On Heavier Chalcogen (Se and Te) Interfacial Chemistry and Charge Transfer in Monolayer-Protected Metal Nanoparticles

金属纳米颗粒是非常小（纳米尺度）尺寸的金属颗粒。 它们具有新颖的化学和物理性质，与大颗粒或大块金属的性质非常不同。 乔治敦大学的YuYe Tong博士和美国国家标准与技术研究所的托马斯阿利森博士进行研究，以更好地了解控制金属纳米颗粒特性的结构参数。 长期目标是利用纳米颗粒的新特性用于实际应用（如电子或光学设备，生物医学诊断和药物输送）。 该项目为学生提供了跨学科的研究机会，培训他们使用最先进的仪器来研究纳米粒子。 通过乔治城大学与华盛顿东南部的塞萨尔查韦斯公立特许学校的合作，童博士参与了一个项目，帮助当地特许学校开发新的化学课程。 这个项目是吸引更多女性和代表性不足的学生进入STEM领域的跳板。Tong博士和Allison博士探索了使用较重的硫族元素（Se和Te）作为替代锚定元素，以替代经常使用的硫，将有机分子线连接到金属表面。 使用实验技术和密度泛函理论（DFT）计算的组合，他们的目标是获得更好的机械理解的金属硫族化合物界面化学及其衍生物的电荷转移/传输在单分子层保护的纳米粒子（MPN）和MPN组件。 具体而言，本研究包括：1）不同尺寸的合成不同金属元素的纳米颗粒（1至5 nm）（Au、Ag、Cu、Pt和Pd），其用不同有机骨架的配体保护（烷基和芳基），烷基链长（C6、C8和C12），以及锚定硫族元素（Se和Te）; 2）通过原位电化学（EC）光谱对上述合成的MPN进行表征（NMR/IR/拉曼）技术和非原位X射线光电子能谱;和3）使用EC扫描隧道显微镜和传统EC测量通过单个MPN和MPN组件的电荷转移的比较机理研究。

Metal nanoparticles are metal particles of very small (nanometer scale) dimensions. They possess novel chemical and physical properties that are very different from those of large particles or bulk metals. Dr. YuYe Tong of Georgetown University and Dr. Thomas Allison at the National Institute of Standards and Technology conduct research to gain a better understanding of the structural parameters that govern the properties of metal nanoparticles. The long-term goal is to harness the novel properties of nanoparticles for practical applications (such as electronic or optical devices, biomedical diagnosis, and drug delivery). This project provides interdisciplinary research opportunities to students, training them in the use of the state-of-the-art instruments for studying nanoparticles. Through Georgetown University's partnership with the Cesar Chavez Public Charter Schools in Southeast Washington DC, which have very high population of students of underrepresented groups or from low-income families, Dr. Tong participates in a project to help develop new chemistry curricula for local charter schools. This project serves as a springboard to attract more women and underrepresented students to STEM fields.Dr. Tong and Dr. Allison explore the use of heavier chalcogen (Se and Te) as alternative anchoring elements to the prevailingly used sulfur for attaching organic molecular wires to metal surfaces. Using a combination of experimental techniques and Density Functional Theory (DFT) computations, they aim to gain a better mechanistic understanding of the metal-chalcogenolate interfacial chemistry and its ramifications on charge transfer/transport in single monolayer-protected nanoparticle (MPN) and MPN assemblies. Specifically, this research entails: 1) the synthesis of different sizes (1 to 5 nm) of nanoparticles of different metal elements (Au, Ag, Cu, Pt, and Pd), which are protected with ligands of different organic backbones (alkyl and aryl), alkyl chain lengths (C6, C8, and C12), and anchoring chalcogen elements (Se and Te); 2) the characterization of the afore-synthesized MPNs by in situ electrochemical (EC) spectroscopic (NMR/IR/Raman) techniques and ex situ X-ray photoemission spectroscopy; and 3) comparative mechanistic investigations of charge transfer through a single MPN and MPN assemblies using EC scanning tunneling microscopy and traditional EC measurements.