The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Vasilios G. Stavros - One of the best experts on this subject based on the ideXlab platform.
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Wavepacket insights into the photoprotection mechanism of the UV filter Methyl Anthranilate.
Nature Communications, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Karl N. Blodgett, Chamara Abeysekera, Timothy S. Zwier, Vasilios G. StavrosAbstract:Meradimate is a broad-spectrum ultraviolet absorber used as a chemical filter in commercial sunscreens. Herein, we explore the ultrafast photodynamics occurring in Methyl Anthranilate (precursor to Meradimate) immediately after photoexcitation with ultraviolet radiation to understand the mechanisms underpinning Meradimate photoprotection. Using time-resolved photoelectron spectroscopy, signal from the first singlet excited state of Methyl Anthranilate shows an oscillatory behavior, i.e., quantum beats. Our studies reveal a dependence of the observed beating frequencies on photoexcitation wavelength and photoelectron kinetic energy, unveiling the different Franck-Condon overlaps between the vibrational levels of the ground electronic, first electronic excited, and ground cationic states of Methyl Anthranilate. By evaluating the behavior of these beats with increasing photon energy, we find evidence for intramolecular vibrational energy redistribution on the first electronic excited state. Such energy redistribution hinders efficient relaxation of the electronic excited state, making Methyl Anthranilate a poor choice for an efficient, efficacious sunscreen chemical filter. Here, the authors explore the ultrafast photodynamics of Methyl Anthranilate. From the quantum beat behavior, the authors find evidence for ultrafast energy redistribution processes which hinder excited state relaxation, making Methyl Anthranilate a poor choice for a sunscreen chemical filter.
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Substituent position effects on sunscreen photodynamics: A closer look at Methyl Anthranilate
Chemical Physics, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Konstantina M. Krokidi, Gareth W. Richings, Matthew S. Turner, Georgia L. Thornton, Nicholas D. M. Hine, Vasilios G. StavrosAbstract:Abstract Towards the development of a bottom-up rationale for sunscreen design, the effects of substituent position on the ultrafast photodynamics of the sunscreen precursor Methyl Anthranilate (MA, an ortho compound) were evaluated by studying para- and meta-MA in vacuum. Time-resolved ion yield (TR-IY) measurements reveal a long-lived S1 excited state (≫1.2 ns) for para-MA, proposed to be the result of a weakly fluorescent, bound excited state. In the case of meta-MA, TR-IY transients reveal a much faster (∼2 ns) excited state relaxation, possibly due to multiple low-lying S1/S0 conical intersections of prefulvenic character. While meta-MA may not be an ideal sunscreen ingredient due to a low ultraviolet absorbance, its comparatively efficient relaxation mechanism may constitute an alternative to common sunscreen relaxation pathways. Thus, our results should prompt further studies of prefulvenic relaxation pathways in potential sunscreen agents.
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Photophysics of the sunscreen ingredient menthyl Anthranilate and its precursor Methyl Anthranilate: A bottom-up approach to photoprotection
Journal of Photochemistry and Photobiology A-chemistry, 2018Co-Authors: Natércia D. N. Rodrigues, Michael D. Horbury, Michael Staniforth, Neil C. Cole-filipiak, Tolga N. V. Karsili, Yoann Peperstraete, Vasilios G. StavrosAbstract:The ultrafast excited state dynamics of the sunscreen ingredient menthyl Anthranilate (MenA) and its precursor Methyl Anthranilate (MA) were studied in vacuum (using time-resolved ion yield spectroscopy) and in solution (using transient electronic absorption spectroscopy). MenA and MA both show long-lived dynamics, with the observation of a kinetic isotope effect suggesting that hydrogen motion acts as the rate determining process in the overall decay. Complementary computational studies exploring the intuitive decay pathways of MA revealed a bound S1 state with a shallow ‘up-hill’ gradient with respect to proton transfer. From these results, it is suggested that photoexcited population is trapped in this excited state from which luminescence occurs as a prominent decay pathway. This work has shown that the photophysics of MA and MenA – and hence their photoprotection capabilities – are not drastically influenced by aliphatic structure or solvent environment alone. A bottom-up approach, such as the one described herein, is essential to understand the combination of factors that afford optimum photoprotection and to develop a new generation of tailor made, efficacious sunscreens.
