Novel 1,4-diketo-3,6-diphenyl pyrrolo[3,4-c]pyrrole (DPP)-based copolymers with large Stokes shift

Two novel alternating π-conjugated copolymers, named PDPPDOPV and PDPPDOPE, constituted of 1,4-diketo-3,6-diphenyl pyrrolo[3,4-c]pyrrole (DPP) with 2,5-dioctyloxy-1,4-phenylenevinylene (DOPV) or 2,5-dioctyloxy-1,4-phenyleneethynylene (DOPE), respectively, were synthesized and characterized by UV-vis, FT-IR, and photoluminescence spectroscopy. They are dark red solid readily soluble in various common organic solvents including THF and chloroform. The UV-vis absorption spectra of the polymers show strong absorption bands, which correspond to the π-π* transition of π-conjugated segments. Photoluminescence (PL) spectra show that both polymer films and solution have large Stokes shifts. From their fluorescence behavior, Stokes shifts of 173 nm and 199 nm are derived for the films of PDPPDOPV and PDPPDOPE, respectively, which are the largest two values ever reported for DPP-containing polymers.