Chirality and Electronic Structure of the Thiolate-Protected Au38 Nanocluster
Chirality and Electronic Structure of the Thiolate-Protected Au38 Nanocluster
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DOI：
10.1021/ja102934q
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发表时间：
2010-06-16
影响因子：
15
通讯作者：
Aikens, Christine M.
中科院分区：
文献类型：
--
作者：
Lopez-Acevedo, Olga;Tsunoyama, Hironori;Aikens, Christine M.
通过密度功能理论计算（R = CH3和R = C6H13）和粉末X射线晶体学（R = C12H25），研究了受硫醇酸盐保护Au-38（SR）（24）群集的结构，电子和光学性质）。一个低能结构，可以写为AU-23@（AU（SR）（2）（2））（3）（Au-2（Sr）（3））（6）具有双核心核心和手性排列在保护金硫醇酸盐的（SR）中，单位在计算的（r = C6H13）和测量（对于r = C12H25）之间的匹配度很高X射线衍射功能。我们通过使用粒子中的缸模型详细解释了AU-23核心的电子结构。尽管烷烃硫醇酸盐配体是精性的，但配体层的手性结构在Au-38（Sch3）（24）的2.2 eV的激发中产生强圆二色性（CD）。我们计算出的CD频谱与先前测量的受谷胱甘肽保护的Au-38（SG）的低能CD信号（SG）（24）符合定量一致。我们的研究证明了一种新的机制，该机制是用精神核和配体对硫醇盐保护的金簇的强烈手性反应。
Structural, electronic, and optical properties of the thiolate-protected Au-38(SR)(24) cluster are studied by density-functional theory computations (R = CH3 and R = C6H13) and by powder X-ray crystallography (R = C12H25). A low-energy structure which can be written as Au-23@(Au(SR)(2))(3)(Au-2(SR)(3))(6) having a bi-icosahedral core and a chiral arrangement of the protecting gold thiolate Au,,(SR), units yields an excellent match between the computed (for R = C6H13) and measured (for R = C12H25) powder X-ray diffraction function. We interpret in detail the electronic structure of the Au-23 core by using a particle-in-a-cylinder model. Although the alkane thiolate ligands are achiral, the chiral structure of the ligand layer yields strong circular dichroism (CD) in the excitations below 2.2 eV for Au-38(SCH3)(24). Our calculated CD spectrum is in quantitative agreement with the previously measured low-energy CD signal of glutathione-protected Au-38(SG)(24). Our study demonstrates a new mechanism for the strong chiral response of thiolate-protected gold clusters with achiral metal cores and ligands.