Ligand Regiochemistry on Gold Nanoclusters

金纳米团簇上的配体区域化学

• 批准号: 2204110
• 负责人: Christopher Ackerson
• 金额: $ 49.9万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-06-15 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2204110&HistoricalAwards=false
• 关键词: Ligand; Regiochemistry; Gold; Nanoclusters

With support from the Macromolecular, Supramolecular and Nanochemistry Program (MSN) in the Division of Chemistry, Professor Christopher Ackerson of Colorado State University is combining chemical synthesis and advanced chemical analysis tools to study how different types of molecules compete for bonding sites on the surfaces of clusters of gold atoms. These surfaces can be low-symmetry, meaning that many different types of bonding sites are present. Different types of molecules prefer different types of bonding sites. Some molecules will bond to two sites at the same time. To determine which molecules prefer which binding sites, Professor Ackerson and his students make well-defined gold clusters, such as Au25, which has 18 molecule binding sites. They mix Au25 with other molecules and use advanced imaging methods to see where the molecules bind. In the long term, they want to write rules that describe where molecules will bind to metal clusters. Their discoveries could lead to methods for making large molecules that cannot currently be synthesized. Those molecules could find use in catalysis, as labels in microscopy, and as medicines. The award supports a workshop that brings together synthetic experts from different sub-specialties in chemistry, as well as training the diverse future scientific workforce.Professor Ackerson aims to transform current understanding of regiochemical control of ligands on metal nanoparticle surfaces. The specific system examined is that of thiolate, acetylide, and similar ligands on magic number gold clusters. These clusters are of low symmetry (e.g., conforming to C2, i, and similar point groups), meaning that there are many symmetry-unique ligand binding sites. The overall goals are to understand the regiochemistry of monodentate ligands on such gold nanoclusters and to determine structurally how bidentate thiolate ligands bind to magic number gold clusters. Questions addressed include: (1) What reaction mechanisms access sites with long-term lifetimes? (2) Do thiolates with distinctive or demanding R-groups localize to specific regiochemical sites based on their shape? (3) Do acetylide ligands exchange associatively under ambient conditions? (4) What is the structural nature of bidentate thiol ligand binding? (5) Do bidentate ligands achieve useful lifetimes (days to weeks) in ambient conditions where monodentate ligands continue to exchange? (6) Can a magic-number cluster protected exclusively by bidentate ligands be produced and crystallized? These questions are addressed with methodological approaches including MALDI-MS to determine extent of ligand exchange, and either single crystal X-ray diffraction or multidimensional NMR spectroscopy to determine regiochemistry of ligand-exchange products.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在化学系大分子、超分子和纳米化学项目（MSN）的支持下，科罗拉多州立大学的Christopher Ackerson教授正在将化学合成和先进的化学分析工具结合起来，研究不同类型的分子如何竞争金原子簇表面的键位。这些表面可能是低对称的，这意味着存在许多不同类型的键合位点。不同类型的分子倾向于不同类型的键位。一些分子会同时与两个位点结合。为了确定哪个分子更喜欢哪个结合位点，阿克森教授和他的学生们制作了定义明确的金簇，比如Au25，它有18个分子结合位点。他们将Au25与其他分子混合，并使用先进的成像方法来观察分子结合的位置。从长远来看，他们想要编写规则来描述分子将在哪里与金属簇结合。他们的发现可能会带来制造目前无法合成的大分子的方法。这些分子可以用于催化、显微镜上的标签和药物。该奖项支持一个研讨会，该研讨会汇集了来自化学不同分支专业的合成专家，并培训了多样化的未来科学劳动力。阿克森教授旨在改变目前对金属纳米颗粒表面配体的区域化学控制的理解。研究的具体体系是硫酸盐、乙酰基酯和类似配体在幻数金簇上的体系。这些簇具有低对称性（例如，符合C2， i和类似的点群），这意味着有许多对称唯一的配体结合位点。总体目标是了解这种金纳米簇上的单齿配体的区域化学，并确定双齿硫酸盐配体如何在结构上与幻数金簇结合。解决的问题包括：(1)哪些反应机制访问具有长期生命周期的位点？(2)具有独特或苛刻r基团的硫代酸盐是否根据其形状定位于特定的区域化学位点？(3)乙酰基配体在环境条件下会发生缔合交换吗？(4)双齿硫醇配体结合的结构性质是什么？(5)在单齿配体持续交换的环境条件下，双齿配体是否达到有效寿命（数天到数周）？(6)双齿配体保护的幻数簇能否产生并结晶？这些问题的解决方法包括MALDI-MS来确定配体交换的程度，以及单晶x射线衍射或多维核磁共振波谱来确定配体交换产物的区域化学。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。