Constructing Endohedral Fullerenes Using Open-Cage Fullerenes and Heterofullerenes

艾伦·L.作者声明：Marilyn M.加州大学戴维斯分校的Olmstead得到了化学系大分子，超分子和纳米化学项目的支持，以开发制备内嵌富勒烯（纳米尺寸的足球状碳笼封装金属离子）的新方法。 这些合成方法被设计成仔细地、选择性地控制金属原子插入富勒烯中，在那里原子将被稳定。 内嵌富勒烯在气相过程中仅以微量制备。 它们已经在医学成像技术中显示出作为磁共振成像（MRI）造影剂（使用顺磁性钆）和X射线造影剂（使用强X射线吸收剂镥）的前景。 该项目的重点是开发大量制备内嵌富勒烯的新方法，以促进其在此类诊断医学成像和其他可能的技术应用中的实际应用。 大学和高中的学生参与了该项目，并接受了最先进的合成和结构表征技术的培训。 正在开展一些外联活动，包括化学同行指导方案和研讨会课程，如“艺术和科学中的对称性”和“化学品及其对加州历史的影响”。 在这个项目中，已知的化学过程被用来在C60和C70的富勒烯笼的织物中形成孔，以形成开笼富勒烯。 这些开笼结构通常在孔附近具有适合于金属离子键合的刘易斯碱位点。随后，金属离子附着在这些开笼富勒烯上，并最终插入它们的内部。笼的还原用于吸引金属离子通过开口并进入内部。这些反应通过光谱手段监测，并且分离产物，包括在外部和内部具有金属离子的开笼富勒烯的金属离子络合物，并且特别是通过单晶X射线衍射进行结构表征。 一旦金属中心进入笼中，化学反应就被用来开始关闭富勒烯网络中的孔。 物理性能，如功能的MRI造影剂和X射线造影剂，新的内的物种的能力将进行检查。该项目还旨在研究两种新的合成路线，以制造宏观量的金属杂富勒烯，碳笼中的一些碳原子被金属原子取代。这种金属杂富勒烯以前从未获得过固体，可以通过光谱和X射线晶体学手段进行表征。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估的支持。

Professors Alan L. Balch and Marilyn M. Olmstead of the University of California-Davis are supported by the Macromolecular, Supramolecular and Nanochemistry Program of the Division of Chemistry to develop new methods for the preparation of endohedral fullerenes (nano-sized soccer ball-like carbon cages encapsulating metal ions). The synthetic methods are designed to carefully, and selectively, control the insertion of metal atoms into fullerenes, where the atom will be stabilized. Endohedral fullerenes have only been prepared in minute quantities in a gas phase process. They have already shown promise in medical imaging technology as magnetic resonance imaging (MRI) contrast agents (using paramagnetic gadolinium) and X-ray contrast agents (using the strong X-ray absorber lutetium). The project is focused on the development of new methods for the preparation of endohedral fullerenes in large quantities to facilitate their practical use for such diagnostic medical imaging and other possible technological applications. Students at college and high school levels are involved in the project and trained in state of the art synthetic and structure characterization techniques. Several outreach activities, including a chemistry peer mentoring program, and seminar courses, such as " Symmetry in Art and Science" and "Chemicals and their Effect on California History" are being developed. In this project, known chemical procedures are used to fashion holes in the fabric of the fullerene cages of C60 and C70 to form open-cage fullerenes. These open cage structures frequently have Lewis base sites suitable for metal ion bonding near the orifice. Subsequently, metal ions are attached to these open cage fullerenes and eventually inserted into their interior. Reduction of the cage is used to attract the metal ion through the opening and into the interior. These reactions are monitored by spectroscopic means and the products, including metal ion complexes of the open cage fullerenes with metal ions on the outside and on the inside, are isolated and structurally characterized, particularly by single crystal X-ray diffraction. Once the metal center enters the cage, chemical reactions are used to begin to close the hole in the fullerene network. Physical properties, such as ability to function as MRI contrast agents and X-ray contrast agents, of the new endohedral species will be examined. The project is also designed to examine two new synthetic routes to make macroscopic amounts of metallo-heterofullerenes, carbon cages with some of the carbon atoms replaced with metal atoms. Such metallo-heterofullerenes have never previously been obtained as solids that can be characterized through spectroscopic and X-ray crystallographic means.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.