Synthesis and Characterization of Monodisperse Oligo(phenyleneethynylene)s

An iterative convergent/divergent synthesis for hexyl- and isopentoxy-substituted, monodisperse oligo(phenyleneethynylene)s is reported. The strategy is based on the bromine−iodine selectivity of the Pd-catalyzed alkyne−aryl-coupling, the conversion of a bromine substituent into an iodine substituent via halogen metal exchange, and trimethylsilyl (TMS) as an acetylene protecting group. The synthesis is efficient and gave gram amounts of octamers. Further derivatization of the octamers to esters and carboxylic acids is described. The compounds are fully characterized by 1H and 13C NMR and UV/vis spectroscopy.