相关联的晶体结构的醇保护Au25集群和光学特性
Manzhou Zhu1, Christine M Aikens, Frederick J Hollander
1Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvannia 15213, USA.
Journal of the American Chemical Society
|April 15, 2008
概括
研究人员确定了25个金原子 (Au25) 集群的独特结构,该集群受到甲醇配体的保护. 这一发现挑战了黄金集群研究中的现有理论.
科学领域:
- 纳米技术和材料科学 材料科学
- 无机化学 无机化学
- 表面科学是一门学科.
背景情况:
- 确定铁保护黄金集群的精确原子结构仍然是集群科学中的一个重大挑战.
- 之前对25原子金属集群的研究经常遵循'集群的集群'模型,预测基于较小的构建块的特定安排.
研究的目的:
- 为了阐明由乙保护的25金原子集群 (Au25(SR) 18的最终单晶结构.
- 为了研究联结体-金核相互作用在决定集群架构中的作用.
- 将实验确定的结构与理论预测和已建立的集群模型进行比较.
主要方法:
- 采用单晶X射线衍射来解析Au25星团的总结构.
- 进行密度函数理论 (DFT) 计算以建模电子结构,并与实验观测进行比较.
- 时间依赖密度函数理论 (TD-DFT) 用于分析光学吸收特性.
主要成果:
- 确定了Au25星团的不寻常,高度对称的结构,其中包括一个中心的Icosahedral Au13核心和十二个封顶的金原子.
- 十八个乙乙酸盐连接体在桥梁配置中仅与金芯结合.
- 确定的结构与基于密度函数理论和"集群的集群"模型的预测有很大差异,特别是在黄金原子和连接体的排列方面.
结论:
- 合金核心相互作用在稳定这种独特的Au25集群结构方面发挥着至关重要的作用,取代了更简单的包装模型.
- 实验结果突出了当前理论模型和经验规则在预测复杂黄金集群结构方面的局限性.
- 在Au25(SR) 18集群中观察到的分子类吸收带与确定结构的TD-DFT计算一致,验证了电子特性.
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