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Chang XP, Fan FR, Zhang TS, Xie BB. Quantum mechanics/molecular mechanics studies on the excited-state decay mechanisms of cytidine aza-analogues: 5-azacytidine and 2'-deoxy-5-azacytidine in aqueous solution. Phys Chem Chem Phys 2023; 25:26258-26269. [PMID: 37743787 DOI: 10.1039/d3cp03628f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The excited state properties and deactivation pathways of two DNA methylation inhibitors, i.e., 5-azacytidine (5ACyd) and 2'-deoxy-5-azacytidine (5AdCyd) in aqueous solution, are comprehensively explored with the QM(CASPT2//CASSCF)/MM protocol. We systematically map the feasible decay mechanisms based on the obtained excited-state decay paths involving all the identified minimum-energy structures, conical intersections, and crossing points driving the different internal conversion (IC) and intersystem crossing (ISC) routes in and between the 1ππ*, 1nπ*, 3ππ*, 3nπ*, and S0 states. Unlike the 1nπ* state below the 1ππ* state in 5ACyd, deoxyribose group substitution at the N1 position leads to the 1ππ* state becoming the S1 state in 5AdCyd. In 5ACyd and 5AdCyd, the initially populated 1ππ* state mainly deactivates to the S0 state through the direct 1ππ* → S0 IC or mediated by the 1nπ* state. The former nearly barrierless IC channel of 1ππ* → S0 occurs ultrafast via the nearby low-lying 1ππ*/S0 conical intersection. In the latter IC channel of 1ππ* → 1nπ* → S0, the initially photoexcited 1ππ* state first approaches the nearby S2/S1 conical section 1ππ*/1nπ* and then undergoes efficient IC to the 1nπ* state, followed by the further IC to the initial S0 state via the S1/S0 conical intersection 1nπ*/S0. The 1nπ*/S0 conical intersection is estimated to be located 6.0 and 4.9 kcal mol-1 above the 1nπ* state minimum in 5ACyd and 5AdCyd, respectively, at the QM(CASPT2)/MM level. In addition to the efficient singlet-mediated IC channels, the minor ISC routes would populate 1ππ* to T1(ππ*) through 1ππ* → T1 or 1ππ* → 1nπ* → T1. Relatively, the 1ππ* → 1nπ* → T1 route benefits from the spin-orbit coupling (SOC) of 1nπ*/3ππ* of 8.7 cm-1 in 5ACyd and 10.2 cm-1 in 5AdCyd, respectively. Subsequently, the T1 system will approach the nearby T1/S0 crossing point 3ππ*/S0 driving it back to the S0 state. Given the 3ππ*/S0 crossing point located above the T1 minimum and the small T1/S0 SOC, i.e., 8.4 kcal mol-1 and 2.1 cm-1 in 5ACyd and 6.8 kcal mol-1 and 1.9 cm-1 in 5AdCyd, respectively, the slow T1 → S0 would trap the system in the T1 state for a while. The present work could contribute to understanding the mechanistic photophysics and photochemistry of similar aza-nucleosides and their derivatives.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China.
