PHOTOCHROMISM IN SPIROPYRANS. PART V.<sup>1</sup> ON THE MECHANISM OF PHOTOTRANSFORMATION

Heiligman-Rim, Rahel; Hirshberg, Yehuda; Fischer, Ernst Otto

doi:10.1021/j100818a036

Cited by 105 publications

(55 citation statements)

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“…Upon further cooling to -196"C, the absorption spectrum of the colored form of 3 does not show any change. This is in contrast to 4 and many spiropyrans which show three distinct colored modification absorptions at low temperature (1,9).…”

Section: The Position Of Low-lying Electronic Excited Statesmentioning

confidence: 86%

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

Chu¹

1983

Can. J. Chem.

202

100

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NOR1 Y. C. CHU. Can. J. Chem. 61, 300 (1983). A solution of spiroindolinonaphthoxazine in a common organic solvent shows profound photochromic effect. The colorless form in ethanol displays three absorption bands (-320, 235, 203 nm) in the ultraviolet region of the spectrum. The absorption spectrum of the colored metastable form shows two prominent absorption peaks at 612 and 578 nm. The triplet state energy level of the colorless form is estimated to be in the range from 2.4 X lo4 to 2.1 x 10' cm-' by the triplet-triplet energytransfer method. There exists a thermal equilibrium between the colorless and colored forms. From the measurement of absorbance of the colored form at different temperatures, the standard enthalpy of equilibrium is obtained (AH" = 1500 cm-I). The thermal decay of the colored form to the colorless form depends strongly on temperature. The decay rate increases three times for every 10°C increase in temperature. From these temperature dependence studies of the thermal decay rate, the thermal energy barrier for the colored metastable state to decay to the colorless form is determined to be 6.9 x 10' cm-I.NORI Y. C. CHU. Can. J. Chem. 61, 300 (1983). La spiroindolinonaphthoxazine en solution dans un solvant organique ordinaire montre un effet photochimique marqui. La forme incolore dans l'ithanol prtsente trois bandes d'absorption (-320, 235, 203 nm) dans l'ultraviolet. Le spectre d'absorption de la forme metastable colorie montre deux pics de forte intensiti a 612 et 578 nm. On Cvalue que le niveau d'tnergie de l'itat triplet de la forme incolore est de l'ordre de 2,4 X 10' a 2,l X lo4 cm-' selon la mtthode de transfert d'tnergie triplet-triplet. I1 existe un Cquilibre thermique entre les formes incolore et colorCe. A partir des mesures d'absorptirn de la forme colorCe a diffirentes tempiratures, on obtient I'enthalpie standard d'iquilibre (AH0 = 1500 cm-I). I I disintegration thermique de la forme colorie en la forme incolore dipend fortement de la tempirature. La vitesse de disintegration augmente par un facteur de 3 pour chaque augmentation de tempirature de 10°C. A partir des etudes de l'influence de la temptrature sur la vitesse de disintegration thermique, on a ditermini la barriere d'inergie thermique de la disintegration de la forme mitastable colorie en la forme incolore. Cette barrikre est de 6,9 X lo3 cm-I.[Traduit par le journal]

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Section: The Position Of Low-lying Electronic Excited Statesmentioning

confidence: 86%

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

Chu¹

1983

Can. J. Chem.

202

100

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“…This primary cisoid isomer was labelled X (ref. 25). Ground and excited singlet and triplet states of X have been implicated in the photocoloration of 6-nitro-BIPS (ref.…”

Section: Primary Photochemical Reaction Steps In Color Formationmentioning

confidence: 99%

The primary photochemical reaction step of unsubstituted indolino-spiropyrans

Érnsting¹,

Dick²,

Arthen-Engeland³

1990

Pure and Applied Chemistry

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-The photochemical ring opening reaction of unsubstituted indolino-spiropyrans in n-pentane, to the corresponding merocyanines, has been followed by transient absorption spectroscopy. The temporal resolution was better than 0.4 ps. During the pump pulse, an ultrafast unstructured absorption covers the entire measurement range 380-680 nm. From it emerges the structured absorption spectrum of a first merocyanine isomer, with typical time constants in the range 0.9 -1.4 ps. The transient merocyanine spectra are compared to the spectra which are obtained when the spiropyrans are irradiated at low temperature in an argon matrix. In conjunction with semiempirical calculations, the first merocyanine isomer is assigned a trans-trans-cis structure.

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“…The output was amplified [ 18 ] in modified capillary prismatic dye cells using the first discharge channel of a XeCl* excimer laser with two channels (Lambda Physik EMG 150). A prism (de-)compressor [ 19 ] was used prior to amplification in order to compensate for the effects of group-velocity dispersion. Amplification proceeded along two branches.…”

Section: The Laser Systemmentioning

confidence: 99%

Transient optical absorption spectroscopy of the photochemical spiropyran-merocyanine conversion

Érnsting

1989

Chemical Physics Letters

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The photochemical ring-opening reaction of 1',3',3'-trimethylspir~[2H-l-benzopyran-2,2'-indoline] has been followed by transient absorption spectroscopy, covering the range 370-650 nm with a temporal resolution of 0.42 ps. During the pump pulse, induced transient absorption is observed only at wavelengths shorter than 500 nm, with a maximum near 440 nm. The absorption at 440 nm decays within K 5 ps, while a broad absorption band appears at 550 nm in the region characteristic of merocyanine absorption. The risetime of the absorption at 550 nm is approximately 1.3 ps. The reaction is described as a barrierless photoisomerisation on the excited singlet potential energy surface towards a-nonplanar cisoid form, followed by internal conversion and

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PHOTOCHROMISM IN SPIROPYRANS. PART V.¹ ON THE MECHANISM OF PHOTOTRANSFORMATION

Cited by 105 publications

References 0 publications

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

The primary photochemical reaction step of unsubstituted indolino-spiropyrans

Transient optical absorption spectroscopy of the photochemical spiropyran-merocyanine conversion

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PHOTOCHROMISM IN SPIROPYRANS. PART V.1 ON THE MECHANISM OF PHOTOTRANSFORMATION

Cited by 105 publications

References 0 publications

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

Photochromism of spiroindolinonaphthoxazine. I. Photophysical properties

The primary photochemical reaction step of unsubstituted indolino-spiropyrans

Transient optical absorption spectroscopy of the photochemical spiropyran-merocyanine conversion

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Product

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PHOTOCHROMISM IN SPIROPYRANS. PART V.¹ ON THE MECHANISM OF PHOTOTRANSFORMATION