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Wavepacket insights into the photoprotection mechanism of the UV filter Methyl Anthranilate
Nature Publishing Group, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Karl N. Blodgett, Chamara Abeysekera, Timothy S. Zwier, Vasilios G. StavrosAbstract:Here, the authors explore the ultrafast photodynamics of Methyl Anthranilate. From the quantum beat behavior, the authors find evidence for ultrafast energy redistribution processes which hinder excited state relaxation, making Methyl Anthranilate a poor choice for a sunscreen chemical filter
Weili Ran - One of the best experts on this subject based on the ideXlab platform.
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liquid liquid equilibria for systems of water methanol Methyl Anthranilate at several temperatures
Fluid Phase Equilibria, 2011Co-Authors: Baohe Wang, Weili RanAbstract:Abstract Liquid–liquid equilibria (LLE) data for the systems of water + Methyl Anthranilate and water + methanol + Methyl Anthranilate were measured under atmospheric pressure over the temperature range of 298.15–323.15 K. Phase diagrams were obtained by determining solubility and tie-line data. The reliability of the experimental tie-line data was determined through the Bachman plots. The data were correlated using the NRTL and UNIQUAC models. Average RMSD obtained from the UNIQUAC and NRTL model were 0.0082 and 0.135, respectively. The correlated results were in agreement with the experiment data, though the average deviations from the UNIQUAC model are slightly smaller than those from the NRTL model.
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Liquid–liquid equilibria for systems of water + methanol + Methyl Anthranilate at several temperatures
Fluid Phase Equilibria, 2011Co-Authors: Baohe Wang, Weili RanAbstract:Abstract Liquid–liquid equilibria (LLE) data for the systems of water + Methyl Anthranilate and water + methanol + Methyl Anthranilate were measured under atmospheric pressure over the temperature range of 298.15–323.15 K. Phase diagrams were obtained by determining solubility and tie-line data. The reliability of the experimental tie-line data was determined through the Bachman plots. The data were correlated using the NRTL and UNIQUAC models. Average RMSD obtained from the UNIQUAC and NRTL model were 0.0082 and 0.135, respectively. The correlated results were in agreement with the experiment data, though the average deviations from the UNIQUAC model are slightly smaller than those from the NRTL model.
Natércia D. N. Rodrigues - One of the best experts on this subject based on the ideXlab platform.
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Wavepacket insights into the photoprotection mechanism of the UV filter Methyl Anthranilate.
Nature Communications, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Karl N. Blodgett, Chamara Abeysekera, Timothy S. Zwier, Vasilios G. StavrosAbstract:Meradimate is a broad-spectrum ultraviolet absorber used as a chemical filter in commercial sunscreens. Herein, we explore the ultrafast photodynamics occurring in Methyl Anthranilate (precursor to Meradimate) immediately after photoexcitation with ultraviolet radiation to understand the mechanisms underpinning Meradimate photoprotection. Using time-resolved photoelectron spectroscopy, signal from the first singlet excited state of Methyl Anthranilate shows an oscillatory behavior, i.e., quantum beats. Our studies reveal a dependence of the observed beating frequencies on photoexcitation wavelength and photoelectron kinetic energy, unveiling the different Franck-Condon overlaps between the vibrational levels of the ground electronic, first electronic excited, and ground cationic states of Methyl Anthranilate. By evaluating the behavior of these beats with increasing photon energy, we find evidence for intramolecular vibrational energy redistribution on the first electronic excited state. Such energy redistribution hinders efficient relaxation of the electronic excited state, making Methyl Anthranilate a poor choice for an efficient, efficacious sunscreen chemical filter. Here, the authors explore the ultrafast photodynamics of Methyl Anthranilate. From the quantum beat behavior, the authors find evidence for ultrafast energy redistribution processes which hinder excited state relaxation, making Methyl Anthranilate a poor choice for a sunscreen chemical filter.
