1
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Fausto R, Ildiz GO, Nunes CM. IR-induced and tunneling reactions in cryogenic matrices: the (incomplete) story of a successful endeavor. Chem Soc Rev 2022; 51:2853-2872. [PMID: 35302145 DOI: 10.1039/d1cs01026c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this article, IR-induced and tunneling-driven reactions observed in cryogenic matrices are described in a historical perspective, the entangling of the two types of processes being highlighted. The story of this still ongoing fascinating scientific endeavor is presented here following closely our own involvement in the field for more than 30 years, and thus focuses mostly on our work. It is, because of this reason, also an incomplete story. Nevertheless, it considers a large range of examples, from very selective IR-induced conformational isomerizations to IR-induced bond-breaking/bond-forming reactions and successful observations of rare heavy atom tunneling processes. As a whole, this article provides a rather general overview of the major progress achieved in the field.
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Affiliation(s)
- Rui Fausto
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
| | - Gulce O Ildiz
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal. .,Department of Physics, Faculty of Sciences and Letters, Istanbul Kultur University, 34158 Bakirkoy, Istanbul, Turkey
| | - Cláudio M Nunes
- CQC-IMS, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal.
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2
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Li W, Tikhonov DS, Schnell M. Double Proton Transfer Across a Table: The Formic Acid Dimer-Fluorobenzene Complex. Angew Chem Int Ed Engl 2021; 60:25674-25679. [PMID: 34448334 PMCID: PMC9293461 DOI: 10.1002/anie.202108242] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/06/2021] [Indexed: 11/30/2022]
Abstract
Proton transfer via tunneling is a fundamental quantum‐mechanical phenomenon. We report rotational spectroscopy measurements of this process in the complex of the formic acid dimer with fluorobenzene. The assignment of the spectrum indicates that this complex exists in the form of a π–π stacked structure. Each rotational transition of the parent isotopologue exhibits splitting. Isotopic substitution experiments show that the spectral splitting results from double‐proton transfer tunneling in the formic acid dimer. Presence of fluorobenzene as a neighboring molecule does not quench the double proton transfer in the formic acid dimer but decreases its tunneling splitting from 341(3) MHz to 267.608(1) MHz. Calculations suggest that the presence of the weakly bounded fluorobenzene does not influence the activation energy of the proton transfer. The fluorobenzene is reoriented with respect to the formic acid dimer during the course of the reaction, slowing down the proton transfer motion.
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Affiliation(s)
- Weixing Li
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany.,Current address: Department of Chemistry, Fudan University, Songhu Rd. 2005, 200438, Shanghai, China
| | - Denis S Tikhonov
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607, Hamburg, Germany.,Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Str. 1, 24118, Kiel, Germany
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3
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Li W, Tikhonov DS, Schnell M. Double Proton Transfer Across a Table: The Formic Acid Dimer–Fluorobenzene Complex. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202108242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Weixing Li
- Deutsches Elektronen-Synchrotron DESY Notkestr. 85 22607 Hamburg Germany
- Institute of Physical Chemistry Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
- Current address: Department of Chemistry Fudan University Songhu Rd. 2005 200438 Shanghai China
| | - Denis S. Tikhonov
- Deutsches Elektronen-Synchrotron DESY Notkestr. 85 22607 Hamburg Germany
- Institute of Physical Chemistry Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron DESY Notkestr. 85 22607 Hamburg Germany
- Institute of Physical Chemistry Christian-Albrechts-Universität zu Kiel Max-Eyth-Str. 1 24118 Kiel Germany
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4
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Roque JPL, Sharma A, Rosado MTS, Fausto R, Reva I. Vibrationally Induced Conformational Isomerization and Tunneling in Pyrrole-2-Carboxylic Acid. J Phys Chem A 2020; 124:10277-10287. [PMID: 33245233 DOI: 10.1021/acs.jpca.0c09141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational behavior of carboxylic acids has attracted considerable attention, as it can be used as a gateway for the study of more complex phenomena. Here, we present an experimental and computational study of pyrrole-2-carboxylic acid (PCA) conformational space and the vibrational characterization of the compound by infrared spectroscopy. The possibility of promoting conformational transformations using selective vibrational excitation of the 2ν(OH) and 2ν(NH) stretching overtones is explored. Two conformers, exhibiting the cis configuration of the COOH group (O═C-O-H dihedral angle near 0°) and differing by the orientation of the carboxylic group with respect to the pyrrole ring (i.e., showing either a cis or a trans NCC═O arrangement), were found to coexist initially for the compound isolated in a cryogenic nitrogen matrix, in an 86:14 ratio, and were characterized by infrared spectroscopy. A third conformer, with the COOH group in the trans configuration, was produced, in situ, by narrowband near-infrared (NIR) excitation of the most stable PCA form (with a cis NCC═O moiety). The photogenerated PCA conformer was found to decay back to the most stable PCA form, by H-atom quantum mechanical tunneling, with a characteristic half-life time of ∼10 min in the nitrogen matrix at 10 K. Tunneling rates were theoretically estimated and compared for the observed isomerization of pyrrole-2-carboxylic acid and for the structurally similar furan-2-carboxylic acid. This comparison showcases the effect of small modifications in the potential energy surface and the implications of quantum tunneling for the stability of short-living species.
