1
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Jordan CJC, Coons MP, Herbert JM, Verlet JRR. Spectroscopy and dynamics of the hydrated electron at the water/air interface. Nat Commun 2024; 15:182. [PMID: 38167300 PMCID: PMC10762076 DOI: 10.1038/s41467-023-44441-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024] Open
Abstract
The hydrated electron, e-(aq), has attracted much attention as a central species in radiation chemistry. However, much less is known about e-(aq) at the water/air surface, despite its fundamental role in electron transfer processes at interfaces. Using time-resolved electronic sum-frequency generation spectroscopy, the electronic spectrum of e-(aq) at the water/air interface and its dynamics are measured here, following photo-oxidation of the phenoxide anion. The spectral maximum agrees with that for bulk e-(aq) and shows that the orbital density resides predominantly within the aqueous phase, in agreement with supporting calculations. In contrast, the chemistry of the interfacial hydrated electron differs from that in bulk water, with e-(aq) diffusing into the bulk and leaving the phenoxyl radical at the surface. Our work resolves long-standing questions about e-(aq) at the water/air interface and highlights its potential role in chemistry at the ubiquitous aqueous interface.
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Affiliation(s)
| | - Marc P Coons
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - John M Herbert
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA.
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 4LJ, UK.
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2
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Whittock AL, Cowden AM, Wills M, Stavros VG. Examining the substituent effect on mycosporine-inspired ultraviolet filters. Phys Chem Chem Phys 2023; 25:7401-7406. [PMID: 36846923 DOI: 10.1039/d2cp05934g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Current organic ultraviolet (UV) filters found in sunscreen formulations suffer a number of drawbacks. In this work, we have synthesised four biomimetic molecules built on the mycosporine molecular scaffold (a natural UV filter) with varying substituents at one of the carbons on the ring and investigated their photoprotective properties. From our findings, we infer design guidelines which may have a direct result on the production of next generation UV filters.
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Affiliation(s)
- Abigail L Whittock
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK. .,Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, CV4 7AL, UK
| | - Adam M Cowden
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK. .,Molecular Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, CV4 7AL, UK
| | - Martin Wills
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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3
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Scholz M, Fortune WG, Tau O, Fielding HH. Accurate Vertical Ionization Energy of Water and Retrieval of True Ultraviolet Photoelectron Spectra of Aqueous Solutions. J Phys Chem Lett 2022; 13:6889-6895. [PMID: 35862937 PMCID: PMC9358712 DOI: 10.1021/acs.jpclett.2c01768] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/14/2022] [Indexed: 05/23/2023]
Abstract
Ultraviolet (UV) photoelectron spectroscopy provides a direct way of measuring valence electronic structure; however, its application to aqueous solutions has been hampered by a lack of quantitative understanding of how inelastic scattering of low-energy (<5 eV) electrons in liquid water distorts the measured electron kinetic energy distributions. Here, we present an efficient and widely applicable method for retrieving true UV photoelectron spectra of aqueous solutions. Our method combines Monte Carlo simulations of electron scattering and spectral inversion, with molecular dynamics simulations of depth profiles of organic solutes in aqueous solution. Its application is demonstrated for both liquid water, and aqueous solutions of phenol and phenolate, which are ubiquitous biologically relevant structural motifs.
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4
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Jordan CJC, Lowe EA, Verlet JRR. Photooxidation of the Phenolate Anion is Accelerated at the Water/Air Interface. J Am Chem Soc 2022; 144:14012-14015. [PMID: 35900260 PMCID: PMC9376918 DOI: 10.1021/jacs.2c04935] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Molecular photodynamics can be dramatically affected
at the water/air
interface. Probing such dynamics is challenging, with product formation
often probed indirectly through its interaction with interfacial water
molecules using time-resolved and phase-sensitive vibrational sum-frequency
generation (SFG). Here, the photoproduct formation of the phenolate
anion at the water/air interface is probed directly using time-resolved
electronic SFG and compared to transient absorption spectra in bulk
water. The mechanisms are broadly similar, but 2 to 4 times faster
at the surface. An additional decay is observed at the surface which
can be assigned to either diffusion of hydrated electrons from the
surface into the bulk or due to increased geminate recombination at
the surface. These overall results are in stark contrast to phenol,
where dynamics were observed to be 104 times faster and
for which the hydrated electron was also a photoproduct. Our attempt
to probe phenol showed no electron signal at the interface.
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Affiliation(s)
- Caleb J C Jordan
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
| | - Eleanor A Lowe
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham, DH1 3LE, United Kingdom
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5
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Bin Mohd Yusof MS, Song H, Debnath T, Lowe B, Yang M, Loh ZH. Ultrafast proton transfer of the aqueous phenol radical cation. Phys Chem Chem Phys 2022; 24:12236-12248. [PMID: 35579397 DOI: 10.1039/d2cp00505k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Proton transfer (PT) reactions are fundamental to numerous chemical and biological processes. While sub-picosecond PT involving electronically excited states has been extensively studied, little is known about ultrafast PT triggered by photoionization. Here, we employ femtosecond optical pump-probe spectroscopy and quantum dynamics calculations to investigate the ultrafast proton transfer dynamics of the aqueous phenol radical cation (PhOH˙+). Analysis of the vibrational wave packet dynamics reveals unusually short dephasing times of 0.18 ± 0.02 ps and 0.16 ± 0.02 ps for the PhOH˙+ O-H wag and bend frequencies, respectively, suggestive of ultrafast PT occurring on the ∼0.1 ps timescale. The reduced potential energy surface obtained from ab initio calculations shows that PT is barrierless when it is coupled to the intermolecular hindered translation between PhOH˙+ and the proton-acceptor water molecule. Quantum dynamics calculations yield a lifetime of 193 fs for PhOH˙+, in good agreement with the experimental results and consistent with the PT reaction being mediated by the intermolecular O⋯O stretch. These results suggest that photoionization can be harnessed to produce photoacids that undergo ultrafast PT. In addition, they also show that PT can serve as an ultrafast deactivation channel for limiting the oxidative damage potential of radical cations.
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Affiliation(s)
- Muhammad Shafiq Bin Mohd Yusof
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Hongwei Song
- State Key Laboratory for Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China
| | - Tushar Debnath
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Bethany Lowe
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
| | - Minghui Yang
- State Key Laboratory for Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.,Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430071, China
| | - Zhi-Heng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
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6
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Investigating the Ultrafast Dynamics and Long-Term Photostability of an Isomer Pair, Usujirene and Palythene, from the Mycosporine-like Amino Acid Family. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27072272. [PMID: 35408670 PMCID: PMC9000306 DOI: 10.3390/molecules27072272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 11/17/2022]
Abstract
Mycosporine-like amino acids are a prevalent form of photoprotection in micro- and macro-organisms. Using a combination of natural product extraction/purification and femtosecond transient absorption spectroscopy, we studied the relaxation pathway for a common mycosporine-like amino acid pair, usujirene and its geometric isomer palythene, in the first few nanoseconds following photoexcitation. Our studies show that the electronic excited state lifetimes of these molecules persist for only a few hundred femtoseconds before the excited state population is funneled through an energetically accessible conical intersection with subsequent vibrational energy transfer to the solvent. We found that a minor portion of the isomer pair did not recover to their original state within 3 ns after photoexcitation. We investigated the long-term photostability using continuous irradiation at a single wavelength and with a solar simulator to mimic a more real-life environment; high levels of photostability were observed in both experiments. Finally, we employed computational methods to elucidate the photochemical and photophysical properties of usujirene and palythene as well as to reconcile the photoprotective mechanism.
