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Whittock AL, Abiola TT, Stavros VG. A Perspective on Femtosecond Pump-Probe Spectroscopy in the Development of Future Sunscreens. J Phys Chem A 2022; 126:2299-2308. [PMID: 35394773 PMCID: PMC9036518 DOI: 10.1021/acs.jpca.2c01000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Given
the negative impacts of overexposure to ultraviolet radiation
(UVR) on humans, sunscreens have become a widely used product. Certain
ingredients within sunscreens are responsible for photoprotection
and these are known, collectively herein, as ultraviolet (UV) filters.
Generally speaking, organic UV filters work by absorbing the potentially
harmful UVR and dissipating this energy as harmless heat. This process
happens on picosecond time scales and so femtosecond pump–probe
spectroscopy (FPPS) is an ideal technique for tracking this energy
conversion in real time. Coupling FPPS with complementary techniques,
including steady-state spectroscopy and computational methods, can
provide a detailed mechanistic picture of how UV filters provide photoprotection.
As such, FPPS is crucial in aiding the future design of UV filters.
This Perspective sheds light on the advancements made over the past
two years on both approved and nature-inspired UV filters. Moreover,
we suggest where FPPS can be further utilized within sunscreen applications
for future considerations.
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Affiliation(s)
- Abigail L Whittock
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.,Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Temitope T Abiola
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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2
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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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3
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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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Whittock AL, Auckloo N, Cowden AM, Turner MAP, Woolley JM, Wills M, Corre C, Stavros VG. Exploring the Blueprint of Photoprotection in Mycosporine-like Amino Acids. J Phys Chem Lett 2021; 12:3641-3646. [PMID: 33826340 DOI: 10.1021/acs.jpclett.1c00728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Microorganisms require protection against the potentially damaging effects of ultraviolet radiation exposure. Photoprotection is, in part, provided by mycosporine-like amino acids (MAAs). Previous reports have proposed that nonradiative decay mediates the impressive photoprotection abilities of MAAs. In this letter, we present the first ultrafast dynamics study of two MAAs, shinorine and porphyra-334. We demonstrate that, in aqueous solution, these MAAs relax along their S1 coordinates toward the S1/S0 conical intersection within a few hundred femtoseconds after photoexcitation and then traverse the conical intersection and vibrationally cool in approximately 1 ps through heat transfer to the solvent. This new insight allows a quintessential component of microbial life to be unraveled and informs the development of molecular photon-to-heat converters for a myriad of applications.
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Affiliation(s)
- Abigail L Whittock
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
- Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Nazia Auckloo
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Adam M Cowden
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
- Molecular Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Matthew A P Turner
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Jack M Woolley
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Martin Wills
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Christophe Corre
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom
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Fois E, Oriani M, Tabacchi G. A post-HF approach to the sunscreen octyl methoxycinnamate. J Chem Phys 2021; 154:144304. [PMID: 33858162 DOI: 10.1063/5.0046118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Octyl methoxycinnamate (2-ethylhexyl 4-methoxycinnamate, OMC) is a commercial sunscreen known as octinoxate with excellent UVB filter properties. However, it is known to undergo a series of photodegradation processes that decrease its effectiveness as a UVB filter. In particular, the trans (E) form-which is considered so far as the most stable isomer-converts to the cis (Z) form under the effect of light. In this work, by using post-Hartree-Fock approaches [CCSD, CCSD(t), and CCSD + T(CCSD)] on ground state OMC geometries optimized at the MP2 level, we show that the cis and trans forms of the gas-phase OMC molecule have comparable stability. Test calculations on the same structures with a series of dispersion-corrected density functional theory-based approaches including the B2PLYP double hybrid predict the trans structures to be energetically favored, missing the subtle stabilization of cis-OMC. Our results suggest that the cis form is stabilized by intra-molecular dispersion interactions, leading to a folded more compact structure than the trans isomer.
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Affiliation(s)
- Ettore Fois
- Department of Science and High Technology, University of Insubria and INSTM UdR Insubria, Via Valleggio 11, I-22100 Como, Italy
| | - Mario Oriani
- Department of Science and High Technology, University of Insubria and INSTM UdR Insubria, Via Valleggio 11, I-22100 Como, Italy
| | - Gloria Tabacchi
- Department of Science and High Technology, University of Insubria and INSTM UdR Insubria, Via Valleggio 11, I-22100 Como, Italy
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