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Lapoot L, Jabeen S, Durantini AM, Greer A. Role of curvature in acridone for 1 O 2 oxidation of a natural product homoallylic alcohol: A novel iso-hydroperoxide intermediate. Photochem Photobiol 2024; 100:455-464. [PMID: 37602967 DOI: 10.1111/php.13843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Revised: 07/19/2023] [Accepted: 07/20/2023] [Indexed: 08/22/2023]
Abstract
A density functional theoretical (DFT) study is presented, implicating a 1 O2 oxidation process to reach a dihydrobenzofuran from the reaction of the natural homoallylic alcohol, glycocitrine. Our results predict an interconversion between glycocitrine and an iso-hydroperoxide intermediate [R(H)O+ -O- ] that provides a key path in the chemistry which then follows. Formations of allylic hydroperoxides are unlikely from a 1 O2 'ene' reaction. Instead, the dihydrobenzofuran arises by 1 O2 oxidation facilitated by a 16° curvature of the glycocitrine ring imposed by a pyramidal N-methyl group. This curvature facilitates the formation of the iso-hydroperoxide, which is analogous to the iso species CH2 I+ -I- and CHI2 + -I- formed by UV photolysis of CH2 I2 and CHI3 . The iso-hydroperoxide is also structurally reminiscent of carbonyl oxides (R2 C=O+ -O- ) formed in the reaction of carbenes and oxygen. Our DFT results point to intermolecular process, in which the iso-hydroperoxide's fate relates to O-transfer and H2 O dehydration reactions for new insight into the biosynthesis of dihydrobenzofuran natural products.
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Affiliation(s)
- Lloyd Lapoot
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA
| | - Shakeela Jabeen
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York, USA
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, USA
| | - Andrés M Durantini
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York, USA
- IDAS-CONICET, Departamento de Química, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Córdoba, Argentina
| | - Alexander Greer
- Department of Chemistry, Brooklyn College, City University of New York, Brooklyn, New York, USA
- Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA
- Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, New York, New York, USA
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2
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Yeung CS, Tse HY, Lau CY, Guan J, Huang J, Phillips DL, Leu SY. Insights into unexpected photoisomerization from photooxidation of tribromoacetic acid in aqueous environment using ultrafast spectroscopy. JOURNAL OF HAZARDOUS MATERIALS 2021; 418:126214. [PMID: 34102359 DOI: 10.1016/j.jhazmat.2021.126214] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/12/2021] [Accepted: 05/21/2021] [Indexed: 06/12/2023]
Abstract
Haloacetic acids are carcinogenic disinfection by-products (DPBs) and their photo-decomposition pathways, especially for those containing bromine and iodine, are not fully understood. In this study, femtosecond transient absorption (fs-TA) spectroscopy experiments were introduced for the first time to investigate the photochemistry of tribromoacetic acid. The fs-TA experiments showed that a photoisomerization intermediate species HOOCCBr2-Br (iso-TBAA) was formed within several picoseconds after the excitation of TBAA. The absorption wavelength of the iso-TBAA was supported by time-dependent density calculations. With the Second-order Møller-Plesset perturbation theory, the structures and thermodynamics of the OH-insertion reactions of iso-TBAA were elucidated when water molecules were involved in the reaction complex. The calculations also revealed that the isomer species were able to react with water with its reaction dynamics dramatically catalyzed by the hydrogen bonding network. The proposed water catalyzed OH-insertion/HBr elimination mechanism predicted three major photoproducts, namely, HBr, CO and CO2, which was consistent with the photolysis experiments with firstly reported CO formation rate and mass conversion yield as 0.096 min-1 and 0.75 ± 0.1 respectively. The spectroscopic technique, numerical tool and disclosed mechanisms provided insights on photodecomposition and subsequent reactions of polyhalo-DPBs contain heavy atom(s) (e.g., Br, I) with water, aliphatic alcohols or other nucleophiles.
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Affiliation(s)
- Chi Shun Yeung
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Ho-Yin Tse
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Chun Yin Lau
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Jianyu Guan
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong
| | - Jinqing Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, Hong Kong
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.
| | - Shao-Yuan Leu
- Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong.
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3
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Filming ultrafast roaming-mediated isomerization of bismuth triiodide in solution. Nat Commun 2021; 12:4732. [PMID: 34354075 PMCID: PMC8342516 DOI: 10.1038/s41467-021-25070-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 07/20/2021] [Indexed: 12/19/2022] Open
Abstract
Roaming reaction, defined as a reaction yielding products via reorientational motion in the long-range region (3 - 8 Å) of the potential, is a relatively recently proposed reaction pathway and is now regarded as a universal mechanism that can explain the unimolecular dissociation and isomerization of various molecules. The structural movements of the partially dissociated fragments originating from the frustrated bond fission at the onset of roaming, however, have been explored mostly via theoretical simulations and rarely observed experimentally. Here, we report an investigation of the structural dynamics during a roaming-mediated isomerization reaction of bismuth triiodide (BiI3) in acetonitrile solution using femtosecond time-resolved x-ray liquidography. Structural analysis of the data visualizes the atomic movements during the roaming-mediated isomerization process including the opening of the Bi-Ib-Ic angle and the closing of Ia-Bi-Ib-Ic dihedral angle, each by ~40°, as well as the shortening of the Ib···Ic distance, following the frustrated bond fission.
