Synthesis of novel phenylenevinylene linkers with electron-donating substituents by the Heck reaction

Phenylenevinylene Systems: The Oligomer Approach

“…Unfortunately, though the reaction conditions are usually simple and there are no specific structural limitations for the precursors, most of the literature reported for the synthesis of PPVs with this methodology produced polymers with very low molecular weights [23,24]. However, many advances in the development of catalytic systems have been employed to improve the degree of polymerization under this protocol [25][26][27][28]. Notably, the most important feature of this reaction is that it allows obtaining configurationally pure trans PPVs.…”

“…As an example of the development of the oligomer approach, in order to solve the problem of low molecular weights obtained in the polymerization of PPVs through the Heck reaction reported by many research groups around the world [22], recent investigations showed that the use of a catalytic system composed of triphenylphosphite and Pd(dba) 2 in the presence of ionic liquids, significantly increases the reaction yields during the synthesis of oPVs and shows the catalyst reusability throughout several cycles [25]. Thus, these reaction conditions were applied to synthesize several oPVs [26][27][28] and according to the results obtained regarding the reaction yields as well as the optoelectronic properties, a segmented PPV with a degree of polymerization close to 20 (twice superior the size obtained previously with conventional Heck conditions) was obtained [27]. The molecular weight obtained for this PPV following the oligomer approach methodology yielded polymer films of sufficient quality to fabricate OLEDs.…”