A precursor route to 2,7-poly(9-fluorenone)

2,7-Poly(S-fluorenone) (PF) (1), a unique electron-deficient conjugated pol ymer, was prepared via a precursor route, using 2,7-poly(spiro[4',4'-diocty l-2',6'-dioxocyclohexane-1', 9-fluorene]) (10b) (POFK) as precursor polymer . Ketalization of 2,7-dibromo-9-fluorenone (6) with the diol 2,2-dioctyl-1, 3-propanediol (8b) afforded a dibrominated ketal derivative of fluorenone ( 9b) which after Ni(0)-induced coupling provided the well-processable, struc turally defined precursor polymer 10b with a polyphenylene backbone. Conver sion to PF (1) proceeded smoothly by treating a; POFK (10b) film with dichl oroacetic acid. The cyclic voltammogram of PF (1) exhibits a reversible red uction with a E-1/2(0) of -1.48 V vs Fc/Fc(+) which qualifies 1, together w ith its facile accessibility, e.g., as electron transport material in multi layer LED.