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4
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Kim H, Kim JG, Kim TW, Lee SJ, Nozawa S, Adachi SI, Yoon K, Kim J, Ihee H. Ultrafast structural dynamics of in-cage isomerization of diiodomethane in solution. Chem Sci 2020; 12:2114-2120. [PMID: 34163975 PMCID: PMC8179290 DOI: 10.1039/d0sc05108j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite extensive studies on the isomer species formed by photodissociation of haloalkanes in solution, the molecular structure of the precursor of the isomer, which is often assumed to be a vibrationally hot isomer formed from the radical pair, and its in-cage isomerization mechanism remain elusive. Here, the structural dynamics of CH2I2 upon 267 nm photoexcitation in methanol were probed with femtosecond X-ray solution scattering at an X-ray free-electron laser. The determined molecular structure of the transiently formed species that converts to the CH2I–I isomer has the I–I distance of 4.17 Å, which is longer than that of the isomer (3.15 Å) by more than 1.0 Å and the mean-squared displacement of 0.45 Å2, which is about 100 times larger than those of typical regular chemical bonds. These unusual structural characteristics are consistent with either a vibrationally hot form of the CH2I–I isomer or the loosely-bound radical pair (CH2I˙⋯I˙). The structural dynamics of in-cage isomerization of CH2I2 and the unusual structure of the loosely-bound isomer precursor were unveiled with femtosecond X-ray liquidography (solution scattering).![]()
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Affiliation(s)
- Hanui Kim
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Jong Goo Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Tae Wu Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Sang Jin Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
| | - Shunsuke Nozawa
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies Tsukuba Ibaraki 305-0801 Japan
| | - Shin-Ichi Adachi
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK) Tsukuba Ibaraki 305-0801 Japan.,Department of Materials Structure Science, School of High Energy Accelerator Science, The Graduate University for Advanced Studies Tsukuba Ibaraki 305-0801 Japan
| | - Kihwan Yoon
- Department of Chemistry, The Catholic University of Korea Bucheon 14662 Republic of Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea Bucheon 14662 Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea .,KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 Republic of Korea.,Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon 34141 Republic of Korea
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5
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Park S, Choi J, Ki H, Kim KH, Oang KY, Roh H, Kim J, Nozawa S, Sato T, Adachi SI, Kim J, Ihee H. Fate of transient isomer of CH 2I 2: Mechanism and origin of ionic photoproducts formation unveiled by time-resolved x-ray liquidography. J Chem Phys 2019; 150:224201. [PMID: 31202228 DOI: 10.1063/1.5099002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Diiodomethane, CH2I2, in a polar solvent undergoes a unique photoinduced reaction whereby I2 - and I3 - are produced from its photodissociation, unlike for other iodine-containing haloalkanes. While previous studies proposed that homolysis, heterolysis, or solvolysis of iso-CH2I-I, which is a major intermediate of the photodissociation, can account for the formation of I2 - and I3 -, there has been no consensus on its mechanism and no clue for the reason why those negative ionic species are not observed in the photodissociation of other iodine-containing chemicals in the same polar solvent, for example, CHI3, C2H4I2, C2F4I2, I3 -, and I2. Here, using time-resolved X-ray liquidography, we revisit the photodissociation mechanism of CH2I2 in methanol and determine the structures of all transient species and photoproducts involved in its photodissociation and reveal that I2 - and I3 - are formed via heterolysis of iso-CH2I-I in the photodissociation of CH2I2 in methanol. In addition, we demonstrate that the high polarity of iso-CH2I-I is responsible for the unique photochemistry of CH2I2.
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Affiliation(s)
- Sungjun Park
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| | - Jungkweon Choi
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, South Korea
| | - Hosung Ki
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 34141, South Korea
| | - Kyung Hwan Kim
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, South Korea
| | - Key Young Oang
- Radiation Center for Ultrafast Science, Quantum Optics Division, Korea Atomic Energy Research Institute (KAERI), Daejeon 34057, South Korea
| | - Heegwang Roh
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea, Bucheon 14662, South Korea
| | - Shunsuke Nozawa
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Tokushi Sato
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Shin-Ichi Adachi
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan
| | - Jeongho Kim
- Department of Chemistry, Inha University, 100 Inha-ro, Michuhol-gu, Incheon 22212, South Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, South Korea
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6
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Choi EH, Ahn DS, Park S, Kim C, Ahn CW, Kim S, Choi M, Yang C, Kim TW, Ki H, Choi J, Pedersen MN, Wulff M, Kim J, Ihee H. Structural Dynamics of Bismuth Triiodide in Solution Triggered by Photoinduced Ligand-to-Metal Charge Transfer. J Phys Chem Lett 2019; 10:1279-1285. [PMID: 30835478 DOI: 10.1021/acs.jpclett.9b00365] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bismuth triiodide, BiI3, is one of the simplest bismuth halides, which have recently attracted considerable attention because of their promising properties. Here, we investigate the structural dynamics of a photoinduced reaction of BiI3 in solution phase using time-resolved X-ray liquidography (TRXL) and density functional theory (DFT) and time-dependent DFT (TDDFT) calculations. The photoreaction was initiated by excitation at 400 nm, which corresponds to the ligand-to-metal charge-transfer transition. The detailed structures and kinetic profiles of all relevant intermediate species from the TRXL data show that the trigonal planar structure of BiI3, which is predicted to be the most stable structure of the lowest excited state by TDDFT calculation, was not observed, and the photoreaction proceeds via two parallel pathways within the time resolution of 100 ps: (i) isomer formation to produce iso-BiI2-I, which relaxes back to the ground-state structure, and (ii) dissociation into BiI2· and I· radicals, which nongeminately recombine to generate ground-state BiI3 and I2.