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7
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Tau O, Henley A, Boichenko AN, Kleshchina NN, Riley R, Wang B, Winning D, Lewin R, Parkin IP, Ward JM, Hailes HC, Bochenkova AV, Fielding HH. Liquid-microjet photoelectron spectroscopy of the green fluorescent protein chromophore. Nat Commun 2022; 13:507. [PMID: 35082282 PMCID: PMC8791993 DOI: 10.1038/s41467-022-28155-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 01/11/2022] [Indexed: 01/08/2023] Open
Abstract
Green fluorescent protein (GFP), the most widely used fluorescent protein for in vivo monitoring of biological processes, is known to undergo photooxidation reactions. However, the most fundamental property underpinning photooxidation, the electron detachment energy, has only been measured for the deprotonated GFP chromophore in the gas phase. Here, we use multiphoton ultraviolet photoelectron spectroscopy in a liquid-microjet and high-level quantum chemistry calculations to determine the electron detachment energy of the GFP chromophore in aqueous solution. The aqueous environment is found to raise the detachment energy by around 4 eV compared to the gas phase, similar to calculations of the chromophore in its native protein environment. In most cases, electron detachment is found to occur resonantly through electronically excited states of the chromophore, highlighting their importance in photo-induced electron transfer processes in the condensed phase. Our results suggest that the photooxidation properties of the GFP chromophore in an aqueous environment will be similar to those in the protein. The electronic structures of photoactive proteins underlie many natural photoinduced processes. The authors, using UV liquid-microjet photoelectron spectroscopy and quantum chemistry calculations, determine electron detachment energies of the green fluorescent protein chromophore in aqueous solution, approaching conditions of the protein environment.
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Affiliation(s)
- Omri Tau
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Alice Henley
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Anton N Boichenko
- Department of Chemistry, Lomonosov Moscow State University, 119991, Moscow, Russia
| | | | - River Riley
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Bingxing Wang
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.,College of Chemistry and Chemical Engineering, Henan Institute of Science and Technology, Eastern Hualan Avenue, Xinxiang, 453003, China
| | - Danielle Winning
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Ross Lewin
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Ivan P Parkin
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - John M Ward
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Gower Street, London, WC1E 6BT, UK
| | - Helen C Hailes
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | | | - Helen H Fielding
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK.
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8
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Sotome H, Koga M, Sawada T, Miyasaka H. Femtosecond Dynamics of Stepwise Two-Photon Ionization in Solutions as Revealed by Pump-Repump-Probe Detection with Burst Mode of Photoexcitation. Phys Chem Chem Phys 2022; 24:14187-14197. [DOI: 10.1039/d1cp03866d] [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
Pump-repump-probe spectroscopy with a burst mode of photoexcitation was applied to the direct observation of photoionization dynamics of perylene in the solution phase. The irradiation of the pump pulse train...
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9
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Tamarit L, El Ouardi M, Lence E, Andreu I, González-Bello C, Vayá I, Miranda MA. Switching from ultrafast electron transfer to proton transfer in excited drug–protein complexes upon biotransformation. Chem Sci 2022; 13:9644-9654. [PMID: 36091919 PMCID: PMC9400592 DOI: 10.1039/d2sc03257k] [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] [Received: 06/10/2022] [Accepted: 08/02/2022] [Indexed: 11/23/2022] Open
Abstract
Photosensitization by drugs is directly related with the excited species and the photoinduced processes arising from interaction with UVA light. In this context, the ability of gefitinib (GFT), a tyrosine kinase inhibitor (TKI) used for the treatment of a variety of cancers, to induce phototoxicity and photooxidation of proteins has recently been demonstrated. In principle, photodamage can be generated not only by a given drug but also by its photoactive metabolites that maintain the relevant chromophore. In the present work, a complete study of O-desmorpholinopropyl gefitinib (GFT-MB) has been performed by means of fluorescence and ultrafast transient absorption spectroscopies, in addition to molecular dynamics (MD) simulations. The photobehavior of the GFT-MB metabolite in solution is similar to that of GFT. However, when the drug or its metabolite are in a constrained environment, i.e. within a protein, their behavior and the photoinduced processes that arise from their interaction with UVA light are completely different. For GFT in complex with human serum albumin (HSA), locally excited (LE) singlet states are mainly formed; these species undergo photoinduced electron transfer with Tyr and Trp. By contrast, since GFT-MB is a phenol, excited state proton transfer (ESPT) to form phenolate-like excited species might become an alternative deactivation pathway. As a matter of fact, the protein-bound metabolite exhibits higher fluorescence yields and longer emission wavelengths and lifetimes than GFT@HSA. Ultrafast transient absorption measurements support direct ESPT deprotonation of LE states (rather than ICT), to form phenolate-like species. This is explained by MD simulations, which reveal a close interaction between the phenolic OH group of GFT-MB and Val116 within site 3 (subdomain IB) of HSA. The reported findings are relevant to understand the photosensitizing properties of TKIs and the role of biotransformation in this type of adverse side effects. The photoinduced processes from the protein-bound GFT result in electron transfer, while those related with the photoactive metabolite GFT-MB induce excited state proton transfer to form phenolate-like excited species.![]()
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Affiliation(s)
- Lorena Tamarit
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain
- Instituto de Investigación Sanitaria La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026 Valencia, Spain
| | - Meryem El Ouardi
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain
- Instituto de Investigación Sanitaria La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026 Valencia, Spain
| | - Emilio Lence
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - Inmaculada Andreu
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain
- Instituto de Investigación Sanitaria La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026 Valencia, Spain
| | - Concepción González-Bello
- Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CiQUS), Departamento de Química Orgánica, Universidade de Santiago de Compostela, Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain
| | - Ignacio Vayá
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain
- Instituto de Investigación Sanitaria La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026 Valencia, Spain
| | - Miguel A. Miranda
- Departamento de Química/Instituto de Tecnología Química UPV-CSIC, Universitat Politècnica de València, Camino de Vera s/n, 46022 València, Spain
- Instituto de Investigación Sanitaria La Fe, Hospital Universitari i Politècnic La Fe, Avenida de Fernando Abril Martorell 106, 46026 Valencia, Spain
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10
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Jordan CJC, Verlet JRR. Time-resolved electronic sum-frequency generation spectroscopy with fluorescence suppression using optical Kerr gating. J Chem Phys 2021; 155:164202. [PMID: 34717361 DOI: 10.1063/5.0065460] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Excited state dynamics of molecules at interfaces can be studied using second-order non-linear spectroscopic methods such as time-resolved electronic sum-frequency generation (SFG). However, as such measurements inherently generate very small signals, they are often overwhelmed by signals originating from fluorescence. Here, this limitation is overcome by optical Kerr gating of the SFG signal to discriminate against fluorescence. The new approach is demonstrated on the excited state dynamics of malachite green at the water/air interface, in the presence of a highly fluorescent coumarin dye, and on the photo-oxidation of the phenolate anion at the water/air interface. The generality of the use of optical Kerr gating to SFG measurements is discussed.
