Highly fluorescent copolymers Oxa-Bz and Thia-Bz consisting of alternating heterocyclic diazole derivative and alkoxy benzene were designed and regioselectively synthesized by the Suzuki-Miyaura reaction with a palladium catalyst. Density functional theory calculation of modeling the repetitive unit suggested the possibility of full conjugation along the polymer chain and the occurrence of intramolecular electron transfer in which the alkoxy benzene moiety was the electron donor and the diazole moiety was the electron acceptor. The extension of conjugation length from the corresponding monomers to the copolymer was confirmed by electrochemical analysis. The redox potentials of the resulting copolymers were significantly reduced in comparison with those of the monomers. The photophysical properties, including absorption and emission spectra, also showed that the energies of the frontier orbitals changed after the covalent bonding between the electron donor and acceptor groups. Moreover, the emission of these two copolymers showed solvent-dependence, whereby the emission band shifted to longer wavelengths in higher polarity solvents. The fluorescence quantum yields of Oxa-Bz reached 68% and that of Thia-Bz 71%. This strong fluorescence might be guaranteed by the rigidity of these copolymers.

No abstract

A novel alternating benzofuran–ethynylene copolymer is designed and synthesized through a series of palladium‐catalyzed reactions, and extremely strong fluorescence is observed. The electronic levels of frontier orbitals are estimated by electrochemical and photophysical measurements for copolymer and corresponding monomers. The extension of π‐electron conjugation is shown after polymerization reaction, in which the energy of highest occupied molecular orbital (HOMO) is increased and that of the lowest unoccupied molecular orbital (LUMO) is decreased, simultaneously. The fluorescence quantum yield of this copolymer is as high as 75%, and time‐resolved fluorescence measurement confirms this intrinsic property. A preliminary optoelectronic device is fabricated to test the potential application of this copolymer as an emitting layer. In comparison with other known dibenzofuran‐based materials, moderate performance is obtained. The incorporation of a benzofuran group combining acetylene moiety in a polymeric skeleton provides a novel choice of highly fluorescent materials.

No abstract