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Wang L, Zhang S, Wang Y, Zhang B. Dispersion-induced structural preference in the ultrafast dynamics of diphenyl ether. RSC Adv 2020; 10:18093-18098. [PMID: 35517230 PMCID: PMC9053750 DOI: 10.1039/d0ra02224a] [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: 03/10/2020] [Accepted: 04/28/2020] [Indexed: 11/21/2022] Open
Abstract
Dispersion interactions are omnipresent in large aromatic systems and influence the dynamics as intermolecular forces. The structural preference induced by dispersion interactions is demonstrated to influence the excited state dynamics of diphenyl ether (DPE) using femtosecond time-resolved transient absorption (TA) associated with quantum chemical calculations. The experimental results in aprotic solvents show that the S1 state is populated upon irradiation at 267 nm with excess vibrational energy dissipating to solvent molecules in several picoseconds, and then decays via internal conversion (IC) within 50 ps as well as intersystem crossing (ISC) and fluorescence with a lifetime of nanoseconds. The polarity of the solvent disturbs the excited state energies and enhances the energy barriers of the ISC channel. Furthermore, the intermolecular dispersion interactions with protic solvents result in the OH–π isomer dominating in methanol and the OH–O isomer is slightly preferred in t-butanol in the ground state. The hydrogen bonded isomer measurements show an additional change from OH–O to OH–π geometry in the first 1 ps besides the relaxation processes in aprotic solvents. The time constants measured in the TA spectra suggest that the OH–O isomer facilitates IC. The results show that the OH–π isomer has a more rigid structure and a higher barrier for IC, making it harder to reach the geometric conical intersection through conformer rearrangement. This work enables us to have a good knowledge of how the structural preference induced by dispersion interactions affects excited state dynamics of the heteroaromatic compounds. Dispersion interactions are omnipresent in large aromatic systems and influence the dynamics as intermolecular forces.![]()
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Affiliation(s)
- Lian Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics
- Innovation Academy for Precision Measurement Science and Technology
- Chinese Academy of Sciences
- Wuhan 430071
- China
| | - Song Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics
- Innovation Academy for Precision Measurement Science and Technology
- Chinese Academy of Sciences
- Wuhan 430071
- China
| | - Ye Wang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics
- Innovation Academy for Precision Measurement Science and Technology
- Chinese Academy of Sciences
- Wuhan 430071
- China
| | - Bing Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics
- Innovation Academy for Precision Measurement Science and Technology
- Chinese Academy of Sciences
- Wuhan 430071
- China
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2
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Ochmann M, Hussain A, von Ahnen I, Cordones AA, Hong K, Lee JH, Ma R, Adamczyk K, Kim TK, Schoenlein RW, Vendrell O, Huse N. UV-photochemistry of the biologically relevant thiol group and the disulfide bond: Evolution of early photoproducts from picosecond X-ray absorption spectroscopy at the sulfur K-Edge. EPJ WEB OF CONFERENCES 2019. [DOI: 10.1051/epjconf/201920509006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We report on the UV-induced photochemistry of the biologically relevant sulfur-containing thiol group and the disulfide bond in solution using picosecond X-ray absorption spectroscopy at the sulfur K-edge. This study provides element-specific insight into the 267-nm induced photo-chemistry of two model compounds, an aromatic thiol and an aliphatic disulfide. Our transient spectra point to two primary and several secondary photoproducts, and our analysis may aid in understanding UV damage in proteins.
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3
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Baker LA, Marchetti B, Karsili TNV, Stavros VG, Ashfold MNR. Photoprotection: extending lessons learned from studying natural sunscreens to the design of artificial sunscreen constituents. Chem Soc Rev 2018; 46:3770-3791. [PMID: 28580469 DOI: 10.1039/c7cs00102a] [Citation(s) in RCA: 106] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Evolution has ensured that plants and animals have developed effective protection mechanisms against the potentially harmful effects of incident ultraviolet radiation (UVR). Tanning is one such mechanism in humans, but tanning only occurs post-exposure to UVR. Hence, there is ever growing use of commercial sunscreens to pre-empt overexposure to UVR. Key requirements for any chemical filter molecule used in such a photoprotective capacity include a large absorption cross-section in the UV-A and UV-B spectral regions and the availability of one or more mechanisms whereby the absorbed photon energy can be dissipated without loss of the molecular integrity of the chemical filter. Here we summarise recent experimental (mostly ultrafast pump-probe spectroscopy studies) and computational progress towards unravelling various excited state decay mechanisms that afford the necessary photostability in chemical filters found in nature and those used in commercial sunscreens. We also outline ways in which a better understanding of the photophysics and photochemistry of sunscreen molecules selected by nature could aid the design of new and improved commercial sunscreen formulations.