| | - Feng-Ran Fan
- 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
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, China
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Chang XP, Zhao G, Zhang TS, Xie BB. Quantum mechanics/molecular mechanics studies on mechanistic photophysics of cytosine aza-analogues: 2,4-diamino-1,3,5-triazine and 2-amino-1,3,5-triazine in aqueous solution. Phys Chem Chem Phys 2023; 25:7669-7680. [PMID: 36857660 DOI: 10.1039/d2cp05639a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The excited-state properties and photophysics of cytosine aza-analogues, i.e., 2,4-diamino-1,3,5-triazine (2,4-DT) and 2-amino-1,3,5-triazine (2-AT) in solution have been systematically explored using the QM(MS-CASPT2//CASSCF)/MM approach. The excited-state nonradiative relaxation mechanisms for the initially photoexcited S1(ππ*) state decay back to the S0 state are proposed in terms of the present computed minima, surface crossings (conical intersections and singlet-triplet crossings), and excited-state decay paths in the S1, S2, T1, T2, and S0 states. Upon photoexcitation to the bright S1(ππ*) state, 2,4-DT quickly relaxes to its S1 minimum and then overcomes a small energy barrier of 5.1 kcal mol-1 to approach a S1/S0 conical intersection, where the S1 system hops to the S0 state through S1 → S0 internal conversion (IC). In addition, at the S1 minimum, the system could partially undergo intersystem crossing (ISC) to the T1 state, followed by further ISC to the S0 state via the T1/S0 crossing point. In the T1 state, an energy barrier of 7.9 kcal mol-1 will trap 2,4-DT for a while. In parallel, for 2-AT, the system first relaxes to the S1 minimum and then S1 → S0 IC or S1 → T1 → S0 ISCs take place to the S0 state by surmounting a large barrier of 15.3 kcal mol-1 or 11.9 kcal mol-1, respectively, which heavily suppress electronic transition to the S0 state. Different from 2,4-DT, upon photoexcitation in the Franck-Condon region, 2-AT can quickly evolve in an essentially barrierless manner to nearby S2/S1 conical intersection, where the S2 and T1 states can be populated. Once it hops to the S2 state, the system will overcome a relatively small barrier (6.6 kcal mol-1vs. 15.3 kcal mol-1) through IC to the S0 state. Similarly, an energy barrier of 11.9 kcal mol-1 heavily suppresses the T1 state transformation to the S0 state. The present work manifests that the amination/deamination of the triazine rings can affect some degree of different vertical and adiabatic excitation energies and nonradiative decay pathways in solution. It not only rationalizes excited-state decay dynamics of 2,4-DT and 2-AT in aqueous solution but could also provide insights into the understanding of the photophysics of aza-nucleobases.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, China.
| | - Geng Zhao
- 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
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, Hangzhou 311231, China
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Tang XF, Jia PK, Zhao Y, Xue J, Cui G, Xie BB. A theoretical insight into excited-state decay and proton transfer of p-nitrophenylphenol in the gas phase and methanol solution. Phys Chem Chem Phys 2022; 24:20517-20529. [PMID: 35993921 DOI: 10.1039/d2cp02452g] [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
The excited-state decay (ESD) and proton transfer (EPT) of p-nitrophenylphenol (NO2-Bp-OH), especially in the triplet states, were not characterized with high-level theoretical methods to date. Herein, the MS-CASPT2//CASSCF and QM(MS-CASPT2//CASSCF)/MM methods were employed to gain an atomic-level understanding of the ESD and EPT of NO2-Bp-OH in the gas phase and its hydrogen-bonded complex in methanol. Our calculation results revealed that the S1 and S2 states of NO2-Bp-OH are of 1ππ* and 1nπ* characters at the Franck-Condon (FC) point, which correspond to the ICT-EPT and intramolecular charge-transfer (ICT) states in spectroscopic experiments. The former state has a charge-transfer property that could facilitate the EPT reaction, while the latter one might be unfavorable for EPT. The vertical excitation energies of these states are almost degenerate at the FC region and the electronic configurations of 1ππ* and 1nπ* will exchange from the S1 FC region to the S1 minimum, which means that the 1nπ* state will participate in ESD once NO2-Bp-OH departs from the S1 FC region. Besides, we found that three triplets lie below the first bright state and will play very important roles in intersystem crossing processes. In terms of several pivotal surface crossings and relevant linearly interpolated internal coordinate (LIIC) paths, three feasible but competing ESD channels that could effectively lead the system to the ground state or the lowest triplet state were put forward. Once arrived at the T1 state, the system has enough time and internal energy to undergo the EPT reaction. The methanol solvent has a certain effect on the relative energies and spin-orbit couplings, but does not qualitatively change the ESD processes of NO2-Bp-OH. By contrast, the solvent effects will remarkably stabilize the proton-transferred product by the hydrogen bond networks and assist to form the triplet anion. Our present work would pave the road to properly understand the mechanistic photochemistry of similar hydroxyaromatic compounds.
