Synthesis and Properties of Conjugated Poly(1,8-carbazole)s

During our search of novel conjugated carbazole polymers, we succeeded in the efficient synthesis of conjugated poly(1,8-carbazole) derivatives. The synthetic route to the 1,8-difunctionalized carbazole monomers and the polymerization methods under the Yamamoto, Sonogashira, and Hay conditions were established. The obtained poly(1,8-carbazole)s were comprehensively characterized by GPC, MALDI-TOF MS, 1H NMR, and IR spectroscopies, and it was found that the alkyne spacer is an important factor in obtaining the high molecular weight polymers. Thermal analysis revealed that the alkyne-linked poly(1,8-carbazole)s possess a higher thermal stability than the directly linked poly(1,8-carbazole). The energy diagrams of a series of polycarbazoles were carefully estimated from the electrochemical and optical measurements. The alkyne-linked carbazole polymers were potent blue-light-emitting polymers due to their narrow band gaps. Furthermore, the remarkable decreased aggregation behavior of the butadiynylene-linked poly(1,8-carbazole) was demonstrated.