Synthesis and characterization of poly(9-ethynyl-9-hydroxyfluorene)

Transition metal-catalyzed polymerizations of 9-ethynyl-9-hydroxyfluorene (EHF) were investigated. EHF was easily polymerized by various transition metal catalysts to give in relatively high yields of polymer. The MoCl5-based catalysts exhibited high catalytic activities, whereas the WCl6-based catalysts showed low catalytic activities for the present polymerization. The highest polymer yield (85%) was obtained when the (NBD)PdCl2 catalyst was used. The polymer structure was identified by such various instrumental methods as NMR, IR, and UV–visible spectroscopies to have a conjugated backbone with the fluorene and hydroxy groups. Poly(EHF) was stable to air oxidation and was soluble in such organic solvents as benzene, chlorobenzene, chloroform, DMF, and DMSO. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors. The oxidation of poly(EHF) was started to occur at 0.42 V (vs Ag/AgNO3), where the vinylene unit of conjugated polymer backbone might be oxidized in the scan. And poly(EHF) also shows the irreversible reduction starting at −1.15 V.