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Affiliation(s)
- Lewis A Baker
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
| | - Barbara Marchetti
- Department of Chemistry, University of Pennsylvania, Philadelphia, USA
| | | | - Vasilios G Stavros
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK.
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
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4
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Ashfold MNR, Bain M, Hansen CS, Ingle RA, Karsili TNV, Marchetti B, Murdock D. Exploring the Dynamics of the Photoinduced Ring-Opening of Heterocyclic Molecules. J Phys Chem Lett 2017; 8:3440-3451. [PMID: 28661140 DOI: 10.1021/acs.jpclett.7b01219] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Excited states formed by electron promotion to an antibonding σ* orbital are now recognized as key to understanding the photofragmentation dynamics of a broad range of heteroatom containing small molecules: alcohols, thiols, amines, and many of their aromatic analogues. Such excited states may be populated by direct photoexcitation, or indirectly by nonadiabatic transfer of population from some other optically excited state (e.g., a ππ* state). This Perspective explores the extent to which the fast-growing literature pertaining to such (n/π)σ*-state mediated bond fissions can inform and enhance our mechanistic understanding of photoinduced ring-opening in heterocyclic molecules.
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Affiliation(s)
- Michael N R Ashfold
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
| | - Matthew Bain
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
| | | | - Rebecca A Ingle
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
| | - Tolga N V Karsili
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
| | - Barbara Marchetti
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
| | - Daniel Murdock
- School of Chemistry, University of Bristol , Bristol, United Kingdom , BS8 1TS
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5
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Marchetti B, Karsili TNV, Cipriani M, Hansen CS, Ashfold MNR. The near ultraviolet photodissociation dynamics of 2- and 3-substituted thiophenols: Geometric vs. electronic structure effects. J Chem Phys 2017; 147:013923. [DOI: 10.1063/1.4980035] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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6
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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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7
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Ochmann M, von Ahnen I, Cordones AA, Hussain A, Lee JH, Hong K, Adamczyk K, Vendrell O, Kim TK, Schoenlein RW, Huse N. Light-Induced Radical Formation and Isomerization of an Aromatic Thiol in Solution Followed by Time-Resolved X-ray Absorption Spectroscopy at the Sulfur K-Edge. J Am Chem Soc 2017; 139:4797-4804. [PMID: 28219243 DOI: 10.1021/jacs.6b12992] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We applied time-resolved sulfur-1s absorption spectroscopy to a model aromatic thiol system as a promising method for tracking chemical reactions in solution. Sulfur-1s absorption spectroscopy allows tracking multiple sulfur species with a time resolution of ∼70 ps at synchrotron radiation facilities. Experimental transient spectra combined with high-level electronic structure theory allow identification of a radical and two thione isomers, which are generated upon illumination with 267 nm radiation. Moreover, the regioselectivity of the thione isomerization is explained by the resulting radical frontier orbitals. This work demonstrates the usefulness and potential of time-resolved sulfur-1s absorption spectroscopy for tracking multiple chemical reaction pathways and transient products of sulfur-containing molecules in solution.