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Affiliation(s)
- Caleb J C Jordan
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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11
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Koga M, Miyake Y, Hayasaka M, Sotome H, Miyasaka H. Slow photoionization via higher excited states of N,N-dimethylaniline in ethanol solution probed by femtosecond transient absorption spectroscopy under two-pulse two-photon excitation. J Chem Phys 2021; 154:054304. [PMID: 33557537 DOI: 10.1063/5.0028018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Photoionization dynamics of N,N-dimethylaniline (DMA) from highly electronically excited states in ethanol solution was investigated by means of femtosecond two-pulse two-photon excitation transient absorption (2PE-TA) spectroscopy. The first pump pulse prepares the lowest singlet excited state (S1 state) of DMA, and the second one excites the S1 state into higher excited states. In the case with the second pulse at 500 nm, the ionization took place via a rapid channel (<100 fs) and a slow one with the time constant of ∼10 ps. The excitation wavelength effect of the second pulse indicated that a specific electronic state produced directly from higher excited states was responsible for the slow ionization. By integrating these results with the time evolution of the transient absorption spectra of the solvated electron in neat ethanol detected by the simultaneous two-photon excitation, it was revealed that the slow ionization of DMA in ethanol was regulated by the formation of the anionic species just before the completion of the solvation of the electron, leading to the solvated electron in the relaxed state. From these results, it was strongly suggested that the capture of the electron of the Rydberg-like state by the solvent or solvent cluster regulates the appearance of the cation radical.
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Affiliation(s)
- Masafumi Koga
- Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Yuto Miyake
- Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Mizuki Hayasaka
- Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hikaru Sotome
- Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Hiroshi Miyasaka
- Division of Frontier Materials Science, Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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12
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Liang K, Li T, Li N, Zhang Y, Shen L, Ma Z, Xia C. Redox-neutral photochemical Heck-type arylation of vinylphenols activated by visible light. Chem Sci 2020; 11:2130-2135. [PMID: 34123301 PMCID: PMC8150107 DOI: 10.1039/c9sc06184c] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 01/10/2020] [Indexed: 12/12/2022] Open
Abstract
Disclosed herein is a photochemical Heck-type arylation of vinylphenols with non-activated aryl and heteroaryl halides under visible light irradiation. Preliminary mechanistic studies suggested that the colored vinylphenolate anions acted as a strong reducing photoactivator to directly activate (hetero)aryl halides without the need for any sacrificial reductants. The photochemically generated aryl radicals coupled with another molecule of vinylphenol to afford the Heck-type arylation product in a regiospecific and stereoselective manner. The developed photochemical arylation protocol showed exceptional functional group tolerance and was successfully applied in the challenging late-stage modification of natural products without any protection-deprotection procedures.
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Affiliation(s)
- Kangjiang Liang
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Tao Li
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Na Li
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Yang Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Lei Shen
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Zhixian Ma
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
| | - Chengfeng Xia
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province), State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, School of Chemical Science and Technology, Library of Yunnan University, Yunnan University 2 North Cuihu Road Kunming 650091 China
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13
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Liang K, Liu Q, Shen L, Li X, Wei D, Zheng L, Xia C. Intermolecular oxyarylation of olefins with aryl halides and TEMPOH catalyzed by the phenolate anion under visible light. Chem Sci 2020. [DOI: 10.1039/d0sc02160a] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The phenolate anion was developed as a new photocatalyst with strong reduction potentials (−3.16 V vs. SCE) to reduction of aryl halides to aryl radicals through single electron transfer.
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Affiliation(s)
- Kangjiang Liang
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Qian Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Lei Shen
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Xipan Li
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Delian Wei
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Liyan Zheng
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
| | - Chengfeng Xia
- Key Laboratory of Medicinal Chemistry for Natural Resource (Ministry of Education and Yunnan Province)
- State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan
- School of Chemical Science and Technology
- Yunnan University
- Kunming 650091
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14
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Ultrafast structural rearrangement dynamics induced by the photodetachment of phenoxide in aqueous solution. Nat Commun 2019; 10:2944. [PMID: 31270331 PMCID: PMC6610110 DOI: 10.1038/s41467-019-10989-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 06/14/2019] [Indexed: 01/28/2023] Open
Abstract
The elementary processes that accompany the interaction of ionizing radiation with biologically relevant molecules are of fundamental importance. However, the ultrafast structural rearrangement dynamics induced by the ionization of biomolecules in aqueous solution remain hitherto unknown. Here, we employ femtosecond optical pump-probe spectroscopy to elucidate the vibrational wave packet dynamics that follow the photodetachment of phenoxide, a structural mimic of tyrosine, in aqueous solution. Photodetachment of phenoxide leads to wave packet dynamics of the phenoxyl radical along 12 different vibrational modes. Eight of the modes are totally symmetric and support structural rearrangement upon electron ejection. Comparison to a previous photodetachment study of phenoxide in the gas phase reveals the important role played by the solvent environment in driving ultrafast structural reorganization induced by ionizing radiation. This work provides insight into the ultrafast molecular dynamics that follow the interaction of ionizing radiation with molecules in aqueous solution. The interaction of biomolecules with ionizing radiation induces structural changes which are still largely unknown. The authors use femtosecond wave packet spectroscopy to observe ultrafast structural dynamics that follow the photodetachment of phenoxide in aqueous solution.
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15
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Rohman MA, Sutradhar D, Bangal PR, Chandra AK, Mitra S. Excited State Decay Dynamics in 3‐Formyl‐4‐hydroxy Benzoic Acid: Understanding the Global Picture of an ESIPT‐Driven Multiple‐Emissive Species. ChemistrySelect 2019. [DOI: 10.1002/slct.201901570] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mostofa Ataur Rohman
- Centre for Advanced StudiesDepartment of ChemistryNorth-Eastern Hill University Shillong – 793022 India
| | - Dipankar Sutradhar
- Centre for Advanced StudiesDepartment of ChemistryNorth-Eastern Hill University Shillong – 793022 India
| | - Prakriti Ranjan Bangal
- Inorganic & Physical Chemistry DivisionCSIR-Indian Institute of Chemical Technology, Tarnaka Hyderabad- 500007, Telangana India
| | - Asit K. Chandra
- Centre for Advanced StudiesDepartment of ChemistryNorth-Eastern Hill University Shillong – 793022 India
| | - Sivaprasad Mitra
- Centre for Advanced StudiesDepartment of ChemistryNorth-Eastern Hill University Shillong – 793022 India
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16
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Tyson AL, Verlet JRR. On the Mechanism of Phenolate Photo-Oxidation in Aqueous Solution. J Phys Chem B 2019; 123:2373-2379. [PMID: 30768899 DOI: 10.1021/acs.jpcb.8b11766] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photo-oxidation dynamics following ultraviolet (257 nm) excitation of the phenolate anion in aqueous solution is studied using broadband (550-950 nm) transient absorption spectroscopy. A clear signature from electron ejection is observed on a sub-picosecond timescale, followed by cooling dynamics and the decay of the signal to a constant offset that is assigned to the hydrated electron. The dynamics are compared to the charge-transfer-to-solvent dynamics from iodide at the same excitation wavelength and are shown to be very similar to these. This is in stark contrast to a previous study on the phenolate anion excited at 266 nm, in which electron emission was observed over longer timescales. We account for the differences using a simple Marcus picture for electron emission in which the electron tunneling rate depends sensitively on the initial excitation energy. After electron emission, a contact pair is formed which undergoes geminate recombination and dissociation to form the free hydrated electron at rates that are slightly faster than those for the iodide system. Our results show that, although the underlying chemical physics of electron emission differs between iodide and phenolate, the observed dynamics can appear very similar.
