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A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo- and electrochemical control

Journal Article


Abstract


  • An electroactive nitrospiropyran-substituted polyterthiophene, poly(2-(3,3′′-dimethylindoline-6′-nitrobenzospiropyranyl) ethyl 4,4′′-didecyloxy-2,2′:5′,2′′- terthiophene-3′-acetate), has been synthesized for the first time. The spiropyran, incorporated into the polymer backbone by covalent attachment to the alkoxyterthiophene monomer units, leads to multiple colored states as a result of both photochemical and electrochemical isomerization of the spiropyran moiety to merocyanine forms as well as electrochemical oxidation of the polyterthiophene backbone and the merocyanine substituents. While electrochemical polymerization of the terthiophene monomer can take place without oxidation of the spiropyran, increasing the oxidation potential leads to complex electrochemistry that clearly involves this substituent. To understand this complex behavior, the first detailed electrochemical study of the oxidation of the precursor spiropyran, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6′- nitrobenzospiropyran, was undertaken, showing that, in solution, an irreversible electrochemical oxidation of the spiropyran occurs leading to reversible redox behavior of at least two merocyanine isomers. With these insights, an extensive electrochemical and spectroelectrochemical study of the nitrospiropyran- substituted polyterthiophene films reveals an initial irreversible electrochemical oxidative ring-opening of the spiropyran to oxidized merocyanine. Subsequent reduction and cyclic voltammetry of the resulting nitromerocyanine-substituted polyterthiophene film gives rise to the formation of both merocyanine π-dimers or oligomers and π-radical cation dimers, between polymer chains. Although merocyanine formation is not electrochemically reversible, the spiropyran can be photochemically regenerated, through irradiation with visible light. Subsequent electrochemical oxidation of the nitrospiropyran-substituted polymer reduces the efficiency of the spiropyran to merocyanine isomerization, providing electrochemical control over the polymer properties. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerized to the planar merocyanine moiety, affording a smoother polymer film. The conductivity of the freestanding polymer film was found to be 0.4 S cm-1.(Figure Presented) © 2011 American Chemical Society.

Publication Date


  • 2011

Citation


  • Wagner, K., Byrne, R., Zanoni, M., Gambhir, S., Dennany, L., Breukers, R., Higgins, M., Wagner, P., Diamond, D., Wallace, G. G. & Officer, D. L. (2011). A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo- and electrochemical control. Journal of the American Chemical Society, 133 (14), 5453-5462.

Scopus Eid


  • 2-s2.0-79953729646

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/3459

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 5453

End Page


  • 5462

Volume


  • 133

Issue


  • 14

Abstract


  • An electroactive nitrospiropyran-substituted polyterthiophene, poly(2-(3,3′′-dimethylindoline-6′-nitrobenzospiropyranyl) ethyl 4,4′′-didecyloxy-2,2′:5′,2′′- terthiophene-3′-acetate), has been synthesized for the first time. The spiropyran, incorporated into the polymer backbone by covalent attachment to the alkoxyterthiophene monomer units, leads to multiple colored states as a result of both photochemical and electrochemical isomerization of the spiropyran moiety to merocyanine forms as well as electrochemical oxidation of the polyterthiophene backbone and the merocyanine substituents. While electrochemical polymerization of the terthiophene monomer can take place without oxidation of the spiropyran, increasing the oxidation potential leads to complex electrochemistry that clearly involves this substituent. To understand this complex behavior, the first detailed electrochemical study of the oxidation of the precursor spiropyran, 1-(2-hydroxyethyl)-3,3-dimethylindoline-6′- nitrobenzospiropyran, was undertaken, showing that, in solution, an irreversible electrochemical oxidation of the spiropyran occurs leading to reversible redox behavior of at least two merocyanine isomers. With these insights, an extensive electrochemical and spectroelectrochemical study of the nitrospiropyran- substituted polyterthiophene films reveals an initial irreversible electrochemical oxidative ring-opening of the spiropyran to oxidized merocyanine. Subsequent reduction and cyclic voltammetry of the resulting nitromerocyanine-substituted polyterthiophene film gives rise to the formation of both merocyanine π-dimers or oligomers and π-radical cation dimers, between polymer chains. Although merocyanine formation is not electrochemically reversible, the spiropyran can be photochemically regenerated, through irradiation with visible light. Subsequent electrochemical oxidation of the nitrospiropyran-substituted polymer reduces the efficiency of the spiropyran to merocyanine isomerization, providing electrochemical control over the polymer properties. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerized to the planar merocyanine moiety, affording a smoother polymer film. The conductivity of the freestanding polymer film was found to be 0.4 S cm-1.(Figure Presented) © 2011 American Chemical Society.

Publication Date


  • 2011

Citation


  • Wagner, K., Byrne, R., Zanoni, M., Gambhir, S., Dennany, L., Breukers, R., Higgins, M., Wagner, P., Diamond, D., Wallace, G. G. & Officer, D. L. (2011). A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo- and electrochemical control. Journal of the American Chemical Society, 133 (14), 5453-5462.

Scopus Eid


  • 2-s2.0-79953729646

Ro Metadata Url


  • http://ro.uow.edu.au/scipapers/3459

Has Global Citation Frequency


Number Of Pages


  • 9

Start Page


  • 5453

End Page


  • 5462

Volume


  • 133

Issue


  • 14