Poly(chromenochromenedione) (PCCD): a structural isomer of poly(benzodifurandione) (PBDF)

Abstract

Access to robust n-type conducting polymers remains a central challenge in advancing organic electronics. Recently, n-doped poly(benzodifurandione) (n-PBDF) has emerged as a solution-processable, air-stable, n-type conducting polymer, which exhibits exceptional properties in electronic, electrochemical, and mixed ionic-electronic devices. PBDF has a structural isomer, poly(chromenochromenedione) (PCCD), whose synthesis and properties have remained unexplored. Here, we report a synthetic strategy that enables the successful transformation of PBDF into its structural isomer, PCCD. The process proceeds via a two-step pathway: aqueous base induced ring opening of n-PBDF to yield a water soluble intermediate poly(phenylenediacetic acid) (PPDA), followed by acid mediated ring closure to form ladder type PCCD. The resulting polymer features fused coumarin units along its backbone, leading to an electronic structure and solid-state organization distinct from that of PBDF. A comparative study of these two isomeric polymers reveals pronounced differences in their structural, optoelectronic, and electrochemical characteristics.