Very-High-Spin Polyradicals

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This award iq made jointly by the Organic Dynamic Program and the Advanced Materials Program in the Chemistry Division in support of the continuing research of Dr. Andrzej Rajca. Two major efforts will be supported; (1) the design, synthesis and characterization of very high spin macrocyclic poyradical systems, and (2) computational and experimental studies on the synthesis and properties of new carbon allotropes and highly condensed network solids based on tetra o-phenylene structural units. In the first research area, polyradicals, all of the triarylmethyl type will be prepared from the corresponding triarylmethyl-methyl ethers by alkali metal reduction to the carbopolyanions followed by iodine oxidation. These elongated macrocyclic polyradicals will have greater than ten spin-coupled electrons and will be designed to minimize defects which interrupt spin-coupling. In the second research area, solid-state and molecular calculations using MNDO, EHT, and MM3 methods will provide thermodynamic stabilities and band structure-properties of the solids. Experiments will evaluate the structures of the network solids, including their response to doping. Molecular and polymeric fragments of the solids will be synthesized, and their solution redox chemistry investigated. Understanding the behavior of macrocyclic polyradicals and controlling spin coupling defects will allow the researcher to use them as building blocks for two and three dimensional network polyradicals, with the potential to be organic ferromagnets with high Curie temperatures. Synthesis and doping of highly condensed carbon networks will facilitate preparation of radical ion-and dianion -based molecular solids which will lead to promising new materials with conducting properties.