Variable temperature UV/Vis spectrophotometer for study of NHC-stabilized gold nanoclusters

用于研究 NHC 稳定金纳米团簇的变温紫外/可见分光光度计

• 批准号: RTI-2020-00059
• 负责人: Crudden, Cathleen
• 金额: $ 3.43万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=689619
• 关键词: Variable; temperature; UV; Vis; spectrophotometer

Metal nanoparticles and nanoclusters are often highly coloured, making UV-vis spectroscopy a powerful technique for their analysis. Metallic nanoparticles were initially developed for their colour. In a technique dating back to the 15th century, artisans added gold chloride to molten glass, which resulted in bright red glasses, which were actually gold nanoparticles trapped in glass. Similarly yellow glasses resulted from the generation of silver nanoparticles. These red and yellow glasses were used in the preparation of stained-glass windows. Metal nanoclusters are also coloured but are substantially different from nanoparticles in several important ways. Firstly, they are typically smaller, with sizes ranging from 3 to 300 gold atoms. Secondly, they are prepared and isolated as single molecular entities, where nanoparticles are still isolated as mixtures with varying levels of polydispersity. Finally, because of these two properties, nanoclusters do not have plasmonic signals in their optical spectra, they have discrete molecular transitions. Because of this, UV-visible spectroscopy is a highly valuable method for the analysis of metal nanoclusters. Decomposition to nanoparticles is characterized by the appearance of plasmonic peaks and loss of individual transitions. The change from small clusters to larger clusters is also easily observed by UV-visible, and, in combination with computational studies, is highly effective at structural identification. *** Although they are fascinating molecules, metallic nanoclusters are still prepared using a black box approach that makes control of and prediction of structure largely a thermodynamic issue: namely, the most stable structures are isolated either by control of synthesis or by selective etching/crystallization or purification methods. Remarkably, despite the fact that these materials have been known for decades, a balanced equation cannot be written for their preparation. The infrastructure requested in this proposal is critical in righting this wrong. The use of N-heterocyclic carbenes as ligands is a key part in simplifying this process, since the starting material for the nanocluster synthesis is a simple organometallic NHC-Au-X species, rather than an unknown [RS-Au-] polymer. However, without the ability to analyze reactions as they progress by UV-visible spectroscopy and understand the process, it will be virtually impossible to gain the insight we need to understand and optimize the synthesis of these interesting materials. Similarly, understanding the stability of the novel NHC-functionalized nanoclusters we are preparing will be exceptionally difficult without temperature-controlled UV/vis analysis. Developing applications of these unique molecular materials, namely in solar cells, bio-imaging and catalysis, will be impossible without this instrument. HQP in the Crudden and Stamplecoskie groups will have hands on use of this instrument on a daily basis. **

金属纳米颗粒和纳米团簇的颜色通常很高，这使得UV-Vis光谱成为分析它们的强大技术。金属纳米颗粒最初是为它们的颜色而开发的。在一项可以追溯到15世纪的技术中，工匠们将氯化金添加到熔化的玻璃中，产生了鲜红色的玻璃，这实际上是困在玻璃中的金纳米颗粒。类似地，黄色玻璃是由银纳米颗粒的产生而产生的。这些红色和黄色的玻璃被用来制作彩色玻璃窗。金属纳米团簇也是有色的，但在几个重要方面与纳米颗粒有很大不同。首先，它们通常较小，大小从3个到300个金原子不等。其次，它们是以单分子实体的形式制备和分离的，其中纳米颗粒仍然以具有不同程度多分散性的混合物的形式被分离。最后，由于这两个性质，纳米团簇的光谱中没有等离子体信号，它们有离散的分子跃迁。正因为如此，紫外可见光谱是一种非常有价值的分析金属纳米团簇的方法。分解为纳米粒子的特征是等离子体峰的出现和单个跃迁的丢失。从小星团到大星团的变化也很容易用紫外可见观察到，结合计算研究，在结构鉴定方面是非常有效的。*尽管金属纳米团簇是令人着迷的分子，但它们仍然使用黑盒方法来制备，这使得结构的控制和预测在很大程度上是一个热力学问题：即最稳定的结构是通过控制合成或通过选择性蚀刻/结晶或纯化方法来分离出来的。值得注意的是，尽管这些材料已经知道了几十年的事实，但无法为它们的准备写出一个平衡的方程式。这项提案中要求的基础设施对于纠正这一错误至关重要。使用N-杂环卡宾作为配体是简化这一过程的关键部分，因为合成纳米簇合物的原料是简单的有机金属NHC-Au-X物种，而不是未知的[RS-Au-]聚合物。然而，如果没有能力通过紫外可见光谱分析反应过程并了解反应过程，几乎不可能获得我们理解和优化这些有趣材料合成所需的洞察力。同样，如果没有温度控制的UV/Vis分析，了解我们正在制备的新型NHC功能化纳米团簇的稳定性将非常困难。没有这台仪器，这些独特的分子材料在太阳能电池、生物成像和催化方面的开发应用将是不可能的。CRUDDEN和STAMPLETESKIE小组的HQP将每天使用该仪器。**