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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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Aswathy LB, Deepthi A, Jayasree EG. An insight into the dual fluorescence of 3,6-dihydroxybenzene-1,2,4,5-tetracarboxylic acid tetraethyl ester - An experimental and theoretical study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 252:119496. [PMID: 33530030 DOI: 10.1016/j.saa.2021.119496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/01/2021] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
The Excited State Intramolecular Proton Transfer (ESIPT) phenomenon involving photo-induced keto-enol tautomerization is known to cause significant variations in the excited state structures and photophysical properties of certain molecules. Here, the dual emission exhibited by 3,6-dihydroxybenzene-1,2,4,5-tetracarboxylic acid tetraethyl ester has been studied both experimentally and theoretically and it is concluded that the second emission is due to ESIPT in polar protic solvents, while it is due to dianion formation in solvents like DMSO and DMF.
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Affiliation(s)
- L B Aswathy
- Department of Chemistry, University of Kerala, Kariavattom Campus, Thiruvananthapuram 695581, Kerala, India
| | - Ani Deepthi
- Department of Chemistry, University of Kerala, Kariavattom Campus, Thiruvananthapuram 695581, Kerala, India.
| | - E G Jayasree
- Department of Chemistry, University of Kerala, Kariavattom Campus, Thiruvananthapuram 695581, Kerala, India.
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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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Singhal D, Althagafi I, Kumar A, Yadav S, Prasad AK, Pratap R. Thieno[3,2-c]pyran: an ESIPT based fluorescence “turn-on” molecular chemosensor with AIE properties for the selective recognition of Zn2+ ion. NEW J CHEM 2020. [DOI: 10.1039/d0nj02236e] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Thieno[3,2-c]pyran was synthesized as a fluorescent turn-on chemosensor for the selective recognition of Zn2+ ions with a low detection limit (0.67 μM), and it also exhibited AIE properties.
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Affiliation(s)
- Divya Singhal
- Department of Chemistry
- University of Delhi, North Campus
- Delhi-110007
- India
| | | | - Ashish Kumar
- Department of Chemistry
- University of Delhi, North Campus
- Delhi-110007
- India
| | - Saroj Yadav
- Department of Chemistry
- University of Delhi, North Campus
- Delhi-110007
- India
| | - Ashok K. Prasad
- Department of Chemistry
- University of Delhi, North Campus
- Delhi-110007
- India
| | - Ramendra Pratap
- Department of Chemistry
- University of Delhi, North Campus
- Delhi-110007
- India
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Ling F, Liu D, Li S, Li W, Zhang B, Wang P. Femtosecond real-time probing of the excited-state intramolecular proton transfer reaction in methyl salicylate. J Chem Phys 2019; 151:094302. [PMID: 31492073 DOI: 10.1063/1.5115307] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The excited-state intramolecular proton transfer (ESIPT) process and subsequent electronic relaxation dynamics in methyl salicylate have been investigated using femtosecond time-resolved ion yield spectroscopy combined with time-resolved photoelectron imaging. Excitation with a tunable pump pulse populates the keto tautomer in the first excited electronic state S1(ππ*). As a hydrogen atom transfers from the phenolic group to the carbonyl group within 100 fs, the molecular geometry changes gradually, leading to a variation in the electronic photoionization channel. By virtue of the accidental resonance with some intermediate Rydberg states, the time-dependent photoelectron spectra provide a direct mapping of the ESIPT reaction from the initially populated keto tautomer to the proton-transferred enol tautomer. Subsequently, the population around the enol configuration undergoes intramolecular vibrational redistribution on a subpicosecond time scale, followed by internal conversion to the ground state with a wavelength-dependent lifetime in the picosecond range. Furthermore, the excitation energies of several Rydberg states in methyl salicylate are determined experimentally.
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Affiliation(s)
- Fengzi Ling
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Dejun Liu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Shuai Li
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Wei Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, 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
| | - Pengfei Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
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Abstract
This work revises some anomalous cases reported in the literature, which seemingly violate Kasha's rule. To the contrary, apart from azulene, the remaining molecules fulfill Kasha's rule. Kasha's rule must be stated just as in the seminal paper (M. Kasha, Discuss. Faraday Soc., 1950, 9, 14-19): "The emitting electronic level of a given multiplicity is the lowest excited level of that multiplicity". Therefore, Kasha's rule focuses on the emission (photophysics) for complex molecules, in condensed phase, for the absorption of one photon per molecule under photostationary conditions, then a rapid internal conversion and a vibrational relaxation warrant that the corresponding emission comes from the first excited electronic level regardless of which electronic state of equal multiplicity is excited.
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Affiliation(s)
- Juan Carlos Del Valle
- Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, C-2-203. E-28049, Cantoblanco, Madrid, Spain.
