Photoreversible Photographic Systems. V. Reverse Photochromism of (Photospiran/Acid) System in Acetone

Dedicated to Professor AndreÂ M. Braun on the occasion of his 60th birthdayThe photoconversion of 2',3'-dihydro-6-nitro-1',3',3'-trimethylspiro[2H-1-benzopyran-2,2'-indole] (Sp) to its open merocyanine form (Mc) in a series of aerated cycloalkanes (cyclopentane, cyclohexane, and trans-and cis-decalin) and of the protonated merocyanine (McH ) to Sp in aqueous solution were studied by laser-induced optoacoustic spectroscopy (LIOAS). The (11 AE 2) ml mol À1 expansion determined for the ring closure is due to deprotonation of McH plus the reaction of the ejected proton with the monoanion of malonic acid (added to stabilize Mc), an intrinsic expansion and a small electrostriction term. The energy difference between Sp and initial McH is (282 AE 110) kJ mol À1 . An intrinsic contraction of À (47 AE 15) ml mol À1 occurs upon ring opening, forming triplet 3 Mc in the cycloalkanes, whereas no volume change was detected for the 3 Mc to Mc relaxation. Electrostriction decreases the 3 Mc energy, (165 AE 18) kJ mol À1 , to 135 kJ mol À1 . The difference in the values of the ring-opening (Sp to Mc) reaction enthalpy in cycloalkanes as derived from the temperature dependence of the Sp > Mc equilibrium, (29 AE 8) kJ mol À1 , and from the LIOAS data, À (9 AE 25) kJ mol À1 , is due to the formation of Mc-Sp aggregates during steady-state measurements. The Sp-sensitized singlet molecular oxygen, O 2 ( 1 D g ), quantum yield (average F D 0.58 AE 0.03) derived from the near-IR emission of O 2 ( 1 D g ), was taken as a measure of Mc production in the cycloalkanes. These solvents, albeit troublesome in their handling, provide an additional series for the determination of structural volume changes in nonaqueous media, besides the alkanes already used.Introduction. ± The knowledge of the structural volume changes in photochemical reactions [1] is not just of academic interest, but also represents a challenge regarding the possibility of creating materials displaying a reversible volume response towards light [2]. Our major interest in this area is the relationship between the structural volume changes and the type of photoreaction, in order to understand the origin of the molecular structural changes upon excitation of biological photoreceptors [3].A quantitative correlation was found between the reaction structural volume changes determined by laser-induced optoacoustic spectroscopy (LIOAS) [4] and the entropy changes of the reaction for intramolecular photoinduced electron-transfer reactions of Ru II bipyridyl cyano complexes as well as for photoinduced intermolecular electron-transfer reactions between Ru(bpy) 3 2 and the methyl viologen cation, in both cases in aqueous solution containing various monovalent salts. Based on the constancy of the reaction free energy, the changes were attributed to an entropy-enthalpy

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“…1. This spectrum is consistent with those reported in literature [19]. The yellowish solution with absorption maximum at ca.…”

supporting

confidence: 93%

“…It is possible to stabilize the merocyanine form of NO 2 -BIPS in H 2 O containing acid (e.g., malonic acid) [17 ± 19]. The quantum yield for the photoinduced ring closure of the protonated merocyanine form (McH 3 Sp, Scheme 2) has been reported to be 0.16 [19]. Thus, the protonated merocyanine form is also suited for studies in aqueous medium.…”

mentioning

confidence: 99%

Time-Resolved Thermodynamic Profile upon Photoexcitation of a Nitrospiropyran in Cycloalkanes and of the Corresponding Merocyanine in Aqueous Solutions

Williams

Klihm

Braslavsky

2001

HCA

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“…2 shows, a new form is produced by irradiation of the acidic solution. In similar investigations with spiropyran derivatives (12)(13)(14)(15)(16)(17)(18) a protonated open structure is suggested for the form existing under the experimental conditions applied. The structure of the C-form in Scheme 1 with the long conjugated T-electron system may account for the maximum absorption at A = 530 nm seen in Fig.…”

Section: Photochromism and Acid-base Equilibriamentioning

confidence: 98%

“…The reverse reaction proceeds thermally or photochemically (5-1 1). In the case of spiropyran derivatives it has been established (12)(13)(14)(15)(16)(17)(18) that the zwitterionic B-form can be protonated to the cationic C-form. The same is expected for spirooxazine compounds.…”

Section: Introductionmentioning

confidence: 99%

Light-induced change of the molecular charge in a spironaphthoxazine compound

Rys¹,

Weber²,

Wu³

1993

Can. J. Chem.

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En l'absence de lumikre UV, il s'ktablit un tquilibre acide-base entre la forme spiro et une forme protonee fermke. Par irradiation dans des conditions acides approprites, on peut transformer la forme spiro en une forme cationique ouverte par le biais de la forme merocyanine. I1 s'ttablit un Cquilibre acide-base entre les deux formes ouvertes. A l'exception de la forme protonte fermCe, on a confirme les structures par RMN. Faisant appel 2i la photolyse eclair, on a CtudiC la cinetique de la reaction thermique de fermeture de cycle des deux formes. I1 est dernontre que la reaction de fermeture de cycle se produit uniquement par le biais de la forrne merocyanine. Les valeurs de pK, dCterminees pour les deux equilibres, fournissent les valeurs de pH dans lesquelles le changement de charge moltculaire induit par la lumikre se produit.[Traduit par la redaction] Introduction Recently, the photochromic behaviour of indolinospirooxazine derivatives has been intensively investigated (1-6). This is mainly due to their rapid photoresponsive change of the molecular structure and the better photodurability as compared to the indolinospiropyran derivatives. The photochromism and the acid-base behaviour of indolinospiro compounds is summarized in Scheme 1.By UV irradiation the C-0 bond of the colourless spiroform A is cleaved and the coloured merocyanine form B is formed. The reverse reaction proceeds thermally or photochemically (5-1 1). In the case of spiropyran derivatives it has been established (12-18) that the zwitterionic B-form can be protonated to the cationic C-form. The same is expected for spirooxazine compounds.Due to the different electronic structures and molecular geometries of the A-, the B-, and the C-forms, their physical and chemical properties, such as colour, polarity, charge, and their acidity and basicity are also different. The possibilitv to switch between the various forms and thus the var-

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“…Photochromic spiropyran dyes are currently used in many commercial applications, such as ophthalmic lenses, sunglasses [4], optical memory, and photooptical switching devices [5], due to their reversible colored-decolored reaction under UV/visible light [6][7][8]. Spiropyran dyes consist of two heterocyclic moieties linked together by a sp3 spirocarbon atom.…”

Section: Introductionmentioning

confidence: 99%

Reversible Visualization for Synchrotron Radiation Using Photochromic Dye and Photostimulable Phosphor Composite Film

Kinashi

Jimbo

Okabe

et al. 2014

International Journal of Photoenergy

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Photoreversible Photographic Systems. V. Reverse Photochromism of (Photospiran/Acid) System in Acetone

Cited by 47 publications

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Time-Resolved Thermodynamic Profile upon Photoexcitation of a Nitrospiropyran in Cycloalkanes and of the Corresponding Merocyanine in Aqueous Solutions

Time-Resolved Thermodynamic Profile upon Photoexcitation of a Nitrospiropyran in Cycloalkanes and of the Corresponding Merocyanine in Aqueous Solutions

Light-induced change of the molecular charge in a spironaphthoxazine compound

Reversible Visualization for Synchrotron Radiation Using Photochromic Dye and Photostimulable Phosphor Composite Film

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