Introduction of methyl groups on vinylene segments of phenylene vinylene systems: synthesis and properties.
A facile synthetic route towards phenylene vinylene systems with methyl substituents at the vinyl linkages is demonstrated through palladium catalyzed Heck coupling of 1,4-diisopropenylbenzene with aryl bromides. The coupling leads to a series of model compounds that feature, in some cases, direct access to a trans-configuration at the double bonds. The oxidative stability of these systems is surprisingly unaffected by the presence of allylic C-H bonds in the methyl substituents. The methyl substituents modulate the electronic properties of the phenylene vinylene systems by inducing a significant twist to the conjugated backbone. The study suggests that the introduction of methyl groups at vinylene sites is a viable alternative to functionalising and tuning the properties of phenylene vinylene systems.
Chan
Khai Leok
KL
Institute of Materials Research and Engineering (IMRE), and the Agency for Science, Technology and Research (A*STAR), 3 Research Link Singapore 117602, Republic of Singapore.
Sellinger
Alan
A