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Affiliation(s)
| | - Jan R R Verlet
- Department of Chemistry , Durham University , Durham DH1 3LE , U.K
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17
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Koga M, Yoneda Y, Sotome H, Miyasaka H. Ionization dynamics of a phenylenediamine derivative in solutions as revealed by femtosecond simultaneous and stepwise two-photon excitation. Phys Chem Chem Phys 2019; 21:2889-2898. [PMID: 30451254 DOI: 10.1039/c8cp06530f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Femtosecond transient absorption spectroscopy with off-resonant simultaneous and resonant stepwise two-photon excitation methods were applied to the direct observation of photoionization dynamics of a phenylenediamine derivative in n-hexane, ethanol and acetonitrile solutions. Upon the selective excitation of the solute via the off-resonant two-photon excitation to the energy level almost equivalent with the ionization potential in the gas phase, rapid appearance of the radical cation (within ca. 100-200 fs) was observed in polar and nonpolar solutions. On the other hand, in the case where the excited energy level from the ground state is 0.8 eV lower than the ionization potential in the gas phase, the radical cation appears only in polar solutions in sub-ps to ps time scales, indicating that the photoionization does not occur directly from the highly electronically excited state even in the polar solution. Comparison of the dynamics between ethanol and acetonitrile solutions strongly suggested that the solvation process of the precursor species leading to the ionization took a crucial role in the electron ejection process with lower energy in polar solutions.
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Affiliation(s)
- Masafumi Koga
- Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
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18
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Bender JA, Raulerson EK, Li X, Goldzak T, Xia P, Van Voorhis T, Tang ML, Roberts ST. Surface States Mediate Triplet Energy Transfer in Nanocrystal-Acene Composite Systems. J Am Chem Soc 2018; 140:7543-7553. [PMID: 29846066 DOI: 10.1021/jacs.8b01966] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Hybrid organic:inorganic materials composed of semiconductor nanocrystals functionalized with acene ligands have recently emerged as a promising platform for photon upconversion. Infrared light absorbed by a nanocrystal excites charge carriers that can pass to surface-bound acenes, forming triplet excitons capable of fusing to produce visible radiation. To fully realize this scheme, energy transfer between nanocrystals and acenes must occur with high efficiency, yet the mechanism of this process remains poorly understood. To improve our knowledge of the fundamental steps involved in nanoparticle:acene energy transfer, we used ultrafast transient absorption to investigate excited electronic dynamics of PbS nanocrystals chemically functionalized with 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) ligands. We find photoexcitation of PbS does not lead to direct triplet energy transfer to surface-bound TIPS-pentacene molecules but rather to the formation of an intermediate state within 40 ps. This intermediate persists for ∼100 ns before evolving to produce TIPS-pentacene triplet excitons. Analysis of transient absorption lineshapes suggests this intermediate corresponds to charge carriers localized at the PbS nanocrystal surface. This hypothesis is supported by constrained DFT calculations that find a large number of spin-triplet states at PbS NC surfaces. Though some of these states can facilitate triplet transfer, others serve as traps that hinder it. Our results highlight that nanocrystal surfaces play an active role in mediating energy transfer to bound acene ligands and must be considered when optimizing composite NC-based materials for photon upconversion, photocatalysis, and other optoelectronic applications.
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Affiliation(s)
- Jon A Bender
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Emily K Raulerson
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
| | - Xin Li
- Department of Chemistry , University of California Riverside , Riverside , California 92521 , United States
| | - Tamar Goldzak
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Pan Xia
- Materials Science & Engineering Program , University of California Riverside , Riverside , California 92521 , United States
| | - Troy Van Voorhis
- Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States
| | - Ming Lee Tang
- Department of Chemistry , University of California Riverside , Riverside , California 92521 , United States.,Materials Science & Engineering Program , University of California Riverside , Riverside , California 92521 , United States
| | - Sean T Roberts
- Department of Chemistry , The University of Texas at Austin , Austin , Texas 78712 , United States
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19
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Najafpour MM, Madadkhani S, Akbarian S, Zand Z, Hołyńska M, Kompany-Zareh M, Tatsuya T, Singh JP, Chae KH, Allakhverdiev SI. Links between peptides and Mn oxide: nano-sized manganese oxide embedded in a peptide matrix. NEW J CHEM 2018. [DOI: 10.1039/c8nj02119h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report on a poly-peptide/Mn oxide nanocomposite as a model for the water-oxidizing catalyst in Photosystem II.
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Affiliation(s)
- Mohammad Mahdi Najafpour
- Department of Chemistry
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
- Center of Climate Change and Global Warming
| | - Sepideh Madadkhani
- Department of Chemistry
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
| | - Somayyeh Akbarian
- Department of Chemistry
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
| | - Zahra Zand
- Department of Chemistry
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
| | - Małgorzata Hołyńska
- Fachbereich Chemie und Wissenschaftliches Zentrum für Materialwissenschaften (WZMW)
- Philipps-Universität Marburg
- Marburg D-35032
- Germany
| | - Mohsen Kompany-Zareh
- Department of Chemistry
- Institute for Advanced Studies in Basic Sciences (IASBS)
- Zanjan
- Iran
- Center of Climate Change and Global Warming
| | - Tomo Tatsuya
- Department of Biology
- Faculty of Science
- Tokyo University of Science
- Tokyo 162-8601
- Japan
| | - Jitendra Pal Singh
- Advanced Analysis Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
| | - Keun Hwa Chae
- Advanced Analysis Center
- Korea Institute of Science and Technology
- Seoul 02792
- Republic of Korea
| | - Suleyman I. Allakhverdiev
- Controlled Photobiosynthesis Laboratory
- Institute of Plant Physiology
- Russian Academy of Sciences
- Moscow 127276
- Russia
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20
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Kumar G, Roy A, McMullen RS, Kutagulla S, Bradforth SE. The influence of aqueous solvent on the electronic structure and non-adiabatic dynamics of indole explored by liquid-jet photoelectron spectroscopy. Faraday Discuss 2018; 212:359-381. [DOI: 10.1039/c8fd00123e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Time-resolved photoelectron spectroscopy (TRPES) in a liquid micro-jet is implemented here to investigate the influence of water on the electronic structure and dynamics of indole, the chromophore of the amino acid tryptophan.
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Affiliation(s)
- Gaurav Kumar
- Department of Chemistry
- University of Southern California
- Los Angeles
- USA
| | - Anirban Roy
- Department of Chemistry
- University of Southern California
- Los Angeles
- USA
| | - Ryan S. McMullen
- Department of Chemistry
- University of Southern California
- Los Angeles
- USA
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21
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Zhou L, Sleiman M, Ferronato C, Chovelon JM, de Sainte-Claire P, Richard C. Sulfate radical induced degradation of β2-adrenoceptor agonists salbutamol and terbutaline: Phenoxyl radical dependent mechanisms. WATER RESEARCH 2017; 123:715-723. [PMID: 28719816 DOI: 10.1016/j.watres.2017.07.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/20/2017] [Accepted: 07/12/2017] [Indexed: 06/07/2023]
Abstract
The present study investigated the reactivity and oxidation mechanisms of salbutamol (SAL) and terbutaline (TBL), two typical β2-adrenoceptor agonists, towards sulfate radical (SO4-) by using photo-activated persulfate (PS). The reaction pathways and mechanisms were proposed based on products identification using high resolution HPLC-ESI-MS, laser flash photolysis (LFP) and molecular orbital calculations. The results indicated that SO4- was the dominant reactive species in the UV/PS process. The second-order rate constants of sulfate radical reaction with SAL and TBL were measured as (3.7 ± 0.3) × 109 and (4.2 ± 0.3) × 109 M-1 s-1 by LFP, respectively. For both SAL and TBL, phenoxyl radicals were found to play key roles in the orientation of the primary pathways. For SAL, a benzophenone derivative was generated by oxidation of the phenoxyl radical. However, in the case of TBL, the transformation of the phenoxyl radical into benzoquinone was impossible. Instead, the addition of OSO3H on the aromatic ring was the major pathway. The same reactivity pattern was observed in the case of TBL structural analogs resorcinol and 3,5-dihydroxybenzyl alcohol. Our results revealed that basic conditions inhibited the decomposition of SAL and TBL, while, increasing PS dose enhanced the degradation. The present work could help for a better understanding of the difference in oxidation reactivity of substituted phenols widely present in natural waters.