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Affiliation(s)
- Eun Hyuk Choi
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Doo-Sik Ahn
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Sungjun Park
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Changwon Kim
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Chi Woo Ahn
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Siin Kim
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Minseo Choi
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Cheolhee Yang
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Tae Wu Kim
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Hosung Ki
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | - Jungkweon Choi
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
| | | | - Michael Wulff
- European Synchrotron Radiation Facility (ESRF) , 38000 Grenoble Cedex 9, France
| | - Jeongho Kim
- Department of Chemistry , Inha University , 100 Inha-ro, Nam-gu , Incheon 22212 , Republic of Korea
| | - Hyotcherl Ihee
- Department of Chemistry and KI for the BioCentury , Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141 , Republic of Korea
- Center for Nanomaterials and Chemical Reactions , Institute for Basic Science (IBS) , Daejeon 34141 , Republic of Korea
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7
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Zhao Y, Antonietti M. Visible-Light-Driven Conversion of Alcohols into Iodide Derivatives with Iodoform. CHEMPHOTOCHEM 2018. [DOI: 10.1002/cptc.201800084] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Yubao Zhao
- Department of Colloid Chemistry; Max Planck Institute of Colloids and Interfaces; 14476 Potsdam Germany
| | - Markus Antonietti
- Department of Colloid Chemistry; Max Planck Institute of Colloids and Interfaces; 14476 Potsdam Germany
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8
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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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9
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Ahn CW, Ki H, Kim J, Kim J, Park S, Lee Y, Kim KH, Kong Q, Moon J, Pedersen MN, Wulff M, Ihee H. Direct Observation of a Transiently Formed Isomer During Iodoform Photolysis in Solution by Time-Resolved X-ray Liquidography. J Phys Chem Lett 2018; 9:647-653. [PMID: 29337571 DOI: 10.1021/acs.jpclett.7b03125] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Photolysis of iodoform (CHI3) in solution has been extensively studied, but its reaction mechanism remains elusive. In particular, iso-iodoform (iso-CHI2-I) is formed as a product of the photolysis reaction, but its detailed structure is not known, and whether it is a major intermediate species has been controversial. Here, by using time-resolved X-ray liquidography, we determined the reaction mechanism of CHI3 photodissociation in cyclohexane as well as the structure of iso-CHI2-I. Both iso-CHI2-I and CHI2 radical were found to be formed within 100 ps with a branching ratio of 40:60. Iodine radicals (I), formed during the course of CHI3 photolysis, recombine nongeminately with either CHI2 or I. Based on our structural analysis, the I-I distance and the C-I-I angle of iso-CHI2-I were determined to be 2.922 ± 0.004 Å and 133.9 ± 0.8°, respectively.
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Affiliation(s)
- Chi Woo Ahn
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
| | - Hosung Ki
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
| | - Joonghan Kim
- Department of Chemistry, The Catholic University of Korea , Bucheon, 14662, Republic of Korea
| | - Jeongho Kim
- Department of Chemistry and Chemical Engineering, Inha University , 100 Inha-ro, Nam-gu, Incheon, 22212, Republic of Korea
| | - Sungjun Park
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
| | - Yunbeom Lee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
| | - Kyung Hwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
| | - Qingyu Kong
- Soleil synchrotron , Saint-Aubin, 91192, France
| | - Jiwon Moon
- Department of Chemistry, The Catholic University of Korea , Bucheon, 14662, Republic of Korea
| | | | - Michael Wulff
- European Synchrotron Radiation Facility (ESRF) , 38000 Grenoble Cedex 9, France
| | - Hyotcherl Ihee
- Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea
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10
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Borin VA, Matveev SM, Budkina DS, El-Khoury PZ, Tarnovsky AN. Direct photoisomerization of CH 2I 2vs. CHBr 3 in the gas phase: a joint 50 fs experimental and multireference resonance-theoretical study. Phys Chem Chem Phys 2018; 18:28883-28892. [PMID: 27722308 DOI: 10.1039/c6cp05129d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Femtosecond transient absorption measurements powered by 40 fs laser pulses reveal that ultrafast isomerization takes place upon S1 excitation of both CH2I2 and CHBr3 in the gas phase. The photochemical conversion process is direct and intramolecular, i.e., it proceeds without caging media that have long been implicated in the photo-induced isomerization of polyhalogenated alkanes in condensed phases. Using multistate complete active space second order perturbation theory (MS-CASPT2) calculations, we investigate the structure of the photochemical reaction paths connecting the photoexcited species to their corresponding isomeric forms. Unconstrained minimum energy paths computed starting from the S1 Franck-Condon points lead to S1/S0 conical intersections, which directly connect the parent CHBr3 and CH2I2 molecules to their isomeric forms. Changes in the chemical bonding picture along the S1/S0 isomerization reaction path are described using multireference average coupled pair functional (MRACPF) calculations in conjunction with natural resonance theory (NRT) analysis. These calculations reveal a complex interplay between covalent, radical, ylidic, and ion-pair dominant resonance structures throughout the nonadiabatic photochemical isomerization processes described in this work.
