Chemistry and Electrochemistry of Molecule-Like Nanoparticles

北卡罗莱纳大学教堂山分校的罗伊斯·w·默里教授得到了分析和表面化学项目的支持，研究金属纳米颗粒，重点研究直径从3纳米到1纳米以下的颗粒。重点是推进制备和表征单层保护金属簇（MPCs）的技术，这些化合物具有金属或类金属核，通过保护硫化物配体的单层来稳定。研究目标尺寸范围内的金属纳米颗粒位于大块金属和离散分子之间的过渡区域，其性能取决于核心尺寸和保护单层的化学性质。研究小组正在探索制备MPCs的合成策略，这些MPCs越来越小，越来越高度单分散，并且能够改变金属核心组成和配体官能团（荧光团，氧化还原基团和分析有用的结合位点）。分析方法正在发展，特别是高效液相色谱（HPLC）分离和光学和电化学检测策略，以阐明MPC尺寸的分散性。通过比较显示连续电子充电的最大MPCs、显示量子化双层充电的较小MPCs和显示类似分子的homo/lumo带隙的最小核心MPCs的响应，探索了不同尺寸MPCs的电子转移化学的能量学和动力学。还研究了配体交换反应和金属核配体单层上的荧光团的激发态行为。本研究正在开发研究溶液中金属团簇的金属-分子过渡区所必需的工具。这项工作对化学传感和纳米尺度电子电荷传输管道的开发等应用领域产生了影响。

Professor Royce W. Murray of the University of North Carolina at Chapel Hill is supported by the Analytical and Surface Chemistry program to investigate metal nanoparticles with emphasis on particles in the range from 3 nm to just below 1 nm in diameter. Focus is on advancing techniques for the preparation and characterization of monolayer-protected metal clusters (MPCs), compounds that have metal, or metal-like, cores stabilized by protecting monolayers of thiolate ligands. Metal nanoparticles in the size range targeted for study lie in the transition region between bulk metals and discrete molecules and exhibit properties that are dependent on both core size and the chemical nature of the protecting monolayer. The research team is exploring synthetic strategies for the preparation of MPCs that are increasingly smaller and more highly mono-disperse and enable variations in metal core composition and ligand functional groups (fluorophores, redox groups, and analytically useful binding sites). Analytical methods are being developed with special focus on high performance liquid chromatographic (HPLC) separations and tactics of optical and electrochemical detection that elucidate MPC size dispersity. The energetics and dynamics of electron transfer chemistry of differently sized MPCs are being explored through comparisons between responses of the largest MPCs that display a continuum of electronic charging, smaller MPCs that display quantized double layer charging and the smallest core MPCs that exhibit molecule-like homo/lumo band gaps. Ligand exchange reactions and the excited state behavior of fluorophores attached to the ligand monolayer of the metal core are also being investigated.This research is developing tools necessary to study the metal-to-molecule transition region of metal clusters in solution. The work has impact in application areas that include chemical sensing and the development of nanometer-scale conduits for electronic charge transport.