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Xiang B, Xiong W. Molecular Polaritons for Chemistry, Photonics and Quantum Technologies. Chem Rev 2024; 124:2512-2552. [PMID: 38416701 PMCID: PMC10941193 DOI: 10.1021/acs.chemrev.3c00662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 01/22/2024] [Accepted: 02/08/2024] [Indexed: 03/01/2024]
Abstract
Molecular polaritons are quasiparticles resulting from the hybridization between molecular and photonic modes. These composite entities, bearing characteristics inherited from both constituents, exhibit modified energy levels and wave functions, thereby capturing the attention of chemists in the past decade. The potential to modify chemical reactions has spurred many investigations, alongside efforts to enhance and manipulate optical responses for photonic and quantum applications. This Review centers on the experimental advances in this burgeoning field. Commencing with an introduction of the fundamentals, including theoretical foundations and various cavity architectures, we discuss outcomes of polariton-modified chemical reactions. Furthermore, we navigate through the ongoing debates and uncertainties surrounding the underpinning mechanism of this innovative method of controlling chemistry. Emphasis is placed on gaining a comprehensive understanding of the energy dynamics of molecular polaritons, in particular, vibrational molecular polaritons─a pivotal facet in steering chemical reactions. Additionally, we discuss the unique capability of coherent two-dimensional spectroscopy to dissect polariton and dark mode dynamics, offering insights into the critical components within the cavity that alter chemical reactions. We further expand to the potential utility of molecular polaritons in quantum applications as well as precise manipulation of molecular and photonic polarizations, notably in the context of chiral phenomena. This discussion aspires to ignite deeper curiosity and engagement in revealing the physics underpinning polariton-modified molecular properties, and a broad fascination with harnessing photonic environments to control chemistry.
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Affiliation(s)
- Bo Xiang
- Department
of Chemistry, School of Science and Research Center for Industries
of the Future, Westlake University, Hangzhou, Zhejiang 310030, China
| | - Wei Xiong
- Department
of Chemistry and Biochemistry, University
of California, San Diego, California 92126, United States
- Materials
Science and Engineering Program, University
of California, San Diego, California 92126, United States
- Department
of Electrical and Computer Engineering, University of California, San
Diego, California 92126, United States
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2
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Raman A, Neelambra AU, Karunakaran V, Easwaramoorthi S. Solvent-Controlled Photoswitching of Azobenzene: An Excited State Shuttle. Chem Asian J 2023; 18:e202201112. [PMID: 36546595 DOI: 10.1002/asia.202201112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
The light-controlled excited state trans-cis isomerization process is a key to the development of conversion of light energy to mechanical motion at the molecular level. Considerable efforts have been made in tuning the isomerization process with electron donor and acceptor substituents by altering the excited state reaction coordinate. Here, we report a two novel push-pull series of para-diethylamino (DEA) and diphenylamino (DPA) substituted (E)-4'-((4-(diethylamino)phenyl)diazenyl)-N,N-diphenyl-[1,1'-biphenyl]-4-amine (1) and (E)-4'-((4-(diphenylamino)phenyl)diazenyl)-N,N-diphenyl-[1,1'-biphenyl]-4-amine (2). Compounds 1 and 2 undergo both photochemical and photophysical excited state deactivation pathways which can be controlled by varying the solvent polarity. These structural motifs of 1 and 2 would undergo torsional motions upon excitation to exhibit either trans→cis photoisomerization or to form a twisted intramolecular charge transfer state and both the process originates from the same excited state and competes with each other. Thus, alternations in the surrounding environment such as solvent polarity, solution viscosity, and protonation were employed to understand the preferential excited state deactivation pathway and thereby these systems could be employed as a new class of azobenzene-based luminescent photochromic molecules. For instance, in nonpolar solvent, toluene photoisomerization is preferred over TICT, but polar solvent, ethanol preferentially stabilizes the TICT state by virtue of N-C rotation which renders the energy barrier unfavourable for photoisomerization. The photostationary state of 1 in toluene is predominantly the Z isomer, whereas in ethanol E isomer is nearly two-fold higher than the Z isomer. These feature sets up a new approach towards the construction of multinary molecular switches and subsequent development in diverse fields.
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Affiliation(s)
- Arunachalam Raman
- Inorganic and Physical Chemistry Laboratory, CSIR-Central Leather Research Institute Adyar, Chennai, 600 020, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
| | - Afeefah U Neelambra
- Photosciences & Photonics Section Chemical Sciences and Technology Division, CSIR - National Institute for Interdisciplinary Science and Technology, 695 019, Thiruvananthapuram, India
| | - Venugopal Karunakaran
- Photosciences & Photonics Section Chemical Sciences and Technology Division, CSIR - National Institute for Interdisciplinary Science and Technology, 695 019, Thiruvananthapuram, India
| | - Shanmugam Easwaramoorthi
- Inorganic and Physical Chemistry Laboratory, CSIR-Central Leather Research Institute Adyar, Chennai, 600 020, India.,Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
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3
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Hanes AT, Grieco C, Lalisse RF, Hadad CM, Kohler B. Vibrational relaxation by methylated xanthines in solution: Insights from 2D IR spectroscopy and calculations. J Chem Phys 2023; 158:044302. [PMID: 36725522 DOI: 10.1063/5.0135412] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Two-dimensional infrared (2D IR) spectroscopy, infrared pump-infrared probe spectroscopy, and density functional theory calculations were used to study vibrational relaxation by ring and carbonyl stretching modes in a series of methylated xanthine derivatives in acetonitrile and deuterium oxide (heavy water). Isotropic signals from the excited symmetric and asymmetric carbonyl stretch modes decay biexponentially in both solvents. Coherent energy transfer between the symmetric and asymmetric carbonyl stretching modes gives rise to a quantum beat in the time-dependent anisotropy signals. The damping time of the coherent oscillation agrees with the fast decay component of the carbonyl bleach recovery signals, indicating that this time constant reflects intramolecular vibrational redistribution (IVR) to other solute modes. Despite their similar frequencies, the excited ring modes decay monoexponentially with a time constant that matches the slow decay component of the carbonyl modes. The slow decay times, which are faster in heavy water than in acetonitrile, approximately match the ones observed in previous UV pump-IR probe measurements on the same compounds. The slow component is assigned to intermolecular energy transfer to solvent bath modes from low-frequency solute modes, which are populated by IVR and are anharmonically coupled to the carbonyl and ring stretch modes. 2D IR measurements indicate that the carbonyl stretching modes are weakly coupled to the delocalized ring modes, resulting in slow exchange that cannot explain the common solvent-dependence. IVR is suggested to occur at different rates for the carbonyl vs ring modes due to differences in mode-specific couplings and not to differences in the density of accessible states.
