論文

査読有り
2011年

Photoexcited triplet states of new UV absorbers, cinnamic acid 2-methylphenyl esters

PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES
  • Azusa Kikuchi
  • ,
  • Haruo Saito
  • ,
  • Masao Mori
  • ,
  • Mikio Yagi

10
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
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

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