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Affiliation(s)
- Veniamin A Borin
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Sergey M Matveev
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Darya S Budkina
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
| | - Patrick Z El-Khoury
- Physical Sciences Division, Pacific Northwest National Laboratory, P. O. Box 999, Richland, WA 99352, USA
| | - Alexander N Tarnovsky
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio, USA.
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11
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Kim KH, Kim J, Oang KY, Lee JH, Grolimund D, Milne CJ, Penfold TJ, Johnson SL, Galler A, Kim TW, Kim JG, Suh D, Moon J, Kim J, Hong K, Guérin L, Kim TK, Wulff M, Bressler C, Ihee H. Identifying the major intermediate species by combining time-resolved X-ray solution scattering and X-ray absorption spectroscopy. Phys Chem Chem Phys 2015; 17:23298-302. [PMID: 26300122 DOI: 10.1039/c5cp03686k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Identifying the intermediate species along a reaction pathway is a first step towards a complete understanding of the reaction mechanism, but often this task is not trivial. There has been a strong on-going debate: which of the three intermediates, the CHI2 radical, the CHI2-I isomer, and the CHI2(+) ion, is the dominant intermediate species formed in the photolysis of iodoform (CHI3)? Herein, by combining time-resolved X-ray liquidography (TRXL) and time-resolved X-ray absorption spectroscopy (TR-XAS), we present strong evidence that the CHI2 radical is dominantly formed from the photolysis of CHI3 in methanol at 267 nm within the available time resolution of the techniques (∼20 ps for TRXL and ∼100 ps for TR-XAS). The TRXL measurement, conducted using the time-slicing scheme, detected no CHI2-I isomer within our signal-to-noise ratio, indicating that, if formed, the CHI2-I isomer must be a minor intermediate. The TR-XAS transient spectra measured at the iodine L1 and L3 edges support the same conclusion. The present work demonstrates that the application of these two complementary time-resolved X-ray methods to the same system can provide a detailed understanding of the reaction mechanism.
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Affiliation(s)
- Kyung Hwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon 305-701, Republic of Korea.
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12
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Reid SA. When isomerisation is electron transfer: the intriguing story of the iso-halocarbons. INT REV PHYS CHEM 2014. [DOI: 10.1080/0144235x.2014.942548] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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13
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Kim KH, Ki H, Oang KY, Nozawa S, Sato T, Kim J, Kim TK, Kim J, Adachi SI, Ihee H. Global reaction pathways in the photodissociation of I3 (-) ions in solution at 267 and 400 nm studied by picosecond X-ray liquidography. Chemphyschem 2013; 14:3687-97. [PMID: 24115265 DOI: 10.1002/cphc.201300713] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Indexed: 11/08/2022]
Abstract
The mechanism of a photochemical reaction involves the formation and dissociation of various short-lived species on ultrafast timescales and therefore its characterization requires detailed structural information on the transient species. By making use of a structurally sensitive X-ray probe, time-resolved X-ray liquidography (TRXL) can directly elucidate the structures of reacting molecules in the solution phase and thus determine the comprehensive reaction mechanism with high accuracy. In this work, by performing TRXL measurements at two different wavelengths (400 and 267 nm), the reaction mechanism of I3 (-) photolysis, which changes subtly depending on the excitation wavelength, is elucidated. Upon 400 nm photoexcitation, the I3 (-) ion dissociates into I2 (-) and I. By contrast, upon 267 nm photoexcitation, the I3 (-) ion undergoes both two-body dissociation (I2 (-) +I) and three-body dissociation (I(-) +2I) with 7:3 molar ratio. At both excitation wavelengths, all the transient species ultimately disappear in 80 ns by recombining to form the I3 (-) ion nongeminately. In addition to the reaction dynamics of solute species, the results reveal the transient structure of the solute/solvent cage and the changes in solvent density and temperature as a function of time.
