Polyaddition of 2,7-Diethynyl-9,9-dioctylfluorene Using Regio- and Stereoselective Alkyne Dimerization Catalysts

Abstract

Three geometrical isomers of poly(9,9-dioctyl-2,7-fluorene ethynylene vinylene) [poly(1)] having (E)-, (Z)-, and gem-vinylene units have been prepared in high regio- and stereoselectivities by polyaddition of 2,7-diethynyl-9,9-dioctylfluorene (1) catalyzed by three kinds of transition metal catalysts. Thus, a palladium catalyst (2), in situ generated from Pd(OAc)2, 1,3-dimesitylimidazolinium chloride (SIMes·HCl), and Cs2CO3, efficiently catalyzes the (E)-selective reaction, giving (E)-rich poly(1) in over 99% selectivity, whereas the reaction using a catalytic amount of RuCl2(CCHPh)(PPri3)2 (3) in the presence of N-methylpyrrolidine forms (Z)-rich poly(1) in over 92% selectivity. On the other hand, a rhodium catalyst [RhCl(PMe3)2]2 (4) forms poly(1) bearing gem-vinylene linkages in 94% selectivity. The regio- and stereochemical courses well preserve the catalyst nature of 2−4 observed in dimerization reactions of arylacetylenes as prototypes of the present polyaddition processes. All polymers exhibit emission property and high thermal stability.