Conjugated Halocarbon Chemistry for New Materials

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This research program addresses the chemistry of unsaturated halocarbon compounds. Given their Lewis acidity and the general reactivity of C-X bonds, conjugated halocarbons such as halocumulenes and haloalkynes provide good starting points for making a large variety of carbon-rich materials. Topochemical polymerization of diiodopolyynes in ordered crystals will form polydiacetylenes made up only of carbon and iodine. Preliminary evidence supports formation of such polymers when cocrystals of diiodobutadiyne and bis(pyridyl) host molecules are subjected to high pressures (3 GPa). The electronic and optical properties of these unprecedented iodine-substituted polydiacetylenes will be examined, and their transformation into iodine-doped carbyne will be explored. In addition, methods will be developed for regioselective halogenation and hydrohalogenation of diynes to make halocumulenes and halobutenynes. Experiments will center on controlling the stoichiometry of addition and on understanding the influences of structure on the regiochemistry of reaction. Further studies will exploit the solution-phase reductive coupling of these halocumulenes and haloenynes to prepare otherwise inaccessible polymers, including polydiacetylenes, poly(ethynylacetylenes), and polyacenes. Larger unsaturated halocarbons, including longer diiodopolyynes and tetraiodocumulenes, will also be targeted, pushing the boundaries of known halocarbon chemistry.With this award, the Organic and Macromolecular Chemistry Program is supporting the research of Professor Nancy S. Goroff, of the Department of Chemistry at SUNY - Stony Brook. Professor Goroff is developing new methods for the preparation of molecules and polymers with unusual architectures and chemical composition. Because of their electronic and optical properties, these materials will have applications as semiconductors and as non-linear optical absorbers. Such organic materials will be lighter in weight, more easily modifiable, and less expensive than their inorganic counterparts. New synthetic methods are critical to the development of this important field. A major component of this proposal involves collaborative research, increasing communication across national and disciplinary boundaries. The graduate students and undergraduates supported by this grant will gain experience in modern organic synthesis, computational modeling, spectroscopy, and polymer characterization methods. They will learn how to communicate about science by working together and by presenting their results at professional meetings. The PI has demonstrated a strong commitment to integrating research and education, an effort that will continue with the proposed research.