Synthesis and properties of fluorinated benzotriazole‐based donor‐acceptor‐type conjugated polymers via Pd‐catalyzed direct CH/CH coupling polymerization

Abstract

AbstractFluorine substituted benzotriazole (BTz) units have shown great potential in improving various conjugated polymers (CPs)‐based optoelectronic devices' performance. Thus, it is highly expected for the establishment of simple, efficient, and inexpensive accesses to such polymers. In this paper, Pd‐catalyzed direct CH/CH coupling polymerization is first employed for the synthesis of 5,6‐difluorobenzotriazole containing π‐CPs, which fully avoids prefunctionalization of monomers. Under the optimized conditions, a series of donor‐acceptor‐type π‐CPs with excellent regio‐regularity are facilely obtained via the direct CH/CH coupling reaction of 5,6‐difluoro‐2‐(2‐hexyldecyl)‐2H‐BTz with different thiophene analogs. The chemical structure of the as‐synthesized polymers are confirmed by NMR technique including 1H NMR, 19F NMR, and the edited heteronuclear singular quantum correlation and heteronuclear multiple bond correlation spectra as well as comparative study on the same polymers obtained via Stille coupling and direct (hetero)arylation polymerization. Further, their optical properties, electrochemical properties, and thermal stabilities are also carefully explored by UV–Vis absorption spectra, cyclic voltammograms as well as thermogravimetric analysis, respectively. On the basis of density functional theory (DFT) simulation, the effect of alkyl substituents attached to thiophene units on the reactivity and optical performance of the resultant polymers is explained. Our protocol exhibits remarkable advantages in synthetic simplicity, atom‐economy, high efficiency, and excellent regioselectivity of cross‐coupling, providing an alternative synthetic strategy for high‐performance optoelectronic materials.