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

Ni(0)-complex promoted dehalogenation polymerization of 1,2-bis(4-bromophen yl)ethylene derivatives gave poly(p-biphenylene vinylene) type polymers, [- C6H2R21-CR2 = CR2-C6H2R21-)(n) (P(R-1,H) and P(H,R-2)], having substituents (R-1 = Me, Et, CHMe2, and n-C8H17, R-2 = 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 tetrahyd rofuran, and gave M-n of 2.4-5.3 x 10(3) in gel permeation chromatography a nalysis. The absorption peak of the polymers appeared at a longer wavelengt h than that of the corresponding monomers by about 30 nm due to the expansi on of the pi-conjugation system. The polymers were photoluminescent in solu tions and in their films, emitting blue or green light. P(R-1,H)s gave high er quantum yields (Phi = 0.35-0.51) than P(H,R-2)s in CHCl3. P(H,R-2)s show ed a large Stokes shift (9600-13,500 cm(-1)) in their photoluminescence. Si nglelayer 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. (C) 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1493-1504, 2000.