Pd/Cu-catalyzed sonogashira cross-coupling polycondensation: A promising approach for synthesizing conjugated polymers with useful applications

Sonogashira cross-coupling polycondensation has been one of the most useful tools for the construction of conjugated polymers with useful properties for multiple applications especially organic electronic/optical materials. Most of Sonogashira-based polymerization reactions are still carried out via traditional procedure based on a combination of palladium (Pd) and copper (Cu) co-catalyst in the presence of an amine as a solvent or co-solvent. Sonogashira polymerization was found to be compatible with a wide variety of monomers ranging from simple iodobenzene to more complex paracyclophanes, rylene diimides or porphyrins. In this review polymerization of various monomers such as BODIPY-dyes, thiophenes, paracyclophanes, rylene diimides, anthracenes, carbazoles, diketopyrrolopyrrole has been discussed along with the applications of the resulting polymers. Sonogashira cross-coupling polymerization for the synthesis of porous conjugated polymers (PCPs) and their applications has also been reviewed. This review provides a comprehensive overview of the developments in the synthesis and applications of linear conjugated as well as porous conjugated polymers that have been synthesized in the last two decades by employing Pd and Cu co-catalyzed Sonogashira cross-coupling reactions.