Geometrical and Electronic Structure, Stability, and Optical Absorption Spectra Comparisons between Thiolate- and Chloride-Stabilized Gold Nanoclusters
Geometrical and Electronic Structure, Stability, and Optical Absorption Spectra Comparisons between Thiolate- and Chloride-Stabilized Gold Nanoclusters
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DOI：
10.1021/acs.jpca.9b06598
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发表时间：
2019-11-14
影响因子：
2.9
通讯作者：
Aikens, Christine M.
中科院分区：
文献类型：
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作者：
Kuda-Singappulige, Gowri U.;Aikens, Christine M.
硫醇盐稳定的金纳米团簇由于其非凡的性质及其在催化、传感、生物医学等领域的应用而引起了人们的极大关注。然而，由于硫醇盐配体的尺寸、复杂性和构象灵活性，使用计算方法进行准确的结构预测可能是一个挑战。用氯化物配体取代硫醇盐配体提供了一种可能的替代方案。在这项工作中，研究了一系列化学计量比为1：1的金硫醇盐和氯化物团簇（AunLn; L = SH，Cl; n = 2-9）以及一些实验观察到的金纳米团簇类似物（AunLn; L = SH，Cl; n = 18-133）的稳定性，并使用密度泛函理论（DFT）确定了结合能、HOMO-LUMO能隙和吸收光谱。我们观察到，优化的几何形状的金纳米团簇的两种类型的配体收敛到相同的局部最小结构的实验观察到的结构。金团簇中每个金原子的平均结合能在Au 4L 4之后收敛。氯化物稳定的金团簇和纳米团簇的结合能平均分别为硫醇盐稳定的团簇和纳米团簇的结合能的87.5%和95.7%。通常，发现硫醇盐比氯化物更稳定。然而，更高的HOMO-LUMO间隙Au 2Cl 2，Au 38 Cl 24，和Au 102 Cl 44相比，它们的硫醇盐类似物表明系统的特别感兴趣的调查可能存在的氯化物为基础的金纳米团簇。无论使用哪种配体，吸收光谱都非常相似。这项研究还表明，在大的纳米团簇的理论研究中，复杂的硫醇盐配体可以取代氯配体预测结构和电子性质与合理的准确性和减少计算工作量。
Thiolate-stabilized gold nanoclusters have drawn significant attention for their extraordinary properties and their applications in many fields such as catalysis, sensing, biomedicine, etc. However, due to the size, complexity, and conformational flexibility of thiolate ligands, accurate structure prediction can be a challenge using computational approaches. Substitution of thiolate ligands with chloride ligands provides a possible alternative. In this work, the stabilities of a series of gold thiolate and chloride clusters with 1:1 stoichiometry (AunLn; L = SH, Cl; n = 2-9) and the analogs of some experimentally observed gold nanoclusters (AunLn; L = SH, Cl; n = 18-133) are examined, and binding energies, HOMO-LUMO gaps, and absorption spectra are determined using density functional theory (DFT). We observed that the optimized geometries of gold nanoclusters for both types of ligands converged to the same local minimum structure as the experimentally observed structures. The average binding energy per gold atom in gold clusters converges after Au4L4. The binding energies of chloride-stabilized gold clusters and nanoclusters average 87.5% and 95.7% of the binding energies of thiolate-stabilized systems for the clusters and nanoclusters, respectively. Typically, thiolates are found to be more stable than the chlorides. However, higher HOMO-LUMO gaps in Au2Cl2, Au38Cl24, and Au102Cl44 compared to their thiolate analogs suggest systems of particular interest for investigating the possible existence of chloride-based gold nanoclusters. Absorption spectra are very similar regardless of the ligand used. This study also demonstrates that in theoretical studies on large nanoclusters, complex thiolate ligands can be replaced by Cl ligands to predict structural and electronic properties with reasonable accuracy and reduced computational effort.