Reactive polythiophenes with zincke salt structure: Synthesis, polymer reactions, and chemical properties

Abstract

Polythiophenes with reactive Zincke salt structure, such as PThThPy+DNP(Cl−)Th, were synthesized by the oxidation polymerization of 3′-(4-N-(2,4-dinitrophenyl)pyridinium chloride)-2,2′:5′,2″-terthiophene (ThThPy+DNP(Cl−)Th) with iron(III) chloride or copper(II) trifluoromethanesulfonate. The reaction of PThThPy+DNP(Cl−)Th 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 PThThPy+R(Cl−)Th. Similarly, model compounds, ThThPy+R(Cl−)Th (R = Hex and Ph), were also synthesized. In contrast to the photoluminescent ThThPyTh and PThThPyTh, the compounds PThThPy+DNP(Cl−)Th, PThThPy+R(Cl−)Th, and ThThPy+R(Cl−)Th showed no photoluminescence because their internal pyridinium rings acted as quenchers. Cyclic voltammetry measurements suggested that PThThPy+DNP(Cl−)Th received an electrochemical reduction of the pyridinium and 2,4-dinitrophenyl groups and oxidation of the polymer backbone. PThThPy+DNP(Cl−)Th was electrically conductive (ρ = 2.0 × 10−6 S cm−1) in the non-doped state. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012