Manipulation of Intraparticle Charge Delocalization by Conjugated Metal-Ligand Interfacial Bonds

纳米粒子的尺寸约为十亿分之一米，显示出许多重要的技术特性，因此正在积极研究中。加州大学圣克鲁兹分校（UCSC）的陈少伟博士（Dr. Shaowei Chen）研究了一种过渡金属纳米颗粒，这种纳米颗粒被有机覆盖层（配体）稳定，使被覆盖的纳米颗粒在普通溶剂中分散，在许多应用中都很有用。陈博士的研究表明，金属纳米粒子核心和有机配体之间的化学键可以作为一种新的、有效的方法来控制纳米粒子的性质。在这个项目中，陈博士和他的学生对纳米粒子-配体界面键的基本化学性质以及纳米粒子核心金属和核心尺寸对键形成的影响感兴趣。这些研究的结果对于建立纳米颗粒结构和性能之间的相关性至关重要，这将使纳米颗粒能够用于光学器件、传感器和其他先进应用。由于电荷转移是纳米颗粒材料独特构建模块的广泛重要应用中的基本过程，因此可以预见，纳米颗粒的研究可能会对电子和能源工业，医疗保健和国土安全产生影响。他的研究涉及高中生、本科生和研究生，并积极参与各种外展计划，如UCSC ACCESS、UC LEADS（加州大学高级学位卓越领导力）、暑期实习计划（SIP）和加州州立大学暑期数学学校（COSMOS）计划。在这个研究项目中，加州大学圣克鲁兹分校（UCSC）的陈少伟博士得到了大分子、超分子和纳米化学（MSN）项目的支持，研究金属-配体界面键作用对纳米粒子化学和物理性质的影响。Chen博士开发了新的表面吸附化学，其中金属-碳，-氧或-氮共价键容易形成，导致由钌，铂和铜组成的过渡金属纳米颗粒的钝化和功能化，以及核/壳和核/壳/壳结构的组合。与常用的巯基衍生物功能化纳米颗粒形成鲜明对比的是，功能化导致的界面阻力降低有助于颗粒间电荷转移。特别是，共轭金属配体界面键的形成导致粒子内电荷在粒子结合的功能基团之间有效地离域，并出现与二聚体类似的光学和电子性质。陈博士的研究促进了对界面键的基本化学性质的理解，并研究了纳米颗粒核心金属和核心尺寸对共轭金属-配体界面键形成的影响。这些研究的结果对于建立纳米颗粒结构和性质之间明确的相关性至关重要。他的研究涉及高中生、本科生和研究生，并积极参与各种外展计划，如UCSC ACCESS、UC LEADS（加州大学高级学位卓越领导力）、暑期实习计划（SIP）和加州州立大学暑期数学学校（COSMOS）计划。

Nanoscaled particles, having dimensions on the order of a billionth of a meter, show many technologically important properties, and are therefore actively under research. Dr. Shaowei Chen of the University of California Santa Cruz (UCSC) studies transition metal nanoparticles that are stabilized with an organic capping layer (the ligand), making the capped nanoparticles dispersible in common solvents and useful in many applications. Dr. Chen's research shows that the chemical bonds between the metal nanoparticle cores and the organic ligands can be exploited as a new, effective way of manipulating nanoparticle properties. In this project, Dr. Chen and his students are interested in examining the fundamental chemical nature of the nanoparticle-ligand interfacial bonds and examining the impacts of nanoparticle core metals and core size on the formation of the bonds. Results from these studies are critical to the establishment of a correlation between the nanoparticle structures and properties that will enable the nanoparticles to be used in optical devices, sensors and other advanced applications. As charge transfer is a fundamental process in a wide range of important applications where nanoparticle materials are unique building blocks, it is envisioned that research on nanoparticles may have impacts on the electronics and energy industries, health care, and homeland security. Dr. Chen involves high school, undergraduate and graduate students in his research and actively participates in various outreach programs such as the UCSC ACCESS, UC LEADS, (the University of California Leadership Excellence through Advanced Degrees), the Summer Internship Program (SIP) and California State Summer School for Mathematics (COSMOS) programs. In this research program, Dr. Shaowei Chen of the University of California Santa Cruz (UCSC) is supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program to study the impacts of metal-ligand interfacial bonding interactions on the nanoparticle chemical and physical properties. Dr. Chen has developed new surface adsorption chemistries in which metal-carbon, -oxygen, or -nitrogen covalent bonds readily form to result in the passivation and functionalization of transition-metal nanoparticles consisting of ruthenium, platinum and copper and combinations of core/shell, and core/shell/shell architectures. The reduced interfacial resistance resulting from the functionalization facilitates interparticle charge transfer, in sharp contrast to nanoparticles functionalized with the more commonly used mercapto derivatives. In particular, the formation of conjugated metal-ligand interfacial bonds leads to effective intraparticle charge delocalization between particle-bound functional moieties, and the emergence of optical and electronic properties that are analogous to those of their dimeric counterparts. Dr. Chen's research advances the understanding of the fundamental chemical nature of the interfacial bonds and examines the impact of nanoparticle core metals and core size on the formation of conjugated metal-ligand interfacial bonds. Results from these studies are critical in the establishment of an unambiguous correlation between the nanoparticle structures and properties. Dr. Chen involves high school, undergraduate and graduate students in his research and actively participates in various outreach programs such as the UCSC ACCESS, UC LEADS, (the University of California Leadership Excellence through Advanced Degrees), the Summer Internship Program (SIP) and California State Summer School for Mathematics (COSMOS) programs.