Stable High-Spin Polyradicals and Chiral pi-Conjugated Systems

通过这个奖项，有机和大分子化学项目支持内布拉斯加大学林肯分校的安杰伊·拉贾卡教授的工作。本研究包括两个领域，即稳定的高自旋多自由基（多个未配对电子）和手性（不与其镜像重叠）π共轭体系的合成和表征。在多自由基领域，将合成和表征具有强铁磁耦合和环境条件下稳定性的高自旋有机分子。研究方法是基于聚自由基的anneloated pi系统，其中氮中心自由基和氮氧自由基都将作为电子自旋的载体。在手性共轭体系方面，将合成和研究具有11个以上邻合芳环的手性螺旋烯及其相关的高邻合pi-体系，包括螺旋烯的自由基阳离子。这些研究旨在促进基于高自旋有机分子的有机磁体和其他材料的发展，并提供对控制强手性有机材料合理设计的原则的理解。建议的研究涉及有机合成和有机分子的综合物理表征，特别是磁测量。这些多学科研究有望为开发轻质有机磁体和具有新型光学和电子特性的手性材料提供重要的基础信息。一批本科生、研究生和博士后将进行这些研究，他们将接受物理有机化学、有机合成、固态化学和磁学方面的多样化培训。研究经验将促进学习，通过接近和解决复杂的问题。此外，从这个项目中获得的材料将提供给美国和国外的其他研究小组。

With this award, the Organic and Macromolecular Chemistry Program supports the work of Professor Andrzej Rajca of the University of Nebraska-Lincoln. This research consists of two areas directed toward the synthesis and characterization of stable high-spin poly-radicals (multiple unpaired electrons) and chiral (not superimposable on its mirror image) pi-conjugated systems. In the area of poly-radicals, high-spin organic molecules with very strong ferromagnetic coupling and with stability at ambient conditions will be synthesized and characterized. The research approach is based upon annelated pi-systems of poly-radicals, for which both nitrogen-centered radicals and nitroxide radicals will be used as carriers of electron spin. In the area of chiral conjugated systems, chiral helicenes with more than eleven ortho-fused aromatic rings and related highly annelated pi-systems, including radical cations of helicenes, will be synthesized and studied. These studies are designed to advance the development of organic magnets and of other materials based upon high-spin organic molecules and to provide an understanding of the principles governing the rational design of strongly chiral organic materials.The proposed research involves organic synthesis and comprehensive physical characterization of organic molecules, in particular magnetic measurements. These multidisciplinary studies are expected to provide important fundamental information that will contribute to development of lightweight organic magnets and of chiral materials with novel optical and electronic properties. A group of undergraduate, graduate and postdoctoral students, who will carry out these studies, will receive diverse training in physical organic chemistry, organic synthesis, solid-state chemistry, and magnetism. The research experience will promote learning, by approaching and solving complex problems. Furthermore, the materials obtained from this project will be made available to other research groups in the United States and abroad.