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Affiliation(s)
- José P L Roque
- CQC, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Archna Sharma
- CQC, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal.,Department of Physics, University of Jammu, Jammu 180001, India
| | - Mário T S Rosado
- CQC, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Rui Fausto
- CQC, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
| | - Igor Reva
- CQC, Department of Chemistry, University of Coimbra, Coimbra 3004-535, Portugal
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5
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Structural Aspects of the Ortho Chloro- and Fluoro- Substituted Benzoic Acids: Implications on Chemical Properties. MOLECULES (BASEL, SWITZERLAND) 2020; 25:molecules25214908. [PMID: 33114074 PMCID: PMC7660354 DOI: 10.3390/molecules25214908] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 10/16/2020] [Accepted: 10/18/2020] [Indexed: 11/21/2022]
Abstract
This article presents a detailed comprehensive investigation of the ortho fluoro- and chloro- substituted benzoic acids both, as isolated molecules and in the crystalline phase. Quantum chemical calculations performed within the density functional theory (DFT) formalism are used to investigate the potential energy landscapes of the molecules, taking into special consideration the effects of the interactions between the carboxylic group and the ortho halogen substituents, as well as the nature of these later on the structure and properties of the investigated systems. The structures of the relevant conformers of the molecules are discussed in comparative terms, and used to rationalize experimental data obtained for the compounds in the gas phase and isolated in low-temperature inert matrices. The UV-induced photofragmentation reactions of two of the compounds isolated in cryogenic inert matrices were studied as illustrative cases. The structures of the crystals reported previously in the literature are revisited and discussed also in a comparative basis. Particular emphasis is given to the analysis of the intermolecular interactions in the different crystals, using Hirshfeld surface analysis, the CE-B3LYP energy decomposition model and the HOMA index, and to their correlation with thermodynamic data.
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6
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Schleif T, Mieres-Perez J, Henkel S, Mendez-Vega E, Inui H, McMahon RJ, Sander W. Conformer-Specific Heavy-Atom Tunneling in the Rearrangement of Benzazirines to Ketenimines. J Org Chem 2019; 84:16013-16018. [PMID: 31730349 DOI: 10.1021/acs.joc.9b02482] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
5-Methoxy-2H-benzazirine was prepared via irradiation of the corresponding phenyl azide, isolated in an argon matrix at cryogenic temperatures. It undergoes ring expansion to the corresponding ketenimine in the dark at T < 30 K despite a calculated activation barrier of 4.9 kcal mol-1 [B3LYP/6-311++G(d,p)]. Since this rearrangement proceeds with a rate constant in the order of 10-4 s-1, exhibiting only a shallow temperature dependence, the results are interpreted in terms of heavy-atom tunneling. Of the four isomeric benzazirines resulting from the initial photolysis, only one can be observed to rearrange; this conformer specificity is explained by the other potentially observable rearrangements being either too fast or too slow to be detected due to the differences in heights and widths of their respective activation barriers.
