The effect of 1,4-di-(4-pyridyl)benzene) for the nickel-mediated polyfluorene synthesis

The use of 1,4-(di-4-pyridyl)benzene L1 as a secondary ligand in the nickel(0)-mediated polycondensation of dihaloarenes such as 4,7-dibromofluorene leading to the corresponding polyfluorene. When the reaction was carried out with Ni0(cod)(dq) (COD: 1,5-cyclooctadiene, DQ: duroquinone)/dt-BPY (4,4'-di-tert-butyl-2,2'-bipyridyl) and a half amount of L1, significant enhancement of the polymerization of dihaloarene was observed to afford polyarylenes with high degree of polymerization (DP). The reaction of 4,7-dibromofluorene afforded polyfluorene of the molecular weight up to 37000 (DP = ca. 100). The improved performance in the polymerization of the fluorene monomer allowed the reaction to undergo the catalytic reaction with nickel in the presence of zinc powder as a reducing agent. Several poly(haloarene)s were obtained in the nickel-catalyzed reaction system in a similar manner.