W(CO)₆-Mediated desulfuroligomerization of bis-dithioacetals. New synthesis of substituted oligo(phenylene-vinylenes)

Treatment of bisdithioacetals of 1,4-diaroylbenzenes (4) with W(CO)₆ in refluxing chlorobenzene afforded the corresponding substituted oligophenylenevinylenes (OPVs) (5). Average molecular weights determined by GPC indicate that OPVs 5 have 5-13 repetitive substituted phenylenevinylene units with narrow polydispersities. Emission in the blue-green to green region was observed for these OPVs depending on the nature of the substituent. The electron-donating alkoxy substituent shifted the emission to the longer wavelength whereas the electron-withdrawing trifluoromethyl group caused a blue shift in the fluorescence spectra.