Synthesis of branched copolymer based on dithienopyrrole and triphenylamine units by direct coupling method under aerobic conditions

Abstract

The hyperbranched conjugated copolymer based on dithienopyrrole (DTP) and triphenylamine (TPA) moieties was successfully synthesised with an average molecular weight of 6242 g/mol and a polydispersity index of 2.12 via an aerobic direct arylation cross-coupling polycondensation using DMF as the solvent at 165^oC and using the Pd(OAc)₂ and pivalic acid (PivOH) as a catalyst system in air. The obtained hyperbranched conjugated copolymer has been characterised by its chemical structure via Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR). The average molecular weight of the hyperbranched conjugated copolymer was estimated by the gel permeation chromatography method (GPC). The optical properties of the hyperbranched conjugated copolymer have been evaluated via ultraviolet-visible spectroscopy (UV-Vis) and fluorescence spectroscopy to identify the optical bandgap of the copolymers. In addition, the density functional theory (DFT) calculations were also applied to study the orbital energy levels, molecular structure of the hyperbranched conjugated copolymer, as well as the interaction between units in the copolymer.