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Affiliation(s)
- Alex T Hanes
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - Christopher Grieco
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - Remy F Lalisse
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - Christopher M Hadad
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
| | - Bern Kohler
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA
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Djavani-Tabrizi I, Jockusch RA. Gas-Phase Fluorescence of Proflavine Reveals Two Close-Lying, Brightly Emitting States. J Phys Chem Lett 2022; 13:2187-2192. [PMID: 35230120 DOI: 10.1021/acs.jpclett.2c00201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Surprising excitation-dependent, dual emission from a small organic model fluorophore is reported. Gas-phase fluorescence spectra of proflavine (a diaminoacridine) ions reveal two long-lived emitting states, with distinct bands separated by just 1700 cm-1. The relative intensities of these two bands depend on the excitation wavelength. Time-dependent density functional theory (TD-DFT) calculations support the existence of two close-lying singlet electronic states, with excitation into S2 predicted to be >1000-fold more likely than into S1. These data strongly suggest that internal conversion (IC) rates are suppressed relative to solvated proflavine, and that IC is competitive with intramolecular vibrational relaxation (IVR). This work offers an in-depth assessment of the gas-phase photophysics of a simple fluorophore that could open a new pathway to understanding dual emission in fluorophores.
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Affiliation(s)
| | - Rebecca A Jockusch
- Department of Chemistry, University of Toronto, Toronto, Ontario M5S3H6, Canada
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5
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Beckwith JS, Aster A, Vauthey E. The excited-state dynamics of the radical anions of cyanoanthracenes. Phys Chem Chem Phys 2021; 24:568-577. [PMID: 34904984 PMCID: PMC8694058 DOI: 10.1039/d1cp04014f] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 11/29/2021] [Indexed: 12/03/2022]
Abstract
The radical anion of 9,10-dicyanoanthracene (DCA) has been suggested to be a promising chromophore for photoredox chemistry, due to its nanosecond excited-state lifetime determined from indirect measurements. Here, we investigate the excited-state dynamics of the radical anion of three cyanoanthracenes, including DCA˙-, produced by photoinduced electron transfer in liquid using both pump-probe and pump-pump probe transient electronic absorption spectroscopy. All three excited radical ions are characterised by a 3-5 ps lifetime, due to efficient non-radiative deactivation to the ground state. The decay pathway most probably involves D1/D0 conical intersection(s), whose presence is favoured by the enhanced flexibility of the radical anions relative to their neutral counterparts. The origin of the discrepancy with the nanosecond lifetime of DCA˙-* reported previously is discussed. These very short lifetimes limit, but do not preclude, photochemical applications of the cyanoanthracene anions.
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Affiliation(s)
- Joseph S Beckwith
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
| | - Alexander Aster
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
| | - Eric Vauthey
- Department of Physical Chemistry, University of Geneva, 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
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Abstract
Photochemical reactions are increasingly being used for chemical and materials synthesis, for example, in photoredox catalysis, and generally involve photoexcitation of molecular chromophores dissolved in a liquid solvent. The choice of solvent influences the outcomes of the photochemistry because solute-solvent interactions modify the energies of and crossings between electronic states of the chromophores, and they affect the evolving structures of the photoexcited molecules. Ultrafast laser spectroscopy methods with femtosecond to picosecond time resolution can resolve the dynamics of these photoexcited molecules as they undergo structural and electronic changes, relax back to the ground state, dissipate their excess internal energy to the surrounding solvent, or undergo photochemical reactions. In this Account, we illustrate how experimental studies using ultrafast lasers can reveal the influences that different solvents or cosolutes exert on the photoinduced nonadiabatic dynamics of internal conversion and intersystem crossing in nonradiative relaxation pathways. Although the environment surrounding a solute molecule is rapidly changing, with fluctuations in the coordination to neighboring solvent molecules occurring on femtosecond or picosecond time scales, we show that it is possible to photoexcite selectively only those molecular chromophores transiently experiencing specific solute-solvent interactions such as intermolecular hydrogen bonding.The effects of different solvation environments on the photodynamics are illustrated using four selected examples of photochemical processes in which the solvent has a marked effect on the outcomes. We first consider two aromatic carbonyl compounds, benzophenone and acetophenone, which are known to undergo fast intersystem crossing to populate the first excited triplet state on time scales of a few picoseconds. We show that the nonadiabatic excited-state dynamics are modified by transient hydrogen bonding of the carbonyl group to a protic solvent or by coordination to a metal cation cosolute. We then examine how different solvents modify the competition between two alternative relaxation pathways in a photoexcited UVA-sunscreen molecule, diethylamino hydroxybenzoyl hexyl benzoate (DHHB). This relaxation back to the ground electronic state is an essential part of the effective operation of the sunscreen compound, but the dynamics are sensitive to the surrounding environment. Finally, we consider how solvents of different polarity affect the energies and lifetimes of excited states with locally excited or charge-transfer character in heterocyclic organic compounds used as excited-state electron donors for photoredox catalysis. With these and other examples, we seek to develop a molecular level understanding of how the choice of solution environment might be used to control the outcomes of photochemical reactions.
