Ambipolar, multichromic metallopolymers of poly(3,4-ethylenedioxythiophene)

In this study, two novel bipyridine-based Ru(II) complexes (E₁-Ru and E₂-Ru) which contain different number of 3,4-ethylenedioxythiophene (EDOT) groups were synthesized and subjected to electrochemical polymerization both in absence and presence comonomer (EDOT). The resultant metallopolymers were examined in terms of their electrochemical and electrochromic properties. Cyclic voltammetry and spectroelectrochemistry studies revealed the ambipolar and multichromic nature of all the polymers where the reversible redox activity in the cathodic region was found to be mainly due to ligand centered reduction of the complex (Ru^2+/1+ and Ru^1+/0) and metal centered oxidation (Ru^2+/3+) was found to be available along with redox activity of the conjugated backbone of the polymers in the anodic region. Contrary to pristine PEDOT all polymers displayed vibrantly multichromic behavior thanks to superimposed but independently functioning electrochromic/redox nature of the conjugated polymer backbone and the Ru complex. In general, increasing the number of polymerizable units in the monomer structure increased the quality of the films and brought color diversity to these metallopolymers. Copolymerization, on the other hand, not only contributed positively to the band gap and switching time but also widened the color pallet of these polymers which became even more remarkable upon changing the comonomer feed ratio.