Stable High-Spin Polyradicals and Chiral pi-Conjugated Systems

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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.