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Affiliation(s)
- Kyung Hwan Kim
- Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810; Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
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14
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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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15
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Preston TJ, Shaloski MA, Crim FF. Probing the Photoisomerization of CHBr3 and CHI3 in Solution with Transient Vibrational and Electronic Spectroscopy. J Phys Chem A 2013; 117:2899-907. [DOI: 10.1021/jp310737d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Thomas J. Preston
- Department of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706,
United States
| | - Michael A. Shaloski
- 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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16
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George L, Kalume A, Esselman BJ, Wagner J, McMahon RJ, Reid SA. Spectroscopic and computational studies of matrix-isolated iso-CHBr3: Structure, properties, and photochemistry of iso-bromoform. J Chem Phys 2011; 135:124503. [PMID: 21974531 DOI: 10.1063/1.3640887] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Lisa George
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53233, USA
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17
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Ihee H, Wulff M, Kim J, Adachi SI. Ultrafast X-ray scattering: structural dynamics from diatomic to protein molecules. INT REV PHYS CHEM 2010. [DOI: 10.1080/0144235x.2010.498938] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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El-Khoury PZ, George L, Kalume A, Reid SA, Ault BS, Tarnovsky AN. Characterization of iso-CF2I2 in frequency and ultrafast time domains. J Chem Phys 2010; 132:124501. [DOI: 10.1063/1.3357728] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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George L, Kalume A, El-Khoury PZ, Tarnovsky A, Reid SA. Matrix isolation and computational study of isodifluorodibromomethane (F2CBr–Br): A route to Br2 formation in CF2Br2 photolysis. J Chem Phys 2010; 132:084503. [DOI: 10.1063/1.3319567] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Carrier SL, Preston TJ, Dutta M, Crowther AC, Crim FF. Ultrafast Observation of Isomerization and Complexation in the Photolysis of Bromoform in Solution. J Phys Chem A 2009; 114:1548-55. [DOI: 10.1021/jp908725t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Stacey L. Carrier
- Department of Chemistry University of Wisconsin—Madison, Madison, Wisconsin 53706
| | - Thomas J. Preston
- Department of Chemistry University of Wisconsin—Madison, Madison, Wisconsin 53706
| | - Maitreya Dutta
- Department of Chemistry University of Wisconsin—Madison, Madison, Wisconsin 53706
| | - Andrew C. Crowther
- Department of Chemistry University of Wisconsin—Madison, Madison, Wisconsin 53706
| | - F. Fleming Crim
- Department of Chemistry University of Wisconsin—Madison, Madison, Wisconsin 53706
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21
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Photochemistry of Iodoform in Methanol: Formation and Fate of theIso-CHI2-I Photoproduct. Chemphyschem 2009; 10:1895-900. [DOI: 10.1002/cphc.200900122] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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22
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Chapter 1 Multireference and Spin–Orbit Calculations on Photodissociations of Hydrocarbon Halides. ADVANCES IN QUANTUM CHEMISTRY 2009. [DOI: 10.1016/s0065-3276(08)00401-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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23
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Lee J, Kim J, Cammarata M, Kong Q, Kim K, Choi J, Kim T, Wulff M, Ihee H. Transient X-ray Diffraction Reveals Global and Major Reaction Pathways for the Photolysis of Iodoform in Solution. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704150] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Lee J, Kim J, Cammarata M, Kong Q, Kim K, Choi J, Kim T, Wulff M, Ihee H. Transient X-ray Diffraction Reveals Global and Major Reaction Pathways for the Photolysis of Iodoform in Solution. Angew Chem Int Ed Engl 2008; 47:1047-50. [DOI: 10.1002/anie.200704150] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Tarnovsky AN, Pascher I, Pascher T. Reactivity of Iso-diiodomethane and Iso-iodoform, Isomers of CH2I2 and CHI3, toward the Double Bond of a Variety of Cycloalkenes. J Phys Chem A 2007; 111:11814-7. [DOI: 10.1021/jp073917u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Alexander N. Tarnovsky
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, Department of Medical Chemistry, University of Gothenburg, SE-40530 Gothenburg, Sweden, and Department of Chemical Physics, Chemical Center, Lund University, Getingevägen 60, SE-22100 Lund, Sweden
| | - Irmin Pascher
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, Department of Medical Chemistry, University of Gothenburg, SE-40530 Gothenburg, Sweden, and Department of Chemical Physics, Chemical Center, Lund University, Getingevägen 60, SE-22100 Lund, Sweden
| | - Torbjörn Pascher
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, Department of Medical Chemistry, University of Gothenburg, SE-40530 Gothenburg, Sweden, and Department of Chemical Physics, Chemical Center, Lund University, Getingevägen 60, SE-22100 Lund, Sweden
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26
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Liu YJ, De Vico L, Lindh R, Fang WH. Spin-Orbit Ab Initio Investigation of the Ultraviolet Photolysis of Diiodomethane. Chemphyschem 2007; 8:890-8. [PMID: 17352002 DOI: 10.1002/cphc.200600737] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The UV photodissociation (<5 eV) of diiodomethane (CH(2)I(2)) is investigated by spin-orbit ab initio calculations. The experimentally observed photodissociation channels in the gas and condensed phases are clearly assigned by multi-state second-order multiconfigurational perturbation theory in conjunction with spin-orbit interaction through complete active space-state interaction potential energy curves. The calculated results indicate that the fast dissociations of the first two singlet states of CH(2)I(2) and CH(2)I--I lead to geminate-radical products, CH(2)I (.)+I((2)P(3/2)) or CH(2)I (.)+ I*((2)P(1/2)). The recombination process from CH(2)I--I to CH(2)I(2) is explained by an isomerization process and a secondary photodissociation reaction of CH(2)I--I. Finally, the study reveals that spin-orbits effects are significant in the quantitative analysis of the electronic spectrum of the CH(2)I--I species.