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Affiliation(s)
- Ravi Kumar Venkatraman
- 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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7
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Zhang X, Vázquez SA, Harvey JN. Vibrational Energy Relaxation of Deuterium Fluoride in d-Dichloromethane: Insights from Different Potentials. J Chem Theory Comput 2021; 17:1277-1289. [PMID: 33550803 DOI: 10.1021/acs.jctc.0c01059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vibrationally excited deuterium fluoride (DF) formed by fluorine atom reaction with a solvent was found (Science, 2015, 347, 530) to relax rapidly (less than 10 ps) in acetonitrile-d3 (CD3CN) and dichloromethane-d2 (CD2Cl2). However, insights into how CD2Cl2 facilitates this energy relaxation have so far been lacking, given the weak interaction between DF and a single CD2Cl2. In this work, we report the results of reactive simulations with a two-state reactive empirical valence bond (EVB) potential to study the energy deposited into nascent DF after transition-state passage and of nonequilibrium molecular dynamics simulations using multiple different potential energy functions to model the relaxation dynamics. For these second simulations, we used the standard Merck molecular force field (MMFF) potential, an MMFF-based covalent-ionic empirical valence bond (EVB) potential (EVBCI), a newly developed potential [referred to as MMFF(rDF)] which extends upon the MMFF potential by making the DF/CD2Cl2 interaction depend on the value of the D-F bond stretching coordinate and by taking the anisotropic charge distribution of the solvent molecules into account, the polarizable atomic multipole optimized energetics for biomolecular applications (AMOEBA) potential, and the quantum mechanics/molecular mechanics (QM/MM) potential. The relaxation is revealed to be highly sensitive to the potential used. Neither standard MMFF nor EVBCI reproduces the experimentally observed rapid relaxation dynamics, and they also fail to provide a good description of the interaction potential between DF and CD2Cl2 as calculated using CCSD(T)-F12. This is attributed to the use of a point-charge model for the solute and to failing to model the anisotropic electrostatic properties of CD2Cl2. The MMFF(rDF), AMOEBA, and QM/MM potentials all reproduce the CCSD(T)-F12 two-body DF---CD2Cl2 interaction potential rather well but only with the QM/MM approach is fast vibrational relaxation obtained (lifetimes of ∼288, ∼186, and ∼8 ps, respectively), which we attribute to differences in the solute-solvent local structure. With QM/MM, a unique "many-body" interaction pattern in which DF is in close contact with two solvent Cl atoms and more than three solvent D atoms is found, but this structure is not seen with other potentials. The QM/MM dynamics also display enhanced solute-solvent interactions with vibrationally excited DF that induce a DF band redshift and hence a resonant overlap with solvent C-D modes, which facilitate the intermolecular energy transfer. Our work also suggests that potentials used to model energy relaxation need to capture the fine structure of solute-solvent interactions and not just the two-body part.
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Affiliation(s)
- Xiaoyong Zhang
- Department of Chemistry and Division of Quantum Chemistry and Physical Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven B-3001, Belgium
| | - Saulo A Vázquez
- Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Santiago de Compostela 15782, Spain
| | - Jeremy N Harvey
- Department of Chemistry and Division of Quantum Chemistry and Physical Chemistry, KU Leuven, Celestijnenlaan 200F, Leuven B-3001, Belgium
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8
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Park S, Lee T, Shin J, Yoon H, Pak Y, Lim M. Conformer-Specific Photodissociation Dynamics of CF2ICF2I in Solution Probed by Time-Resolved Infrared Spectroscopy. J Phys Chem B 2020; 124:8640-8650. [DOI: 10.1021/acs.jpcb.0c06241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Seongchul Park
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Taegon Lee
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Juhyang Shin
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Hojeong Yoon
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Youngshang Pak
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan 46241, Korea
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9
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Straub S, Stubbe J, Lindner J, Sarkar B, Vöhringer P. Vibrational Relaxation Dynamics of an Azido–Cobalt(II) Complex from Femtosecond UV-Pump/MIR-Probe Spectroscopy and Model Simulations with Ab Initio Anharmonic Couplings. Inorg Chem 2020; 59:14629-14642. [DOI: 10.1021/acs.inorgchem.0c00553] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Steffen Straub
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
| | - Jessica Stubbe
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/34, 14195 Berlin, Germany
| | - Jörg Lindner
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
| | - Biprajit Sarkar
- Institut für Chemie und Biochemie, Anorganische Chemie, Freie Universität Berlin, Fabeckstraße 34/34, 14195 Berlin, Germany
- Lehrstuhl für Anorganische Koordinationschemie, Institut für Anorganische Chemie Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Peter Vöhringer
- Lehrstuhl für Molekulare Physikalische Chemie, Institut für Physikalische und Theoretische Chemie, Rheinische Friedrich-Wilhelms-Universität, Wegelerstraße 12, 53115 Bonn, Germany
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10
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Barber VP, Hansen AS, Georgievskii Y, Klippenstein SJ, Lester MI. Experimental and theoretical studies of the doubly substituted methyl-ethyl Criegee intermediate: Infrared action spectroscopy and unimolecular decay to OH radical products. J Chem Phys 2020; 152:094301. [PMID: 33480748 DOI: 10.1063/5.0002422] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The infrared (IR) action spectrum of the doubly substituted methyl-ethyl Criegee intermediate (MECI) is observed in the CH stretch overtone region with detection of OH products. The MECI exhibits four conformers, all of which undergo unimolecular decay via a 1,4 H-atom transfer mechanism, followed by the rapid release of OH products. Conformers with different orientations of the carbonyl oxide group with respect to the methyl and ethyl substituents (i.e., anti and syn) decay via distinct transition state barriers (16.1 kcal mol-1 and 15.4 kcal mol-1, respectively). The observed IR action spectrum is in good agreement with the predicted anharmonic IR absorption spectrum, but exhibits significant congestion, which is attributed to couplings between spectroscopic bright states and nearby dark states. Energy-dependent OH appearance rates are measured upon IR excitation of the strongest features in the IR action spectrum and are found to be on the order of 106-107 s-1. The experimental rates are in good agreement with computed Rice-Ramsperger-Kassel-Marcus rates for the unimolecular decay of MECI at these energies, which incorporate quantum mechanical tunneling and sophisticated hindered rotor treatments, as well as high-level theoretical calculations of the TS barrier heights, rovibrational properties, and torsional barriers associated with the MECI conformers. Master equation modeling is used to predict thermal rates for the unimolecular decay of anti- and syn-MECI of 473 s-1 and 660 s-1, respectively. Comparison with other previously studied Criegee intermediate systems provides insights into substituent effects on unimolecular decay under both energy-dependent and thermal conditions.