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Affiliation(s)
- Lei Zhou
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, 2 Avenue Albert Einstein, Villeurbanne, France; Université Clermont Auvergne, CNRS, Sigma-Clermont, Institut de Chimie de Clermont-Ferrand, F-63178, Aubière, France
| | - Mohamad Sleiman
- Université Clermont Auvergne, CNRS, Sigma-Clermont, Institut de Chimie de Clermont-Ferrand, F-63178, Aubière, France
| | - Corinne Ferronato
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, 2 Avenue Albert Einstein, Villeurbanne, France
| | - Jean-Marc Chovelon
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, 2 Avenue Albert Einstein, Villeurbanne, France.
| | - Pascal de Sainte-Claire
- Université Clermont Auvergne, CNRS, Sigma-Clermont, Institut de Chimie de Clermont-Ferrand, F-63178, Aubière, France
| | - Claire Richard
- Université Clermont Auvergne, CNRS, Sigma-Clermont, Institut de Chimie de Clermont-Ferrand, F-63178, Aubière, France.
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22
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Reinhard M, Auböck G, Besley NA, Clark IP, Greetham GM, Hanson-Heine MWD, Horvath R, Murphy TS, Penfold TJ, Towrie M, George MW, Chergui M. Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies. J Am Chem Soc 2017; 139:7335-7347. [DOI: 10.1021/jacs.7b02769] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Marco Reinhard
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
| | - Gerald Auböck
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
| | - Nicholas A. Besley
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | | | - Raphael Horvath
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Thomas S. Murphy
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Thomas J. Penfold
- School
of Chemistry, Newcastle University, Newcastle upon Tyne NE1
7RU, United Kingdom
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Michael W. George
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, United Kingdom
- Department
of Chemical and Environmental Engineering, University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China
| | - Majed Chergui
- Ecole polytechnique Fédérale de Lausanne, Laboratoire de spectroscopie ultrarapide, ISIC, and Lausanne Centre
for Ultrafast Science (LACUS), FSB, Station 6, CH-1015 Lausanne, Switzerland
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23
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Ashfold MN, Murdock D, Oliver TA. Molecular Photofragmentation Dynamics in the Gas and Condensed Phases. Annu Rev Phys Chem 2017; 68:63-82. [DOI: 10.1146/annurev-physchem-052516-050756] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Exciting a molecule with an ultraviolet photon often leads to bond fission, but the final outcome of the bond cleavage is typically both molecule and phase dependent. The photodissociation of an isolated gas-phase molecule can be viewed as a closed system: Energy and momentum are conserved, and the fragmentation is irreversible. The same is not true in a solution-phase photodissociation process. Solvent interactions may dissipate some of the photoexcitation energy prior to bond fission and will dissipate any excess energy partitioned into the dissociation products. Products that have no analog in the corresponding gas-phase study may arise by, for example, geminate recombination. Here, we illustrate the extent to which dynamical insights from gas-phase studies can inform our understanding of the corresponding solution-phase photochemistry and how, in the specific case of photoinduced ring-opening reactions, solution-phase studies can in some cases reveal dynamical insights more clearly than the corresponding gas-phase study.
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Affiliation(s)
| | - Daniel Murdock
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
| | - Thomas A.A. Oliver
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
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24
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Verma S, Aute S, Das A, Ghosh HN. Proton-Coupled Electron Transfer in a Hydrogen-Bonded Charge-Transfer Complex. J Phys Chem B 2016; 120:10780-10785. [DOI: 10.1021/acs.jpcb.6b06032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sandeep Verma
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Sunil Aute
- CSIR-National Chemical Laboratory, Pune 411008, India
| | - Amitava Das
- CSIR-National Chemical Laboratory, Pune 411008, India
- CSIR-Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, India
| | - Hirendra N. Ghosh
- Radiation
and Photochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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25
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Manbeck GF, Fujita E, Concepcion JJ. Proton-Coupled Electron Transfer in a Strongly Coupled Photosystem II-Inspired Chromophore–Imidazole–Phenol Complex: Stepwise Oxidation and Concerted Reduction. J Am Chem Soc 2016; 138:11536-49. [DOI: 10.1021/jacs.6b03506] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Gerald F. Manbeck
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Etsuko Fujita
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
| | - Javier J. Concepcion
- Chemistry Division, Brookhaven National Laboratory, Upton, New York 11973-5000, United States
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26
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Pan PR, Lu EP, Kuo JL, Tsai MK. The Spectroscopic Features of Ionized Water Medium: Theoretical Characterization and Implication Using (H 2O) n+, n=3-4, Cluster Model. J CHIN CHEM SOC-TAIP 2016. [DOI: 10.1002/jccs.201600030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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27
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Pagba CV, McCaslin TG, Chi SH, Perry JW, Barry BA. Proton-Coupled Electron Transfer and a Tyrosine-Histidine Pair in a Photosystem II-Inspired β-Hairpin Maquette: Kinetics on the Picosecond Time Scale. J Phys Chem B 2016; 120:1259-72. [PMID: 26886811 DOI: 10.1021/acs.jpcb.6b00560] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Photosystem II (PSII) and ribonucleotide reductase employ oxidation and reduction of the tyrosine aromatic ring in radical transport pathways. Tyrosine-based reactions involve either proton-coupled electron transfer (PCET) or electron transfer (ET) alone, depending on the pH and the pKa of tyrosine's phenolic oxygen. In PSII, a subset of the PCET reactions are mediated by a tyrosine-histidine redox-driven proton relay, YD-His189. Peptide A is a PSII-inspired β-hairpin, which contains a single tyrosine (Y5) and histidine (H14). Previous electrochemical characterization indicated that Peptide A conducts a net PCET reaction between Y5 and H14, which have a cross-strand π-π interaction. The kinetic impact of H14 has not yet been explored. Here, we address this question through time-resolved absorption spectroscopy and 280-nm photolysis, which generates a neutral tyrosyl radical. The formation and decay of the neutral tyrosyl radical at 410 nm were monitored in Peptide A and its variant, Peptide C, in which H14 is replaced by cyclohexylalanine (Cha14). Significantly, both electron transfer (ET, pL 11, L = lyonium) and PCET (pL 9) were accelerated in Peptide A and C, compared to model tyrosinate or tyrosine at the same pL. Increased electronic coupling, mediated by the peptide backbone, can account for this rate acceleration. Deuterium exchange gave no significant solvent isotope effect in the peptides. At pL 9, but not at pL 11, the reaction rate decreased when H14 was mutated to Cha14. This decrease in rate is attributed to an increase in reorganization energy in the Cha14 mutant. The Y5-H14 mechanism in Peptide A is reminiscent of proton- and electron-transfer events involving YD-H189 in PSII. These results document a mechanism by which proton donors and acceptors can regulate the rate of PCET reactions.
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Affiliation(s)
- Cynthia V Pagba
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Tyler G McCaslin
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - San-Hui Chi
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Joseph W Perry
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
| | - Bridgette A Barry
- School of Chemistry and Biochemistry, the Petit Institute for Bioengineering and Bioscience, and the ‡Center for Organic Photonics and Electronics, Georgia Institute of Technology , Atlanta, Georgia 30332, United States
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28
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Oliver TAA, Zhang Y, Roy A, Ashfold MNR, Bradforth SE. Exploring Autoionization and Photoinduced Proton-Coupled Electron Transfer Pathways of Phenol in Aqueous Solution. J Phys Chem Lett 2015; 6:4159-4164. [PMID: 26722792 DOI: 10.1021/acs.jpclett.5b01861] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The excited state dynamics of phenol in water have been investigated using transient absorption spectroscopy. Solvated electrons and vibrationally cold phenoxyl radicals are observed upon 200 and 267 nm excitation, but with formation time scales that differ by more than 4 orders of magnitude. The impact of these findings is assessed in terms of the relative importance of autoionization versus proton-coupled electron transfer mechanisms in this computationally tractable model system.
