1
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Peng LY, Li ZW, Fang Q, Xie BB, Xia SH, Cui G. Combined QM (MS-CASPT2)/MM studies on photocyclization and photoisomerization of a fulgide derivative in toluene solution. Phys Chem Chem Phys 2022; 24:29918-29926. [PMID: 36468632 DOI: 10.1039/d2cp03807b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Photocyclization and photoisomerization of fulgides have been extensively studied experimentally and computationally due to their significant potential applications for example as photoswitches in memory devices. However, the reported excited-state decay mechanisms of fulgides do not include the effects of solvation explicitly to date. Herein, calculations using the high-level MS-CASPT2//CASSCF method were conducted to explore the photoinduced excited-state decay processes of the Eα conformer of a fulgide derivative in toluene with solvent effects treated by implicit PCM and explicit QM/MM models, respectively. Several minima and conical intersections were optimized successfully in and between the S0 and S1 states; then, two nonadiabatic excited-state decay channels that could efficiently drive the system to the ground state were proposed based on the excited-state ring-closure and isomerization paths. In addition, we also found that in the ring-closure path, the potential energy surface is essentially barrierless before approaching the conical intersection, while it needs to overcome a small energy barrier along the E → Z photoisomerization path for the nonadiabatic S1 → S0 internal conversion process. The present computational results could provide useful mechanistic insights into the photoinduced cyclization and isomerization reactions of fulgide and its derivatives.
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Affiliation(s)
- Ling-Ya Peng
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Zi-Wen Li
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Qiu Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, Zhejiang, China
| | - Shu-Hua Xia
- College of Life and Environmental Sciences, Minzu University of China, Beijing 100081, China.
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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2
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Rioux B, Combes J, Woolley JM, Rodrigues NDN, Mention MM, Stavros VG, Allais F. From Biomass-Derived p-Hydroxycinnamic Acids to Novel Sustainable and Non-Toxic Phenolics-Based UV-Filters: A Multidisciplinary Journey. Front Chem 2022; 10:886367. [PMID: 35864863 PMCID: PMC9294603 DOI: 10.3389/fchem.2022.886367] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 06/01/2022] [Indexed: 11/30/2022] Open
Abstract
Although organic UV-filters are extensively used in cosmetics to protect consumers from the deleterious effects of solar UV radiation-exposure, they suffer from some major drawbacks such as their fossil origin and their toxicity to both humans and the environment. Thus, finding sustainable and non-toxic UV-filters is becoming a topic of great interest for the cosmetic industry. A few years ago, sinapoyl malate was shown to be a powerful naturally occurring UV-filter. Building on these findings, we decided to design and optimize an entire value chain that goes from biomass to innovative biobased and non-toxic lignin-derived UV-filters. This multidisciplinary approach relies on: 1) The production of phenolic synthons using either metabolite extraction from biomass or their bioproduction through synthetic biology/fermentation/in stream product recovery; 2) their functionalization using green chemistry to access sinapoyl malate and analogues; 3) the study of their UV-filtering activity, their photostability, their biological properties; and 4) their photodynamics. This mini-review aims at demonstrating that combining biotechnology, green chemistry, downstream process and photochemistry is a powerful approach to transform biomass and, in particular lignins, into high value-added innovative UV-filters.
