Laser photolysis study of the photoisomerization of retinals

Veyret, B.; Davis, Stephen G.; Yoshida, Massayoshi; Weiss, Karl

doi:10.1021/ja00479a004

Cited by 41 publications

(27 citation statements)

References 12 publications

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“…Although, we have not measured the triplet-triplet absorption spectrum of 11-cis-retinal it is reasonable to assume that it is very similar to those in Fig. 1 as it has been shown in other non-polar solvents (Azerad et al, 1976;Veyret et al, 1978). This leads us thus to conclude, that we observe different triplet Raman spectra upon sensitized excitation of 11-cis-, 13-cis-and all-trans-retinal, and that the resonance Raman spectrum from 9 4 sretinal in its relaxed triplet is very similar to that of the all-trans-isomer.…”

Section: Resonance Raman Spectrasupporting

confidence: 59%

“…Although the lowest electronically excited triplet state of retinal has not directly been invoked in the mechanism of vision, its photophysical properties have been the subject of a number of studies. Direct (Rosenfeld et al, 1974;Waddell et al, 1976Waddell et al, , 1977Waddell et al, , 1981Veyret et al, 1978;Denny and Liu, 1977) and sensitized (Rosenfeld et at., 1974(Rosenfeld et at., , 1977Waddeli et al, 1976) photoisomerization have been studied and primary photoproducts and relative quantum yields have been determined. Triplet-triplet absorption spectra, intersystem crossing efficiencies and formation and decay rates have been investigated for different isomers in polar and nonpolar solvents (Dawson and Abrahamson, 1962;Bensasson et al, 1973Bensasson et al, , 1978Rosenfeld et al, 1974;Azerad et al, 1976;Harriman and Liu, 1977;Veyret et al, 1978;Das and Becker, 1979;Grodowski et al, 1979;Wilbrandt and Jensen, 1981;Das and Hug, 1982).…”

Section: Introductionmentioning

confidence: 99%

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RESONANCE RAMAN and ABSORPTION SPECTRA OF ISOMERIC RETINALS IN THEIR LOWEST EXCITED TRIPLET STATES

Wilbrandt

Jensen

Houée-Levin⊥

1985

Photochem & Photobiology

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Abstract— The triplet‐triplet absorption spectra of 9‐cis‐, 13‐cis‐ and all‐fraw‐retinal as well as the time‐resolved resonance Raman spectra of the lowest electronically excited triplet states of 9‐cis‐, 11‐cis, 13‐ciy and all‐trans‐retinal in aromatic solvents at room temperature have been obtained under conditions ensuring the isomeric purity of the starting materials. The triplet states were produced by triplet energy transfer from a sensitizer in pulse‐radiolysis experiments. The overall results suggest that the isomeric retinals form either different relaxed triplet species or different mixtures of relaxed triplet species. The possible implications about the size of the energy barriers separating the various triplet species are discussed. The resonance Raman spectra obtained by using either anthracene (ET= 177.7 kJ mol‐1) or naphthalene (ET= 254.8 kJ mol‐1) as sensitizers were virtually identical for the corresponding triplet states from each of the isomers 11‐cis‐, 13‐a's‐ and all‐tams‐retinal, suggesting that the relaxed triplet species or the mixture of relaxed triplet species formed from each isomer is independent of the energy of the sensitizer.

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Section: Resonance Raman Spectrasupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

RESONANCE RAMAN and ABSORPTION SPECTRA OF ISOMERIC RETINALS IN THEIR LOWEST EXCITED TRIPLET STATES

Wilbrandt

Jensen

Houée-Levin⊥

1985

Photochem & Photobiology

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“…However, very little is known about the photochemistry of RAL (4). The quantum yield for intersystem crossing (⌽ isc ) has been reported to be solvent dependent and decreases dramatically on changing the solvent from methylcyclohexane to methanol (CH 3 OH) (8)(9)(10)(11)(12)(13). Fluorescence from RAL has only been detected at low temperatures in glasses (9,(13)(14)(15)(16)(17), except for a recent report utilizing fluorescence upconversion at room temperature (18).…”

Section: Introductionmentioning

confidence: 99%

“…The quantum yield for intersystem crossing (⌽ isc ) has been reported to be solvent dependent and decreases dramatically on changing the solvent from methylcyclohexane to methanol (CH 3 OH) (8)(9)(10)(11)(12)(13). Fluorescence from RAL has only been detected at low temperatures in glasses (9,(13)(14)(15)(16)(17), except for a recent report utilizing fluorescence upconversion at room temperature (18). Interestingly, fluorescence at low temperature was observed only in alcohol glasses and not in methylcyclohexane (9,(13)(14)(15)(16)(17).…”