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Affiliation(s)
- Victoria P Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Anne S Hansen
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Yuri Georgievskii
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Stephen J Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Marsha I Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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11
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Venkatraman RK, Orr-Ewing AJ. Photochemistry of Benzophenone in Solution: A Tale of Two Different Solvent Environments. J Am Chem Soc 2019; 141:15222-15229. [DOI: 10.1021/jacs.9b07047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Ravi Kumar Venkatraman
- 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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12
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Mensa-Bonsu G, Tozer DJ, Verlet JRR. Photoelectron spectroscopic study of I -·ICF 3: a frontside attack S N2 pre-reaction complex. Phys Chem Chem Phys 2019; 21:13977-13985. [PMID: 30534728 DOI: 10.1039/c8cp06593d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photodetachment and 2D photoelectron spectra of the mass-selected I-·CF3I complex are presented together with electronic structure calculations. Calculations show that the I- is located at the iodine side of CF3I. Vertical and adiabatic detachment energies were measured at 4.03 and approximately 3.8 eV, respectively. The photoelectron spectra and molecular orbitals show a significant covalent bonding character in the cluster. The presence of electronic excited states is observed. Below threshold, iodide is generated which can be assigned to the photoexcitation of degenerate charge-transfer bands from the off-axis p-orbitals localised on iodide. Near the onset of two spin-orbit thresholds, bright excited states are seen in the experiment and calculations. Excitation of these leads to the formation of slow electrons. The spectroscopy of I-·CF3I is compared to the well-studied I-·CH3I cluster, a pre-reaction complex in the text-book I- + CH3I SN2 reaction. Despite the reversed stereodynamics (i.e. inversion of the CX3 between X = H and F) of the SN2 reaction, striking similarities are seen. Both complexes possess charge transfer excited states near their respective vertical detachment energies and exhibit vibrational structure in their photoelectron spectra. The strong binding is consistent with observations in crossed molecular beam studies and molecular dynamics simulations that suggest that iodine as a leaving group in an SN2 reaction affects the reaction dynamics.
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13
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Otolski CJ, Mohan Raj A, Sharma G, Prabhakar R, Ramamurthy V, Elles CG. Ultrafast trans → cis Photoisomerization Dynamics of Alkyl-Substituted Stilbenes in a Supramolecular Capsule. J Phys Chem A 2019; 123:5061-5071. [PMID: 31140802 DOI: 10.1021/acs.jpca.9b03285] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ultrafast spectroscopy reveals the effects of confinement on the excited-state photoisomerization dynamics for a series of alkyl-substituted trans-stilbenes encapsulated in the hydrophobic cavity of an aqueous supramolecular organic host-guest complex. Compared with the solvated compounds, encapsulated trans-stilbenes have broader excited-state absorption spectra, excited-state lifetimes that are 3-4 times longer, and photoisomerization quantum yields that are 1.7-6.5 times lower in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central C═C double bond in the excited state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. The location and identity of alkyl substituents play a significant role in determining the excited-state dynamics and photoisomerization quantum yields by tuning the relative crowding inside the capsule. The results are discussed in terms of distortions of the ground- and excited-state potential energy surfaces, including the topology of the S1-S0 conical intersection.
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Affiliation(s)
- Christopher J Otolski
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
| | - A Mohan Raj
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | - Gaurav Sharma
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | - Rajeev Prabhakar
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | | | - Christopher G Elles
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
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14
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15
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Barber VP, Pandit S, Esposito VJ, McCoy AB, Lester MI. CH Stretch Activation of CH3CHOO: Deep Tunneling to Hydroxyl Radical Products. J Phys Chem A 2019; 123:2559-2569. [DOI: 10.1021/acs.jpca.8b12324] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Victoria P. Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Shubhrangshu Pandit
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Vincent J. Esposito
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Anne B. McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195-1700, United States
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
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16
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Matyushov DV. Nonequilibrium vibrational population and donor-acceptor vibrations affecting rates of radiationless transitions. J Chem Phys 2019; 150:074504. [DOI: 10.1063/1.5082970] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dmitry V. Matyushov
- Department of Physics and School of Molecular Sciences, Arizona State University, P.O. Box 871504, Tempe, Arizona 85287, USA
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17
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Unke OT, Brickel S, Meuwly M. Sampling reactive regions in phase space by following the minimum dynamic path. J Chem Phys 2019; 150:074107. [DOI: 10.1063/1.5082885] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Affiliation(s)
- Oliver T. Unke
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Sebastian Brickel
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Markus Meuwly
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
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18
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Zhang X, Harvey JN. EVB and polarizable MM study of energy relaxation in fluorine–acetonitrile reactions. Phys Chem Chem Phys 2019; 21:14331-14340. [DOI: 10.1039/c8cp06686h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many-body effects can impact on rates of energy transfer from a ‘hot’ DF solute to acetonitrile solvent.
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Affiliation(s)
- Xiaoyong Zhang
- Department of Chemistry and Division of Quantum Chemistry and Physical Chemistry
- KU Leuven
- B-3001 Leuven
- Belgium
| | - Jeremy N. Harvey
- Department of Chemistry and Division of Quantum Chemistry and Physical Chemistry
- KU Leuven
- B-3001 Leuven
- Belgium
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19
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Park S, Shin J, Yoon H, Pak Y, Lim M. Complete photodissociation dynamics of CF2I2in solution. Phys Chem Chem Phys 2019; 21:6859-6867. [DOI: 10.1039/c9cp00507b] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photoexcited CF2I2in c-C6H12undergoes various secondary reactions including complex and isomer formation, after ultrafast two- or three-body dissociations.
