Photochromisme des Spiropyranes. Étude de la Colorabilité et de la Photodégradation de Dérivés Non‐Azahétérocycliques

Gaude, Didier; Gautron, R.; Guglielmetti, R.

doi:10.1002/bscb.19911000404

Cited by 9 publications

(2 citation statements)

References 10 publications

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“…However, a mechanism through the SP intermediate cannot be excluded due to the reported photoactivity of spiropyrans. 33,34 The photochemistry carried out at pH = 4.9 ( Figure 10B) is similar to the one observed for chalcones derived from flavylium compounds, exhibiting as photoproducts the quinoidal bases in equilibrium with the respective styrylflavylium cations.…”

Section: ■ Experimental Sectionmentioning

confidence: 91%

Isomerization between 2-(2,4-Dihydroxystyryl)-1-benzopyrylium and 7-Hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium

2012

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2-Phenyl-1-benzopyrylium (flavylium) and 2-styryl-1-benzopyrylium (styrylflavylium) cations establish in aqueous solution a series of equilibria defining chemical reaction networks responsive to several stimuli (pH, light, redox potential). Control over the mole fraction distribution of species by applying the appropiate stimuli defines a horizontal approach to supramolecular chemistry, in agreement with the customary bottom-up approach toward complex systems. In this work, we designed an asymmetric styrylchalcone able to cyclize in two different ways, producing two isomeric styrylflavylium cations whose chemical reaction networks are thus interconnected. The chemical reaction networks of 2-(2,4-dihydroxystyryl)-1-benzopyrylium (AH(+)) and 7-hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium (AH(+)(iso)) comprise the usual species observed in flavylium-derived networks, in this case, the styryl derivatives of quinoidal bases, hemiketals, and chalcones. The thermodynamics and kinetics of the crossed networks were characterized by the use of UV-vis absorption and NMR spectroscopy as well as time-resolved pH jumps followed by stopped-flow. The two styrylflavylium cations are connected (isomerize) through two alternative intermediates, the asymmetric trans-styrylchalcone (Ct) and a spiropyran-type intermediate (SP). At pH = 1, AH(+) slowly evolves (k(obs) ≈ 10(-5) s(-1)) to a mixture containing 62% AH(+)(iso) through the Ct intermediate, while at pH = 5, the SP intermediate is involved. The observed rate constants for the conversion of the styrylflavylim cations into equilibrium mixtures containing essentially Ct follow a pH-dependent bell-shaped curve in both networks. While at pH = 1 in the dark, AH(+) evolves to an equilibrium mixture containing predominantly AH(+)(iso), irradiation at λ > 435 nm induces the opposite conversion.

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Section: ■ Experimental Sectionmentioning

confidence: 91%

Isomerization between 2-(2,4-Dihydroxystyryl)-1-benzopyrylium and 7-Hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium

2012

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“…Qualitative definitions of photo-colourability of this kind of molecule have been previously proposed (Samat et al 1975(Samat et al , 1991Appriou et al 1978;Gaude et al 1991;Gautron et al 1991;Eloy et al 1992), but not of thermo-colourability. The difficulties encountered in giving such definitions earlier derived mainly from the problem of the determination of epM.…”

Section: Thermo-colourability and Photo-colourabilitymentioning

confidence: 99%

A comprehensive kinetic, thermodynamic and photochemical study of some spiro-indoline-oxazines

Favaro

Malatesta²,

Mazzucato

et al. 1995

Proc. Indian Acad. Sci. (Chem. Sci.)

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The thermoreversible photochromic reaction of spiro-indolineoxazines to photo-merocyanines has been studied by stationary spectrophotometric techniques. Two methods are described for determining the molar absorption coefficient of the metastable photomerocyanine and the quantum yield of the colour-forming photoreaction. Kinetic parameters (reaction rate and activation energy) and thermodynamic quantities (equilibrium constant and enthalpy) of the thermal reaction have also been determined. Based on the results obtained, some general correlations between the structure of these molecules and their photochromic and thermochromic properties have been drawn.

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Etude Par Photolyse‐Eclair De La Photodegradation Sensibilisee De Spiro (Indoline‐Pyranes) Et De Spiro (Indoline‐Oxazines) Photochromiques

Eloy

Escaffre

Gautron

et al. 1992

Bulletin des Soc Chimique

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The photodegradation and the "colorability" of photochromic spiro (indoline-pyrans) and spiro (indoline-oxazines) have been made by repeated flashes in solution open to the air. The photosensitization proceeds by triplet-triplet energy transfert. For hight ratios photosensitizer/photochrome.(>>loo), the quenching by oxygen has no influence on the "colorability" which like that is optimized. The sensitized photodegradation is very important with a lifetime Vo about 3-5 flashes whereas for the spirooxazines unsensitized V, exceeds several thousands. This study enhances the hypothesis describing the photodegradation process of these molecules mainly via the triplet state.

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Photochromisme des Spiropyranes. Étude de la Colorabilité et de la Photodégradation de Dérivés Non‐Azahétérocycliques

Cited by 9 publications

References 10 publications

Isomerization between 2-(2,4-Dihydroxystyryl)-1-benzopyrylium and 7-Hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium

Isomerization between 2-(2,4-Dihydroxystyryl)-1-benzopyrylium and 7-Hydroxy-2-(4-hydroxystyryl)-1-benzopyrylium

A comprehensive kinetic, thermodynamic and photochemical study of some spiro-indoline-oxazines

Etude Par Photolyse‐Eclair De La Photodegradation Sensibilisee De Spiro (Indoline‐Pyranes) Et De Spiro (Indoline‐Oxazines) Photochromiques

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