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Affiliation(s)
- Ya-Jun Liu
- College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
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27
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Grimm C, Kandratsenka A, Wagener P, Zerbs J, Schroeder J. Photoinduced Isomerization Kinetics of Diiodomethane in Supercritical Fluid Solution: Local Density Effects. J Phys Chem A 2006; 110:3320-9. [PMID: 16509658 DOI: 10.1021/jp055608e] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The density dependence of diiodomethane photoinduced isomerization in supercritical (sc) CO2, CHF3, and C2H6 was investigated by transient absorption spectroscopy, covering a fluid density range from 0.7 to 2.5 (in reduced units). The solvent-caged photoproduct iso-diiodomethane is formed even at the lowest density, and its yield increases about 4-fold over the whole range. At the same time, isomer formation rate constants increase by roughly an order of magnitude and show little variation between CO2, C2H6, and CHF3. Furthermore, the formation rate constant decreases significantly with increasing excitation energy. We propose an isomer formation mechanism involving a rapidly established preequilibrium between a solvent-caged iodine atom-methyliodide radical pair and a loosely bound iodine-methyliodide radical complex, from which the reaction subsequently proceeds to the isomer. The latter step seems to be controlled by collisional stabilization of the initially hot radical moiety, as the formation rate constant increases linearly with sc solvent viscosity. The model predicts a quadratic dependence of relative isomer yield on fluid density. A corresponding correlation is found with the local fluid density, calculated via solute-solvent radial distribution functions obtained from molecular dynamics (MD) simulations.
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Affiliation(s)
- Christian Grimm
- Institut für Physikalische Chemie, Universität Göttingen, Tammannstrasse 6, 37077 Göttingen, Germany
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28
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Du Y, Guan X, Kwok WM, Chu LM, Phillips DL. Comparison of the Dehalogenation of Dihalomethanes (CH2XI, where X = Cl, Br, I) Following Ultraviolet Photolysis in Aqueous and NaCl Saltwater Environments. J Phys Chem A 2005; 109:5872-82. [PMID: 16833922 DOI: 10.1021/jp0504928] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ultraviolet photolysis of low concentrations of CH(2)XI (X = Cl, Br, I) were investigated in water and saltwater solutions by photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both kinds of solutions formed mostly CH(2)(OH)(2) and HI and HX products. However, photolysis of the CH(2)XI molecules in saltwater resulted in production of some CH(2)XCl products not observed in aqueous solutions without salt present. The appearance of these new products in saltwater solutions is accompanied by a decrease in the amount of CH(2)(OH)(2), HI, and HX products compared to photolysis in aqueous solutions without salt present. The possible implications for photolysis of CH(2)XI and other polyhalomethanes in seawater and other salt aqueous environments compared to nonsaltwater solvated environments is briefly discussed.
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Affiliation(s)
- Yong Du
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P.R. China
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29
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Zhao C, Lin X, Kwok WM, Guan X, Du Y, Wang D, Hung KF, Phillips DL. Water-Catalyzed Dehalogenation Reactions of the Isomer of CBr4 and Its Reaction Products and a Comparison to Analogous Reactions of the Isomers of Di- and Trihalomethanes. Chemistry 2005; 11:1093-108. [PMID: 15742469 DOI: 10.1002/chem.200400695] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A combined experimental and theoretical study of the UV photolysis of a typical tetrahalomethane, CBr4, in water and acetonitrile/water was performed. Ultraviolet photolysis of low concentrations of CBr4 in water mostly leads to the production of four HBr leaving groups and CO2. Picosecond time-resolved resonance Raman (Ps-TR3) experiments and ab initio calculations indicate that water-catalyzed O-H insertion/HBr elimination of the isomer of CBr4 and subsequent reactions of its products lead to the formation of these products. The UV photolyses of di-, tri-, and tetrahalomethanes at low concentrations in water-solvated environments are compared to one another. This comparison enables a general reaction scheme to be deduced that can account for the different products produced by UV photolysis of low concentrations of di-, tri-, and tetrahalomethanes in water. The fate of the (halo)formaldehyde intermediate in the chemical reaction mechanism is the key to determining how many strong acid leaving groups are produced and which carbon atom final product is likely formed by UV photolysis of a polyhalomethane at low concentrations in a water-solvated environment.
