p-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-Nsubstituted maleimide (DBrRMI) (R¼benzyl, phenyl, cyclohexyl, n-hexyl and n-dodecyl) were carried out using palladium or nickel catalysts. The number-average molecular weights of poly(RMI-alt-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-alt-Ph). Copolymers showed strong photoluminescence from yellow to light blue colors in tetrahydrofuran.

2,3‐Diaryl substituted maleimides as model compounds of conjugated maleimide polymers [poly(RMI‐alt‐Ar) and poly(RMI‐co‐Ar)] were synthesized from 2,3‐dibromo‐N‐substituted maleimide (DBrRMI) [R= cyclohexyl (DBrCHMI) and n‐hexyl (DBrHMI)] and aryl boronic acid using palladium catalysts. To clarify structures of conjugated polymer containing maleimide units at the main chain, 13C NMR spectra of 2‐aryl or 2,3‐diaryl substituted maleimides were compared with those of N‐substituted maleimide polymers. Copolymers obtained with DBrRMI via Suzuki‐Miyaura cross‐coupling polymerizations or Yamamoto coupling polymerizations were dehalogenated structures at the terminal end. This dehalogenation may contribute to the low polymerizability of DBrRMIs. On the other hand, the π‐conjugated compounds showed high solubility in common organic solvents. The N‐substituents of maleimide cannot significantly affect the photoluminescence spectra of 2,3‐diaryl substituted maleimides derivatives. The fluorescence spectra of poly(RMI‐alt‐Ar) and poly(RMI‐co‐Ar) varied with N‐substituents of the maleimide ring. When exposed to ultraviolet light of wavelength 352 nm, a series of 1,4‐phenylene‐ and/or 2,5‐thienylene‐based copolymers containing N‐substituted maleimide derivatives fluoresced in a yellow to blue color. It was found that photoluminescence emissions and electronic state of π‐conjugated maleimide derivatives were controlled by aryl‐ and N‐substituents, and maleimide sequences of copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Yamamoto coupling polymerizations of 2,3-dihalido-N-substituted maleimides (DXRMI) were carried out using nickel catalysts. In addition, coupling reactions of 2,3-dihalido-N-cyclohexylmaleimide (DXCHMI) were performed with nickel complexes in the presence of directly coupled chiral bisoxazolines (R′box) to give optically active poly(N-substituted maleimide-2,3-diyl)s [poly(RMI)s] (specific rotation [α]435 = +6.0 to −34.6°). Polymers with number-average molecular weights (Mn) ranging from 270 to 36200 were obtained in 17% to quantitative yields. Poly(N-cyclohexylmaleimide-2,3-diyl) [poly(CHMI)] formed with [Ni(cod)2]–R′box exhibited the largest absolute value, [α]435 = −34.6°.