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Affiliation(s)
- Tim Schleif
- Lehrstuhl für Organische Chemie II , Ruhr-Universität Bochum , 44801 Bochum , Germany
| | - Joel Mieres-Perez
- Lehrstuhl für Organische Chemie II , Ruhr-Universität Bochum , 44801 Bochum , Germany
| | - Stefan Henkel
- Lehrstuhl für Organische Chemie II , Ruhr-Universität Bochum , 44801 Bochum , Germany
| | - Enrique Mendez-Vega
- Lehrstuhl für Organische Chemie II , Ruhr-Universität Bochum , 44801 Bochum , Germany
| | - Hiroshi Inui
- Department of Chemistry, School of Science , Kitasato University , 1-15-1 Kitasato, Minami-ku , Sagamihara , Kanagawa 252-0373 , Japan
| | - Robert J McMahon
- Department of Chemistry , University of Wisconsin-Madison , 1101 University Avenue , Madison , Wisconsin 53706-1322 , United States
| | - Wolfram Sander
- Lehrstuhl für Organische Chemie II , Ruhr-Universität Bochum , 44801 Bochum , Germany
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7
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Hayashi M, Koga H, Kumakura T, Akai N, Nakata M. Photoinduced Wolff rearrangement and tautomerization of 3-chloro-2-hydroxypyridine isolated in an Ar matrix. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.07.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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8
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Góbi S, Nunes CM, Reva I, Tarczay G, Fausto R. S–H rotamerizationviatunneling in a thiol form of thioacetamide. Phys Chem Chem Phys 2019; 21:17063-17071. [DOI: 10.1039/c9cp03417j] [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
Rotamerization of the S–H groupviahydrogen tunneling is reported for the first time.
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Affiliation(s)
- Sándor Góbi
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| | | | - Igor Reva
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| | - György Tarczay
- Laboratory of Molecular Spectroscopy
- Institute of Chemistry
- ELTE Eötvös Loránd University
- H-1518 Budapest
- Hungary
| | - Rui Fausto
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
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9
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Pitsawong W, Haynes CA, Koder RL, Rodgers DW, Miller AF. Mechanism-Informed Refinement Reveals Altered Substrate-Binding Mode for Catalytically Competent Nitroreductase. Structure 2017; 25:978-987.e4. [PMID: 28578873 DOI: 10.1016/j.str.2017.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 04/02/2017] [Accepted: 05/05/2017] [Indexed: 01/25/2023]
Abstract
Nitroreductase (NR) from Enterobacter cloacae reduces diverse nitroaromatics including herbicides, explosives, and prodrugs, and holds promise for bioremediation, prodrug activation, and enzyme-assisted synthesis. We solved crystal structures of NR complexes with bound substrate or analog for each of its two half-reactions. We complemented these with kinetic isotope effect (KIE) measurements elucidating H-transfer steps essential to each half-reaction. KIEs indicate hydride transfer from NADH to the flavin consistent with our structure of NR with the NADH analog nicotinic acid adenine dinucleotide (NAAD). The KIE on reduction of p-nitrobenzoic acid (p-NBA) also indicates hydride transfer, and requires revision of prior computational mechanisms. Our mechanistic information provided a structural restraint for the orientation of bound substrate, placing the nitro group closer to the flavin N5 in the pocket that binds the amide of NADH. KIEs show that solvent provides a proton, enabling accommodation of different nitro group placements, consistent with the broad repertoire of NR.
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Affiliation(s)
- Warintra Pitsawong
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - Chad A Haynes
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA
| | - Ronald L Koder
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA
| | - David W Rodgers
- Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
| | - Anne-Frances Miller
- Department of Chemistry, University of Kentucky, 505 Rose Street, Lexington, KY 40506-0055, USA; Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone Street, Lexington, KY 40536-0509, USA.
