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Physicochemical study of spiropyran-terthiophene derivatives: photochemistry and thermodynamics
Zanoni, Michele; Coleman, Simon; Fraser, Kevin J.; Byrne, Robert; Wagner, Klaudia; Gambhir, Sanjeev; Officer, David; Wallace, Gordon; Diamond, Dermot
The photochemistry and thermodynamics of two terthiophene (TTh) derivatives bearing benzospiropyran (BSP) moieties, 1-(3,3’’-dimethylindoline-6’-nitrobenzospiropyranyl)-2-ethyl 4,4’’-didecyloxy-2,2’:5’,2’’-terthiophene-3’-acetate (BSP-2) and 1-(3,3’’-dimethylindoline-6’-nitrobenzospiropyranyl)-2-10 ethyl 4,4’’-didecyloxy-2,2’:5’,2’’-terthiophene-3’-carboxylate (BSP-3), differing only by a single methylene spacer unit, have been studied. The kinetics of photogeneration of the equivalent merocyanine (MC) isomers (MC-2 and MC-3, respectively), the isomerisation properties of MC-2 and MC-3, and the thermodynamic parameters have been studied in cetonitrile, and compared to the parent, non-TThfunctionalised, benzospiropyran derivative, BSP-1. Despite the close structural similarity of BSP-2 and 15 BSP-3, their physicochemical properties were found to differ significantly; examples include activation energies (Ea(MC-2) = 75.05 KJ mol-1, Ea(MC-3) = 100.39 kJ mol-1) and entropies of activation (S‡ MC-2 = - 43.38 J K-1 mol-1, S‡ MC-3 = 37.78 J K-1 mol-1) for the thermal relaxation from MC to BSP, with the MC-3 value much closer to the unmodified MC-1 value (46.48 J K -1 mol-1) for this latter quantity. The thermal relaxation kinetics and solvatochromic behaviour of the derivatives in a range of solvents of 20 differing polarity (ethanol, dichloromethane, acetone, toluene and diethyl ether) are also presented. Differences in the estimated values of these thermodynamic and kinetic parameters are discussed with reference to the molecular structure of the derivatives.
Keyword(s): Analytical chemistry; Photochemistry; Spectrum analysis; Organic chemistry; Chemistry
Publication Date:
Type: Other
Peer-Reviewed: Unknown
Language(s): English
Institution: Dublin City University
Citation(s): Zanoni, Michele, Coleman, Simon, Fraser, Kevin J. ORCID: 0000-0002-9718-5405 <>, Byrne, Robert, Wagner, Klaudia, Gambhir, Sanjeev, Officer, David, Wallace, Gordon and Diamond, Dermot ORCID: 0000-0003-2944-4839 <> (2012) Physicochemical study of spiropyran-terthiophene derivatives: photochemistry and thermodynamics. Physical Chemistry Chemical Physics, 14 . pp. 9112-9120. ISSN 1463-9076
Publisher(s): Royal Society of Chemistry
File Format(s): application/pdf
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First Indexed: 2013-05-12 05:29:41 Last Updated: 2019-02-09 06:43:28