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Affiliation(s)
- Cunyuan Zhao
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
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30
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Lin X, Guan X, Kwok WM, Zhao C, Du Y, Li YL, Phillips DL. Water-Catalyzed O−H Insertion/HI Elimination Reactions of Isodihalomethanes (CH2X−I, Where X = Cl, Br, I) with Water and the Dehalogenation of Dihalomethanes in Water-Solvated Environments. J Phys Chem A 2005; 109:981-98. [PMID: 16833405 DOI: 10.1021/jp0450843] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A combined experimental and theoretical investigation of the ultraviolet photolysis of CH2XI (where X = Cl, Br, I) dihalomethanes in water is presented. Ultraviolet photolysis of low concentrations of CH2XI (where X = Cl, Br, I) in water appears to lead to almost complete conversion into CH2(OH)2 and HX and HI products. Picosecond time-resolved resonance Raman (ps-TR3) spectroscopy experiments revealed that noticeable amounts of CH2X-I isodihalomethane intermediates were formed within several picoseconds after photolysis of the CH2XI parent compound in mixed aqueous solutions. The ps-TR3 experiments in mixed aqueous solutions revealed that the decay of the CH2X-I isodihalomethane intermediates become significantly shorter as the water concentration increases, indicating that the CH2X-I intermediates may be reacting with water. Ab initio calculations found that the CH2X-I intermediates are able to react relatively easily with water via a water-catalyzed O-H insertion/HI elimination reaction to produce CH2X(OH) and HI products, with the barrier for these reactions increasing as X changes from Cl to Br to I. The ab initio calculations also found that the CH2X(OH) product can undergo a water-catalyzed HX elimination reaction to make H2C=O and HX products, with the barrier to reaction decreasing as X changes from Cl to Br to I. The preceding two water-catalyzed reactions produce the HI and HX leaving groups observed experimentally, and the H2C=O product further reacts with water to make the other CH2(OH)2 product observed in the photochemistry experiments. This suggests that that the CH2X-I intermediates react with water to form the CH2(OH)2 and HI and HX products observed in the photochemistry experiments. Ultraviolet photolysis of CH2XI (where X = Cl, Br, I) at low concentrations in water-solvated environments appears to lead to efficient dehalogenation and release of two strong acid leaving groups. We very briefly discuss the potential influence of this photochemistry in water on the decomposition of polyhalomethanes and halomethanols in aqueous environments.
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Affiliation(s)
- Xufeng Lin
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China
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31
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Affiliation(s)
- Wolfgang Kirmse
- Fakultät für Chemie, Ruhr‐Universität Bochum, 44780 Bochum, Germany
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32
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Kwok WM, Zhao C, Guan X, Li YL, Du Y, Phillips DL. Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water. J Chem Phys 2004; 120:9017-32. [PMID: 15267837 DOI: 10.1063/1.1701699] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A combined experimental and theoretical study of the ultraviolet photolysis of CH2I2 in water is reported. Ultraviolet photolysis of low concentrations of CH2I2 in water was experimentally observed to lead to almost complete conversion into CH2(OH)2 and 2HI products. Picosecond time-resolved resonance Raman spectroscopy experiments in mixed water/acetonitrile solvents (25%-75% water) showed that appreciable amounts of isodiiodomethane (CH2I-I) were formed within several picoseconds and the decay of the CH2I-I species became substantially shorter with increasing water concentration, suggesting that CH2I-I may be reacting with water. Ab initio calculations demonstrate the CH2I-I species is able to react readily with water via a water-catalyzed O--H-insertion and HI-elimination reaction followed by its CH2I(OH) product undergoing a further water-catalyzed HI-elimination reaction to make a H2C=O product. These HI-elimination reactions produce the two HI leaving groups observed experimentally and the H2C=O product further reacts with water to produce the other final CH2(OH)2 product observed in the photochemistry experiments. These results suggest that CH2I-I is the species that reacts with water to produce the CH2(OH)2 and 2HI products seen in the photochemistry experiments. The present study demonstrates that ultraviolet photolysis of CH2I2 at low concentration leads to efficient dehalogenation and release of multiple strong acid (HI) leaving groups. Some possible ramifications for the decomposition of polyhalomethanes and halomethanols in aqueous environments as well as the photochemistry of polyhalomethanes in the natural environment are briefly discussed.
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Affiliation(s)
- Wai Ming Kwok
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, China
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Kwok WM, Zhao C, Li YL, Guan X, Wang D, Phillips DL. Water-Catalyzed Dehalogenation Reactions of Isobromoform and Its Reaction Products. J Am Chem Soc 2004; 126:3119-31. [PMID: 15012142 DOI: 10.1021/ja0390552] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A combined experimental and theoretical study of the photochemistry of CHBr(3) in pure water and in acetonitrile/water mixed solvents is reported that elucidates the reactions and mechanisms responsible for the photochemical conversion of the halogen atoms in CHBr(3) into three bromide ions in water solution. Ultraviolet excitation at 240 nm of CHBr(3) (9 x 10(-)(5) M) in water resulted in almost complete conversion into 3HBr leaving groups and CO (major product) and HCOOH (minor product) molecules. Picosecond time-resolved resonance Raman (ps-TR(3)) experiments and ab initio calculations indicate that the water-catalyzed O-H insertion/HBr elimination reaction of isobromoform and subsequent reactions of its products are responsible for the production of the final products observed following ultraviolet excitation of CHBr(3) in water. These results have important implications for the phase-dependent behavior of polyhalomethane photochemistry and chemistry in water-solvated environments as compared to gas-phase reactions. The dissociation reaction of HBr into H(+) and Br(-) ions is the driving force for several O-H insertion and HBr elimination reactions and allows O-H and C-H bonds to be cleaved more easily than in the absence of water molecules. This water-catalysis by solvation of a leaving group and its dissociation into ions (e.g., H(+) and Br(-) in the examples investigated here) may occur for a wide range of chemical reactions taking place in water-solvated environments.