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10
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Lopes Jesus AJ, Reva I, Araujo-Andrade C, Fausto R. Conformational changes in matrix-isolated 6-methoxyindole: Effects of the thermal and infrared light excitations. J Chem Phys 2016; 144:124306. [PMID: 27036447 DOI: 10.1063/1.4944528] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Conformational changes induced thermally or upon infrared excitation of matrix-isolated 6-methoxyindole were investigated. Narrowband near-infrared excitation of the first overtone of the N-H stretching vibration of each one of the two identified conformers is found to induce a selective large-scale conversion of the pumped conformer into the other one. This easily controllable bidirectional process consists in the intramolecular reorientation of the methoxy group and allowed a full assignment of the infrared spectra of the two conformers. Matrices with different conformational compositions prepared by narrow-band irradiations were subsequently used to investigate the effects of both thermal and broadband infrared excitations on the conformational mixtures. Particular attention is given to the influence of the matrix medium (Ar vs. Xe) and conformational effects of exposition of the sample to the spectrometer light source during the measurements.
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Affiliation(s)
- A J Lopes Jesus
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - I Reva
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - C Araujo-Andrade
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
| | - R Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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11
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Miyazaki Y, Inokuchi Y, Akai N, Ebata T. Direct Spectroscopic Evidence of Photoisomerization in para-Methoxy Methylcinnamate Revealed by Low-Temperature Matrix-Isolation FTIR Spectroscopy. J Phys Chem Lett 2015; 6:1134-1139. [PMID: 26262962 DOI: 10.1021/acs.jpclett.5b00203] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The photoisomerization of para-methoxy methylcinnamate (p-MMC) has been studied by low-temperature matrix-isolation FTIR spectroscopy. In particular, the difference spectrum of the mid-IR frequency region (1100-1800 cm(-1)) allows us to distinguish the structural change before and after ultraviolet (UV) light irradiation at ≥300 nm and to convince that the cis-isomer is produced from the trans-isomer by comparing with the calculated IR spectra. Additionally, a reversible isomerization of p-MMC is demonstrated upon a sequential irradiation with different wavelengths of UV light. These findings provide a new insight into the electronic excited-state dynamics of p-MMC.
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Affiliation(s)
- Yasunori Miyazaki
- †Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Yoshiya Inokuchi
- †Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - Nobuyuki Akai
- ‡Graduate School of Bio-Applications and Systems Engineering (BASE), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
| | - Takayuki Ebata
- †Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan
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12
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UV-light induced conformational changes of 2-pyridinecarboxylic acid in low-temperature argon matrices. J Mol Struct 2015. [DOI: 10.1016/j.molstruc.2015.01.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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13
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Gerbig D, Schreiner PR. Hydrogen-Tunneling in Biologically Relevant Small Molecules: The Rotamerizations of α-Ketocarboxylic Acids. J Phys Chem B 2014; 119:693-703. [DOI: 10.1021/jp503633m] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dennis Gerbig
- Institute of Organic Chemistry, Justus-Liebig-University, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
| | - Peter R. Schreiner
- Institute of Organic Chemistry, Justus-Liebig-University, Heinrich-Buff-Ring 58, 35392 Giessen, Germany
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14
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Miyagawa M, Akai N, Nakata M. UV-induced photoreaction pathways of salicylic acid: Identification of the fourth stable conformer and ketoketene–water complex. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.04.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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15
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Araujo-Andrade C, Reva I, Fausto R. Tetrazole acetic acid: Tautomers, conformers, and isomerization. J Chem Phys 2014; 140:064306. [DOI: 10.1063/1.4864119] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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16
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Miyagawa M, Akai N, Nakata M. UV-light induced conformational changes of 3-chlorosalicylic acid in low-temperature argon matrices. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2013.11.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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17
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Nunes CM, Lapinski L, Fausto R, Reva I. Near-IR laser generation of a high-energy conformer of L-alanine and the mechanism of its decay in a low-temperature nitrogen matrix. J Chem Phys 2013; 138:125101. [DOI: 10.1063/1.4795823] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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18