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Substituent position effects on sunscreen photodynamics: A closer look at Methyl Anthranilate
Chemical Physics, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Konstantina M. Krokidi, Gareth W. Richings, Matthew S. Turner, Georgia L. Thornton, Nicholas D. M. Hine, Vasilios G. StavrosAbstract:Abstract Towards the development of a bottom-up rationale for sunscreen design, the effects of substituent position on the ultrafast photodynamics of the sunscreen precursor Methyl Anthranilate (MA, an ortho compound) were evaluated by studying para- and meta-MA in vacuum. Time-resolved ion yield (TR-IY) measurements reveal a long-lived S1 excited state (≫1.2 ns) for para-MA, proposed to be the result of a weakly fluorescent, bound excited state. In the case of meta-MA, TR-IY transients reveal a much faster (∼2 ns) excited state relaxation, possibly due to multiple low-lying S1/S0 conical intersections of prefulvenic character. While meta-MA may not be an ideal sunscreen ingredient due to a low ultraviolet absorbance, its comparatively efficient relaxation mechanism may constitute an alternative to common sunscreen relaxation pathways. Thus, our results should prompt further studies of prefulvenic relaxation pathways in potential sunscreen agents.
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Photophysics of the sunscreen ingredient menthyl Anthranilate and its precursor Methyl Anthranilate: A bottom-up approach to photoprotection
Journal of Photochemistry and Photobiology A-chemistry, 2018Co-Authors: Natércia D. N. Rodrigues, Michael D. Horbury, Michael Staniforth, Neil C. Cole-filipiak, Tolga N. V. Karsili, Yoann Peperstraete, Vasilios G. StavrosAbstract:The ultrafast excited state dynamics of the sunscreen ingredient menthyl Anthranilate (MenA) and its precursor Methyl Anthranilate (MA) were studied in vacuum (using time-resolved ion yield spectroscopy) and in solution (using transient electronic absorption spectroscopy). MenA and MA both show long-lived dynamics, with the observation of a kinetic isotope effect suggesting that hydrogen motion acts as the rate determining process in the overall decay. Complementary computational studies exploring the intuitive decay pathways of MA revealed a bound S1 state with a shallow ‘up-hill’ gradient with respect to proton transfer. From these results, it is suggested that photoexcited population is trapped in this excited state from which luminescence occurs as a prominent decay pathway. This work has shown that the photophysics of MA and MenA – and hence their photoprotection capabilities – are not drastically influenced by aliphatic structure or solvent environment alone. A bottom-up approach, such as the one described herein, is essential to understand the combination of factors that afford optimum photoprotection and to develop a new generation of tailor made, efficacious sunscreens.
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Wavepacket insights into the photoprotection mechanism of the UV filter Methyl Anthranilate
Nature Publishing Group, 2018Co-Authors: Natércia D. N. Rodrigues, Neil C. Cole-filipiak, Karl N. Blodgett, Chamara Abeysekera, Timothy S. Zwier, Vasilios G. StavrosAbstract:Here, the authors explore the ultrafast photodynamics of Methyl Anthranilate. From the quantum beat behavior, the authors find evidence for ultrafast energy redistribution processes which hinder excited state relaxation, making Methyl Anthranilate a poor choice for a sunscreen chemical filter
Syed S.h. Rizvi - One of the best experts on this subject based on the ideXlab platform.
