Correlation between the absorption spectra and resonance Raman excitation profiles of astaxanthin

Salares, V. R.; Mendelsohn, Richard; Carey, Paul R.; Bernstein, H. J.

doi:10.1021/j100552a004

Cited by 21 publications

(21 citation statements)

References 7 publications

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“…No frequency changes were observed compared to room temperature (Champion, Collins & Fitchen, 1976a). However, resonance effects were perturbed as absorption structure became more pronounced at low temperature, as in the case of the carotenoid astaxanthin (Salares et al 1976).…”

Section: Chemical Studiesmentioning

confidence: 94%

Resonance Raman spectroscopy in biochemistry and biology

Carey

1978

Quart. Rev. Biophys.

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Resonance Raman (RR) spectroscopy provides detailed information on the vibrational and electronic properties of biochemical and biological chromophores. The analysis of RR spectra, using for example model compounds or a group frequency approach, enables us to form an accurate structural picture of the chromophore in its natural biological site. Moreover, the insight gained into the electronic states of a biological chromophore can be crucial to our understanding of its function. Thus the RR technique represents a powerful means of eliciting precise structural and electronic data from a coloured species and of focusing upon key aspects of its function. It has even been possible to obtain RR spectra from some natural chromophores in vivo, giving spectra detailed and informative enough to please a spectroscopist from a system complex enough to satisfy a biologist.

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Section: Chemical Studiesmentioning

confidence: 94%

Resonance Raman spectroscopy in biochemistry and biology

Carey

1978

Quart. Rev. Biophys.

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“…It is thus relegated to the role of an end group such as a keto moiety at the end of a polyene chain which has only very weak intensity in preresonance and resonance Raman spectra. This analogy is strengthened by the fact that subtle changes at the end of polyene chains have no effect in the position of h,,, or in the resonance Raman spectrum but can have a marked effect on the appearance of vibronic structure in the absorption spectra (21). In the cis-oxazolinone the benzylidene may cause a loss of resolution of vibronic structure by perturbing solvent interactions around the C=O o r possibly by existing in more than one conformation about the Ph-C(H)=C single bond.…”

Section: Dinitrobenzylidene)-2-phenyloxazoli~~-5-one (1 7)mentioning

confidence: 99%

Resonance Raman labels: spectroscopic studies on cis- and trans-4-benzylidene-2-phenyl-Δ² -oxazolin-5-one and an isotopically substituted analog

Kumar¹,

Phelps²,

Carey³

1978

Can. J. Chem.

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The absorption and preresonance Raman spectra of cis- and trans-4-benzylidene-2-phenyl-Δ2-oxazoIin-5-one are reported. Although steric considerations suggest that the π electron pathway in the cis isomer is considerably distorted compared to the trans isomer, the Raman and absorption spectra of the two isomers are strikingly similar. Preresonance Raman excitation profiles for the cis and trans isomers indicate that the main features in the Raman spectra owe their intensity to coupling to the 360 nm absorption band present in both isomers. It is proposed that both the electronic dipole transition responsible for this absorption and the vibrational modes giving rise to the intense Raman bands are localized in the —C=C—N=C—Ph part of the molecule. Thus the main Raman and absorption bands are insensitive to isomerization in the benzylidene portion. Support for a localized electronic transition, polarized along the —C=C—N=C—Ph long axis, comes from Raman depolarization ratio (ρ) measurements which show that ail intense Raman features in both cis and trans isomers have ρ ∼ 0.33. Further support comes from ir and resonance Raman spectra of trans-4-(4-dimethylamino-3-nitrobenzylidene)-2-phenyloxazolin-5-one substituted either with 13C in the 4 position, or with 15N, in the oxazolinone ring. These spectra indicate that the main Raman feature seen in all 4-benzylidene-2-phenyloxazolinonesat 1561 cm−1 is a symmetric stretching mode associated with the —C=C—N=C— chain and that this feature has some C=N stretching character. The substitution experiments also show that the weak 1654 cm−1 Raman band has a high degree of C=C stretching character and may represent an essentially antisymmetric mode from the C=C—N=C moiety. The preresonance Raman excitation profiles show that the intensity enhancement follows an FB2 type dependence. The utility of the Raman spectrum as a probe for the chromophore responsible for the electronic transition in a highly conjugated system is discussed.

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“…The decreased contribution of the C(11)AC (12) (14) and C(13Ј)AC(14Ј) stretch vibrations to the lower component of the CAC spectral range should be a consequence of the increase in the bond length which can be related to a small decrease of the bond order. In our AM1 calculation, and in the X-ray data, the C(15)AC(15Ј) bond appears to be shorter than the C(13)AC (14) and C(13Ј)AC(14Ј) bonds. The fact that the observed shift in the [13,13Ј-13 C 2 ] astaxanthin is more important than that for [14,14Ј-13 C 2 ] astaxanthin could suggest more motion of C(13) than of C (14) in the C(13)AC (14) stretch.…”

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confidence: 54%

“…14 The AM1 calculations, performed on the molecule in vacuum, correctly predict the position of the Franck-Condon maxima (0 -1) of the strongly allowed 3 * transition (HOMO 3 LUMO) for ␤-carotene and zeaxanthin in petroleum ether, whereas a difference of 20 nm is found between calculated and experimental max for canthaxanthin and astaxanthin [Table II(A)]. If we consider that ␤-carotene and zeaxanthin are nonpolar, only dispersion forces contribute to the solvation of the solute, and the magnitude of the bathochromic shift, in comparison with the theoretical value, is a function of the only solvent refractive index.…”

Section: Excited State Properties and Electronic Absorption Spectramentioning

confidence: 99%

“…The low-frequency component of the 1 line in the spectra of [14,14Ј- 13 C 2 ] and [13,13Ј-13 C 2 ] astaxanthins, which can be attributed to a mode in which the C(13)AC (14) and C(14Ј)AC(13Ј) stretch vibrations have a significant contribution, and which only contain one 13 C isotope label per CAC stretch vibration, appears at 1500 and 1509 cm Ϫ1 , respectively. As the shift for [15,15Ј-13 C 2 ] astaxanthin which contains two 13 C isotope labels per CAC stretch vibration is expected to be more important than that observed for [13,13Ј- 13 C 2 ] and [14,14Ј-13 C 2 ] astaxanthin, it can be concluded that the C(15)AC(15Ј) stretch vibration should be at a slightly higher frequency than the C(13)AC (14) and C(14Ј)AC(13Ј) vibrations and therefore does not contribute towards the 1 line of astaxanthin at 1523 cm…”

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confidence: 99%

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