2016-08-01
期刊：
影响因子：
17.1
通讯作者：
Jin, Rongchao
中科院分区：
文献类型：
--
作者：
Li, Gao;Abroshan, Hadi;Jin, Rongchao
为了探索纳米团簇的电子和催化性质，本文报道了一种芳香硫醇盐保护的金纳米团簇[Au-25（SNap）（18）]（-）[TOA]（+），其中SNap = 1-萘硫醇盐，TOA =四辛基铵。与先前报道的[Au-25（SCH 2CH 2 Ph）（18）]（-）相比，它在电子和催化性质上表现出明显的差异，尽管它们的骨架（即，Au 25 S18框架）类似。芳香硫醇保护的纳米团簇的HOMO-LUMO电子吸收峰波长发生了约10 nm的红移，这归因于其膨胀的Au-13核.未负载的[Au-25（SNap）（18）]（-）纳米团簇显示出高的热稳定性和抗氧化稳定性（例如，在O-2、过量H2 O2或TBHP的存在下，在80 ℃下），这是由于芳香配体对纳米团簇的前线轨道（HOMO和LUMO）的稳定化的影响。此外，还考察了负载型Au-25（SR）（18）/CeO_2（R = Nap，Ph，CH_2CH_2 Ph，n-C_6 H_（13））催化4-甲基碘苯与4-硝基碘苯的Ullmann偶联反应的催化活性。结果表明，硫醇保护配体的化学性质对催化剂的活性和选择性有很大影响。研究结果表明，芳香配体不仅能提高催化反应的转化率，而且能显著提高杂环偶联产物4-甲基-4 '-硝基-1，1'-联苯的产率。通过实验和理论相结合的方法，这项研究揭示了Au-25纳米团簇的结构活性关系，也提供了指导方针，定制纳米团簇的性能，通过配体工程的具体应用。
To explore the electronic and catalytic properties of nanoclusters, here we report an aromatic-thiolate-protected gold nanocluster, [Au-25(SNap)(18)](-) [TOA](+), where SNap = 1-naphthalenethiolate and TOA = tetraoctylammonium. It exhibits distinct differences in electronic and catalytic properties in comparison with the previously reported [Au-25(SCH2CH2Ph)(18)](-), albeit their skeletons (i.e., Au25S18 framework) are similar. A red shift by similar to 10 nm in the HOMO-LUMO electronic absorption peak wavelength is observed for the aromatic-thiolate-protected nanocluster, which is attributed to its dilated Au-13 kernel. The unsupported [Au-25(SNap)(18)](-) nanoclusters show high thermal and antioxidation stabilities (e.g., at 80 degrees C in the present of O-2, excess H2O2, or TBHP) due to the effects of aromatic ligands on stabilization of the nanocluster's frontier orbitals (HOMO and LUMO). Furthermore, the catalytic activity of the supported Au-25(SR)(18)/CeO2 (R = Nap, Ph, CH2CH2Ph, and n-C6H13) is examined in the Ullmann heterocoupling reaction between 4-methyl-iodobenzene and 4-nitro-iodobenzene. Results show that the activity and selectivity of the catalysts are largely influenced by the chemical nature of the protecting thiolate ligands. This study highlights that the aromatic ligands not only lead to a higher conversion in catalytic reaction but also markedly increase the yield of the heterocoupling product (4-methyl-4'-nitro-1,1'-biphenyl). Through a combined approach of experiment and theory, this study sheds light on the structure activity relationships of the Au-25 nanoclusters and also offers guidelines for tailoring nanocluster properties by ligand engineering for specific applications.