New, Chemically Reactive Fullerene-Based Assemblies: Accomplishment Based Renewal

在这个由化学部大分子、超分子和纳米化学计划资助的项目中，加州大学戴维斯分校的Alan L.Balch和Marilyn M.Olmstead将探索一组有希望的面体内富勒烯的结构和化学反应活性，这些富勒烯是包裹各种原子、离子或小分子的碳原子笼子。用X射线衍射法对大的富勒烯笼子和手性富勒烯笼子的结构进行表征的工作涉及到在更小的、接近球形的富勒烯分子(如Bucky球、C60)和碳纳米管之间提供桥梁的分子。面内富勒烯在捕光和其他光电及电化学器件中的应用涉及到这些分子的还原和氧化，但对外部功能化的面体内富勒烯的结构和化学反应活性以及这些面体内富勒烯氧化和还原形成的阳离子和阴离子的结构和化学反应活性知之甚少。研究人员打算制备各种内面体富勒烯的结晶盐，以确定氧化和还原行为如何改变它们的结构，内容物相对于笼子的位置，以及笼子内原子之间相互作用的性质。他们发现了几个新的富勒烯家族，组成为M3C106-124，M4C122-154，M3C107-125，并将探索这些非凡分子的化学反应和结构。这个项目将为研究生和本科生提供最先进的实验室经验，他们将学习化学合成技术，富勒烯在电弧中的形成，富勒烯分离和提纯的色谱方法，晶体和共晶生长，以及单晶X射线衍射方法，包括传统的内部源和同步辐射。学生们还将学习如何在团队内部以及与全球不同地点的科学家合作。曾经是一种稀有的化学品，典型的富勒烯C60，现在可以买到吨级的数量。Balch和Olmstead教授预计，内面体富勒烯的可获得性也会出现类似的增长。面内富勒烯是一种多功能材料，其性质反映了被困在其中的原子的性质。因此，含Gd的内面体是磁共振成像的有效造影剂，并且具有安全地将有毒的Gd原子捕获在非活性碳笼中的优势。含钚的内面体在X射线对比度成像中是有用的。富勒烯是设计新型塑料太阳能电池的首选分子，而面体内富勒烯代表着一套很有前途的新分子，可以改善和提高这些电池的运行特性。

In this project, funded by the Macromolecular, Supramolecular and Nanochemistry Program of the Chemistry Division, Alan L. Balch and Marilyn M. Olmstead of the University of California, Davis will explore the structures and chemical reactivity of a promising group of endohedral fullerenes, cages of carbon atoms that encapsulate a variety of atoms, ions or small molecules. Work on the structural characterization of large fullerene cages and chiral fullerene cages by X-ray diffraction involves molecules that provide a bridge between smaller, nearly spherical fullerenes like the Bucky ball, C60, and carbon nanotubes. The use of endohedral fullerenes in light harvesting and other electro-optical and electrochemical devices involves reduction and oxidation of these molecules, yet little is known about the structures and chemical reactivities of externally functionalized endohedral fullerenes and of the cations and anions formed by oxidation and reduction of these endohedral fullerenes. The researchers intend to prepare crystalline salts of a variety of endohedral fullerenes to determine how oxidation and reduction behavior alters their structure, the location of the contents with regard to the cage, and the nature of interactions between atoms inside cages. They have discovered several new families of fullerenes with compositions M3C106-124, M4C122-154, M3C107-125 and will explore the chemical reactivity and structures of these remarkable molecules.This project will provide state of the art laboratory experiences for graduate and undergraduate students who will be learning the techniques of chemical synthesis, fullerene formation in an electric arc, chromatographic methods of fullerene separation and purification, crystal and cocrystal growth, and single crystal X-ray diffraction methods including both conventional in-house sources and synchrotron radiation. The students will also learn how to collaborate within the group and also with scientists in varied locations globally. Once a rare chemical, the prototypical fullerene, C60, is now available in ton quantities. Professors Balch and Olmstead anticipate a similar increase in the availability of endohedral fullerenes. Endohedral fullerenes are versatile materials that have properties that reflect the nature of the atoms trapped inside. Thus, gadolinium-containing endohedrals are effective contrast agents for magnetic resonance imaging and have the advantage of safely trapping the toxic gadolinium atoms inside an unreactive carbon cage. Lutetium-containing endohedrals are useful in X-ray contrast imaging. Fullerenes are the molecules of choice in the design of new plastic solar cells, and endohedral fullerenes represent a promising new set of molecules to improve and enhance the operational characteristics of these cells.