Collaborative Research: Electronic and Geometric Structure of n-Glyme Assembled Metal Clusters

金属纳米颗粒可能只有几个纳米大小，只包含几十到数百个金属原子。当纳米颗粒彼此隔离时，暴露在光线下通常会导致颗粒受热，然后将能量耗散到周围的溶剂中。然而，将两个粒子连接在一起，光吸收就可以转化为明亮的发光。在化学系大分子、超分子和纳米化学项目的支持下，科罗拉多州立大学的Christopher Ackerson教授、堪萨斯州立大学的Christine Aikens教授和宾夕法尼亚州立大学的Kenneth Knappberger教授正在努力了解这种光发射的机制。该团队将精确的纳米颗粒合成和表征与尖端的理论计算和实验光谱相结合，以确定这些系统的独特发光特性。他们的发现可能会改善生物成像，并影响新兴的量子信息技术。该项目还为学生培训提供了独特的多学科环境，面向K-12学生的外联活动正在向代表性不足的学生介绍科学研究。这个方案的主要目的是确定配体取代如何影响量子受限金纳米团簇(AuNC)及其组装的几何和电子结构，并了解这些性质对电子驰豫动力学和光致发光产额的影响。该团队还在发展对AuNC单体的性质如何影响电子耦合二聚体和扩展结构的理解。拟议的研究以结构上精确的单分子膜保护的金簇为特征，并取得了包括n-甘氨酸桥联多聚体的进展。具体目标包括：1)确定Glyme分子可被纳入AuNC钝化外壳的相容配体，并了解可使用Glyme驱动的化学组装的团簇的范围；2)描述Glyme与AuNC单体和较大组装物在电子和几何上相互作用的性质；以及3)描述1和2中描述的性质如何影响AuNC单体的状态分辨载流子动力学、簇间电子耦合和转移以及光致发光发射。这些目标是通过结合胶体AuNC的合成和纯化、基于计算的预测和实验电子动力学研究来实现的。拟议的努力包括在研究生和本科生层面提供纳米科学三大支柱的学生教育计划。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Metal nanoparticles can be just a few nanometers in size and contain just tens to hundreds of metal atoms. When the nanoparticles are isolated from one another, exposure to light typically results in heating of the particle, which then dissipates energy into the surrounding solvent. However, connect two particles together and that light absorption can be converted into a bright luminescence. With support from the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professors Christopher Ackerson (Colorado State University), Christine Aikens (Kansas State University), and Kenneth Knappenberger (Pennsylvania State University) are working to understand the mechanism of this light emission. The team combines precision nanoparticle synthesis and characterization with cutting-edge theoretical calculations and experimental spectroscopy to determine the unique luminescence properties of these systems. Their discoveries could improve bioimaging and impact emerging quantum information technologies. The project also provides a unique multi-disciplinary environment for student training, and outreach activities to K-12 students are introducing underrepresented students to scientific research. The primary thrusts of this proposal are to determine how ligand substitution affects the geometric and electronic structure of quantum-confined gold nanoclusters (AuNCs) and their assemblies, and to understand the influence of these properties on electronic relaxation dynamics and photoluminescence yields. The team is also developing an understanding of how the properties of AuNC monomers impact electronically coupled dimers and extended structures. The proposed research features structurally precise monolayer-protected gold clusters and progresses to include n-glyme-bridged multimers. The specific objectives include: 1) to determine the compatible ligands for which glyme molecules can be incorporated into the AuNC passivation shell, and to understand the range of clusters that can be assembled using glyme-driven chemistry; 2) to describe the nature of the interaction -- both electronically and geometrically -- of glyme with AuNC monomers and larger assemblies; and 3) to describe how the properties described in 1 and 2 affect state-resolved carrier dynamics of AuNC monomers, inter-cluster electronic coupling and transfer, and photoluminescence emission. These goals are being achieved by combining colloidal AuNC synthesis and purification, computational-based predictions, and experimental electron dynamics research. The proposed efforts include plans to provide student education at the graduate and undergraduate levels in three pillars of nanoscience.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.