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Solvent effects on the S0(1(1)Ag-) --> S2(1(1)Bu+) transition of beta-carotene, echinenone, canthaxanthin, and astaxanthin in supercritical CO2 and CF3H.
J Phys Chem A. 2006 Oct 05; 110(39):11291-7.JP

Abstract

Solvent-induced spectral shifts of the four C40 carotenoids, beta-carotene, echinenone, canthaxantin, and astaxanthin, have been studied in supercritical CO2 and CF3H. In situ absorption spectroscopic analysis was used to determine the maximum peak position of the electronic transitions from the ground state (1(1)Ag-) to the S2 state (1(1)Bu+) of the carotenoids. The medium polarizability function, R(n) = (n2 - 1)/(n2 + 2) of the refractive index of the solvent was varied over the range R(n) = 0.08-0.14, by changing the pressure of CO2 or CF3H between 90 and 300 bar at the temperature 308 K. For all the carotenoids studied here, a significant hypsochromic shift of ca. 20-30 nm was observed in supercritical fluids as compared to that in nonpolar liquids. The spectral shifts in supercritical fluids were compared with those in liquids and showed a clear linear dependence on the medium polarizability. The temperature-dependent shift of the absorption maxima was less significant. Interestingly, there was almost no difference in the energetic position of the absorption maxima in supercritical CO2 and CF3H at a given R(n) value. This is in contrast to previous extrapolations from studies in liquids at larger R(n) values, which yielded different slopes of the R(n)-dependent spectral shifts for polar and nonpolar solvents toward the gas-phase limit of R(n) = 0. The current experimental results in the gas-to-liquid range show that the polarity of the solvent has only a minor influence on the 1(1)Ag- --> 1(1)Bu+ transition energy in the region of low R(n). We also obtain more reliable extrapolations of this 0-0 transition energy to the gas-phase limit nu(0-0)(gas-phase) approximately (23,000 +/- 120) cm(-1) for beta-carotene.

Authors+Show Affiliations

Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, D-37077 Göttingen, Germany.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17004738

Citation

Chen, Zhenguo, et al. "Solvent Effects On the S0(1(1)Ag-) --> S2(1(1)Bu+) Transition of Beta-carotene, Echinenone, Canthaxanthin, and Astaxanthin in Supercritical CO2 and CF3H." The Journal of Physical Chemistry. A, vol. 110, no. 39, 2006, pp. 11291-7.
Chen Z, Lee C, Lenzer T, et al. Solvent effects on the S0(1(1)Ag-) --> S2(1(1)Bu+) transition of beta-carotene, echinenone, canthaxanthin, and astaxanthin in supercritical CO2 and CF3H. J Phys Chem A. 2006;110(39):11291-7.
Chen, Z., Lee, C., Lenzer, T., & Oum, K. (2006). Solvent effects on the S0(1(1)Ag-) --> S2(1(1)Bu+) transition of beta-carotene, echinenone, canthaxanthin, and astaxanthin in supercritical CO2 and CF3H. The Journal of Physical Chemistry. A, 110(39), 11291-7.
Chen Z, et al. Solvent Effects On the S0(1(1)Ag-) --> S2(1(1)Bu+) Transition of Beta-carotene, Echinenone, Canthaxanthin, and Astaxanthin in Supercritical CO2 and CF3H. J Phys Chem A. 2006 Oct 5;110(39):11291-7. PubMed PMID: 17004738.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Solvent effects on the S0(1(1)Ag-) --> S2(1(1)Bu+) transition of beta-carotene, echinenone, canthaxanthin, and astaxanthin in supercritical CO2 and CF3H. AU - Chen,Zhenguo, AU - Lee,Changyoul, AU - Lenzer,Thomas, AU - Oum,Kawon, PY - 2006/9/29/pubmed PY - 2007/11/6/medline PY - 2006/9/29/entrez SP - 11291 EP - 7 JF - The journal of physical chemistry. A JO - J Phys Chem A VL - 110 IS - 39 N2 - Solvent-induced spectral shifts of the four C40 carotenoids, beta-carotene, echinenone, canthaxantin, and astaxanthin, have been studied in supercritical CO2 and CF3H. In situ absorption spectroscopic analysis was used to determine the maximum peak position of the electronic transitions from the ground state (1(1)Ag-) to the S2 state (1(1)Bu+) of the carotenoids. The medium polarizability function, R(n) = (n2 - 1)/(n2 + 2) of the refractive index of the solvent was varied over the range R(n) = 0.08-0.14, by changing the pressure of CO2 or CF3H between 90 and 300 bar at the temperature 308 K. For all the carotenoids studied here, a significant hypsochromic shift of ca. 20-30 nm was observed in supercritical fluids as compared to that in nonpolar liquids. The spectral shifts in supercritical fluids were compared with those in liquids and showed a clear linear dependence on the medium polarizability. The temperature-dependent shift of the absorption maxima was less significant. Interestingly, there was almost no difference in the energetic position of the absorption maxima in supercritical CO2 and CF3H at a given R(n) value. This is in contrast to previous extrapolations from studies in liquids at larger R(n) values, which yielded different slopes of the R(n)-dependent spectral shifts for polar and nonpolar solvents toward the gas-phase limit of R(n) = 0. The current experimental results in the gas-to-liquid range show that the polarity of the solvent has only a minor influence on the 1(1)Ag- --> 1(1)Bu+ transition energy in the region of low R(n). We also obtain more reliable extrapolations of this 0-0 transition energy to the gas-phase limit nu(0-0)(gas-phase) approximately (23,000 +/- 120) cm(-1) for beta-carotene. SN - 1089-5639 UR - https://www.unboundmedicine.com/medline/citation/17004738/Solvent_effects_on_the_S0_1_1_Ag_____>_S2_1_1_Bu+__transition_of_beta_carotene_echinenone_canthaxanthin_and_astaxanthin_in_supercritical_CO2_and_CF3H_ L2 - https://dx.doi.org/10.1021/jp0643247 DB - PRIME DP - Unbound Medicine ER -