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

金属纳米颗粒的大小可以只有几纳米，并且只包含几十到几百个金属原子。当纳米颗粒彼此分离时，暴露于光通常导致颗粒加热，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，克里斯托弗·阿克森教授（科罗拉多州立大学）、克莉丝汀·艾肯斯教授（堪萨斯州立大学）和肯尼思·纳彭伯格教授（宾夕法尼亚州立大学）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学相结合，以确定这些系统的独特发光特性。 他们的发现可以改善生物成像，并影响新兴的量子信息技术。该项目还为学生培训提供了一个独特的多学科环境，对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。该提案的主要目的是确定配体取代如何影响量子限制金纳米团簇（AuNCs）及其组装体的几何和电子结构，并了解这些性质对电子弛豫动力学和光致发光产率的影响。该团队还正在了解AuNC单体的性质如何影响电子耦合二聚体和扩展结构。拟议的研究功能结构精确的单层保护的金簇和进展，包括n-甘醇二甲醚桥接多聚体。具体目标包括：1）确定可以将甘醇二甲醚分子结合到AuNC钝化壳中的相容配体，并了解可以使用甘醇二甲醚驱动的化学组装的簇的范围; 2）描述甘醇二甲醚与AuNC单体和更大组装体的相互作用的性质-电子和几何性质;以及3）描述在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。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。

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.