Unexpected reactivity of Au25(SCH2CH2Ph)18 nanoclusters with salts.
Unexpected reactivity of Au25(SCH2CH2Ph)18 nanoclusters with salts.
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DOI：
10.1039/c0nr00878h
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发表时间：
2011-04
期刊：
影响因子：
6.7
通讯作者：
Manzhou Zhu;Gerentt Chan;Huifeng Qian;Rongchao Jin
中科院分区：
文献类型：
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作者：
Manzhou Zhu;Gerentt Chan;Huifeng Qian;Rongchao Jin
我们报道了硫醇盐保护的[Au（25）（SCH（2）CH（2）Ph）（18）]（0）纳米团簇与两种类型的盐（包括四辛基卤化铵（TOAX）和NaX）的化学反应性的一些有趣结果。在反应的早期阶段，发现[Au（25）（SCH（2）CH（2）Ph）（18）]（0）在任一类型的盐存在下自发地转化为其阴离子形式（[Au（25）（SCH（2）CH（2）Ph）（18）]（-））。然而，在反应的第二阶段中观察到大的差异。用NaX，我们观察到阴离子簇的分解，而用TOAX，簇显示出优异的稳定性。我们对反应机理有了一些了解. X（-）离子似乎攻击[Au（25）（SCH（2）CH（2）Ph）（18）]（q）表面并置换一些硫醇盐，这通过在质谱分析中观察到卤素结合的簇如Au（25）（SCH（2）CH（2）Ph）（18-x）Br（x）得到证明。这些卤素键合的团簇显示出降低的稳定性，并且它们分解成Au（I）络合物导致团簇的金价电子的释放;同时，非卤素键合的[Au（25）（SCH（2）CH（2）Ph）（18）]（0）团簇被还原成[Au（25）（SCH（2）CH（2）Ph）（18）]（-）。对于与有机盐如TOA-Br反应的第二阶段，在[Au（25）（SCH（2）CH（2）Ph）（18）]（0）簇转化为[Au（25）（SCH（2）CH（2）Ph）（18）]（-））之后，TOA（+）抗衡离子令人惊讶地保护阴离子簇免受卤离子的进一步攻击，因此，TOA（+）阳离子能稳定[Au（25）（SCH（2）CH（2）Ph）（18）]（-）团簇。相比之下，对于NaX盐，Na（+）离子不提供[Au（25）（SCH（2）CH（2）Ph）（18）]（-）簇的任何空间稳定性，因此，当被卤离子，特别是Br（-）和I（-）进一步攻击时，发生降解。
We report some interesting results of the chemical reactivity of thiolate-protected [Au(25)(SCH(2)CH(2)Ph)(18)](0) nanoclusters with two types of salts, including tetraoctylammonium halide (TOAX) and NaX. At the early stage of the reaction, [Au(25)(SCH(2)CH(2)Ph)(18)](0) was found to spontaneously convert to its anionic form ([Au(25)(SCH(2)CH(2)Ph)(18)](-)) in the presence of either type of salt. However, a large difference was observed in the second stage of the reaction. With NaX, we observed decomposition of anionic clusters, while with TOAX, the clusters show excellent stability. We have gained some insight into the reaction mechanism. The X(-) ions seem to attack [Au(25)(SCH(2)CH(2)Ph)(18)](q) surface and displace some thiolates, evidenced by the observation of halide-bound clusters such as Au(25)(SCH(2)CH(2)Ph)(18-x)Br(x) in mass spectrometry analysis. These halide-bound clusters show a reduced stability, and their decomposition into Au(I) complexes leads to the release of gold valence electrons of the clusters; concurrently, the non-halide-bound [Au(25)(SCH(2)CH(2)Ph)(18)](0) clusters are reduced into [Au(25)(SCH(2)CH(2)Ph)(18)](-). For the second stage of reaction with organic salts such as TOA-Br, after [Au(25)(SCH(2)CH(2)Ph)(18)](0) clusters are converted to [Au(25)(SCH(2)CH(2)Ph)(18)](-)) the TOA(+) counterions surprisingly protect the anionic clusters from further attack by halide ions, hence, TOA(+) cations can stabilize [Au(25)(SCH(2)CH(2)Ph)(18)](-) clusters. In contrast, with NaX salts the Na(+) ions do not provide any steric stabilization of the [Au(25)(SCH(2)CH(2)Ph)(18)](-) clusters, hence, degradation occurs when being further attacked by halide ions, especially Br(-) and I(-).