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Affiliation(s)
- Seongchul Park
- Department of Chemistry and Chemistry Institute for Functional Materials
- Pusan National University
- Busan 46241
- Korea
| | - Juhyang Shin
- Department of Chemistry and Chemistry Institute for Functional Materials
- Pusan National University
- Busan 46241
- Korea
| | - Hojeong Yoon
- Department of Chemistry and Chemistry Institute for Functional Materials
- Pusan National University
- Busan 46241
- Korea
| | - Youngshang Pak
- Department of Chemistry and Chemistry Institute for Functional Materials
- Pusan National University
- Busan 46241
- Korea
| | - Manho Lim
- Department of Chemistry and Chemistry Institute for Functional Materials
- Pusan National University
- Busan 46241
- Korea
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20
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Monte Carlo stochastic simulation of the master equation for unimolecular reaction systems. ACTA ACUST UNITED AC 2019. [DOI: 10.1016/b978-0-444-64207-3.00007-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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21
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Paul AK, West NA, Winner JD, Bowersox RDW, North SW, Hase WL. Non-statistical intermolecular energy transfer from vibrationally excited benzene in a mixed nitrogen-benzene bath. J Chem Phys 2018; 149:134101. [DOI: 10.1063/1.5043139] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Amit K. Paul
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
- Department of Chemistry, National Institute of Technology Meghalaya, Shillong 793003, India
| | - Niclas A. West
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Joshua D. Winner
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | | | - Simon W. North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409, USA
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22
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Abstract
The dynamics of chemical reactions in liquid solutions are now amenable to direct study using ultrafast laser spectroscopy techniques and advances in computer simulation methods. The surrounding solvent affects the chemical reaction dynamics in numerous ways, which include: (i) formation of complexes between reactants and solvent molecules; (ii) modifications to transition state energies and structures relative to the reactants and products; (iii) coupling between the motions of the reacting molecules and the solvent modes, and exchange of energy; (iv) solvent caging of reactants and products; and (v) structural changes to the solvation shells in response to the changing chemical identity of the solutes, on timescales which may be slower than the reactive events. This article reviews progress in the study of bimolecular chemical reaction dynamics in solution, concentrating on reactions which occur on ground electronic states. It illustrates this progress with reference to recent experimental and computational studies, and considers how the various ways in which a solvent affects the chemical reaction dynamics can be unravelled. Implications are considered for research in fields such as mechanistic synthetic chemistry.
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Affiliation(s)
- Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, UK.
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23
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Gaining control. Nat Chem 2018; 10:113-114. [DOI: 10.1038/nchem.2937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Kayal S, Roy K, Umapathy S. Femtosecond coherent nuclear dynamics of excited tetraphenylethylene: Ultrafast transient absorption and ultrafast Raman loss spectroscopic studies. J Chem Phys 2018; 148:024301. [DOI: 10.1063/1.5008726] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Surajit Kayal
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Khokan Roy
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
| | - Siva Umapathy
- Inorganic and Physical Chemistry Department, Indian Institute of Science, Bangalore 560012, India
- Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012, India
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25
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Inagaki M, Motobayashi K, Ikeda K. Electrochemical THz-SERS Observation of Thiol Monolayers on Au(111) and (100) Using Nanoparticle-assisted Gap-Mode Plasmon Excitation. J Phys Chem Lett 2017; 8:4236-4240. [PMID: 28830138 DOI: 10.1021/acs.jpclett.7b01901] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Surface-enhanced Raman scattering (SERS) microscopy using nanoparticle-assisted gap-mode plasmon excitation, which enables us to observe an atomically defined planar metal surface, was combined with THz-Raman spectroscopy to observe ultra-low-frequency vibration modes under electrochemical conditions. This combination helps us to gain deeper insights into electrode/electrolyte interfaces via direct observation of extramolecular vibrations including information on intermolecular and substrate/molecule interactions. Electrochemical reductive desorption of benzenethiol derivatives from Au(111) and (100) was monitored to demonstrate the power of this spectroscopy. Structural differences of the monolayers between these surfaces were seen only in the extramolecular vibration modes such as a large-amplitude hinge-bending motion of the phenyl ring. On the Au(111), where hollow-site and bridge-site adsorption coexisted, the electrochemical reductive desorption was preferentially induced at the hollow sites.