Section: Introductionmentioning

confidence: 99%

Studies of All-trans-retinal as a Photooxidizing Agent¶

Harper¹,

Gaillard²

2007

Photochemistry and Photobiology

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The photophysical properties of all‐trans‐retinal (RAL) have been extensively studied because of the importance of the retinoids in the visual process. However, little information is available regarding the participation of RAL in photochemical transformations such as photooxidation. RAL is one of several native chromophores that have been suggested to act as photosensitizers of damage in the human retina, and this damage would likely occur through oxidative pathways. Time‐resolved and steady state techniques have been used to examine the photoreactivity of RAL toward several suitable substrates. The lifetime of the RAL triplet excited state is observed to decrease with increasing concentration of the well‐known electron and hydrogen atom donors, 2,3,5,6‐tetramethyl‐1,4‐phenylenediamine (DAD), hydroquinone (HQ), methylhydroquinone (MHQ), 2,3‐dimethylhydroquinone (DMHQ) and trimethylhydroquinone (TMHQ), although the bimolecular rate constants for the reaction are much less than that of diffusion controlled (2.9 × 107M−1 s−1, 1.2 × 105M−1 s−1, 1.2 × 105M−1 s−1, 1.5 × 105M−1 s−1 and 1.6 × 106M−1 s−1, for DAD, HQ, MHQ, DMHQ and TMHQ, respectively). In the presence of the donors, new absorptions grow concomitant with the decay of the triplet excited state, and for DAD and TMHQ, the observed spectra are similar to the spectra of p‐phenylenediamine and TMHQ radicals. Irradiation of RAL in argon‐saturated methanol results in fairly efficient photobleaching of RAL and in the formation of two new compounds having absorption spectra that are shifted below 300 nm. Irradiation of RAL in argon‐saturated acetonitrile also results in photobleaching of RAL, but the reaction proceeds at a slower rate.

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“…In the absence of Eu(fod)3, the quantum efficiency for the disappearance of all-trans-retinal, id, in nonpolar solvents is ""0.1 for UV (==350 nm) excitation (16). We used electronic spectroscopic changes, similar to those shown in Fig.…”

mentioning

confidence: 99%

Mediation of retinal photoisomerization by adduct formation with tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)-europium(II).

Ellis¹,

Schreiner²,

Ulkus³

1981

Proc. Natl. Acad. Sci. U.S.A.

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Several retinal isomers are shown to form adducts in isooctane solution with a lanthanide P-diketonate complex, tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III) [Eu(fod)3]. The adducts are characterized by an absorption band whose A.. at z420 nm is red-shifted by =60 nm from the lowest-energy absorption band in the free retinal isomers. Irradiation into this adduct band leads to photoisomer ization. For example, photolysis ofa 1 mM all-trans-retinal/3 mM Eu(fod)3 isooctane solution at 514.5 nm leads, with reasonable quantum efficiency (O Z 0.05), to isomeric mixtures that are considerably different from those produced with UV excitation in the absence of Eu(fod)3. Particularly noteworthy for a photolysis conducted in a nonpolar solvent is the presence of an appreciable quantity of 11-cu-retinal in the adduct photolysate.The ability of light to isomerize opsin-bound 11-cis-retinal to its all-trans isomer and thereby affect the binding to opsin highlights the importance of photoisomerization in the visual cycle (1). Studies ofthe photoisomerization ofretinal and related compounds have played a key role in establishing relationships between molecular conformations and excited-state properties. Perhaps not surprisingly, these structure-reactivity relationships can be influenced by experimental parameters; for example, the isomeric composition of retinal photolysates is sensitive to solvent and excitation wavelength (2, 3).Adduct formation represents another experimental tool that can be utilized in studies of retinal photoisomerization. Complexation potentially can perturb photoisomerization, for example by inducing ground-state conformational changes or by influencing excited-state deactivation processes through some combination of steric and electronic interactions. Novel patterns of photoisomerization can be anticipated if the various retinal isomers differ in their degree ofinteraction with adductforming species.The aldehyde function ofretinal permits it to engage in Lewis acid-base reactions wherein retinal serves as the Lewis base.Adducts ofseveral retinal isomers with lanthanide ,B3diketonate complexes (LDCs) have been studied by NMR (4). The Lewis acids used were tris(dipivaloylmethanato) complexes ofEu, Gd, Yb, and La; the retinal isomers were all-trans, 9-cis, 11-cis, and 13-cis. Evidence was presented for 1:1 complexes, as represented by Eq. 1, having equilibrium constants of '100 M'.retinal + LDC = retinalLDC.[1] To our knowledge the excited-state properties of adducts formed between retinal isomers and LDCs have not been examined. We now report on studies involving adducts of retinal with tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)europium(III) [Eu(fod)3] which demonstrate that adduct formation perturbs photoisomerization. Specifically, we show that adduct formation effectively extends the spectral region over which photoisomerization obtains and that photolysis of the adduct proceeds with reasonable quantum efficiency to yield mixtures of retinal...

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Laser photolysis study of the photoisomerization of retinals

Cited by 41 publications

References 12 publications

RESONANCE RAMAN and ABSORPTION SPECTRA OF ISOMERIC RETINALS IN THEIR LOWEST EXCITED TRIPLET STATES

RESONANCE RAMAN and ABSORPTION SPECTRA OF ISOMERIC RETINALS IN THEIR LOWEST EXCITED TRIPLET STATES

Studies of All-trans-retinal as a Photooxidizing Agent¶

Mediation of retinal photoisomerization by adduct formation with tris(6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato)-europium(II).

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