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Affiliation(s)
- Miguel Ochmann
- Department of Physics, University of Hamburg and Center for Free Electron Laser Science , 22761 Hamburg, Germany.,Max Planck Institute for the Structure and Dynamics of Matter , 22761 Hamburg, Germany
| | - Inga von Ahnen
- Department of Physics, University of Hamburg and Center for Free Electron Laser Science , 22761 Hamburg, Germany
| | - Amy A Cordones
- Ultrafast X-ray Science Lab, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Abid Hussain
- Department of Physics, University of Hamburg and Center for Free Electron Laser Science , 22761 Hamburg, Germany.,Max Planck Institute for the Structure and Dynamics of Matter , 22761 Hamburg, Germany
| | - Jae Hyuk Lee
- Ultrafast X-ray Science Lab, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Kiryong Hong
- Ultrafast X-ray Science Lab, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.,Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University , Busan 46241, South Korea
| | - Katrin Adamczyk
- Department of Physics, University of Hamburg and Center for Free Electron Laser Science , 22761 Hamburg, Germany.,Max Planck Institute for the Structure and Dynamics of Matter , 22761 Hamburg, Germany
| | - Oriol Vendrell
- Center for Free-Electron Laser Science, DESY and The Hamburg Centre for Ultrafast Imaging , 22607 Hamburg, Germany
| | - Tae Kyu Kim
- Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University , Busan 46241, South Korea
| | - Robert W Schoenlein
- Ultrafast X-ray Science Lab, Chemical Sciences Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States
| | - Nils Huse
- Department of Physics, University of Hamburg and Center for Free Electron Laser Science , 22761 Hamburg, Germany.,Max Planck Institute for the Structure and Dynamics of Matter , 22761 Hamburg, Germany
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8
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Lee YR, Park CB, Hwang J, Sung BJ, Kim HL, Kwon CH. Observation of the Ring-Puckering Vibrational Mode in Thietane Cation. J Phys Chem A 2017; 121:1163-1167. [DOI: 10.1021/acs.jpca.6b12724] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yu Ran Lee
- Department
of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Korea
| | - Chung Bin Park
- Department
of Chemistry, Sogang University, Seoul 04107, Korea
| | - Jiye Hwang
- Department
of Chemistry, Sogang University, Seoul 04107, Korea
| | - Bong June Sung
- Department
of Chemistry, Sogang University, Seoul 04107, Korea
| | - Hong Lae Kim
- Department
of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Korea
| | - Chan Ho Kwon
- Department
of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Korea
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9
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Stavros VG, Verlet JRR. Gas-Phase Femtosecond Particle Spectroscopy: A Bottom-Up Approach to Nucleotide Dynamics. Annu Rev Phys Chem 2016; 67:211-32. [PMID: 26980306 DOI: 10.1146/annurev-physchem-040215-112428] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We summarize how gas-phase ultrafast charged-particle spectroscopy has been used to provide an understanding of the photophysics of DNA building blocks. We focus on adenine and discuss how, following UV excitation, specific interactions determine the fates of its excited states. The dynamics can be probed using a systematic bottom-up approach that provides control over these interactions and that allows ever-larger complexes to be studied. Starting from a chromophore in adenine, the excited state decay mechanisms of adenine and chemically substituted or clustered adenine are considered and then extended to adenosine mono-, di-, and trinucleotides. We show that the gas-phase approach can offer exquisite insight into the dynamics observed in aqueous solution, but we also highlight stark differences. An outlook is provided that discusses some of the most promising developments in this bottom-up approach.
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Affiliation(s)
- Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom;
| | - Jan R R Verlet
- Department of Chemistry, University of Durham, Durham, DH1 3LE, United Kingdom;
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10
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Greenough SE, Horbury MD, Thompson JOF, Roberts GM, Karsili TNV, Marchetti B, Townsend D, Stavros VG. Solvent induced conformer specific photochemistry of guaiacol. Phys Chem Chem Phys 2015; 16:16187-95. [PMID: 24967653 DOI: 10.1039/c4cp02424a] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a combination of ultrafast solution- and gas-phase spectroscopies, together with high-level theory calculations, we demonstrate that we are able to track conformer-specific photodissociation dynamics in solution through solvent choice. We reveal this phenomenon in guaiacol (2-methoxyphenol), a key subunit of the natural biopolymer lignin. In cyclohexane, the first electronically excited (1)ππ* (S1) state in guaiacol relaxes with a time-constant of τ = 4.5 ± 0.2 ns, mediated through intersystem crossing to lower lying triplet (Tn) states and internal conversion and fluorescence back to the ground state (S0). In contrast, in methanol, a further relaxation channel is also present; the S1 state relaxes with a time-constant of τ = 2.9 ± 0.1 ns, which is now additionally mediated through coupling onto a dissociative (1)πσ* (S2) state and subsequent O-H bond fission, evidenced through the appearance of a spectral signature for the guaiacoxyl radical after ∼250 ps. With the aid of complementary calculations, we attribute this to the now absent intramolecular H-bond between OH and OMe moieties, which now favours intermolecular H-bonding to methanol, lowering the barrier to O-H dissociation and facilitating H-atom loss via tunnelling.
