Change of static electric polarizability upon transition into excited molecular states

Seibold, K.; Navangul, Himanshoo V.; Labhart, Heinrich

doi:10.1016/0009-2614(69)80228-9

Cited by 45 publications

(6 citation statements)

References 16 publications

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“…In carotenoids, that would correspond to an increase of long-axis polarizability with about 1100 A3 (Aa,) upon excitation from the ground to lB, state. Electrochromic measurements have been done on the carotenoid lutein (Schmidt and Reich, 1972) and on lycopene in 3-methylpentane (Seibold, 1969) and the results were Aa, = 910 A3 and A a = 246 f 22 A3, respectively.…”

Section: Methodsmentioning

confidence: 99%

Absorption Spectral Shifts of Carotenoids Related to Medium Polarizability

Andersson

Gillbro

Ferguson

et al. 1991

Photochem & Photobiology

175

132

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Abstract–Solvent induced absorption spectral shifts of the electronic transition from ground 1 Ag state to the excited 1Bu state in carotenoids have been studied. It is shown that the shift depends only on dispersion interactions in non‐polar solvents. In polar media there is just a small extra contribution to the red‐shift, due to other forms of interactions. The spectral shifts are well described by the theory, which expresses the shift relative to the gas phase value, as a function of solvent polarizability. The main conclusion is that the dominating mechanism behind the large red‐shifted absorbance of carotenoids in the proteinacous environment, in vivo, is the mutual polarizability interactions between the carotenoids and the surrounding medium. The solution‐phase values of the dipole moments of the lAg to 1Bu transitions and the differences of isotropic polarizability between 1Bu and lAg states of carotenoids in non‐polar solvents are calculated and found to be around 13 D and 360 Å3 respectively. From the great overlap of absorption spectra between carotenoids in quinoline and carotenoids in vivo in purple bacterial antenna complexes, it can be expected that the carotenoids are surrounded by several aromatic amino acids in vivo. Comparisons have been done between the exicted states in carotenoids and in linear conjugated polyenes.

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Section: Methodsmentioning

confidence: 99%

Absorption Spectral Shifts of Carotenoids Related to Medium Polarizability

Andersson

Gillbro

Ferguson

et al. 1991

Photochem & Photobiology

175

132

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“…6 lolgt sofort im Rahmen der Fehler P a , + Ada, = 0, d. h., nennenswert iindert sich mit der Anregung nur die z-Komponente der Polarisierbarkeit. Lost man Gleichung (25) nach Dagegen spricht allerdings die brauchbare Ubereinstimmung der Untcrsuchungen in Dekalin [9], worin andererseits aber nach unseren Erfahrungen die Gefahr von Mikrokristallitbildung nicht ganz auszuschliefien ist.…”

Section: Auswertung A) Allgemeinesunclassified

“…wo in guter Niiherung die Dielektrizitiitszahl c gleich dem Quadrat der Brechzahl 12 ist: Uni den Beitrag der Anderung der Polarisierbarkeit mit der Anregung A"a abzuschiitzen, wurden bei 121 K in gla,ig erstarrten 1 : 1 n-Butanol-iso-Propanolgemischen elektrooptische Absorptionsmessungen an DMANS durchgefiihrt und analog dem oben Gesagten nach Liptay [5] ausgewertet. Seibold et al [9] …”

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Elektrooptische Emissionsuntersuchungen, III. Das Dipolmoment von trans‐p‐Dimethylamino‐p′‐nitrostilben im ersten angeregten Singulettzustand

