Poly p-Phenylene Vinylene Copolymers with Electron-Withdrawing Substituents

2 Poly(p-Phenylene Vinylene) Copolymers with Electron-Withdrawing Substituents 

EL 560 nm, Eg = 2.3 eV SCHEME 2.18 Band gap and emission tuning in cyano-substituted PPYs. 

Hanack and coworkers [161] reported related cyano-substituted naphthalene vinylene derivatives 126 and 127. Interestingly, replacing the phenylene unit in CN-PPV 113 with naphthalene in polymers 126 and 127 results in significant blue shift of the emission maxima from 710 to 595 nm (for 126a) and 500 nm (for 127). In addition, the efficiency, tested for double-layer device ITO/l/127/Mg Al(3 97), was rather low (3 el = 0.017%). 

5-dicyanophenylene unit has also been used by Jen and coworkers [164] in the synthesis of a series of polyfluorene (PF) PPV copolymers 129-131 through Suzuki-coupling 

SCHEME 2.19 Synthesis of dicyanophenylene vinylene copolymers by Wittig condensation. 

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