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Affiliation(s)
- Benjamin Rioux
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France
| | - Jeanne Combes
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France
| | - Jack M. Woolley
- Department of Chemistry, University of Warwick, Coventry, United Kingtom
| | - Natércia d. N. Rodrigues
- Department of Chemistry, University of Warwick, Coventry, United Kingtom
- Lipotec SAU, Barcelona, Spain
| | - Matthieu M. Mention
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Coventry, United Kingtom
- *Correspondence: Vasilios G. Stavros, ; Florent Allais,
| | - Florent Allais
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France
- *Correspondence: Vasilios G. Stavros, ; Florent Allais,
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3
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Chang XP, Yu L, Zhang TS, Cui G. Quantum mechanics/molecular mechanics studies on the mechanistic photophysics of sunscreen oxybenzone in methanol solution. Phys Chem Chem Phys 2022; 24:13293-13304. [PMID: 35607908 DOI: 10.1039/d2cp01263d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Herein, we have employed the QM(CASPT2//CASSCF)/MM method to explore the photophysical and photochemical mechanism of oxybenzone (OB) in methanol solution. Based on the optimized minima, conical intersections and crossing points, and minimum-energy reaction paths related to excited-state intramolecular proton transfer (ESIPT) and excited-state decay paths in the 1ππ*, 1nπ*, 3ππ*, 3nπ*, and S0 states, we have identified several feasible excited-state relaxation pathways for the initially populated S2(1ππ*) state to decay to the initial enol isomer' S0 state. The major one is the singlet-mediated and stretch-torsion coupled ESIPT pathway, in which the system first undergoes an essentially barrierless 1ππ* ESIPT process to generate the 1ππ* keto species, and finally realizes its ground state recovery through the subsequent carbonyl stretch-torsion facilitating S1 → S0 internal conversion (IC) and the reverse ground-state intramolecular proton transfer (GSIPT) process. The minor ones are related to intersystem crossing (ISC) processes. At the S2(1ππ*) minimum, an S2(1ππ*)/S1(1nπ*)/T2(3nπ*) three-state intersection region helps the S2 system branch into the T1 state through a S2 → S1 → T1 or S2 → T2 → T1 process. Once it has reached the T1 state, the system may relax to the S0 state via direct ISC or via subsequent nearly barrierless 3ππ* ESIPT to yield the T1 keto tautomer and ISC. The resultant S0 keto species significantly undergoes reverse GSIPT and only a small fraction yields the trans-keto form that relaxes back more slowly. However, due to small spin-orbit couplings at T1/S0 crossing points, the ISC to S0 state occurs very slowly. The present work rationalizes not only the ultrafast excited-state decay dynamics of OB but also its phosphorescence emission at low temperature.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China.
| | - Li Yu
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China.
| | - Teng-Shuo Zhang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China
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4
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Wong NGK, Dessent CEH. Illuminating the Effect of the Local Environment on the Performance of Organic Sunscreens: Insights From Laser Spectroscopy of Isolated Molecules and Complexes. Front Chem 2022; 9:812098. [PMID: 35096773 PMCID: PMC8789676 DOI: 10.3389/fchem.2021.812098] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/20/2021] [Indexed: 12/11/2022] Open
Abstract
Sunscreens are essential for protecting the skin from UV radiation, but significant questions remain about the fundamental molecular-level processes by which they operate. In this mini review, we provide an overview of recent advanced laser spectroscopic studies that have probed how the local, chemical environment of an organic sunscreen affects its performance. We highlight experiments where UV laser spectroscopy has been performed on isolated gas-phase sunscreen molecules and complexes. These experiments reveal how pH, alkali metal cation binding, and solvation perturb the geometric and hence electronic structures of sunscreen molecules, and hence their non-radiative decay pathways. A better understanding of how these interactions impact on the performance of individual sunscreens will inform the rational design of future sunscreens and their optimum formulations.
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Affiliation(s)
- Natalie G K Wong
- Department of Chemistry, University of York, York, United Kingdom
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5
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Chang XP, Zhang TS, Cui G. Theoretical Studies on the Excited-State Decay Mechanism of Homomenthyl Salicylate in a Gas Phase and an Acetonitrile Solution. J Phys Chem A 2021; 126:16-28. [PMID: 34963284 DOI: 10.1021/acs.jpca.1c07108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Here, we employ the CASPT2//CASSCF and QM(CASPT2//CASSCF)/MM approaches to explore the photochemical mechanism of homomenthyl salicylate (HMS) in vacuum and an acetonitrile solution. The results show that in both cases, the excited-state relaxation mainly involves a spectroscopically "bright" S1(1ππ*) state and the lower-lying T1 and T2 states. In the major relaxation pathway, the photoexcited S1 keto system first undergoes an essentially barrierless excited-state intramolecular proton transfer (ESIPT) to generate the S1 enol minimum, near which a favorable S1/S0 conical intersection decays the system to the S0 state followed by a reverse ground-state intramolecular proton transfer (GSIPT) to repopulate the initial S0 keto species. In the minor one, an S1/T2/T1 three-state intersection in the keto region makes the T1 state populated via direct and T2-mediated intersystem crossing (ISC) processes. In the T1 state, an ESIPT occurs, which is followed by ISC near a T1/S0 crossing point in the enol region to the S0 state and finally back to the S0 keto species. In addition, a T1/S0 crossing point near the T1 keto minimum can also help the system decay to the S0 keto species. However, small spin-orbit couplings between T1 and S0 at these T1/S0 crossing points make ISC to the S0 state very slow and make the system trapped in the T1 state for a while. The present work rationalizes not only the ultrafast excited-state decay dynamics of HMS but also its low quantum yield of phosphorescence at 77 K.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, P. R. China
| | - Teng-Shuo Zhang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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6
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Xie BB, Tang XF, Liu XY, Chang XP, Cui G. Mechanistic photophysics and photochemistry of unnatural bases and sunscreen molecules: insights from electronic structure calculations. Phys Chem Chem Phys 2021; 23:27124-27149. [PMID: 34849517 DOI: 10.1039/d1cp03994f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photophysics and photochemistry are basic subjects in the study of light-matter interactions and are ubiquitous in diverse fields such as biology, energy, materials, and environment. A full understanding of mechanistic photophysics and photochemistry underpins many recent advances and applications. This contribution first provides a short discussion on the theoretical calculation methods we have used in relevant studies, then we introduce our latest progress on the mechanistic photophysics and photochemistry of two classes of molecular systems, namely unnatural bases and sunscreens. For unnatural bases, we disclose the intrinsic driving forces for the ultrafast population to reactive triplet states, impacts of the position and degree of chalcogen substitutions, and the effects of complex environments. For sunscreen molecules, we reveal the photoprotection mechanisms that dissipate excess photon energy to the surroundings by ultrafast internal conversion to the ground state. Finally, relevant theoretical challenges and outlooks are discussed.
