Conjugated metallopolymers containing 2,2'-bithiazole

Abstract

Ruthenium and osmium conjugated metallopolymers containing a bithiophene-co-bithiazole backbone have been synthesized and their electrochemistry investigated. This relatively new class of materials has demonstrated enhanced rates of charge transport relative to redox metallopolymers in which a saturated organic network connects pendant metal complexes. Applications requiring fast electrochemistry, such as molecular switching and electrocatalysis, clearly can benefit from this enhancement. -- Electropolymerization from boron trifluoride dethyletherate (BF₃ OEt₂) permitted facile deposition of polymer films for electrochemical experiments. Impedance spectroscopy has been used to investigate electron transport rates in these metallopolymers. DcCM² was found to be over 20 times greater in poly-[Ru(5,5'-bis(2-thienyl)-2,2’-bithiazole)(bpy)₂³⁺/²⁺] than in poly-[Ru((6,6'-bibenzimidazole-2,2’-diyl)-2,5-pyridine)(bpy)₂³⁺/²⁺] as a result of better energy matching of the ruthenium t₂g orbital with the HOMO band in the poly[5,5'-bis(2-thienyl)-2,2'-bithiazole] backbone. A hole-type mechanism of superexchange is proposed for this system.