Baumann

Deckers

Loosen

et al. 1977

Ber Bunsenges Phys Chem

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CV-' m2. Es zeigte sich, da13 die elektrooptischen Absorptions-und Emissionsuntersuchungen an DMANS in unpolaren Losungen zu einem konsistenten Satz von Dipolmomenten fiihren, daB also die Aquilibrierung mit der Umgebung nach Anregung im unpolaren Cyclohexan keinen EinfluB auf das permanente Dipolmonient hat.From electrooptical emission and absorption measurements in liquid and glassy frozen solutions and with dielectric investigations the dipole moment pf and the component & of the polarizability parallel to p: of trans-p-dimethylamino-p'-nitrostilbene (DMANS) in its first excited singlet state has been determined to be p: = (63 f 5 ) -10-30 Cm and a:z = (442 f 6 5 ) . 10-' O CV-' m2, respectively. It could be shown that both electrooptical absorption and emission measurements give the same dipole moments, indicating that there is no change of the dipole moment with equilibration of DMANS and its surrounding after excitation in nonpolar cyclohexane solution. Voraussetzungen Elektrooptische Emissionsuntersuchungen an trans-p-dimethylamino-p'-nitrostilben (DMANS) wurden in nicht entI" = ( m , A " p ( ' .( 1 5)Temperatur. Weiter ist in unpolaren Liisungsmitteln. wo in guter Niiherung die Dielektrizitiitszahl c gleich dem Quadrat der Brechzahl 12 ist: Uni den Beitrag der Anderung der Polarisierbarkeit mit der Anregung A"a abzuschiitzen, wurden bei 121 K in gla,ig erstarrten 1 : 1 n-Butanol-iso-Propanolgemischen elektrooptische Absorptionsmessungen an DMANS durchgefiihrt und analog dem oben Gesagten nach Liptay [5] ausgewertet. Seibold et al. [9] Auswertung a) AllgemeinesSchiitzt man mit D" aus Tab. 2 den Beitrag der von mi abhiingigen Glieder zu E", F" und G" ab, so zeigt sich, daD diese Beitriige weit unterhalb der Fehler von E". Fa und G" liegen und selbst bei den Tieftemperaturmessungen, Tab Die Meljwerte der dielektrischen Untersuchungen aus [ 101 sind zusainmen mit den Ergebnissen der Auswertung nach den Gleichungen (36) und (37) DiskussionDie aus elektrooptischen Absorptions-und Emissionsuntersuchungen gefundenen, noch nicht feldkorrigierten Dipolmomente von DMANS in Cyclohexan sowie die Dipolmomente des freien DMANS nach Berucksichtigung des inneren Feldes in einer Losung sind in Tab. 9 einander gegeniibergestell t. Mit der Beriicksichtigung des inneren Feldes nach den Gleichungen (17) und (23)

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“…Since then, several laboratories have determined both ground and excited-state dipole moments (11,12) and polarizabilities (13)(14)(15) by studying the effects of intense electric fields on absorption and fluorescence (16,17). For a comprehensive review, see Liptay (18).…”

mentioning

confidence: 99%

Retinal has a highly dipolar vertically excited singlet state: implications for vision.

Mathies¹,

Stryer²

1976

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

277

213

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We have measured the effect of an intense electric field on the absorption spectrum of solutions of all-trans retinal, its unprotonated Schiff base with n-butylamine, and the Cl-salt of this protonated Schiff base. The field-induced change in extinction coefficient as a function of wavelength was analyzed to determine the ground-state dipole moment (), the change in dipole moment on excitation (Z), and the direction of A and AU. These experiments have shown that all three species become highly dipolar upon excitation to the first allowed excited singlet state (1IAA = 15.6,9.9,12 D, respectively). The chromophore in all known vertebrate visual pigments is I1-cis retinal (or dehydroretinal) which is isomerized by light to all-trans retinal (1). In rhodopsin, 11-cis retinal is attached to a specific lysine residue of opsin by a protonated Schiff base linkage (2-6). The known properties of this chromophore have recently been reviewed (7,8). A more detailed knowledge of the excited state properties of retinal should facilitate the elucidation of its function since its absorption spectrum and mechanism of isomerization depend on the character of its excited electronic states. However, relatively few direct measurements have been made on the excited states of retinal because of the difficulty of such experiments.We report here the first determination of the ground and excited state dipole moments of all-trans retinal, its Schiff bases, and 11-cis retinal. This was accomplished by measuring the effect of an intense electric field on the absorption spectrum of solutions of these molecules. The Schiff bases of the all-trans isomer were chosen for this initial study because the interpretation of their electric field spectra is more direct than for those of the 11-cis isomer. The striking finding is that excitation of all-trans retinal and its Schiff bases is accompanied by a large shift in negative charge away from the ionone ring end of the molecule. These observations help to characterize the excited states and isomerization mechanism of retinal. Furthermore, these measurements give insight into the interactions between retinal and opsin during the initial stages of visual excitation.

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Change of static electric polarizability upon transition into excited molecular states

Cited by 45 publications

References 16 publications

Absorption Spectral Shifts of Carotenoids Related to Medium Polarizability

Absorption Spectral Shifts of Carotenoids Related to Medium Polarizability

Elektrooptische Emissionsuntersuchungen, III. Das Dipolmoment von trans‐p‐Dimethylamino‐p′‐nitrostilben im ersten angeregten Singulettzustand

Retinal has a highly dipolar vertically excited singlet state: implications for vision.

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