One-Shot Deprotonative Metalation/Transmetalation/Polymerization of Halothiophenes Catalyzed by Nickel Complex for Polythiophene Synthesis

AbstractEffect of divalent metals was studied in the cross-coupling polymerization of thiophenes leading to head-to-tail-type poly-3-hexyl­thiophene. Deprotonation of the C–H bond at the 5-position of 2-halo-3-hexylthiophene by LDA followed by metal exchange was carried out in one pot and following addition of nickel catalyst underwent polymerization. One-shot reaction involving deprotonation/transmetalation/ cross coupling polymerization was also examined with manganese(II) chloride and nickel(II) catalyst.</jats:p

Synthesis and properties of polythiophene bearing an alkylsulfonic acid ester at the side chain

Introduction of an alkylsulfonic acid moiety into the side chain of polythiophene was carried out. Synthesis of 2,5-dihalothiophene bearing an alkylsulfonate group at the 3-position was performed. The reaction of 2-chloro-5-iodothiophene with a Grignard reagent to form organometallic monomer of the corresponding thiophene followed by nickel(II)-catalyzed cross-coupling polymerization lead to head-to-tail-type regioregular polythiophene. The ester group at the side chain was converted into alkali metal sulfonate by treatment with NaI or metal hydroxides (Li, Na, K). The obtained metal salts were successfully transformed to sulfonic acid by the treatment with ion exchange resin. The electric conductivity of the regioregular polythiophene bearing sulfonic acid was remarkably improved ca. 102 times from the corresponding metal salts. (106 times higher than sulfonate ester

Cross-Coupling Polymerization of Organosodium for Polythiophene Synthesis

Treatment of 2-chloro-3-hexylthiophene with sodium 2,2,6,6-tetramethylpiperidin-1-yl (TMPNa) in hexane resulted in deprotonation at the 5-position to afford the thiophene–sodium species, whose formation was confirmed by quenching with iodine, leading to 2-chloro-3-hexyl-5-iodothiophene in 85% yield. Addition of a nickel catalyst bearing an N-heterocyclic carbene (NHC) to the thus-formed thiophene–sodium species in cyclopentyl methyl ether induced a cross-coupling polymerization at −20 °C. After the reaction mixture was stirred for 24 h, poly­(3-hexylthiophen-2,5-diyl) was obtained in 56% yield. The average molecular weight Mn was revealed to be 9700, which was close to the theoretical molecular weight (M = 8500) on the basis of the monomer feed/catalyst loading ratio (2.0 mol %), and the molecular weight distribution was found to be 2.1

Orthogonal electric and ionic conductivities in the thin film of a thiophene–thiophene block copolymer

Orthogonal electric and ionic conductivities were measured in thiophene–thiophene block copolymer thin films with different side chain functionalities.</jats:p