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Affiliation(s)
- Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
| | - Xiu-Fang Tang
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
| | - Xiang-Yang Liu
- College of Chemistry and Material Science, Sichuan Normal University, Chengdu, Sichuan, 610068, China
| | - Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, P. R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
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"On-The-Fly" Non-Adiabatic Dynamics Simulations on Photoinduced Ring-Closing Reaction of a Nucleoside-Based Diarylethene Photoswitch. Molecules 2021; 26:molecules26092724. [PMID: 34066431 PMCID: PMC8125013 DOI: 10.3390/molecules26092724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 04/29/2021] [Accepted: 05/03/2021] [Indexed: 11/17/2022] Open
Abstract
Nucleoside-based diarylethenes are emerging as an especial class of photochromic compounds that have potential applications in regulating biological systems using noninvasive light with high spatio-temporal resolution. However, relevant microscopic photochromic mechanisms at atomic level of these novel diarylethenes remain to be explored. Herein, we have employed static electronic structure calculations (MS-CASPT2//M06-2X, MS-CASPT2//SA-CASSCF) in combination with non-adiabatic dynamics simulations to explore the related photoinduced ring-closing reaction of a typical nucleoside-based diarylethene photoswitch, namely, PS-IV. Upon excitation with UV light, the open form PS-IV can be excited to a spectroscopically bright S1 state. After that, the molecule relaxes to the conical intersection region within 150 fs according to the barrierless relaxed scan of the C1–C6 bond, which is followed by an immediate deactivation to the ground state. The conical intersection structure is very similar to the ground state transition state structure which connects the open and closed forms of PS-IV, and therefore plays a crucial role in the photochromism of PS-IV. Besides, after analyzing the hopping structures, we conclude that the ring closing reaction cannot complete in the S1 state alone since all the C1–C6 distances of the hopping structures are larger than 2.00 Å. Once hopping to the ground state, the molecules either return to the original open form of PS-IV or produce the closed form of PS-IV within 100 fs, and the ring closing quantum yield is estimated to be 56%. Our present work not only elucidates the ultrafast photoinduced pericyclic reaction of the nucleoside-based diarylethene PS-IV, but can also be helpful for the future design of novel nucleoside-based diarylethenes with better performance.
