Novel multiredox π-conjugated perimidine polymers with ultra-low band gap

Abstract

Abstract The electropolymerization of prepared monomers 1 (mixture of perimidino[1',2':1,5]pyrrolo[3,4-m]phthaloperine-9,19-dione and 17H,19H-perimidino[1',2':1,2]pyrrolo[3,4-m]phthaloperine-17,19-dione) and 2 (benzo[lmn]diperimidino[2,1-b:2',1'-i][3,8]phenanthroline-10,21-dione and benzo[lmn]diperimidino[2,1-b:1',2'-j][3,8]phenanthroline-18,21-dione) resulted in the synthesis of electroactive conductive materials with structures similar to fused perinone dyes. Polymer p1 was obtained via the electropolymerization of monomer 1 with low yield and low stability, which was insufficient for further analysis. However, fundamental perinone polymer p2, containing a perimidinobenzophenanthroline skeleton, which was obtained by electropolymerization of 2, where its thickness and structure could be controlled in a one-step electrochemical process. This novel poly(perimidinobenzophenanthroline) polymer was electrically conductive and displayed a complex redox activity, mixed conductivity, and an ultra-low band gap of 0.14 eV. The regular D-A structure and specific intermolecular interactions also played a role in its characteristics. The mechanism of the electrooxidation process, which led to the formation of protonated, semi-ladder, and ladder bis-perimidine segments in polymers, was proposed using electrochemical analysis and quantum-chemical calculations.