We report an externally initiated, Pd-catalyzed chain-growth polycondensation using Buchwald-type precatalysts for the synthesis of acetylene-end-functionalized poly(bithiophene-naphthalene diimide), P(TNDIT), conjugated polymers. Screening of six commercial precatalysts identified (t-BuXPhos)Pd (precatalyst 1), having in the structure phosphine ligands bearing two tert-butyl and one biphenyl ligand, as enabling efficient polymerization under mild conditions with moderate molecular weight control. The method supports the transfer of synthetically versatile, complex end-groups directly in the initiating step, an approach rarely achieved in catalyst-transfer polycondensation and unprecedented for donor–acceptor monomers such as TNDIT. NMR and MALDI-TOF end-group analysis, aided by fractionation, confirm that functionalization occurs during initiation and supports a chain-growth mechanism facilitated by Pd ring-walking. By varying initiator loading and timing, either mono- or bis-functionalized polymers can be selectively accessed. This strategy enables the high-yield synthesis of functionalized n-type conjugated polymers with tailored end-groups, offering new opportunities for postpolymer modification, block copolymer construction, cross-linking, and supramolecular assembly.
Zhang et al. (Thu,) studied this question.