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8
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Chang XP, Zhang TS, Fang YG, Cui G. Quantum Mechanics/Molecular Mechanics Studies on the Photophysical Mechanism of Methyl Salicylate. J Phys Chem A 2021; 125:1880-1891. [PMID: 33645980 DOI: 10.1021/acs.jpca.0c10589] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methyl salicylate (MS) as a subunit of larger salicylates found in commercial sunscreens has been shown to exhibit keto-enol tautomerization and dual fluorescence emission via excited-state intramolecular proton transfer (ESIPT) after the absorption of ultraviolet (UV) radiation. However, its excited-state relaxation mechanism is unclear. Herein, we have employed the quantum mechanics(CASPT2//CASSCF)/molecular mechanics method to explore the ESIPT and excited-state relaxation mechanism of MS in the lowest three electronic states, that is, S0, S1, and T1 states, in a methanol solution. Based on the optimized geometric and electronic structures, conical intersections and crossing points, and minimum-energy paths combined with the computed linearly interpolated Cartesian coordinate paths, the photophysical mechanism of MS has been proposed. The S1 state is a spectroscopically bright 1ππ* state in the Franck-Condon region. From the initially populated S1 state, there exist three nonradiative relaxation paths to repopulate the S0 state. In the first one, the S1 system (i.e., ketoB form) first undergoes an ESIPT path to generate an S1 tautomer (i.e., enol form) that exhibits a large Stokes shift in experiments. The generated S1 enol tautomer further evolves toward the nearby S1/S0 conical intersection and then hops to the S0 state, followed by the backward ground-state intramolecular proton transfer (GSIPT) to the initial ketoB form S0 state. In the second one, the S1 system first hops through the S1 → T1 intersystem crossing (ISC) to the T1 state, which then further decays to the S0 state via T1 → S0 ISC at the T1/S0 crossing point. In the third path, the T1 system that stems from the S1 → T1 ISC process via the S1/T1 crossing point first takes place a T1 ESIPT to generate a T1 enol tautomer, which can further decay to the S0 state via T1-to-S0 ISC. Finally, the GSIPT occurs to back the system to the initial ketoB form S0 state. Our present work could contribute to understanding the photophysics of MS and its derivatives.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, P. R. China
| | - Teng-Shuo Zhang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Ye-Guang Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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9
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Shi Y, Zhao X, Wang C, Wang Y, Zhang S, Li P, Feng X, Jin B, Yuan M, Cui S, Sun Y, Zhang B, Sun S, Jin X, Wang H, Zhao G. Ultrafast Nonadiabatic Photoisomerization Dynamics Mechanism for the UV Photoprotection of Stilbenoids in Grape Skin. Chem Asian J 2020; 15:1478-1483. [PMID: 32196972 DOI: 10.1002/asia.202000219] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 03/18/2020] [Indexed: 12/12/2022]
Abstract
Natural UV photoprotection plays a vital role in physiological protection. It has been reported that UVC radiation can make resveratrol (RSV) and piceatannol (PIC) accumulate in grape skin. In this work, we demonstrated that RSV and PIC could significantly absorb UVA and UVB, and confirmed their satisfactory photostability. Furthermore, we clarified the UV photoprotection mechanism of typical stilbenoids of RSV and PIC for the first time by using combined femtosecond transient absorption (FTA) spectroscopy and time-dependent density functional theory (TD-DFT) calculations. RSV and PIC can be photoexcited to the excited state after UVA and UVB absorption. Subsequently, the photoisomerized RSV and PIC quickly relax to the ground state via nonadiabatic transition from the S1 state at a conical intersection (CI) position between potential energy surfaces (PESs) of S1 and S0 states. This ultrafast trans-cis photoisomerization will take place within a few tens of picoseconds. As a result, the UV energy absorbed by RSV and PIC could be dissipated by an ultrafast nonadiabatic photoisomerization process.
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Affiliation(s)
- Yanan Shi
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Xiaoying Zhao
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Chao Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Ye Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Song Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Peng Li
- Institute of Molecular Sciences and Engineering, Shandong University, Qingdao, 266235, P. R. China
| | - Xia Feng
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Bing Jin
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Minghu Yuan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Shen Cui
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Yan Sun
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Bing Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Shuqing Sun
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Xiaoning Jin
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Haiyuan Wang
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
| | - Guangjiu Zhao
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences National Demonstration Center for Experimental Chemistry & Chemical engineering Education National Virtual Simulation Experimental Teaching Center for Chemistry & Chemical Engineering Education Department of Chemistry, School of Science Tianjin University, Tianjin, 300354, P. R. China
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10
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Berenbeim JA, Wong NGK, Cockett MCR, Berden G, Oomens J, Rijs AM, Dessent CEH. Unravelling the Keto-Enol Tautomer Dependent Photochemistry and Degradation Pathways of the Protonated UVA Filter Avobenzone. J Phys Chem A 2020; 124:2919-2930. [PMID: 32208697 PMCID: PMC7168606 DOI: 10.1021/acs.jpca.0c01295] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Avobenzone (AB) is
a widely used UVA filter known to undergo irreversible
photodegradation. Here, we investigate the detailed pathways by which
AB photodegrades by applying UV laser-interfaced mass spectrometry
to protonated AB ions. Gas-phase infrared multiple-photon dissociation
(IRMPD) spectra obtained with the free electron laser for infrared
experiments, FELIX, (600–1800 cm–1) are also
presented to confirm the geometric structures. The UV gas-phase absorption
spectrum (2.5–5 eV) of protonated AB contains bands that correspond
to selective excitation of either the enol or diketo forms, allowing
us to probe the resulting, tautomer-dependent photochemistry. Numerous
photofragments (i.e., photodegradants) are directly identified for
the first time, with m/z 135 and
161 dominating, and m/z 146 and
177 also appearing prominently. Analysis of the production spectra
of these photofragments reveals that that strong enol to keto photoisomerism
is occurring, and that protonation significantly disrupts the stability
of the enol (UVA active) tautomer. Close comparison of fragment ion
yields with the TD-DFT-calculated absorption spectra give detailed
information on the location and identity of the dissociative excited
state surfaces, and thus provide new insight into the photodegradation
pathways of avobenzone, and photoisomerization of the wider class
of β-diketone containing molecules.