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Affiliation(s)
- Thomas A A Oliver
- School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
| | - Yuyuan Zhang
- University of Southern California , Los Angeles, California 90089, United States
| | - Anirban Roy
- University of Southern California , Los Angeles, California 90089, United States
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol , Bristol, BS8 1TS, United Kingdom
| | - Stephen E Bradforth
- University of Southern California , Los Angeles, California 90089, United States
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29
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Opalka D, Pham TA, Sprik M, Galli G. Electronic Energy Levels and Band Alignment for Aqueous Phenol and Phenolate from First Principles. J Phys Chem B 2015; 119:9651-60. [DOI: 10.1021/acs.jpcb.5b04189] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Opalka
- Max Planck Institute
for Solid State Research, Heisenbergstraße
1, 70569 Stuttgart, Germany
| | - Tuan Anh Pham
- Lawrence Livermore
National Laboratory, Livermore, California 94551, United States
| | - Michiel Sprik
- Department
of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom
| | - Giulia Galli
- The
Institute for Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States
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30
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31
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Kerzig C, Goez M. Generating hydrated electrons through photoredox catalysis with 9-anthrolate. Phys Chem Chem Phys 2015; 17:13829-36. [PMID: 25929856 DOI: 10.1039/c5cp01711d] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Hydrated electrons are among the strongest reductants known. Adding the ascorbate dianion as a sacrificial donor turns the photoionization of 9-anthrolate in water into a catalytic cycle for their in situ production with near-UV light (355 nm). The photoionization step is exclusively biphotonic and occurs via the first excited singlet state of the catalyst. Neither triplet formation nor any photochemical side reactions interfere. The ionization by-product, the anthroxy radical, is inert towards the ascorbate monoanion but is rapidly reduced by the dianion, thereby recovering the starting catalyst. A sufficient amount of the sacrificial donor makes that reduction quantitative and leads to a sustainable generation of hydrated electrons, as is evidenced by electron yields greatly surpassing the catalyst concentration. Control experiments established that the superincrease is indeed due to the catalyst regeneration and not to an ionization of other species involved in the reaction.
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Affiliation(s)
- Christoph Kerzig
- Martin-Luther-Universität Halle-Wittenberg, Institut für Chemie, Kurt-Mothes-Str. 2, D-06120 Halle (Saale), Germany.
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32
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Zhang Y, Dood J, Beckstead AA, Li XB, Nguyen KV, Burrows CJ, Improta R, Kohler B. Photoinduced Electron Transfer in DNA: Charge Shift Dynamics Between 8-Oxo-Guanine Anion and Adenine. J Phys Chem B 2015; 119:7491-502. [PMID: 25660103 DOI: 10.1021/jp511220x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Femtosecond time-resolved IR spectroscopy is used to investigate the excited-state dynamics of a dinucleotide containing an 8-oxoguanine anion at the 5'-end and neutral adenine at the 3'-end. UV excitation of the dinucleotide transfers an electron from deprotonated 8-oxoguanine to its π-stacked neighbor adenine in less than 1 ps, generating a neutral 8-oxoguanine radical and an adenine radical anion. These species are identified by the excellent agreement between the experimental and calculated IR difference spectra. The quantum efficiency of this ultrafast charge shift reaction approaches unity. Back electron transfer from the adenine radical anion to the 8-oxguanine neutral radical occurs in 9 ps, or approximately 6 times faster than between the adenine radical anion and the 8-oxoguanine radical cation (Zhang, Y. et al. Proc. Natl. Acad. Sci. U.S.A. 2014, 111, 11612-11617). The large asymmetry in forward and back electron transfer rates is fully rationalized by semiclassical nonadiabatic electron transfer theory. Forward electron transfer is ultrafast because the driving force is nearly equal to the reorganization energy, which is estimated to lie between 1 and 2 eV. Back electron transfer is highly exergonic and takes place much more slowly in the Marcus inverted region.
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Affiliation(s)
- Yuyuan Zhang
- †Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Jordan Dood
- †Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Ashley A Beckstead
- †Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Xi-Bo Li
- ‡Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, Utah 84112, United States
| | - Khiem V Nguyen
- ‡Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, Utah 84112, United States
| | - Cynthia J Burrows
- ‡Department of Chemistry, University of Utah, 315 S. 1400 East, Salt Lake City, Utah 84112, United States
| | - Roberto Improta
- §CNR-Consiglio Nazionale delle Ricerche Istituto di Biostrutture e Bioimmagini (IBB-CNR), Via Mezzocannone 16, 80136 Napoli, Italy
| | - Bern Kohler
- †Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
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Pagba CV, Chi SH, Perry J, Barry BA. Proton-Coupled Electron Transfer in Tyrosine and a β-Hairpin Maquette: Reaction Dynamics on the Picosecond Time Scale. J Phys Chem B 2014; 119:2726-36. [DOI: 10.1021/jp510171z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Cynthia V. Pagba
- School of Chemistry and Biochemistry, Petit Institute for Bioengineering
and Bioscience, and ‡Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - San-Hui Chi
- School of Chemistry and Biochemistry, Petit Institute for Bioengineering
and Bioscience, and ‡Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Joseph Perry
- School of Chemistry and Biochemistry, Petit Institute for Bioengineering
and Bioscience, and ‡Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Bridgette A. Barry
- School of Chemistry and Biochemistry, Petit Institute for Bioengineering
and Bioscience, and ‡Center of Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
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Roberts GM, Marroux HJB, Grubb MP, Ashfold MNR, Orr-Ewing AJ. On the Participation of Photoinduced N–H Bond Fission in Aqueous Adenine at 266 and 220 nm: A Combined Ultrafast Transient Electronic and Vibrational Absorption Spectroscopy Study. J Phys Chem A 2014; 118:11211-25. [DOI: 10.1021/jp508501w] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gareth M. Roberts
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Hugo J. B. Marroux
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Michael P. Grubb
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Michael N. R. Ashfold
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J. Orr-Ewing
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
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Parker AW, Bisby RH, Greetham GM, Kukura P, Scherer KM, Towrie M. Ultrafast vibrational spectroscopic studies on the photoionization of the α-tocopherol analogue trolox C. J Phys Chem B 2014; 118:12087-97. [PMID: 25260188 DOI: 10.1021/jp505113k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The initial events after photoexcitation and photoionization of α-tocopherol (vitamin E) and the analogue Trolox C have been studied by femtosecond stimulated Raman spectroscopy, transient absorption spectroscopy and time-resolved infrared spectroscopy. Using these techniques it was possible to follow the formation and decay of the excited state, neutral and radical cation radicals and the hydrated electron that are produced under the various conditions examined. α-Tocopherol and Trolox C in methanol solution appear to undergo efficient homolytic dissociation of the phenolic -OH bond to directly produce the tocopheroxyl radical. In contrast, Trolox C photochemistry in neutral aqueous solutions involves intermediate formation of a radical cation and the hydrated electron which undergo geminate recombination within 100 ps in competition with deprotonation of the radical cation. The results are discussed in relation to recently proposed mechanisms for the reaction of α-tocopherol with peroxyl radicals, which represents the best understood biological activity of this vitamin.