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Affiliation(s)
- Motoharu Inagaki
- Department of Physical Science and Engineering, Nagoya Institute of Technology , Nagoya 466-8555, Japan
| | - Kenta Motobayashi
- Department of Physical Science and Engineering, Nagoya Institute of Technology , Nagoya 466-8555, Japan
| | - Katsuyoshi Ikeda
- Department of Physical Science and Engineering, Nagoya Institute of Technology , Nagoya 466-8555, Japan
- Frontier Research Institute for Materials Science (FRIMS), Nagoya Institute of Technology , Nagoya 466-8555, Japan
- Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS) , Tsukuba 305-0044, Japan
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26
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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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27
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Coherent ultrafast lattice-directed reaction dynamics of triiodide anion photodissociation. Nat Chem 2017; 9:516-522. [DOI: 10.1038/nchem.2751] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 02/13/2017] [Indexed: 01/21/2023]
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28
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Kieda RD, Dunkelberger AD, Case AS, Crim FF. Solvent Dependent Dynamics of Salicylidene Aniline in Binary Mixtures of Supercritical CO2 with 1-Propanol or Cyclohexane. J Phys Chem B 2017; 121:835-842. [DOI: 10.1021/acs.jpcb.6b05959] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ryan D. Kieda
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Adam D. Dunkelberger
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Amanda S. Case
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - F. Fleming Crim
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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29
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Fang Y, Liu F, Barber VP, Klippenstein SJ, McCoy AB, Lester MI. Deep tunneling in the unimolecular decay of CH3CHOO Criegee intermediates to OH radical products. J Chem Phys 2016; 145:234308. [DOI: 10.1063/1.4972015] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Yi Fang
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Fang Liu
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Victoria P. Barber
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
| | - Stephen J. Klippenstein
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Anne B. McCoy
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Marsha I. Lester
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, USA
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30
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Kumpulainen T, Lang B, Rosspeintner A, Vauthey E. Ultrafast Elementary Photochemical Processes of Organic Molecules in Liquid Solution. Chem Rev 2016; 117:10826-10939. [DOI: 10.1021/acs.chemrev.6b00491] [Citation(s) in RCA: 249] [Impact Index Per Article: 31.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Tatu Kumpulainen
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Bernhard Lang
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Arnulf Rosspeintner
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Eric Vauthey
- Department of Physical Chemistry,
Sciences II, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
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31
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Rather SR, Scholes GD. Slow Intramolecular Vibrational Relaxation Leads to Long-Lived Excited-State Wavepackets. J Phys Chem A 2016; 120:6792-9. [PMID: 27510098 DOI: 10.1021/acs.jpca.6b07796] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Broadband optical pump and compressed white light continuum probe were used to measure the transient excited-state absorption, ground-state bleach, and stimulated emission signals of cresyl violet solution in methanol. Amplitude oscillations caused by wavepacket motion in the ground and excited electronic states were analyzed. It was found that vibrational coherences in the excited state persist for more than the experimental waiting time window of 6 ps, and the strongest mode had a dephasing time constant of 2.4 ps. We hypothesize the dephasing of the wavepacket in the excited state is predominantly caused by intramolecular vibrational relaxation (IVR). Slow IVR indicates weak mode-mode coupling and therefore weak anharmonicity of the potential of this vibration. Thus, the initially prepared vibrational wavepacket in the excited state is not significantly perturbed by nonadiabatic coupling to other electronic states, and hence the diabatic and adiabatic representations of the system are essentially identical within the Born-Oppenheimer approximation. The wavepacket therefore evolves with time in an almost harmonic potential, slowly dephased by IVR and the pure vibrational decoherence. The consistency in the position of node (phase change in the wavepacket) in the excited-state absorption and stimulated emission signals without undergoing any frequency shift until the wavepacket is completely dephased conforms to the absence of any reactive internal conversion.
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Affiliation(s)
- Shahnawaz R. Rather
- Frick Chemistry Laboratory, Princeton University , Princeton, New Jersey 08544, United States
| | - Gregory D Scholes
- Frick Chemistry Laboratory, Princeton University , Princeton, New Jersey 08544, United States
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32
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Kunnus K, Josefsson I, Rajkovic I, Schreck S, Quevedo W, Beye M, Weniger C, Grübel S, Scholz M, Nordlund D, Zhang W, Hartsock RW, Gaffney KJ, Schlotter WF, Turner JJ, Kennedy B, Hennies F, de Groot FMF, Techert S, Odelius M, Wernet P, Föhlisch A. Identification of the dominant photochemical pathways and mechanistic insights to the ultrafast ligand exchange of Fe(CO)5 to Fe(CO)4EtOH. STRUCTURAL DYNAMICS (MELVILLE, N.Y.) 2016; 3:043204. [PMID: 26958587 PMCID: PMC4752567 DOI: 10.1063/1.4941602] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 01/22/2016] [Indexed: 05/19/2023]
Abstract
We utilized femtosecond time-resolved resonant inelastic X-ray scattering and ab initio theory to study the transient electronic structure and the photoinduced molecular dynamics of a model metal carbonyl photocatalyst Fe(CO)5 in ethanol solution. We propose mechanistic explanation for the parallel ultrafast intra-molecular spin crossover and ligation of the Fe(CO)4 which are observed following a charge transfer photoexcitation of Fe(CO)5 as reported in our previous study [Wernet et al., Nature 520, 78 (2015)]. We find that branching of the reaction pathway likely happens in the (1)A1 state of Fe(CO)4. A sub-picosecond time constant of the spin crossover from (1)B2 to (3)B2 is rationalized by the proposed (1)B2 → (1)A1 → (3)B2 mechanism. Ultrafast ligation of the (1)B2 Fe(CO)4 state is significantly faster than the spin-forbidden and diffusion limited ligation process occurring from the (3)B2 Fe(CO)4 ground state that has been observed in the previous studies. We propose that the ultrafast ligation occurs via (1)B2 → (1)A1 → (1)A' Fe(CO)4EtOH pathway and the time scale of the (1)A1 Fe(CO)4 state ligation is governed by the solute-solvent collision frequency. Our study emphasizes the importance of understanding the interaction of molecular excited states with the surrounding environment to explain the relaxation pathways of photoexcited metal carbonyls in solution.
