Marked dependence of multiplicity in direct , photoisomerization of a series of methyl cinnamtes on their -substituents

Ishigami, Tatsuzo; Nakazato, Kenji; Uehara, Masatoshi; Endo, Tadashi

doi:10.1016/s0040-4039(01)93572-5

Cited by 22 publications

(11 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…13,14 The comparative studies of various cinnamate derivatives in the condensed phase addressed that nonradiative decay is strongly dependent upon the substituent and the position in the aromatic ring. [15][16][17][18] For example, para-methoxy a) Author to whom correspondence should be addressed. Electronic mail:…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study on the excited-state dynamics of ortho-, meta-, and para-methoxy methylcinnamate

Miyazaki

Yamamoto

Aoki

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

The S1 state dynamics of methoxy methylcinnamate (MMC) has been investigated under supersonic jet-cooled conditions. The vibrationally resolved S1-S0 absorption spectrum was recorded by laser induced fluorescence and mass-resolved resonant two-photon ionization spectroscopy and separated into conformers by UV-UV hole-burning (UV-UV HB) spectroscopy. The S1 lifetime measurements revealed different dynamics of para-methoxy methylcinnamate from ortho-methoxy methylcinnamate and meta-methoxy methylcinnamate (hereafter, abbreviated as p-, o-, and m-MMCs, respectively). The lifetimes of o-MMC and m-MMC are on the nanosecond time scale and exhibit little tendency of excess energy dependence. On the other hand, p-MMC decays much faster and its lifetime is conformer and excess energy dependent. In addition, the p-MMC-H2O complex was studied to explore the effect of hydration on the S1 state dynamics of p-MMC, and it was found that the hydration significantly accelerates the nonradiative decay. Quantum chemical calculation was employed to search the major decay route from S1(ππ(∗)) for three MMCs and p-MMC-H2O in terms of (i) trans → cis isomerization and (ii) internal conversion to the (1)nπ(∗) state. In o-MMC and m-MMC, the large energy barrier is created for the nonradiative decay along (i) the double-bond twisting coordinate (∼1000 cm(-1)) in S1 as well as (ii) the linear interpolating internal coordinate (∼1000 cm(-1)) from S1 to (1)nπ(∗) states. The calculation on p-MMC decay dynamics suggests that both (i) and (ii) are available due to small energy barrier, i.e., 160 cm(-1) by the double-bond twisting and 390 cm(-1) by the potential energy crossing. The hydration of p-MMC raises the energy barrier of the IC route to the S1/(1)nπ(∗) conical intersection, convincing that the direct isomerization is more likely to occur.

show abstract

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study on the excited-state dynamics of ortho-, meta-, and para-methoxy methylcinnamate

Miyazaki

Yamamoto

Aoki

et al. 2014

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…It has been speculated that a E to Z con¢guration change occurs upon light exposure [4,6]. This speculation was probably based on the report of a E to Z photo-isomerization of cinnamic acids and cinnamic acid esters [7,8]. A study of photo-isomerization of OMC has been done using steady state and laser £ash photolysis [9].This paper presents the HPLC-isolation of the OMC's photo-degradation product generated by exposing the OMC to the sunlight.…”

Section: Introductionmentioning

confidence: 99%

Stability of octyl methoxycinnamate and identification of its photo‐degradation product

Pattanaargson

Limphong

2001

Intern J of Cosmetic Sci

View full text Add to dashboard Cite

A stability study of octyl methoxycinnamate (OMC) using C-18 HPLC indicated that OMC degraded into a new product when exposed to sunlight. When kept in the dark at 4, 20, 32 and 60 degrees C for one month, no degradation of OMC was detected. Online HPLC-APCI-MS revealed similar APCI mass spectra for OMC and its degradation product. Isolation of the photo-degradation product was done using semi-preparative HPLC. NMR spectra of OMC and the isolated photo-degradation product indicated the change from an E-octyl-p-methoxycinnamate into a Z-octyl-p-methoxycinnamate. NMR spectra of the unfractionated-light-exposed-OMC showed that the Z-OMC was the only product generated.

show abstract

“…As a result, the recordings of IR spectra during the 60 min UVB exposure period were carried out every 1 min for the first 10 min and every 5 min for the next 50 min light exposure. In summary, IR recordings of the sample were done immediately after the sample received UVB doses of 0, 15,30,45,60,75,90,105,120,135,150,225,300,375,450, 525, 600, 675, 750, 825, and 900 mJ/cm 2 . The background spectrum was then subtracted from each IR spectrum obtained.…”

Section: Methodsmentioning

confidence: 99%

“…13 Photophysical characterization of various cinnamate derivatives have suggested a singlet or very short lived triplet excited state for EHMC, indicating that the compound is unlikely to be a photosentisizer. [14][15][16] Since all EHMC photoisomerization reports have been done in solution, but the use of EHMC as sunscreen is on skin, it is interesting to monitor the photochemical change of this sunscreen when directly applied to skin. In this paper, we report the monitoring of E to Z and Z to E photoisomerization and dimerization of the compound on a ZnSe surface and on baby mouse (Mus musculus Linn.)…”

Section: Introductionmentioning

confidence: 99%

Monitoring 2-Ethylhexyl-4-Methoxycinnamate Photoisomerization on Skin Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy

et al. 2007

View full text Add to dashboard Cite

Photoisomerization and photodimerization of a widely used UVB filter, 2-ethylhexy-4-methoxycinnamate (EHMC) on a ZnSe surface and baby mouse (Mus musculus Linn.) skin were monitored using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR). Differentiation between the E- and the Z-EHMC could be achieved by examining the infrared (IR) peak at 981 cm(-1) (b peak), which corresponds to the CH rocking deformation vibration of Ph-CH=CH- detected only in the E configuration. By plotting the ratios of the peak area of the b peak and an internal standard peak (1060-998 cm(-1)) against mole percentage of Z-isomer in the E-Z mixtures, a linear calibration plot was obtained. Thus, a simple estimation of the mole percentage of each configuration in a sample was obtained. At the same UVB exposure, photostationary equilibrium of the E/Z isomerization on the surface varied with the applied amounts of EHMC. Photoisomerizations on ZnSe and on baby mouse skin were comparable. Less than 10% of E-EHMC changed configuration when the mouse skins applied with 1.0-4.0 mg/cm(2) E-EHMC were exposed to sunlight for 60 min (UVB radiant exposure of approximately 0.30 J/cm(2)). This corresponded to less than 5% loss in UV filtering efficiency. However, at a typical EHMC skin coverage ( approximately 0.2 mg/cm(2)), 0.30 J/cm(2) UVB exposure induced approximately 50% photoisomerization resulting in 25% loss of UV filtering efficiency. No photodimerization was detected even at the extreme EHMC coverage of 4.0 mg/cm(2) after a UVB exposure of 0.90 J/cm(2).

show abstract

Marked dependence of multiplicity in direct , photoisomerization of a series of methyl cinnamtes on their -substituents

Cited by 22 publications

References 5 publications

Experimental and theoretical study on the excited-state dynamics of ortho-, meta-, and para-methoxy methylcinnamate

Experimental and theoretical study on the excited-state dynamics of ortho-, meta-, and para-methoxy methylcinnamate

Stability of octyl methoxycinnamate and identification of its photo‐degradation product

Monitoring 2-Ethylhexyl-4-Methoxycinnamate Photoisomerization on Skin Using Attenuated Total Reflection Fourier Transform Infrared Spectroscopy

Contact Info

Product

Resources

About