Synthesis and properties of N-substituted maleimides conjugated with 1,4-phenylene or 2,5-thienylene polymers

pi-Conjugated polymers are particularly interesting in the field of electro-optic materials because of their desirable properties such as electrical conductivity, nonlinear optics and electroluminescence. Coupling polymerizations of 2,3-dibromo-N-substituted maleimide (DBrRMI) (R=benzyl, phenyl, cyclohexyl, n-hexyl and n-dodecyl) were carried out using palladium or nickel catalysts. The number-average molecular weights of poly(RMI-a/t-Ph) obtained by Suzuki-Miyaura cross-coupling polymerizations of DBrRMI with benzene-1,4-boronic acid or 2,5-thiophene diboronic acid were 680-1270 by gel permeation chromatographic analyses. By contrast, Yamamoto coupling polymerizations of DBrRMI with diiodobenzene gave random poly(RMI-co-Ph) results. Poly(RMI-co-Ph)s exhibited a higher thermal stability than monomer and poly(RMI-a/t-Ph). Copolymers showed strong photoluminescence from yellow to light blue colors in tetrahydrofuran. Polymer Journal (2010) 42, 290-297; doi:10.1038/pj.2009.341; published online 27 January 2010