p-benzoquinone diimines and thiophene based alternating copolymers: organometallic catalyzed syntheses and elementary characterization

A series of alternating polymers, which were prepared by coupling of N, N’-dichloro-benzoquinonediimine (a) or 2, 5-dimethyl-N, N’-dichloro-benzoquinonediimine (b) with Grignard reagents of thiophene, were successfully prepared using Ni(II) complexes as catalyst with moderate yields (54–88%) and molecular weights (4.3–7.0 × 10³). The basic properties of the obtained copolymers were characterized by FT-IR, ¹H NMR, UV-vis absorption, cyclic voltammetry, thermal analysis and Gel permeation chromatography (GPC). The maximum UV–vis absorption of these polymers appears in the range of 410–430 nm and 437–494 nm in DMF and CF₃COOH, respectively. XRD patterns of these polymers suggest the low crystallinty. After doped by iodine, conductivity of obtained polymers was improved five-eight orders of magnitude relative to their corresponding neutral precursors (the conductivity of them was <10⁻¹³ S/cm). The electrochemical activity of iodine-doped polymers was greatly improved as compared to un-doped ones. The reduction of pristine benzoquinone polymers was also studied in order to tune their properties conveniently.