Facile preparation of palladium catalyst supported on silica nanoparticles through CS2 plasma pretreatment: Application to the Heck reaction for vinyl monomers and π-conjugated polymer synthesis

Abstract The preparation of a recyclable palladium complex supported on coated silica nanoparticles (SiNP) and its effectiveness as a catalyst in the Heck reaction is described. Functionalized silica-based NP were synthesized in three steps. First, commercial SiNP were subjected to a CS 2 cold plasma. Thus, a thin coating film was formed, along with the creation of a thiol functional surface. Subsequently, a thiol-ene reaction with 2-vinylpyridine induced by AIBN produced ( Py)-CH 2 -CH 2 S covalently bonded to the SiNP, which after PdCl 2 (CH 3 CN) 2 , ligand exchange afforded the corresponding palladium complex catalyst ( Pd-SiNP ). Functionalized Pd-SiNP were characterized by SEM, ICP, and XPS spectroscopy. The SiNP were straightforwardly converted to an effective palladium catalyst applicable in a number of Heck cross-coupling reactions with iodobenzene (IBz) and a variety of vinyls. Indeed, such heterogeneous catalyst probed to be recyclable (up to 9 times). Nevertheless, leaching of metal was evidenced by TEM, HRTEM, XRD, and XPS. Furthermore, due to the outstanding results, we extended the use of the new heterogeneous catalyst to achieve the synthesis of a soluble phenylenevinylene type (PPV) copolymer from 1,4-bis(dodecyloxy)-2,5-diiodobenzene and p -divinylbenzene (DVB).