Pd/Halloysite as a Novel, Efficient and Reusable Heterogeneous Nanocatalyst for the Synthesis of p-Phenylenevinylene Oligomers

The potential applications of poly(p-phenylene vinylene) derivatives and its oligomers in organic electronics have attracted great interest in recent years. In this study, a novel palladium supported on halloysite heterogeneous catalyst (Pd/HNTs) was prepared, characterized and its catalytic activity for obtaining p-phenylenevinylene oligomers was investigated in the Heck coupling of styrene and 2,5-diiodo-1,4-dimethoxybenzene using conventional and environmentally benign solvents. Thus, in the presence of 0.75 mol% catalyst, the product was obtained in 76% yield using ethanol as solvent. To evaluate the versatility of the Pd/HNTs catalyst, the synthesis of a series of p-phenylenevinylene oligomers and divinylbenzene derivatives was performed obtaining yields between 58 and 93%. In addition, the catalyst could be recovered and reused for four reaction cycles without significant loss of its catalytic activity. Finally, the photophysical characterization of the synthesized molecules was performed.