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Affiliation(s)
- Anthony W Parker
- Central Laser Facility, Research Complex at Harwell, STFC Rutherford Appleton Laboratory, Harwell Oxford , Didcot, Oxfordshire, OX11 0QX, U.K
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Roberts GM, Stavros VG. The role of πσ* states in the photochemistry of heteroaromatic biomolecules and their subunits: insights from gas-phase femtosecond spectroscopy. Chem Sci 2014. [DOI: 10.1039/c3sc53175a] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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37
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Harris SJ, Murdock D, Grubb MP, Greetham GM, Clark IP, Towrie M, Ashfold MNR. Transient electronic and vibrational absorption studies of the photo-Claisen and photo-Fries rearrangements. Chem Sci 2014. [DOI: 10.1039/c3sc52893f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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38
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Zhang Y, Dood J, Beckstead A, Chen J, Li XB, Burrows CJ, Lu Z, Matsika S, Kohler B. Ultrafast excited-state dynamics and vibrational cooling of 8-oxo-7,8-dihydro-2'-deoxyguanosine in D2O. J Phys Chem A 2013; 117:12851-7. [PMID: 24215180 DOI: 10.1021/jp4095529] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nguyen and Burrows recently demonstrated that UV-B irradiation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a signature product of oxidatively damaged DNA, can repair cyclobutane pyrimidine dimers in double-stranded DNA (J. Am. Chem. Soc. 2011, 133, 14586 - 14589). In order to test the hypothesis that repair occurs by photoinduced electron transfer, it is critical to determine basic photophysical parameters of 8-oxodG including the excited-state lifetime. Here, femtosecond transient absorption spectroscopy was used to study the ultrafast excited-state dynamics of 8-oxodG with excitation in the UV and probing at visible and mid-IR wavelengths. The excited-state lifetimes of both neutral and basic forms of 8-oxodG in D2O are reported for the first time by monitoring the disappearance of excited-state absorption at 570 nm. The lifetime of the first excited state of the neutral form is 0.9 ± 0.1 ps, or nearly twice as long as that of 2'-deoxyguanosine. The basic form of 8-oxodG exhibits a much longer excited-state lifetime of 43 ± 3 ps. Following ultrafast internal conversion by neutral 8-oxodG, a vibrationally hot ground state is created that dissipates its excess vibrational energy to the solvent on a time scale of 2.4 ± 0.4 ps. Femtosecond time-resolved IR experiments provide additional insights into excited-state dynamics and the vibrational relaxation of several modes in the fingerprint region.
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Affiliation(s)
- Yuyuan Zhang
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
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Zhang Y, Oliver TAA, Das S, Roy A, Ashfold MNR, Bradforth SE. Exploring the Energy Disposal Immediately After Bond-Breaking in Solution: The Wavelength-Dependent Excited State Dissociation Pathways of para-Methylthiophenol. J Phys Chem A 2013; 117:12125-37. [DOI: 10.1021/jp405160n] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuyuan Zhang
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Thomas A. A. Oliver
- School of Chemistry, Cantocks Close, University of Bristol, Bristol BS8 1TS, U.K
| | - Saptaparna Das
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Anirban Roy
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | | | - Stephen E. Bradforth
- Department
of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
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Lopata K, Govind N. Near and Above Ionization Electronic Excitations with Non-Hermitian Real-Time Time-Dependent Density Functional Theory. J Chem Theory Comput 2013; 9:4939-46. [DOI: 10.1021/ct400569s] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Kenneth Lopata
- William R. Wiley Environmental
Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Niranjan Govind
- William R. Wiley Environmental
Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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41
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Zhang Y, Oliver TAA, Ashfold MNR, Bradforth SE. Contrasting the excited state reaction pathways of phenol and para-methylthiophenol in the gas and liquid phases. Faraday Discuss 2013; 157:141-63; discussion 243-84. [PMID: 23230767 DOI: 10.1039/c2fd20043k] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
To explore how the solvent influences primary aspects of bond breaking, the gas and solution phase photochemistries of phenol and ofpara-methylthiophenol are directly compared using, respectively, H (Rydberg) atom photofragment translation spectroscopy and femtosecond transient absorption spectroscopy. Approaches are demonstrated that allow explicit comparisons of the nascent product energy disposals and dissociation mechanisms in the two phases. It is found, at least for the case of the weakly perturbing cyclohexane environment, that most aspects of the primary reaction dynamics of the isolated molecule are reproduced in solution. Specifically, in the gas phase, both molecules can undergo fast X-H (X = O, S) bond dissociation upon excitation with short wavelengths (193 < lambda(pump) < 216 nm), following population of the dissociative S2 (1 1(pi sigma*)) state. Product electronic branching, vibrational and translational energy disposals are determined. Photolysis of phenol and para-methylthiophenol in solution at 200 nm results in formation of vibrationally excited radicals on a timescale shorter than 200 fs. Excitation of para-methylthiophenol at 267 nm reaches close to the S1 (1 1(pipi*))/S2 (11(pi sigma*)) conical intersection (CI): ultrafast dissociation is observed in both the isolated and solution systems-again indicating direct dissociation on the S2 potential energy surface. Comparing results for this precursor at different excitation energies, the extent of geminate recombination and the derived H-atom ejection lengths in the condensed phase photolyses are in qualitative agreement with the translational energy release measured in the gas phase studies. Conversely, excitation of phenol at 267 nm prepares the system in its S1 state at an energy well below its S1/S2 CI; the slow O-H bond fission inferred in the gas phase experiments is observed directly in the time-resolved studies in cyclohexane solution via the appearance of phenoxyl radical absorption after -1 ns, with only S1 excited state absorption discernible at earlier delay times. The slow O-H bond fission in solution provides additional evidence for a tunnelling dissociation mechanism, where the H atom tunnels beneath the lower diabats of the S2/S1 CI. Finally, the photodissociation of phenol clusters in solution is considered, where evidence is presented that the O-H dissociation coordinate is impeded in H-bonded dimers.
