In the present work a novel improved and convenient procedure for the synthesis of oxazoles has been developed. Acetamide, instead of ammonium acetate, was used to react with phenacyl benzoates in boiling xylene in the presence of BF3/Et2O as the catalyst. According to this new synthetic route, nine oxazole compounds were readily prepared as single products in reasonably high yields. On the basis of the experimental results, a plausible mechanism of this reaction is proposed. Copyright

A new series of p-n diblock conjugated copolymers consisting of alternate 1,4-bis- (oxadiazolyl)-2,5-dialkyloxybenzene and oligothiophenes with one to three thiophene rings (P1-P3) have been synthesized. The polymers have well-defined structures and exhibit good thermal stability with the onset decomposition temperatures in nitrogen at around 300℃. The glass transition temperature (Tg) of the polymers decreases with increasing the length of oligothiophene blocks. Both the absorption spectra and photoluminescence spectra shift to longer wavelength with increase in the length of oligothiophene blocks. The emissive color of the polymers could be tuned from blue to green to orange just by increasing the number of thiophene rings in the oilgothiophene blocks from one to three. No obvious change in reduction potential is found for the polymers with variation in the length of oligothiophene blocks. The reduction potential E1/2 of the polymers is measured by cyclic voltammetry to be around -1.7V vs SCE, comparable to those of poly(cyanoterephthalyidene) (CN-PPV) and other good electron-transporting materials. The oxidation potential of the polymers can be reduced remarkably by increasing the length of oligothiophene blocks. The oxidation potential E1/2 of P3 is measured to be 1.25V with the onset potential at 1.0V vs SCE. These values are comparable to those of some hole-injection favorable electroluminescent polymers. The results prove that the p-n diblock structure may be a promising molecular design for synthetically tuning the HOMO and LUMO of conjugated polymers.

The synthesis, by the Suzuki coupling reaction, of a novel soluble blue light emitting polymer, poly{(9,9-dihexyl-2,7-fluorene-alt-co-[2,5-bis(decyloxy)-1,4-phenylene]}(PDHFDDOP) is reported. PDHFDDOP exhibits photoluminescence (PL quantum efficiency of 40% in neat films) and electroluminescence (EL) with deep blue emission.

Deep blue photoluminescence and electroluminescence are demonstrated from a soluble conjugated polymer, poly (9,9-dihexylfluorene-alt-co-2,5-didecyloxy-para-phenylene). The PL quantum efficiency is approximately 40%. Cyclic voltammetry measurements indicate that the highest occupied molecular orbital and lowest unoccupied molecular orbital energies are 5.66 and 2.62 eV below vacuum, respectively. Single-layer and multilayer light-emitting diodes emit deep blue light (peak at; 420nm).

Poly[1,4-bis(4-alkyl-2-thienyl)-2,5-disubstituted phenylene]s and their monomers have been regioselectively synthesized in high yield. The head-to-head defined structures of all polymers and monomers are demonstrated by FT-IR, 1H, 13C NMR and elemental analysis. All new materials exhibit good thermally stability, optical, electrochemical properties. Their HOMO and LUMO energy levels are determined by cyclic voltammetry and UV-vis measurement. The improvement of absolute PL quantum yields of all six polymers in the solid films have been approved after the aromatic groups were introduced into the main chain of polythiophene. Three materials were chosen to be fabricated as single layer LED devices.