Synthesis, Metal Complex Formation, and Electronic Properties of a Novel Conjugate Polymer with a Tridentate 2,6-Bis(benzimidazol-2-yl)pyridine Ligand

This paper reports the synthesis and physical properties of a novel aromatic polymer which contains the tridentate 2,6-bis(benzimidazol-2-yl)pyridine moiety. It was found that the polymer exhibits different luminescence properties in solution and in the solid state because of the formation of polymer aggregates. Upon doping with iodine, the electrical conductivity of the polymer film was increased to 2.4 × 10-6 S/cm. The polymer was fabricated into a single-layer light-emitting device, and yellow light emission was observed under forward bias. Besides, it is able to form complexes with ruthenium, and the resulting polymer−metal complexes exhibit different solubilities and physical properties. The ruthenium complexes strongly enhance the absorption and photosensitivity beyond 500 nm due to the presence of the metal−ligand charge-transfer transitions. As a result, a large photocurrent response was observed when the polymer was irradiated with visible light. On the other hand, there was no electroluminescence in the metal-containing polymers because of the intrinsic nonemitting properties in ruthenium terpyridine complexes.