Synthesis of New Poly(arylamine)s (Aryl = Oligo-p-phenyl or Pyridyl) by Organometallic Polycondensation and Chemical Properties of the Polymers

A series of poly(arylamine)s formulated as [−(Ar)_mNR−]_n (Ar = p-phenylene or pyridine-2,5-diyl; m = 2−4; R = H or alkyl) were prepared. Ni- or Pd-promoted dehalogenative polycondensation of the corresponding BOC- (tert-butoxycarbonyl-) substituted dibromo monomers afforded poly(oligo-p-phenylene-amine)s, [−(p-C₆H₄)_mN(BOC)−]_n (m = 2−4). Deprotection of the BOC group of the polymer at 200 °C gave [−(p-C₆H₄)_mNH−]_n (m = 2−4). The polymer behaved as an intermediate polymer between poly(aniline) PAn and poly(p-phenylene) PPP. For example, [−(p-C₆H₄)₂NH−]_n, P(DPA), showed two oxidation peaks at around 0.3 and 0.65 V vs Ag⁺/Ag with equal intensity in its CV (cyclic voltammetry) chart, similar to PAn; in contrast, the CV chart of [−(p-C₆H₄)₄NH-]_n exhibited a main oxidation peak at 0.60 V vs Ag⁺/Ag, similar to PPP. ESR data of iodine-doped polymers supported the formation of radical species in oxidation of the polymer. The polymers were photoluminescent and gave quantum yields of 12−46%. Polymers with the pyridine unit formed metal complexes with MX₂ (M = Cu, Ni, Co), and CD (circular dichroism) spectra of the metal complexes of the pyridine polymer having chiral side chains suggested formation of a helical structure by the metal complexation.