Reactive regioregular oligothiophenes and polythiophenes with Zincke salt structure: Synthesis, reactions, and chemical properties. Issue 4 (22nd November 2013) - Yamaguchi, Isao
ABSTRACT Polythiophenes with reactive Zincke salt structure, P4ThPy+DNP(Cl−)‐a and P5ThPy+DNP(Cl−)‐a, were synthesized by the oxidation polymerization of oligothiophenes, such as 3'‐(4‐N‐(2, 4‐dinitrophenyl)pyridinium chloride)−2, 2':5', 2'';5'', 2'''‐quarterthiophene (4ThPy+DNP(Cl−)) and 4''‐(4‐N‐(2, 4‐dinitrophenyl)pyridinium chloride)−2, 2';5', 2'';5'', 2''';5''', 2''''‐quinquethiophene (5ThPy+DNP(Cl−)), with iron(III) chloride. The reaction of P5ThPy+DNP(Cl−)‐a with R‐NH2 [R = n‐hexyl (Hex) and phenyl (Ph)] substituted the 2, 4‐dinitrophenyl group into the R group with the elimination of 2, 4‐dinitroaniline to yield P5ThPy+R(Cl−). Similarly, model compounds, 4ThPy+R(Cl−) and 5ThPy+R(Cl−) (R = Hex and Ph), were also synthesized. In contrast to the photoluminescent 4ThPy and 5ThPy, the compounds P4ThPy+DNP(Cl−)‐a, P5ThPy+DNP(Cl−)‐a, and P5ThPy+R(Cl−) showed no photoluminescence because their internal pyridinium rings acted as quenchers. Cyclic voltammetry measurements suggested that P4ThPy+DNP(Cl−)‐a, P5ThPy+DNP(Cl−)‐a, and P5ThPy+R(Cl−) received an electrochemical reduction of the pyridinium and 2, 4‐dinitrophenyl groups and oxidation of the polymer backbone. P4ThPy+DNP(Cl−)‐a and P5ThPy+DNP(Cl−)‐a were electrically conductive (ρ = 3.0 × 10−6 S cm−1 and 2.1 × 10−6 S cm−1, respectively) in the nondoped state. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 481–492