| Abstract
| - Two series of monodisperse cross-conjugated oligomers based on enyne repeat units have beenrealized. The first class of molecules, iso-polytriacetylenes (iso-PTAs, 2), was divergently synthesizedusing an iterative sequence of palladium-catalyzed cross-coupling reactions of vinyl triflate 5 withterminal alkynes. The second series of oligoenynes (17−20) are based on an octatetrayne backbone,and result from homocoupling of the differentially protected iso-PTA oligomers 8−11. The longestmember of this series, 20, spans ca. 5.6 nm from Si atom to Si atom and is composed of a contiguoussequence of 44 sp and sp2 carbons. The lowest energy electronic absorption band for iso-PTA dimersin the progression 13 → 9 → 16 is consistently red-shifted as a result of extending thecross-conjugated structure. A similar comparison within each series (i.e., 16, 6−7, or 17−20),however, suggests little effect on the electronic characteristics of these molecules as oligomer lengthis increased. The solid-state properties of one derivative, 17, are also described.
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