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Measurement and Correlation of Citronellal and Methyl Anthranilate Solubilities in Supercritical Carbon Dioxide
Journal of Chemical & Engineering Data, 2015Co-Authors: Wen-chyan Tsai, Syed S.h. RizviAbstract:Citronellal and Methyl Anthranilate (MA) are both nonpolar molecules with similar physical properties except for their molecular structures. The solubility of citronellal in supercritical carbon dioxide (SC-CO2) was measured using a static equilibrium system in the pressure range of (9.1 to 14.2) MPa and at (313.15 and 333.15) K. For MA, (9.1 to 24.3) MPa was used at the same temperatures. Solubility data of citronellal and MA in SC-CO2 were well correlated using the Chrastil equation and Peng–Robinson equation of state. Under comparable operating conditions, the linear-chained citronellal solubility in SC-CO2 was three to four times higher than its aromatic derivative MA. The acentric factor of citronellal (ω = 1.004) is higher than that of MA (ω = 0.577), indicating that citronellal has larger molecular asymmetry. This difference allows less intermolecular binding energy but gives higher vapor pressure to citronellal, making it more readily soluble in SC-CO2. The results suggest that the acentric factor...
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Solubility measurement of Methyl Anthranilate in supercritical carbon dioxide using dynamic and static equilibrium systems
Journal of the Science of Food and Agriculture, 2006Co-Authors: Wen-chyan Tsai, Yonghong Ruan, Syed S.h. RizviAbstract:The solubility of Methyl Anthranilate in supercritical carbon dioxide was determined using dynamic and static equilibrium systems. Three temperatures (40, 60 and 80 °C) and a pressure range between 160 and 340 atm were applied for the dynamic solubility measurements. The flow rate was maintained at 0.5 mL min−1 in the dynamic solubility measurements, where the solute solubility was claimed to be independent of the flow-rate factor. Two temperatures (40 and 60 °C) and the pressure range between 100 and 265 atm were used in the static equilibrium system. The crossover pressure region was observed between 220 and 240 atm in the static system, but was not seen in the dynamic system. The solubility of Methyl Anthranilate determined by the static system was consistently higher than the dynamic solubility measurement, indicating that the static technique provided more reliable solubility data for Methyl Anthranilate than the dynamic technique. The solubility data obtained with the static system were in good agreement with the predictive models based on the Chrastil equation and the Peng–Robinson equation of state with the Panagiotopoulos and Reid mixing rule. Copyright © 2006 Society of Chemical Industry
Baohe Wang - One of the best experts on this subject based on the ideXlab platform.
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liquid liquid equilibria for systems of water methanol Methyl Anthranilate at several temperatures
Fluid Phase Equilibria, 2011Co-Authors: Baohe Wang, Weili RanAbstract:Abstract Liquid–liquid equilibria (LLE) data for the systems of water + Methyl Anthranilate and water + methanol + Methyl Anthranilate were measured under atmospheric pressure over the temperature range of 298.15–323.15 K. Phase diagrams were obtained by determining solubility and tie-line data. The reliability of the experimental tie-line data was determined through the Bachman plots. The data were correlated using the NRTL and UNIQUAC models. Average RMSD obtained from the UNIQUAC and NRTL model were 0.0082 and 0.135, respectively. The correlated results were in agreement with the experiment data, though the average deviations from the UNIQUAC model are slightly smaller than those from the NRTL model.
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Liquid–liquid equilibria for systems of water + methanol + Methyl Anthranilate at several temperatures
Fluid Phase Equilibria, 2011Co-Authors: Baohe Wang, Weili RanAbstract:Abstract Liquid–liquid equilibria (LLE) data for the systems of water + Methyl Anthranilate and water + methanol + Methyl Anthranilate were measured under atmospheric pressure over the temperature range of 298.15–323.15 K. Phase diagrams were obtained by determining solubility and tie-line data. The reliability of the experimental tie-line data was determined through the Bachman plots. The data were correlated using the NRTL and UNIQUAC models. Average RMSD obtained from the UNIQUAC and NRTL model were 0.0082 and 0.135, respectively. The correlated results were in agreement with the experiment data, though the average deviations from the UNIQUAC model are slightly smaller than those from the NRTL model.