Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes
Steady-state and ultrafast transient absorption spectra were obtained for a series of conformationally constrained, isomerically pure polyenes with 5–23 conjugated double bonds (N). These data and fluorescence spectra of the shorter polyenes reveal the N dependence of the energies of six [superscrip...
| Main Authors: | , , , , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
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American Chemical Society (ACS)
2015
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| Online Access: | http://hdl.handle.net/1721.1/95626 https://orcid.org/0000-0001-5827-3552 |
| _version_ | 1826217175673733120 |
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| author | Christensen, Ronald L. Enriquez, Miriam M. Wagner, Nicole L. Peacock-Villada, Alexandra Y. Scriban, Corina Polívka, Tomáš Frank, Harry A. Birge, Robert R. Schrock, Richard Royce |
| author2 | Massachusetts Institute of Technology. Department of Chemistry |
| author_facet | Massachusetts Institute of Technology. Department of Chemistry Christensen, Ronald L. Enriquez, Miriam M. Wagner, Nicole L. Peacock-Villada, Alexandra Y. Scriban, Corina Polívka, Tomáš Frank, Harry A. Birge, Robert R. Schrock, Richard Royce |
| author_sort | Christensen, Ronald L. |
| collection | MIT |
| description | Steady-state and ultrafast transient absorption spectra were obtained for a series of conformationally constrained, isomerically pure polyenes with 5–23 conjugated double bonds (N). These data and fluorescence spectra of the shorter polyenes reveal the N dependence of the energies of six [superscript 1]B[subscript u] [superscript +] and two [superscript 1]A[subscript g] [superscript –] excited states. The [superscript 1]B[subscript u] [superscript +] states converge to a common infinite polyene limit of 15 900 ± 100 cm [superscript –1]. The two excited [superscript 1]A[subscript g] [superscript –] states, however, exhibit a large (∼9000 cm–1) energy difference in the infinite polyene limit, in contrast to the common value previously predicted by theory. EOM-CCSD ab initio and MNDO-PSDCI semiempirical MO theories account for the experimental transition energies and intensities. The complex, multistep dynamics of the 1[superscript 1]B[subscript u] [superscript +] → 2 [superscript 1]A[subscript g] [superscript –] → 1 [superscript 1]A[subscript g] [superscript –] excited state decay pathways as a function of N are compared with kinetic data from several natural and synthetic carotenoids. Distinctive transient absorption signals in the visible region, previously identified with S* states in carotenoids, also are observed for the longer polyenes. Analysis of the lifetimes of the 2 [superscript 1]A[subscript g] [superscript –] states, using the energy gap law for nonradiative decay, reveals remarkable similarities in the N dependence of the 2 [superscript 1]A[subscript g] [superscript –] decay kinetics of the carotenoid and polyene systems. These findings are important for understanding the mechanisms by which carotenoids carry out their roles as light-harvesting molecules and photoprotective agents in biological systems. |
| first_indexed | 2024-09-23T16:59:15Z |
| format | Article |
| id | mit-1721.1/95626 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:59:15Z |
| publishDate | 2015 |
| publisher | American Chemical Society (ACS) |
| record_format | dspace |
| spelling | mit-1721.1/956262022-09-29T22:51:38Z Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes Christensen, Ronald L. Enriquez, Miriam M. Wagner, Nicole L. Peacock-Villada, Alexandra Y. Scriban, Corina Polívka, Tomáš Frank, Harry A. Birge, Robert R. Schrock, Richard Royce Massachusetts Institute of Technology. Department of Chemistry Schrock, Richard Royce Scriban, Corina Steady-state and ultrafast transient absorption spectra were obtained for a series of conformationally constrained, isomerically pure polyenes with 5–23 conjugated double bonds (N). These data and fluorescence spectra of the shorter polyenes reveal the N dependence of the energies of six [superscript 1]B[subscript u] [superscript +] and two [superscript 1]A[subscript g] [superscript –] excited states. The [superscript 1]B[subscript u] [superscript +] states converge to a common infinite polyene limit of 15 900 ± 100 cm [superscript –1]. The two excited [superscript 1]A[subscript g] [superscript –] states, however, exhibit a large (∼9000 cm–1) energy difference in the infinite polyene limit, in contrast to the common value previously predicted by theory. EOM-CCSD ab initio and MNDO-PSDCI semiempirical MO theories account for the experimental transition energies and intensities. The complex, multistep dynamics of the 1[superscript 1]B[subscript u] [superscript +] → 2 [superscript 1]A[subscript g] [superscript –] → 1 [superscript 1]A[subscript g] [superscript –] excited state decay pathways as a function of N are compared with kinetic data from several natural and synthetic carotenoids. Distinctive transient absorption signals in the visible region, previously identified with S* states in carotenoids, also are observed for the longer polyenes. Analysis of the lifetimes of the 2 [superscript 1]A[subscript g] [superscript –] states, using the energy gap law for nonradiative decay, reveals remarkable similarities in the N dependence of the 2 [superscript 1]A[subscript g] [superscript –] decay kinetics of the carotenoid and polyene systems. These findings are important for understanding the mechanisms by which carotenoids carry out their roles as light-harvesting molecules and photoprotective agents in biological systems. United States. Dept. of Energy (DE-FG02-86ER13564) National Science Foundation (U.S.) (Grant EMT-0829916) National Institutes of Health (U.S.) (Grant GM-34548) 2015-02-25T19:31:39Z 2015-02-25T19:31:39Z 2013-01 2013-01 Article http://purl.org/eprint/type/JournalArticle 1089-5639 1520-5215 http://hdl.handle.net/1721.1/95626 Christensen, Ronald L., Miriam M. Enriquez, Nicole L. Wagner, Alexandra Y. Peacock-Villada, Corina Scriban, Richard R. Schrock, Tomáš Polívka, Harry A. Frank, and Robert R. Birge. “Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes.” The Journal of Physical Chemistry A 117, no. 7 (February 21, 2013): 1449–1465. https://orcid.org/0000-0001-5827-3552 en_US http://dx.doi.org/10.1021/jp310592s Journal of Physical Chemistry A Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Chemical Society (ACS) PMC |
| spellingShingle | Christensen, Ronald L. Enriquez, Miriam M. Wagner, Nicole L. Peacock-Villada, Alexandra Y. Scriban, Corina Polívka, Tomáš Frank, Harry A. Birge, Robert R. Schrock, Richard Royce Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title | Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title_full | Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title_fullStr | Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title_full_unstemmed | Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title_short | Energetics and Dynamics of the Low-Lying Electronic States of Constrained Polyenes: Implications for Infinite Polyenes |
| title_sort | energetics and dynamics of the low lying electronic states of constrained polyenes implications for infinite polyenes |
| url | http://hdl.handle.net/1721.1/95626 https://orcid.org/0000-0001-5827-3552 |
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