Synthesis and light-emitting properties of carbazole-based copolymers bearing cyano-substituted arylenevinylene chromophore

Abstract

Two arylenevinylene compounds bearing the cyano group at α-position (6) and β-position (9) from the dialkoxylphenylene unit were synthesized, in which the molecular termini were functionalized with 3-bromocarbazole. The Suzuki coupling copolymerization of these compounds with 1,4-bis[(3′-bromocarbazole-9′-yl)methylene]-2,5-didecyloxybenzene and 9,9-dihexylfluorene-2,7-bis(boronic acid) was carried out to obtain copolymers (cp67 and cp97) containing the cyano-substituted arylenevinylene fluorophore of 7 mol %. Model compounds (6′ and 9′) corresponding to the arylenevinylene fluorophore were also prepared. The UV spectra of copolymers resembled that of homopolymer hp with no arylenevinylene segment in both CHCl3 solution and thin film. The emission maxima of copolymers in CHCl3 (394 nm) agreed with that of homopolymer indicating that the emission bands originated from the carbazole-fluorene-carbazole segment. The emission maximum wavelength of copolymer cp67 in thin film (477 nm) indicated fluorescence from the cyano-substituted arylenevinylene fluorophore because of the occurrence of fluorescence resonance electron transfer. In contrast, copolymer cp97 showed fluorescence at 528 nm to suggest the formation of a new emissive species such as a charge-transfer complex (exciplex). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 91–98, 2010