2011年
Photoexcited triplet states of new UV absorbers, cinnamic acid 2-methylphenyl esters
PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
- ,
- ,
- ,
- 巻
- 10
- 号
- 12
- 開始ページ
- 1902
- 終了ページ
- 1909
- 記述言語
- 英語
- 掲載種別
- 研究論文(学術雑誌)
- DOI
- 10.1039/c1pp05168g
- 出版者・発行元
- ROYAL SOC CHEMISTRY
Phosphorescence spectra of nonphosphorescent or very weakly phosphorescent new UV absorbers, 2-methylphenyl cinnamate (MePC), 2-methylphenyl 4-methoxycinnamate (MePMC) and 2-methylphenyl 4-ethoxycinnamate (MePEC) have been observed by using external heavy atom effects of ethyl iodide in ethanol at 77 K. The lowest excited triplet (T-1) energies of these new UV absorbers are lower than those of a widely used UV-A absorber, 4-tert-butyl-4'-methoxydibenzoylmethane (BM-DBM), in both keto and enol forms. The intermolecular triplet-triplet energy transfer from photolabile BM-DBM to MePMC was observed by measuring the time-resolved phosphorescence spectra. Electron paramagnetic resonance spectra have been observed for the T-1 states of these new UV absorbers in ethanol at 77 K by using benzophenone as a triplet sensitizer. The observed T-1 lifetimes, zero-field splitting (ZFS) parameters and molecular orbital calculations of the ZFS parameters suggest that T-1 states of these new UV absorbers posses mainly (3)pi pi* character. The deactivation processes of the lowest excited singlet (S-1) states are predominantly fluorescence and internal conversion to the ground (G) states in MePMC and MePEC, while the main deactivation process of the S-1 state of MePC is internal conversion to the G state. The molar absorption coefficients of MePMC and MePEC in the UV-A and UV-B regions are larger than that of most widely used UV-B absorber, octyl methoxycinnamate.
- リンク情報
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- DOI
- https://doi.org/10.1039/c1pp05168g
- J-GLOBAL
- https://jglobal.jst.go.jp/detail?JGLOBAL_ID=201202296839838569
- PubMed
- https://www.ncbi.nlm.nih.gov/pubmed/22002255
- Web of Science
- https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000297267200007&DestApp=WOS_CPL
- ID情報
-
- DOI : 10.1039/c1pp05168g
- ISSN : 1474-905X
- J-Global ID : 201202296839838569
- PubMed ID : 22002255
- Web of Science ID : WOS:000297267200007