Synthesis and electrochromic properties of polyamines containing a 4,4′-diaminotriphenylamine-N,N′-diyl unit in the polymer backbone: Ru-catalyzed N–H insertion polycondensation of 1,4-phenylenebis(diazoacetate) with 4,4′-diaminotriphenylamine derivatives

Abstract

A new type of polyamine containing a 4,4′-diaminotriphenylamine-N,N′-diyl unit in the main chain was prepared by Ru-catalyzed polycondensation of a bis(diazocarbonyl) compound with 4,4′-diaminotriphenylamine, where the propagation is N–H insertion of a carbene–carbon atom generated from the diazocarbonyl group of the former monomer with N₂ elimination. In the well-defined polyamines newly prepared in this study, the two primary amino groups in the diamine monomer remain as secondary amino groups in the polymer main chain, in contrast to the previously reported polymers prepared by polycondensation of the same diamine monomers, where the amino groups were incorporated into an amide or imide linkage. The resulting triphenyl amino framework in the polymer main chain possesses three amino groups, each of which can independently participate in the electrochemical process as a redox center with applied electrochemical potentials. The electrochromic properties of thin films and electrochromic devices of the polyamines were evaluated with cyclic voltammetry and spectroelectrochemistry, revealing that the polyamines indeed underwent an expected three-stage redox process.