Stabilization of the merocyanine form of photochromic compounds in fluoro alcohols is due to a hydrogen bond

Suzuki, Takayuki; Lin, Fu-Tyan; Priyadashy, Satyam; Weber, Stephen G.

doi:10.1039/a806316h

Cited by 45 publications

(40 citation statements)

References 12 publications

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“…The proposed reasons are better solvation of T C and of the released CN − (Scheme ), as well as the possible formation of hydrogen cyanide. It is interesting to note that for the photoheterolysis of 9‐fluorenol, a related case, it has been suggested that protonation of the molecule occurs even in the ground state and that the driving force is separation of the two ions by one water molecule 26. Analogously, we propose that the photoheterolysis of DHN‐1 involves an assistance of ion separation by a water molecule.…”

Section: Resultssupporting

confidence: 52%

“…Fluoroalcohols are able to stabilise the zwitterionic merocyanine form of spiropyrans and spirooxazines by hydrogen bonding 26. The appearance of T C in polar media, with a maximum in the visible region at λ C =545 nm, might be suggestive of it being a zwitterion.…”

Section: Resultsmentioning

confidence: 99%

“…These fluoroalcohols are solvents that are known to stabilise ions 21–25. They are also able to stabilise the zwitterionic merocyanine form of spiropyrans and spirooxazines 26. On addition of water to DHN‐1 in TFE or HFP, the yield of the observed carbocation remains substantial, but its decay is strongly accelerated.…”

Section: Introductionmentioning

confidence: 99%

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1,1-Dicyano-2,2-diphenyl-1,2-dihydronaphthalene: Photochromism and Evidence for Photochemically Induced CCN Bond Cleavage

Görner¹,

Mrozek²,

Daub³

2002

Chem. Eur. J.

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The photoreactions of the 1,1‐dicyano‐2,2‐diphenyl‐1,2‐dihydronaphthalene (DHN‐1) have been studied by photochemical techniques under various conditions at room temperature. A transient species, TC, with a major maximum at 545 nm in the UV‐visible spectrum, detected in small yield in polar aprotic solvents and in large yield in trifluoroethanol (TFE) and hexafluoropropan‐2‐ol (HFP), is assigned as a carbocation (1‐cyano‐2,2‐diphenylnaphthalenium), which is generated photochemically by elimination of CN−. The decay of TC was found to be a first‐order process in HFP, in which the longest lifetime of 0.4 s was observed; in TFE, the carbocation decays on the ms timescale, while the shortest lifetime of 1 μs was found in ethanol. The yield of TC increases strongly upon addition of water to alcohols or acetonitrile, and remains substantial in the presence of large amounts of water (1–20 M). On addition of water to TFE or HFP, the lifetime of the carbocation becomes much shorter. This is supported by pulse‐induced charge formation due to the carbocation and release of CN−; the conductivity decay is related to the lifetime of the carbocation under selected conditions. In addition, a major irreversible and a minor thermally reversible photoprocess were spectroscopically observed in solvents of low as well as high polarity. The former photoproduct, absorbing below 300 nm, is tentatively ascribed to benzobicyclohexenes A produced by phenyl‐vinylmethane rearrangement. In the latter process, a longer‐lived benzoquinodimethane derivative B, having a maximum at 400–430 nm, is formed; this is related to ring opening and closure and represents a new example of photochromic ten‐electron electrocyclisation. The distinct differences between the photochromism of DHN and that of dihydroazulene (DHA) stem mainly from stereoelectronic effects. This study, however, has also revealed that photochemically induced bond heterolysis and photochemical/thermal electrocyclisation, representing two basic processes of photochromism, may occur in one molecular unit.

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Section: Resultssupporting

confidence: 52%

Section: Resultsmentioning

confidence: 99%

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1,1-Dicyano-2,2-diphenyl-1,2-dihydronaphthalene: Photochromism and Evidence for Photochemically Induced CCN Bond Cleavage

Görner¹,

Mrozek²,

Daub³

2002

Chem. Eur. J.

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“…Photochromic compounds that reversibly change their physical and chemical properties upon light irradiation [1] can be used to achieve this goal. Until now, a great number of photochromic molecular systems or devices have been proposed, involving various photochromic families such as spiropyrans [2], spirooxazines [3], azobenzenes [4], fulgides [5], and diarylethenes [6].…”

mentioning

confidence: 99%

Photomodulable Materials. Synthesis and Properties of Photochromic 3H-Naphtho[2,1-b]pyrans Linked to Thiophene Unitsvia an Acetylenic Junction

Frigoli¹,

Moustrou²,

Samat³

et al. 2000

HCA

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“…The MC form is occasionally further stabilized under certain conditions, such as hydrogen bonding, 8 combination with crown ether or cyclodextrin 9 and complexation with metal. 10,11 Recently, the stability of the MC form of spiropyran 6-carboxylates was reported to be affected markedly in aqueous binary solvents.…”

Section: Introductionmentioning

confidence: 99%

Facile Evaluation of Thermodynamic Parameters for Reverse Thermochromism of Indolinobenzospiropyran-6-carboxylates in Aqueous Binary Solvents

Keum¹,

Ma²,

Lim³

et al. 2012

Bulletin of the Korean Chemical Society

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The position of the thermodynamic equilibrium for reverse thermochromic spiropyran 6-carboxylates (SPCOOHs) was easily determined in aqueous binary mixtures, such as water-methanol, water-acetonitrile and water-dimethyl sulfoxide. The existence of more than one type of interconvertible species of the ring-opened form of SP-COOH in aqueous binary solvents enables us to evaluate the molar extinction coefficients of the ring-opened species of SP-COOH and to obtain the thermodynamic parameters.

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Stabilization of the merocyanine form of photochromic compounds in fluoro alcohols is due to a hydrogen bond

Cited by 45 publications

References 12 publications

1,1-Dicyano-2,2-diphenyl-1,2-dihydronaphthalene: Photochromism and Evidence for Photochemically Induced CCN Bond Cleavage

1,1-Dicyano-2,2-diphenyl-1,2-dihydronaphthalene: Photochromism and Evidence for Photochemically Induced CCN Bond Cleavage

Photomodulable Materials. Synthesis and Properties of Photochromic 3H-Naphtho[2,1-b]pyrans Linked to Thiophene Unitsvia an Acetylenic Junction

Facile Evaluation of Thermodynamic Parameters for Reverse Thermochromism of Indolinobenzospiropyran-6-carboxylates in Aqueous Binary Solvents

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