Dendrimer-Encapsulated Metal Nanoparticles

在这个由分析和表面化学计划支持的项目中，德克萨斯农工大学的理查德·克鲁克斯教授和他的同事们将合成和表征树枝状大分子包裹的金属颗粒。这些材料的潜在优势是可以方便地获得1-3纳米量级的纳米金属颗粒，具有高度的单分散性和良好的稳定性。这些纳米材料将通过两步法制备。首先，将树状大分子暴露在含有金属离子的溶液中。这会导致金属离子与树枝状大分子中的配体之间的络合作用。第二步是有机/无机复合材料的化学还原，形成树枝状大分子金属纳米颗粒。每个树枝状大分子都充当一个谨慎的纳米反应器，只有树枝状大分子中的金属离子才能聚合成纳米粒子。这意味着原则上每个纳米颗粒都将包含相同数量的金属原子。这一点意义重大，因为目前很少有方法可以制备1-3 nm尺寸范围内的单分散金属团簇，这些金属团簇既具有表面活性，又可溶于多种溶剂。这个大小范围很有趣，原因有很多，但主要是因为它是金属原子从原子性质向金属性质过渡的范围。单分散金属纳米颗粒在科技领域有着广泛的应用。应用包括电子学、生物医学应用、催化基础研究以及化学和生物传感器。除了这些更广泛的影响外，这项工作还邀请了许多合作研究项目。树枝状大分子包裹的金属颗粒的催化性能将由三一大学的同事评估。商业应用将与密歇根分子研究所的同事一起进行评估。对纳米粒子的进一步表征将在韩国进行同步加速器实验。最后，这项提案将支持当地高中生和本科生在暑假期间参与该项目。

In this project supported by the Analytical and Surface Chemistry Program, Professor Richard Crooks and coworkers at Texas A&M University will synthesize and characterize dendrimer-encapsulated metal particles. The potential advantage of these materials is convenient access to nanometer-sized metal particles, on the order of 1-3 nanometers, having both high monodispersity and good stability. These nanomaterials are to be prepared by a two step process. First, the dendrimer is exposed to a metal ion-containing solution. This results in complexation between the metal ions and ligands within the dendrimer. The second step involves chemical reduction of the organic/inorganic composite, which results in formation of an intradendrimer metal nanoparticle. Each dendrimer acts as a discreet nanoreactor, and only those metal ions within the dendrimer coalesce into the resulting nanoparticle. This means that in principle every nanoparticle will contain the same number of metal atoms. This is significant because at the present time there are few methods available for preparing monodisperse metallic metal clusters in the 1-3 nm size range that are both surface active and soluble in many solvents. This size range is interesting for a number of reasons, but mainly because it is the range over which metal atoms undergo a transition from atomic to metallic properties. Monodispersed metal nanoparticles have many applications to the technology sector. Applications include electronics, biomedical applications, fundamental studies of catalysis, and chemical and biological sensors. In addition to these broader impacts, this work invites many collaborative research projects. Catalytic properties of the dendrimer-encapsulated metal particles will be evaluated by colleagues at Trinity University. Commercial applications will be evaluated with colleagues at the Michigan Molecular Institute. Additional characterization of the nanoparticles is to be done with synchrotron experiments to be performed in South Korea. Finally, this proposal will support local high school students and undergraduates to work on the project during the summers.