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Affiliation(s)
- Jacob A Berenbeim
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Natalie G K Wong
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Martin C R Cockett
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Anouk M Rijs
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
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11
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Chang XP, Fang YG, Cui G. QM/MM Studies on the Photophysical Mechanism of a Truncated Octocrylene Model. J Phys Chem A 2019; 123:8823-8831. [PMID: 31550143 DOI: 10.1021/acs.jpca.9b07280] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Methyl 2-cyano-3,3-diphenylacrylate (MCDPA) shares the same molecular skeleton with octocrylene (OCR) that is one of the most common molecules used in commercially available sunscreens. However, its excited-state relaxation mechanism is unclear. Herein, we have used the QM(CASPT2//CASSCF)/MM method to explore spectroscopic properties, geometric and electronic structures, relevant conical intersections and crossing points, and excited-state relaxation paths of MCDPA in methanol solution. We found that in the Franck-Condon (FC) region, the V(1ππ*) state is energetically lower than the V'(1ππ*) state only by 2.8 kcal/mol and is assigned to experimentally observed maximum absorption band. From these two initially populated singlet states, there exist three nonradiative relaxation paths to repopulate the S0 state. In the first one, when the V(1ππ*) state is populated in the FC region, the system diabatically evolves along the V(1ππ*) state into its minimum where the internal conversion to S0 occurs. In the second one, the V'(1ππ*) state is populated in the FC region and the system adiabatically overcomes a barrier of ca. 3.0 kcal/mol to approach the V(1ππ*) minimum eventually leading to a V(1ππ*)-to-S0 internal conversion. In the third one, the V'(1ππ*) state first hops via the intersystem crossing to the T2 state, which then decays through the internal conversion to the T1 state. The T1 state is finally converted to the S0 state via the T1/S0 crossing point. Our present work contributes to understanding the photophysics of OCR and its variants.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering , Xinyang Normal University , Xinyang 464000 , P. R. China
| | - Ye-Guang Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , P. R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry , Beijing Normal University , Beijing 100875 , P. R. China
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Wong NGK, Berenbeim JA, Hawkridge M, Matthews E, Dessent CEH. Mapping the intrinsic absorption properties and photodegradation pathways of the protonated and deprotonated forms of the sunscreen oxybenzone. Phys Chem Chem Phys 2019; 21:14311-14321. [PMID: 30680382 DOI: 10.1039/c8cp06794e] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sunscreens provide vital protection against the photodamaging effects of UV radiation, however, many fundamental questions remain about the detailed mechanisms by which they dissipate UV energy. One such issue is the extent to which the pH environment of an organic sunscreen molecule alters its effectiveness, both in terms of ability to absorb UV radiation, and also its potential to photodegrade. Here, we use gas-phase laser photodissociation spectroscopy for the first time to measure the intrinsic UVA-UVC absorption spectra and associated photodegradation products of protonated and deprotonated oxybenzone, away from the complications of bulk mixtures. Our results reveal that protonation state has a dramatic effect on the absorption and photodissociation properties of this sunscreen. While the UV absorption profile of oxybenzone is only modestly affected by protonation across the range from 400-216 nm, deprotonated oxybenzone displays a significantly modified absorption spectrum, with very low photoabsorption between 370-330 nm. Protonated oxybenzone primarily photofragments by rupture of the bonds on either side of the central carbonyl group, producing cationic fragments with m/z 151 and 105. Additional lower mass photofragments (e.g. m/z 95 and 77) are also observed. The production spectra for the photofragments from protonated oxybenzone fall into two distinct categories, which we discuss in the context of different excited state decay pathways. For deprotonated oxybenzone, the major photofragments observed are m/z 211 and 212, which are associated with the ejection of methane and the methyl free radical from the parent ion, respectively. Implications for the suitability of oxybenzone in its protonated and deprotonated forms as an optimum sunscreen molecule are discussed.
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Affiliation(s)
- Natalie G K Wong
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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