Poly(dibenzo[a,c]phenazine-2,7-diyl)s - Synthesis and characterisation of a new family of electron-accepting conjugated polymers

A new family of conjugated polymers containing dibenzo[a,c]phenazine moieties, and hence having moderately high electron affinities, has been synthesized. Syntheses were achieved using Yamamoto or Suzuki couplings with 2,7-dibromodibenzo[a,c]phenazine derivatives as monomers. Several of the polymers had significant molecular weights and were still soluble in tetrahydrofuran or chloroform. A series of model compounds were also synthesized to assist in characterizing the polymers. The UV-vis spectra of the various materials gave clear evidence of the existence of conjugation along the polymer backbones. Fluorescence measurements indicate that emission in the green to orange region, and possibly beyond, is sensitive to the 11- and 12-substituents on the dibenzophenazine moieties. Finally, cyclic voltammetry demonstrates the electron-accepting nature of these materials with electron affinities in the range 2.6-3.2 eV.