Preparation of poly(biphenylene vinylene) type polymers by Ni-promoted polycondensation and their basic optical properties

Abstract

Ni(0)-complex promoted dehalogenation polymerization of 1,2-bis(4-bromophenyl)ethylene derivatives gave poly(p-biphenylene vinylene) type polymers, [—C6H2R—CR2 = CR2—C6H2R—)n (P(R1,H) and P(H,R2)], having substituents (R1 = Me, Et, CHMe2, and n-C8H17, R2 = Me, Et, n-C6H13, n-C11H23, and Ph) at the benzene ring or vinylene group in 90–99% yields. The polymers were soluble in organic solvents such as CHCl3, dimethylformamide, and tetrahydrofuran, and gave Mn of 2.4–5.3 × 103 in gel permeation chromatography analysis. The absorption peak of the polymers appeared at a longer wavelength than that of the corresponding monomers by about 30 nm due to the expansion of the π-conjugation system. The polymers were photoluminescent in solutions and in their films, emitting blue or green light. P(R1,H)s gave higher quantum yields (Φ = 0.35–0.51) than P(H,R2)s in CHCl3. P(H,R2)s showed a large Stokes shift (9600–13,500 cm−1) in their photoluminescence. Single-layer and multilayer light emitting diodes using vacuum deposited thin film of P(H,Ph) were prepared. Polymers with long alkyl substituents formed an ordered structure in the solid state as judged from their XRD patterns. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1493–1504, 2000