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Affiliation(s)
- Yuyuan Zhang
- Department of Chemistry, University of Southern California, Los Angeles, CA 90089, USA
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42
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Busby E, Thibert A, Page LE, Jawaid AM, Snee PT, Larsen DS. Primary charge carrier dynamics of water-solubilized CdZnS/ZnS core/shell and CdZnS/ZnS·Pd nanoparticle adducts. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.04.045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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43
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Zhu J, Paparelli L, Hospes M, Arents J, Kennis JTM, van Stokkum IHM, Hellingwerf KJ, Groot ML. Photoionization and Electron Radical Recombination Dynamics in Photoactive Yellow Protein Investigated by Ultrafast Spectroscopy in the Visible and Near-Infrared Spectral Region. J Phys Chem B 2013; 117:11042-8. [DOI: 10.1021/jp311906f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Jingyi Zhu
- Department
of Physics and Astronomy,
Faculty of Sciences, VU University, De
Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Laura Paparelli
- Department
of Physics and Astronomy,
Faculty of Sciences, VU University, De
Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Marijke Hospes
- Laboratory for Microbiology,
Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The
Netherlands
| | - Jos Arents
- Laboratory for Microbiology,
Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The
Netherlands
| | - John T. M. Kennis
- Department
of Physics and Astronomy,
Faculty of Sciences, VU University, De
Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Ivo H. M. van Stokkum
- Department
of Physics and Astronomy,
Faculty of Sciences, VU University, De
Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
| | - Klaas J. Hellingwerf
- Laboratory for Microbiology,
Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The
Netherlands
| | - Marie Louise Groot
- Department
of Physics and Astronomy,
Faculty of Sciences, VU University, De
Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
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44
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Harris SJ, Murdock D, Zhang Y, Oliver TAA, Grubb MP, Orr-Ewing AJ, Greetham GM, Clark IP, Towrie M, Bradforth SE, Ashfold MNR. Comparing molecular photofragmentation dynamics in the gas and liquid phases. Phys Chem Chem Phys 2013; 15:6567-82. [PMID: 23552482 DOI: 10.1039/c3cp50756d] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This article explores the extent to which insights gleaned from detailed studies of molecular photodissociations in the gas phase (i.e. under isolated molecule conditions) can inform our understanding of the corresponding photofragmentation processes in solution. Systems selected for comparison include a thiophenol (p-methylthiophenol), a thioanisole (p-methylthioanisole) and phenol, in vacuum and in cyclohexane solution. UV excitation in the gas phase results in RX-Y (X = O, S; Y = H, CH3) bond fission in all cases, but over timescales that vary by ~4 orders of magnitude - all of which behaviours can be rationalised on the basis of the relevant bound and dissociative excited state potential energy surfaces (PESs) accessed by UV photoexcitation, and of the conical intersections that facilitate radiationless transfer between these PESs. Time-resolved UV pump-broadband UV/visible probe and/or UV pump-broadband IR probe studies of the corresponding systems in cyclohexane solution reveal additional processes that are unique to the condensed phase. Thus, for example, the data clearly reveal evidence of (i) vibrational relaxation of the photoexcited molecules prior to their dissociation and of the radical fragments formed upon X-Y bond fission, and (ii) geminate recombination of the RX and Y products (leading to reformation of the ground state parent and/or isomeric adducts). Nonetheless, the data also show that, in each case, the characteristics (and the timescale) of the initial bond fission process that occurs under isolated molecule conditions are barely changed by the presence of a weakly interacting solvent like cyclohexane. These condensed phase studies are then extended to an ether analogue of phenol (allyl phenyl ether), wherein UV photo-induced RO-allyl bond fission constitutes the first step of a photo-Claisen rearrangement.
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Affiliation(s)
- Stephanie J Harris
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
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45
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Lincoln CN, Fitzpatrick AE, van Thor JJ. Photoisomerisation quantum yield and non-linear cross-sections with femtosecond excitation of the photoactive yellow protein. Phys Chem Chem Phys 2012; 14:15752-64. [PMID: 23090503 DOI: 10.1039/c2cp41718a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The quantum yield of photoisomerisation of the photoactive yellow protein (PYP) strongly depends on peak power and wavelength with femtosecond optical excitation. Using systematic power titrations and addition of second order dispersion resulting in 140, 300 and 600 fs pulse durations, the one and multi-photon cross-sections at 400, 450 and 490 nm have been assessed from transient absorption spectroscopy and additionally the Z-scan technique. Applying a target model that incorporates photoselection theory, estimates for the cross-sections for stimulated emission and absorption of the first excited state, the amount of ultrafast internal conversion and the underlying species associated dynamics have been determined. The final quantum yields for photoisomerisation were found to be 0.06, 0.14-0.19 and 0.02 for excitation wavelengths 400, 450 and 490 nm and found to increase with increasing pulse durations. Transient absorption measurements and Z-scan measurements at 450 nm, coinciding with the maximum wavelength of the ground state absorption, indicate that the photochemical quantum yield is intrinsically limited by an ultrafast internal conversion reaction as well as by stimulated emission cross-section. With excitation at 400 nm photoisomerisation quantum yield is further significantly limited by competing multi-photon excitation into excited state absorption at 385 nm previously proposed to result in photoionisation. With excitation at 490 nm the photoisomerisation quantum yield is predominantly limited further by the significantly higher stimulated emission cross-section compared to ground state cross-section as well as multi-photon processes. In addition to photoionisation, a second product of multi-photon excitation is identified and characterised by an induced absorption at 500 nm and a time constant of 2 ps for relaxation. With power densities up to 138 GW cm(-2) the measurements have not provided indication for coherent multi-photon absorption of PYP. In the saturation regime with 450 nm excitation, the limit for the photoisomerisation quantum yield was found to be 0.14-0.19 and the excited state absorption cross-section 6.1 × 10(-17) cm(2) or 0.36 times the ground state cross-section of 1.68 × 10(-16) cm(2) per molecule. This places a fundamental restriction on the maximum populations and sample penetration that may be achieved for instance in femtosecond pump-probe experiments with molecular crystals of PYP.
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Affiliation(s)
- Craig N Lincoln
- Imperial College London, Division of Molecular Biosciences, South Kensington campus, SW7 2AZ, London, UK
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Marsalek O, Elles CG, Pieniazek PA, Pluhařová E, VandeVondele J, Bradforth SE, Jungwirth P. Chasing charge localization and chemical reactivity following photoionization in liquid water. J Chem Phys 2012; 135:224510. [PMID: 22168706 DOI: 10.1063/1.3664746] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The ultrafast dynamics of the cationic hole formed in bulk liquid water following ionization is investigated by ab initio molecular dynamics simulations and an experimentally accessible signature is suggested that might be tracked by femtosecond pump-probe spectroscopy. This is one of the fastest fundamental processes occurring in radiation-induced chemistry in aqueous systems and biological tissue. However, unlike the excess electron formed in the same process, the nature and time evolution of the cationic hole has been hitherto little studied. Simulations show that an initially partially delocalized cationic hole localizes within ~30 fs after which proton transfer to a neighboring water molecule proceeds practically immediately, leading to the formation of the OH radical and the hydronium cation in a reaction which can be formally written as H(2)O(+) + H(2)O → OH + H(3)O(+). The exact amount of initial spin delocalization is, however, somewhat method dependent, being realistically described by approximate density functional theory methods corrected for the self-interaction error. Localization, and then the evolving separation of spin and charge, changes the electronic structure of the radical center. This is manifested in the spectrum of electronic excitations which is calculated for the ensemble of ab initio molecular dynamics trajectories using a quantum mechanics/molecular mechanics (QM∕MM) formalism applying the equation of motion coupled-clusters method to the radical core. A clear spectroscopic signature is predicted by the theoretical model: as the hole transforms into a hydroxyl radical, a transient electronic absorption in the visible shifts to the blue, growing toward the near ultraviolet. Experimental evidence for this primary radiation-induced process is sought using femtosecond photoionization of liquid water excited with two photons at 11 eV. Transient absorption measurements carried out with ~40 fs time resolution and broadband spectral probing across the near-UV and visible are presented and direct comparisons with the theoretical simulations are made. Within the sensitivity and time resolution of the current measurement, a matching spectral signature is not detected. This result is used to place an upper limit on the absorption strength and/or lifetime of the localized H(2)O(+) ((aq)) species.
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Affiliation(s)
- Ondrej Marsalek
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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Ruckebusch C, Sliwa M, Pernot P, de Juan A, Tauler R. Comprehensive data analysis of femtosecond transient absorption spectra: A review. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY C-PHOTOCHEMISTRY REVIEWS 2012. [DOI: 10.1016/j.jphotochemrev.2011.10.002] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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48
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Simulation of electronic excitation in the liquid state by quantum mechanical charge field molecular dynamics. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2011.11.066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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49
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Rivera CA, Winter N, Harper RV, Benjamin I, Bradforth SE. The dynamical role of solvent on the ICN photodissociation reaction: connecting experimental observables directly with molecular dynamics simulations. Phys Chem Chem Phys 2011; 13:8269-83. [DOI: 10.1039/c1cp20252a] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Slavíček P, Fárník M. Photochemistry of hydrogen bonded heterocycles probed by photodissociation experiments and ab initio methods. Phys Chem Chem Phys 2011; 13:12123-37. [DOI: 10.1039/c1cp20674e] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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