Branched poly(p-phenylenevinylene): Synthesis, optical and electrochemical properties

A series of poly(p-phenylene vinylene) (PPV) derivatives with phenylene vinylene side chains (branched PFVs), PPV0, PPV1, PPV2, and PPV3, were synthesized by the Heck coupling reaction and characterized by TGA, absorption spectra, photoluminescence (PL) spectra, and electrochemical cyclic voltammetry. The branched PPVs showed two absorption peaks in the UV-vis region, corresponding to the conjugated side chains (UV absorption) and the main chains (the visible absorption). Especially the absorption spectrum of PPV3 covers a broad wavelength range from 300 to 500 nm. Introducing the electron-donating alkoxy substituents on the PPV main chains and increasing the content of the alkoxy groups lead to bathochromic shift of both absorption and PL spectra from PPV1 to PPV2 to PPV3. The onset oxidation potential of the branched PPVs is lower by 0.1-0.2 V than that of PPV, indicating that the electron-donating ability of the branched PPVs enhanced in comparison with that of PPV.