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Affiliation(s)
- Wai Ming Kwok
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., P. R. China
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34
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Kwok WM, Zhao C, Li YL, Guan X, Phillips DL. Direct observation of an isopolyhalomethane O–H insertion reaction with water: Picosecond time-resolved resonance Raman (ps-TR3) study of the isobromoform reaction with water to produce a CHBr2OH product. J Chem Phys 2004; 120:3323-32. [PMID: 15268486 DOI: 10.1063/1.1640997] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Picosecond time-resolved resonance Raman (ps-TR3) spectroscopy was used to obtain the first definitive spectroscopic observation of an isopolyhalomethane O-H insertion reaction with water. The ps-TR3 spectra show that isobromoform is produced within several picoseconds after photolysis of CHBr3 and then reacts on the hundreds of picosecond time scale with water to produce a CHBr2OH reaction product. Photolysis of low concentrations of bromoform in aqueous solution resulted in noticeable formation of HBr strong acid. Ab initio calculations show that isobromoform can react with water to produce a CHBr2(OH) O-H insertion reaction product and a HBr leaving group. This is consistent with both the ps-TR3 experiments that observe the reaction of isobromoform with water to form a CHBr2(OH) product and photolysis experiments that show HBr acid formation. We briefly discuss the implications of these results for the phase dependent behavior of polyhalomethane photochemistry in the gas phase versus water solvated environments.
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Affiliation(s)
- Wai Ming Kwok
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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35
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Guan X, Du Y, Li YL, Kwok WM, Phillips DL. Comparison of the dehalogenation of polyhalomethanes and production of strong acids in aqueous and salt (NaCl) water environments: Ultraviolet photolysis of CH[sub 2]I[sub 2]. J Chem Phys 2004; 121:8399-409. [PMID: 15511161 DOI: 10.1063/1.1803508] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ultraviolet photolysis of CH(2)I(2) was studied in water and salt water solutions using photochemistry and picosecond time-resolved resonance Raman spectroscopy. Photolysis in both types of environments produces mainly CH(2)(OH)(2) and HI products. However, photolysis of CH(2)I(2) in salt water leads to the formation of different products/intermediates (CH(2)ICl and Cl(2) (-)) not observed in the absence of salt in aqueous solutions. The amount of CH(2)(OH)(2) and HI products appears to decrease after photolysis of CH(2)I(2) in salt water compared to pure water. We briefly discuss possible implications of these results for photolysis of CH(2)I(2) and other polyhalomethanes in sea water and other salt aqueous environments compared to nonsalt water solvated environments.
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Affiliation(s)
- Xiangguo Guan
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, People's Republic of China
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36
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Tarnovsky AN, Sundström V, Åkesson E, Pascher T. Photochemistry of Diiodomethane in Solution Studied by Femtosecond and Nanosecond Laser Photolysis. Formation and Dark Reactions of the CH2I−I Isomer Photoproduct and Its Role in Cyclopropanation of Olefins. J Phys Chem A 2003. [DOI: 10.1021/jp035406n] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alexander N. Tarnovsky
- Contribution from the Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Villy Sundström
- Contribution from the Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Eva Åkesson
- Contribution from the Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
| | - Torbjörn Pascher
- Contribution from the Department of Chemical Physics, Lund University, Box 124, 221 00 Lund, Sweden
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Grimm C, Kling M, Schroeder J, Troe J, Zerbs J, Schroeder J, Troe J. Density-dependent photochemical branching ratio in supercritical CO2: Photodissociation and isomerization of diiodomethane. Isr J Chem 2003. [DOI: 10.1560/d8hj-jqtw-w43y-qf1g] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Zhao C, Wang D, Phillips DL. Theoretical Study of Samarium (II) Carbenoid (ISmCH2I) Promoted Cyclopropanation Reactions with Ethylene and the Effect of THF Solvent on the Reaction Pathways. J Am Chem Soc 2003; 125:15200-9. [PMID: 14653755 DOI: 10.1021/ja030280t] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A computational study of the cyclopropanation reactions of divalent samarium carbenoid ISmCH(2)I with ethylene is presented. The reaction proceeds through two competing pathways: methylene transfer and carbometalation. The ISmCH(2)I species was found to have a "samarium carbene complex" character with properties similar to previously investigated lithium carbenoids (LiCH(2)X where X = Cl, Br, I). The ISmCH(2)I carbenoid was found to be noticeably different in structure with more electrophilic character and higher chemical reactivity than the closely related classical Simmons-Smith (IZnCH(2)I) carbenoid. The effect of THF solvent was investigated by explicit coordination of the solvent THF molecules to the Sm (II) center in the carbenoid. The ISmCH(2)I/(THF)(n)() (where n = 0, 1, 2) carbenoid methylene transfer pathway barriers to reaction become systematically lower as more THF solvent is added (from 12.9 to 14.5 kcal/mol for no THF molecules to 8.8 to 10.7 kcal/mol for two THF molecules). In contrast, the reaction barriers for cyclopropanation via the carbometalation pathway remain high (>15 kcal/mol). The computational results are briefly compared to other carbenoid reactions and related species.
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Affiliation(s)
- Cunyuan Zhao
- Contribution from the Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
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