The chemistry of aromatic compounds represents one of the oldest areas of organic chemistry. Dr. Hart's recent work has revealed a new facet of this field, the ability to design aromatic compounds that will form solid state complexes with special classes of compounds. This project is in the Organic and Macromolecular Chemistry Program. Two separate research areas will be investigated. Each is a continuation and extension of research currently supported by NSF CHE-8319578. The first area involves new synthetic uses of diarynes or their equivalents. A new, efficient method for constructing linear acenes (compounds with an odd or even number of linearly fused six-membered rings) and their oxygenated analogs will be developed. The method relies on cycloadditions to novel reactive intermediates, bis-isobenzofurans or their equivalents. Trapping of the intermediates, which represent new 14pi or 18pi electron aromatic systems, will be attempted. Diaryne equivalents will also be used to construct novel iptycenes, a class of compounds with rigid, three-dimensional carbon frameworks containing hydrophobic intramolecular cavities capable of binding small molecules. The second area involves new host designs for crystalline molecular complexes. Based on a design that features a fairly long, rigid molecular axis with rigid spacer groups at each end, N,N'-ditritylurea (DTU) was developed as an exceptionally effective host. X-ray structures of many DTU and DTU-related complexes will be determined, to define the geometric requirements of such hosts. Emphasis will be placed on developing chiral hosts, and on the separation of various structural and stereoisomers.