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Affiliation(s)
| | - I Josefsson
- Department of Physics, Stockholm University , AlbaNova University Centre, 10691 Stockholm, Sweden
| | - I Rajkovic
- Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37070 Göttingen, Germany
| | | | - W Quevedo
- Institute for Methods and Instrumentation for Synchrotron Radiation Research , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - M Beye
- Institute for Methods and Instrumentation for Synchrotron Radiation Research , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - C Weniger
- Institute for Methods and Instrumentation for Synchrotron Radiation Research , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - S Grübel
- Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37070 Göttingen, Germany
| | - M Scholz
- Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37070 Göttingen, Germany
| | - D Nordlund
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - W Zhang
- PULSE Institute , SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - R W Hartsock
- PULSE Institute , SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - K J Gaffney
- PULSE Institute , SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - W F Schlotter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - J J Turner
- Linac Coherent Light Source, SLAC National Accelerator Laboratory , Menlo Park, California 94025, USA
| | - B Kennedy
- Institute for Methods and Instrumentation for Synchrotron Radiation Research , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - F Hennies
- MAX-lab , P.O. Box 118, 221 00 Lund, Sweden
| | - F M F de Groot
- Department of Chemistry, Utrecht University , Universiteitsweg 99, 3584 CG Utrecht, The Netherlands
| | | | - M Odelius
- Department of Physics, Stockholm University , AlbaNova University Centre, 10691 Stockholm, Sweden
| | - Ph Wernet
- Institute for Methods and Instrumentation for Synchrotron Radiation Research , Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
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33
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Rodgers JM, Zhang W, Bazewicz CG, Chen J, Brewer SH, Gai F. Kinetic Isotope Effect Provides Insight into the Vibrational Relaxation Mechanism of Aromatic Molecules: Application to Cyano-phenylalanine. J Phys Chem Lett 2016; 7:1281-1287. [PMID: 26990401 PMCID: PMC4824650 DOI: 10.1021/acs.jpclett.6b00325] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Varying the reduced mass of an oscillator via isotopic substitution provides a convenient means to alter its vibrational frequency and hence has found wide applications. Herein, we show that this method can also help delineate the vibrational relaxation mechanism, using four isotopomers of the unnatural amino acid p-cyano-phenylalanine (Phe-CN) as models. In water, the nitrile stretching frequencies of these isotopomers, Phe-(12)C(14)N (1), Phe-(12)C(15)N (2), Phe-(13)C(14)N (3), and Phe-(13)C(15)N (4), are found to be equally separated by ∼27 cm(-1), whereas their vibrational lifetimes are determined to be 4.0 ± 0.2 (1), 2.2 ± 0.1 (2), 3.4 ± 0.2 (3), and 7.9 ± 0.5 ps (4), respectively. We find that an empirical relationship that considers the effective reduced mass of CN can accurately account for the observed frequency gaps, while the vibrational lifetime distribution, which suggests an intramolecular relaxation mechanism, can be rationalized by the order-specific density of states near the CN stretching frequency.
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Affiliation(s)
- Jeffrey M. Rodgers
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Wenkai Zhang
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | | | - Jianxin Chen
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
| | - Scott H. Brewer
- Department of Chemistry, Franklin & Marshall College, Lancaster, Pennsylvania 17604-3003
| | - Feng Gai
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
- The Ultrafast Optical Processes Laboratory, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323
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34
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Koyama D, Coulter P, Grubb MP, Greetham GM, Clark IP, Orr-Ewing AJ. Reaction Dynamics of CN Radicals in Acetonitrile Solutions. J Phys Chem A 2015; 119:12924-34. [DOI: 10.1021/acs.jpca.5b10720] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daisuke Koyama
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - Philip Coulter
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - Michael P. Grubb
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
| | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0QX, U.K
| | - Andrew J. Orr-Ewing
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, U.K
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35
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Glowacki DR, Orr-Ewing AJ, Harvey JN. Non-equilibrium reaction and relaxation dynamics in a strongly interacting explicit solvent: F + CD3CN treated with a parallel multi-state EVB model. J Chem Phys 2015; 143:044120. [DOI: 10.1063/1.4926996] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- David R. Glowacki
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom
- Department of Computer Science, University of Bristol, Bristol BS8 1UB, United Kingdom
- PULSE Institute and Department of Chemistry, Stanford University, Stanford, California 94305, USA
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | | | - Jeremy N. Harvey
- Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee, Belgium
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36
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Mereshchenko AS, Butaeva EV, Borin VA, Eyzips A, Tarnovsky AN. Roaming-mediated ultrafast isomerization of geminal tri-bromides in the gas and liquid phases. Nat Chem 2015; 7:562-8. [DOI: 10.1038/nchem.2278] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 05/09/2015] [Indexed: 11/09/2022]
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37
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Horbury MD, Baker LA, Quan WD, Young JD, Staniforth M, Greenough SE, Stavros VG. Bridging the Gap between the Gas Phase and Solution Phase: Solvent Specific Photochemistry in 4-tert-Butylcatechol. J Phys Chem A 2015; 119:11989-96. [DOI: 10.1021/acs.jpca.5b03621] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael D. Horbury
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Lewis A. Baker
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Wen-Dong Quan
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Jamie D. Young
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Michael Staniforth
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Simon E. Greenough
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Gibbet Hill
Road, Coventry, CV4 7AL, U.K
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38
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Carbonniere P, Pouchan C, Improta R. Intramolecular vibrational redistribution in the non-radiative excited state decay of uracil in the gas phase: an ab initio molecular dynamics study. Phys Chem Chem Phys 2015; 17:11615-26. [PMID: 25866850 DOI: 10.1039/c4cp05265j] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report a study of intramolecular vibrational distribution (IVR) occurring in the electronic ground state of uracil (S0) in the gas phase, following photoexcitation in the lowest energy bright excited state (Sπ) and decay through the ethylene-like Sπ/S0 Conical Intersection (CI-0π). To this aim we have performed 20 independent ab initio molecular dynamics simulations starting from CI-0π (ten of them with 1 eV kinetic energy randomly distributed over the different molecular degrees of freedom) and 10 starting from the ground state minimum (Franck-Condon, FC, point), with the excess kinetic energy equal to the energy gap between CI-0π and the FC point. The simulations, exploiting PBE0/6-31G(d) calculations, were performed over an overall period of 10 ps. A thorough statistical analysis of the variation of the geometrical parameters of uracil during the simulation time and of the distribution of the kinetic energy among the different vibrational degrees of freedom provides a consistent picture of the IVR process. In the first 0-200 fs the structural dynamics involve mainly the recovery of the average planarity. In the 200-600 fs time range, a substantial activation of CO and NH degrees of freedom is observed. After 500-600 fs most of the geometrical parameters reach average values similar to those found after 10 ps, though the system cannot be considered to be in equilibrium yet.
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Affiliation(s)
- Philippe Carbonniere
- Université de Pau et des Pays de l'Adour UMR5254, IPREM, Equipe Chimie-Physique Hélioparc, 2 av. Président Angot 64053, Pau Cedex 09, France.
