A new polymerisation route to conjugated polymers: regio- and stereoselective synthesis of linear and hyperbranched poly(arylene chlorovinylene)s by decarbonylative polyaddition of aroyl chlorides and alkynes

Abstract

We present here a new polymerisation route for the synthesis of new conjugated polymers. Decarbonylative polyadditions of diyne monomers [bis(4-ethynylphenyl)dimethylsilane, 4,4′-diethynylbiphenyl, and 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene] with respective terephthaloyl dichloride and benzene-1,3,5-tricarbonyl trichloride catalyzed by [Rh(cod)Cl]₂/PPh₃, [Rh(nbd)Cl]₂/PPh₃, [RhCp*Cl₂]₂/PPh₃, [Rh(cod)(PPh₃)₂]⁺PF₆⁻, or [Rh(cod)(PPh₂)(CH₂)₄(PPh₂)]⁺BF₄⁻ (cod = 1,5-cyclooctadiene, nbd = 2,5-norbornadiene, Cp* = pentamethyl cyclopentadienyl), proceed smoothly, producing linear and hyperbranched poly(arylene chloroZ-vinylene)s (PACVs) in regio- and stereoselective manners with high molecular weights (absolute M_w up to 5.31 × 10⁵) in high yields (up to 92%). Model reactions are designed to confirm the chemical structures of the PACVs. The resultant polymers are processable and enjoy high thermal stability. The linear PAVCs can undergo thermal curing at high temperatures and compared with their hyperbranched counterparts, they are more electronically conjugated due to the para-conjugation effect, as revealed by both experimental and theoretical studies. The light emissions of linear PAVCs with twisted tetraphenylethene units are enhanced by aggregate formation, demonstrating an unusual aggregation-enhanced emission characteristic.