Electrochemical polymerisation of n-arylated and n-alkylated EDOT-substituted pyrrolo[3,4-c]pyrrole-1,4-dione (dpp) derivatives: influence of substitution pattern on optical and electronic properties

New pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) derivatives carrying 3,4-ethylenedioxy-thiophenylphenyl (EDOT-phenyl) substituent groups in the 3- and 6-position, or in the 2- and 5-position of the DPP chromophore were synthesised and electrochemically polymerised. The properties of the polymers were investigated using cyclic voltammetry and UV/Vis absorption spectroscopy. It was found that the optical and electronic properties differ greatly between the two polymers. Materials with EDOT-phenyl groups in the 3- and 6-positions represent conjugated polymers with a low oxidation potential and reversible electrochromic properties, whereas the polymer with EDOT-phenyl groups in the 2- and 5-positions is non-conjugated and possesses a high oxidation potential and irreversible redox behaviour.