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Bazsó G, Magyarfalvi G, Tarczay G. Tunneling Lifetime of the ttc/VIp Conformer of Glycine in Low-Temperature Matrices. J Phys Chem A 2012; 116:10539-47. [DOI: 10.1021/jp3076436] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gábor Bazsó
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
| | - Gábor Magyarfalvi
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
| | - György Tarczay
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, P.O. Box 32, H-1518, Budapest 112, Hungary
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19
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Bazsó G, Góbi S, Tarczay G. Near-Infrared Radiation Induced Conformational Change and Hydrogen Atom Tunneling of 2-Chloropropionic Acid in Low-Temperature Ar Matrix. J Phys Chem A 2012; 116:4823-32. [DOI: 10.1021/jp212597y] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gábor Bazsó
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, PO Box 32, H-1518, Budapest 112, Hungary
| | - Sándor Góbi
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, PO Box 32, H-1518, Budapest 112, Hungary
| | - György Tarczay
- Laboratory of Molecular
Spectroscopy, Institute of
Chemistry, Eötvös University, PO Box 32, H-1518, Budapest 112, Hungary
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20
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Nanbu S, Sekine M, Nakata M. Hydrogen-atom tunneling in isomerization around the C-O bond of 2-chloro-6-fluorophenol in low-temperature argon matrixes. J Phys Chem A 2011; 115:9911-8. [PMID: 21793595 DOI: 10.1021/jp2048585] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Infrared spectra of 2-chloro-6-fluorophenol in argon matrixes at 20 K revealed the presence of a "Cl-type" isomer, which has the OH···Cl hydrogen bond, but no "F-type" isomer with OH···F bonding, in striking contrast to the existence of both isomers in the gas and liquid phases at room temperature. This finding suggests that the F-type isomer changes to the more stable Cl-type one by hydrogen-atom tunneling in the matrixes. Similar experiments on the OD···X analog species were performed to confirm the tunneling isomerization, resulting in an O-D stretching band of the F-type isomer appearing as well as that of the Cl type, like the spectra reported in the gas and liquid phases. This implies that tunneling migration of the D atom is inhibited in the argon matrix. In addition, UV-induced photoreactions of 2-chloro-6-fluorophenol were studied by a joint use of matrix-isolation IR spectroscopy assisted by density functional theory calculations. It was found that 2-fluorocyclopentadienylidenemethanone and 4-chloro-2-fluorocyclohexadienone were produced from the Cl type; the former was by the Wolff rearrangement after dissociation of the H atom in the OH group and the Cl atom, and the latter was by intramolecular migration of the H and Cl atoms. As for the deuterated F-type isomer, however, 2-chlorocyclopentadienylidenemethanone was produced by the Wolff rearrangement after dissociation of the D atom in the OD group and the F atom, besides other photoproducts of the deuterated Cl-type isomer. It is thus concluded that the tunneling isomerization around the C-O bond occurs in the OH···X species but not in the OD···X species.
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Affiliation(s)
- Shota Nanbu
- Graduate School of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan
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21
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Marushkevich K, Räsänen M, Khriachtchev L. Interaction of Formic Acid with Nitrogen: Stabilization of the Higher-Energy Conformer. J Phys Chem A 2010; 114:10584-9. [DOI: 10.1021/jp105044r] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Markku Räsänen
- Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Finland
| | - Leonid Khriachtchev
- Department of Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Finland
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22
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Sekine M, Nagai Y, Sekiya H, Nakata M. Photoinduced Hydrogen-Atom Eliminations of 6-Hydroxyquinoline and 7-Hydroxyquinoline Studied by Low-Temperature Matrix-Isolation Infrared Spectroscopy and Density-Functional-Theory Calculations. J Phys Chem A 2009; 113:8286-98. [DOI: 10.1021/jp903146v] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masahiko Sekine
- Graduate School of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan, and Department of Chemistry, Faculty of Sciences, Graduate School of Molecular Chemistry, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Yuko Nagai
- Graduate School of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan, and Department of Chemistry, Faculty of Sciences, Graduate School of Molecular Chemistry, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Hiroshi Sekiya
- Graduate School of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan, and Department of Chemistry, Faculty of Sciences, Graduate School of Molecular Chemistry, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
| | - Munetaka Nakata
- Graduate School of BASE (Bio-Applications and Systems Engineering), Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184-8588, Japan, and Department of Chemistry, Faculty of Sciences, Graduate School of Molecular Chemistry, Kyushu University, Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan
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