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

Wagner, Klaudia and Byrne, Robert and Zanoni, Michele and Gambhir, Sanjeev and Dennany, Lynn and Breukers, Robert and Higgins, Michael and Wagner, Pawel and Diamond, Dermot and Wallace, Gordon and Officer, David (2011) A multiswitchable poly(terthiophene) bearing a spiropyran functionality: understanding photo and electrochemical control. Journal of the American Chemical Society, 133 (14). pp. 5453-5462. ISSN 1520-5126

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Abstract

An electroactive nitrospiropyran-substituted polyterthiophene, 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 coloured states as a result of both 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 could occurs without the apparent oxidation of the spiropyran, the subsequent electrochemistry is complex and clearly involves this substituent. In order to understand this complex behaviour, 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 behaviour 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, at least in part, through irradiation with visible light. SEM and AFM images support the conclusion that the bulky spiropyran substituent is electrochemically isomerizes 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.

Item Type:Article (Published)
Refereed:Yes
Subjects:Physical Sciences > Analytical chemistry
Physical Sciences > Photochemistry
Physical Sciences > Electrochemistry
Physical Sciences > Organic chemistry
Physical Sciences > Chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Research Initiatives and Centres > CLARITY: The Centre for Sensor Web Technologies
Research Initiatives and Centres > National Centre for Sensor Research (NCSR)
Publisher:American Chemical Society
Official URL:http:/dx.doi.org/10.1021/ja1114634
Copyright Information:© 2011 ACS
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 3.0 License. View License
ID Code:17895
Deposited On:28 Mar 2013 14:26 by Mr. Michele Zanoni. Last Modified 03 Mar 2017 10:59

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