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39
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Description of cross-peaks induced by intermolecular vibrational energy transfer in two-dimensional infrared spectroscopy. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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40
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Affiliation(s)
- Andrew J. Orr-Ewing
- School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom;
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41
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Hewage D, Roudjane M, Silva WR, Kumari S, Yang DS. Lanthanum-Mediated C–H Bond Activation of Propyne and Identification of La(C3H2) Isomers. J Phys Chem A 2015; 119:2857-62. [DOI: 10.1021/jp512777e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Dilrukshi Hewage
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Mourad Roudjane
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - W. Ruchira Silva
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Sudesh Kumari
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
| | - Dong-Sheng Yang
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, United States
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42
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Rivera-Rivera LA, Wagner AF, Sewell TD, Thompson DL. Pressure effects on the relaxation of an excited nitromethane molecule in an argon bath. J Chem Phys 2015; 142:014303. [PMID: 25573557 DOI: 10.1063/1.4904314] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Classical molecular dynamics simulations were performed to study the relaxation of nitromethane in an Ar bath (of 1000 atoms) at 300 K and pressures 10, 50, 75, 100, 125, 150, 300, and 400 atm. The molecule was instantaneously excited by statistically distributing 50 kcal/mol among the internal degrees of freedom. At each pressure, 1000 trajectories were integrated for 1000 ps, except for 10 atm, for which the integration time was 5000 ps. The computed ensemble-averaged rotational energy decay is ∼100 times faster than the vibrational energy decay. Both rotational and vibrational decay curves can be satisfactorily fit with the Lendvay-Schatz function, which involves two parameters: one for the initial rate and one for the curvature of the decay curve. The decay curves for all pressures exhibit positive curvature implying the rate slows as the molecule loses energy. The initial rotational relaxation rate is directly proportional to density over the interval of simulated densities, but the initial vibrational relaxation rate decreases with increasing density relative to the extrapolation of the limiting low-pressure proportionality to density. The initial vibrational relaxation rate and curvature are fit as functions of density. For the initial vibrational relaxation rate, the functional form of the fit arises from a combinatorial model for the frequency of nitromethane "simultaneously" colliding with multiple Ar atoms. Roll-off of the initial rate from its low-density extrapolation occurs because the cross section for collision events with L Ar atoms increases with L more slowly than L times the cross section for collision events with one Ar atom. The resulting density-dependent functions of the initial rate and curvature represent, reasonably well, all the vibrational decay curves except at the lowest density for which the functions overestimate the rate of decay. The decay over all gas phase densities is predicted by extrapolating the fits to condensed-phase densities.
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Affiliation(s)
- Luis A Rivera-Rivera
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA
| | - Albert F Wagner
- Argonne National Laboratory, Chemical Sciences and Engineering Division, Argonne, Illinois 60439, USA
| | - Thomas D Sewell
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA
| | - Donald L Thompson
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA
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43
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Orr-Ewing AJ. Perspective: Bimolecular chemical reaction dynamics in liquids. J Chem Phys 2014; 140:090901. [PMID: 24606343 DOI: 10.1063/1.4866761] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bimolecular reactions in the gas phase exhibit rich and varied dynamical behaviour, but whether a profound knowledge of the mechanisms of isolated reactive collisions can usefully inform our understanding of reactions in liquid solutions remains an open question. The fluctuating environment in a liquid may significantly alter the motions of the reacting particles and the flow of energy into the reaction products after a transition state has been crossed. Recent experimental and computational studies of exothermic reactions of CN radicals with organic molecules indicate that many features of the gas-phase dynamics are retained in solution. However, observed differences may also provide information on the ways in which a solvent modifies fundamental chemical mechanisms. This perspective examines progress in the use of time-resolved infra-red spectroscopy to study reaction dynamics in liquids, discusses how existing theories can guide the interpretation of experimental data, and suggests future challenges for this field of research.
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Affiliation(s)
- Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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44
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Harris SJ, Murdock D, Grubb MP, Clark IP, Greetham GM, Towrie M, Ashfold MNR. Tracking a Paternò–Büchi Reaction in Real Time Using Transient Electronic and Vibrational Spectroscopies. J Phys Chem A 2014; 118:10240-5. [DOI: 10.1021/jp507958y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Stephanie J. Harris
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
| | - Daniel Murdock
- 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
| | - Ian P. Clark
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0QX, United Kingdom
| | - Gregory M. Greetham
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0QX, United Kingdom
| | - Michael Towrie
- Central
Laser Facility, Research Complex at Harwell, Science and Technology
Facilities Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire, OX11 0QX, United Kingdom
| | - Michael N. R. Ashfold
- School
of Chemistry, University of Bristol, Cantock’s Close, Bristol, BS8 1TS, United Kingdom
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45
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Molloy MS, Snyder JA, Bragg AE. Structural and Solvent Control of Nonadiabatic Photochemical Bond Formation: Photocyclization of o-Terphenyl in Solution. J Phys Chem A 2014; 118:3913-25. [DOI: 10.1021/jp501988g] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Molly S. Molloy
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Joshua A. Snyder
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Arthur E. Bragg
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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46
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Sen S, Talukder S, Chaudhury P. Optimal designing of polychromatic field for maximum dissociation of LiH molecule. INDIAN JOURNAL OF PHYSICS 2013; 87:865-872. [DOI: 10.1007/s12648-013-0307-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/19/2023]
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47
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Kalume A, George L, Cunningham N, Reid SA. Case of the Missing Isomer: Pathways for Molecular Elimination in the Photoinduced Decomposition of 1,1-Dibromoethane. J Phys Chem A 2013; 117:11915-23. [DOI: 10.1021/jp403114s] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Aimable Kalume
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881,
United States
| | - Lisa George
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881,
United States
| | - Nicole Cunningham
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881,
United States
| | - Scott A. Reid
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201-1881,
United States
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Zhang Y, Chen J, Kohler B. Hydrogen Bond Donors Accelerate Vibrational Cooling of Hot Purine Derivatives in Heavy Water. J Phys Chem A 2013; 117:6771-80. [DOI: 10.1021/jp4040002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuyuan Zhang
- Department
of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United
States
| | - Jinquan Chen
- Department
of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United
States
| | - Bern Kohler
- Department
of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United
States
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49
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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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50
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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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