A Precursor Route to 2,7-Poly(9-fluorenone)

2,7-Poly(9-fluorenone) (PF) ( 1 ), a unique electron-deficient conjugated polymer, was prepared via a precursor route, using 2,7-poly(spiro[4‘,4‘-dioctyl-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, structurally defined precursor polymer 10b with a polyphenylene backbone. Conversion to PF ( 1 ) proceeded smoothly by treating a POFK ( 10b ) film with dichloroacetic acid. The cyclic voltammogram of PF ( 1 ) exhibits a reversible reduction with a E 1/2 0 of −1.48 V vs Fc/Fc + which qualifies 1, together with its facile accessibility, e.g., as electron transport material in multilayer LED.