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Affiliation(s)
- Xiu-Fang Tang
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
| | - Pei-Ke Jia
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
| | - Yanying Zhao
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, Zhejiang, P. R. China.
| | - Jiadan Xue
- Department of Chemistry, Zhejiang Sci-Tech University, Hangzhou 310018, Zhejiang, 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
| | - Bin-Bin Xie
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
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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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Nomoto A, Inai N, Yanai T, Okuno Y. Substituent and Solvent Effects on the Photoisomerization of Cinnamate Derivatives: An XMS-CASPT2 Study. J Phys Chem A 2022; 126:497-505. [PMID: 35067053 DOI: 10.1021/acs.jpca.1c08504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cinnamate derivatives show a variety of photo-induced reactions. Among them is trans-cis photoisomerization, which may involve the nonradiative decay (NRD) process. The extended multistate complete active space second-order perturbation (XMS-CASPT2) method was used in this study as a suitable theory for treating multireference electronic nature, which was frequently manifested in the photoisomerization process. The minimum energy paths of the trans-cis photoisomerization process of cinnamate derivatives were determined, and the activation energies were estimated using the resulting intrinsic reaction coordinate (IRC) paths. Natural orbital analysis revealed that the transition state's (TS) electronic structure is zwitterionic-like, elucidating the solvent and substituent effect on the energy barrier of photoisomerization paths. Furthermore, it was found that the charge on the pyramidalized carbon atom at the TS structure was strongly correlated with the activation energy barrier for the cinnamate derivatives. Thus, it seemingly provided a physical picture of the photoisomerization of cinnamates and was a good descriptor potentially applicable to molecular design for controlling the rate constant of the photoisomerization reaction.
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Affiliation(s)
- Atsuro Nomoto
- Analysis Technology Center, FUJIFILM Corporation, 210 Nakanuma, Minamiashigara, Kanagawa 250-0193, Japan
| | - Naoto Inai
- Department of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Takeshi Yanai
- Department of Chemistry, Graduate School of Science, Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan.,Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furocho, Chikusa, Nagoya, Aichi 464-8601, Japan
| | - Yukihiro Okuno
- Analysis Technology Center, FUJIFILM Corporation, 210 Nakanuma, Minamiashigara, Kanagawa 250-0193, Japan
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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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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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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: 12] [Impact Index Per Article: 4.0] [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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Li B, Zhang TS, Xue J, Xie BB, Fang WH, Shen L. Theoretical studies on the photochemistry of 2-nitrofluorene in the gas phase and acetonitrile solution. Phys Chem Chem Phys 2020; 22:16772-16782. [PMID: 32662496 DOI: 10.1039/d0cp01969k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The photophysical and photochemical mechanisms of 2-nitrofluorene (2-NF) in the gas phase and acetonitrile solution have been studied theoretically. Upon ∼330 nm irradiation to the first bright state (1ππ*), the 2-NF system can decay to triplet excited states via rapid intersystem crossing (ISC) processes through different surface crossing points or to the ground state via an ultrafast internal conversion (IC) process through the S1/S0 conical intersection. The 1nπ* dark state will serve as a bridge when the system leaves the Franck-Condon (FC) region and approaches to the S1 minimum. The molecule maintains a planar geometry during the excited-state relaxation processes. The differences on excitation properties such as electronic configurations and spin-orbit coupling (SOC) interactions between those in the gas phase and acetonitrile solution cannot be neglected, indicating possible changes on the efficiency of the related ISC processes for the 2-NF system in solution. Once arrived at the T1 state, it would further decay to the S0 state or photodegrade into the Ar-O˙ and NO˙ free radicals. During the intramolecular rearrangement process, the twisting of the nitro group out of the aromatic-ring plane is regarded as a critical structural variation for the photodegradation of the 2-NF system. The free radicals finally form through oxaziridine-type intermediate and transition state structures. The present work provides important mechanistic insights to the photochemistry of nitro-substituted polyaromatic compounds.
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Affiliation(s)
- Bo Li
- Hangzhou Institute of Advanced Studies, Zhejiang Normal University, 1108 Gengwen Road, Hangzhou 311231, Zhejiang, P. R. China.
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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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