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Sai Reddy D, Mukhina OA, Cole Cronk W, Kutateladze AG. Polyheterocycle-carbohydrate chimeras: photoassisted synthesis of 2,5-epoxybenzoxacines and 2,5-epoxybenzazocine scaffolds and their postphotochemical hydroxylations. PURE APPL CHEM 2017. [DOI: 10.1515/pac-2016-0915] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AbstractPhotoassisted synthesis of complex polyheterocyclic molecular architectures via excited state intramolecular proton transfer (ESIPT) is for the first time implemented for the reactions of o-keto phenols. This adds the 2,5-epoxybenzoxacine core to the previously obtained 2,5-epoxybenzazocine cores and offers rapid access to primary photoproducts which lend themselves to diverse yet simple postphotochemical modifications to further grow the complexity of the target structures, specifically – access to polyheterocycle-carbohydrate chimeras containing up to five contiguous stereogenic centers and benzazocine or benzoxacine heterocyclic cores.
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Affiliation(s)
- D. Sai Reddy
- 1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Olga A. Mukhina
- 1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - W. Cole Cronk
- 1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Andrei G. Kutateladze
- 1Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
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Catalán J. Effects of Charge Transfer on the ESIPT Process in Methyl 5-R-Salicylates. J Phys Chem B 2014; 119:2132-9. [DOI: 10.1021/jp502691y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- J. Catalán
- Departamento de Química
Física Aplicada, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
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Zhou P, Hoffmann MR, Han K, He G. New Insights into the Dual Fluorescence of Methyl Salicylate: Effects of Intermolecular Hydrogen Bonding and Solvation. J Phys Chem B 2014; 119:2125-31. [DOI: 10.1021/jp501881j] [Citation(s) in RCA: 138] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Panwang Zhou
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
| | - Mark R. Hoffmann
- Department
of Chemistry, University of North Dakota, Abbott Hall Room 236, 151 Cornell
Street Stop 9024, Grand Forks, North Dakota 58202-9024, United States
| | - Keli Han
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
| | - Guozhong He
- State
Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of
Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China
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Qu P, Tian D. TDDFT study on intramolecular hydrogen bond of photoexcited methyl salicylate. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 120:529-533. [PMID: 24374479 DOI: 10.1016/j.saa.2013.11.112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 11/01/2013] [Accepted: 11/26/2013] [Indexed: 06/03/2023]
Abstract
The equilibrium geometries, IR-spectra and transition mechanism of intramolecular hydrogen-bonded methyl salicylate in excited state were studied using DFT and TDDFT with 6-31++G (d, p) basis set. The length of hydrogen bond OH⋯OC is decreased from 1.73 Å in the ground state to 1.41 and 1.69 Å in the excited S1 and S3 states. The increase of bond length for HO and CO group also indicates that in excited state the hydrogen bond OH⋯OC is strengthened. IR spectra show HO and CO stretching bands are strongly redshifted by 1387 and 67 cm(-1) in the excited S1 and S3 states comparing to the ground state. The excitation energy and the absorption spectrum show the S3 state is the main excited state of the low-lying excited states. By analyzing the frontier molecular orbitals, the transition from the ground state to the excited S1 and S3 states was predicted to be the π→π∗ mode.
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Affiliation(s)
- Peng Qu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Dongxu Tian
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China.
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Lan X, Yang D, Sui X, Wang D. Time-dependent density functional theory (TD-DFT) study on the excited-state intramolecular proton transfer (ESIPT) in 2-hydroxybenzoyl compounds: significance of the intramolecular hydrogen bonding. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2013; 102:281-285. [PMID: 23220669 DOI: 10.1016/j.saa.2012.10.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 10/08/2012] [Accepted: 10/13/2012] [Indexed: 06/01/2023]
Abstract
The excited-state properties of intramolecular hydrogen bonding (IMHB) in methyl salicylate (MS) and its effects on the excited-state intramolecular proton transfer (ESIPT) have been investigated using theoretical methods. From the geometric optimization and IR spectra in the ground and excited states calculated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods respectively, the IMHB is demonstrated to be significantly strengthened upon excitation to excited state S(1). Thereby, the ESIPT is facilitated by the excited-state IMHB strengthening since ESIPT takes place through IMHB. In addition, the absorption and fluorescence peaks of the S(1) state are also calculated using the TD-DFT method. It is noted that the calculated spectra are in good agreement with the experimental results, which has confirmed the ESIPT mechanism of MS first proposed by Weller. Moreover, other four 2-hydroxybenzoyl compounds forming strong IMHB are investigated to understand the effect of substituent R on the ESIPT process. We find that the hydrogen bond strength can be controlled by the inductive field effect of the substituent. Thus it is inferred that the ESIPT reaction can be facilitated by the inductive effect of electron-donating substituent.
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Affiliation(s)
- Xin Lan
- School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
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