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Affiliation(s)
- Simon E Greenough
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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11
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Hansen CS, Blanksby SJ, Chalyavi N, Bieske EJ, Reimers JR, Trevitt AJ. Ultraviolet photodissociation action spectroscopy of the N-pyridinium cation. J Chem Phys 2015; 142:014301. [DOI: 10.1063/1.4904267] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
| | - Stephen J. Blanksby
- Central Analytical Research Facility, Queensland University of Technology, QLD 4000, Australia
| | - Nahid Chalyavi
- School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Evan J. Bieske
- School of Chemistry, The University of Melbourne, VIC 3010, Australia
| | - Jeffrey R. Reimers
- School of Physics and Materials Science, University of Technology Sydney, NSW 2007, Australia
- International Centre for Quantum and Molecular Structure, Shanghai University, Shanghai 200444, China
| | - Adam J. Trevitt
- School of Chemistry, University of Wollongong, NSW 2522, Australia
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12
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Godfrey TJ, Yu H, Biddle MS, Ullrich S. A wavelength dependent investigation of the indole photophysics via ionization and fragmentation pump–probe spectroscopies. Phys Chem Chem Phys 2015; 17:25197-209. [DOI: 10.1039/c5cp02975a] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a variety of gas-phase pump–probe spectroscopic techniques, this work investigates indole excited-state relaxation dynamics at several pump wavelengths with a particular focus on 1πσ*-state involvement.
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Affiliation(s)
| | - Hui Yu
- University of Georgia
- Athens
- USA
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13
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Murdock D, Harris SJ, Clark IP, Greetham GM, Towrie M, Orr-Ewing AJ, Ashfold MNR. UV-induced isomerization dynamics of N-methyl-2-pyridone in solution. J Phys Chem A 2014; 119:88-94. [PMID: 25469643 DOI: 10.1021/jp511818k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The photoisomerization dynamics of N-methyl-2-pyridone (NMP) dissolved in CH3CN have been interrogated by time-resolved electronic and vibrational absorption spectroscopy. Irradiation at two different wavelengths (330 or 267 nm) prepares NMP(S1) molecules with very different levels of vibrational excitation, which rapidly relax to low vibrational levels of the S1 state. Internal conversion with an associated time constant of 110(4) ps, leading to reformation of NMP(S0) molecules, is identified as the dominant (>90%) decay pathway. Much of the remaining fraction undergoes a photoinitiated rearrangement to yield two ketenes (revealed by their characteristic antisymmetric C═C═O stretching modes at 2110 and 2120 cm(-1)), which are in equilibrium. The rate of ketene formation is found to be pump-wavelength dependent, consistent with ab initio electronic structure calculations which predict a barrier on the S1 potential energy surface en route to a prefulvenic conical intersection, by which isomerization is deduced to occur. Two kinetic models-differentiated by whether product branching occurs in the S1 or S0 electronic states-are presented and used with equal success in the analysis of the experimental data, highlighting the difficulties associated with deducing unambiguous mechanistic information from kinetic data alone.
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Affiliation(s)
- Daniel Murdock
- School of Chemistry, University of Bristol , Cantock's Close, Bristol, BS8 1TS, United Kingdom
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14
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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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15
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Murdock D, Harris SJ, Luke J, Grubb MP, Orr-Ewing AJ, Ashfold MNR. Transient UV pump-IR probe investigation of heterocyclic ring-opening dynamics in the solution phase: the role played by nσ* states in the photoinduced reactions of thiophenone and furanone. Phys Chem Chem Phys 2014; 16:21271-9. [PMID: 25175813 DOI: 10.1039/c4cp03653k] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The heterocyclic ring-opening dynamics of thiophenone and furanone dissolved in CH3CN have been probed by ultrafast transient infrared spectroscopy. Following irradiation at 267 nm (thiophenone) or 225 nm (furanone), prompt (τ < 1 ps) ring-opening is confirmed by the appearance of a characteristic antisymmetric ketene stretching feature around 2150 cm(-1). The ring-opened product molecules are formed highly vibrationally excited, and cool subsequently on a ∼6.7 ps timescale. By monitoring the recovery of the parent (S0) bleach, it is found that ∼60% of the initially photoexcited thiophenone molecules reform the parent molecule, in stark contrast with the case in furanone where there is less than 10% parent bleach recovery. Complementary ab initio calculations of potential energy cuts along the S-C([double bond, length as m-dash]O) and O-C([double bond, length as m-dash]O) ring-opening coordinate reveals insights into the reaction mechanism, and the important role played by dissociative (n/π)σ* states in the UV-induced photochemistry of such heterocyclic systems.
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Affiliation(s)
- Daniel Murdock
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, UKBS8 1TS.
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16
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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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17
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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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18
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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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19
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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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20
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Roberts GM, Williams CA, Yu H, Chatterley AS, Young JD, Ullrich S, Stavros VG. Probing ultrafast dynamics in photoexcited pyrrole: timescales for 1πσ* mediated H-atom elimination. Faraday Discuss 2013; 163:95-116; discussion 117-38. [DOI: 10.1039/c2fd20140b] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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