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Góbi S, Keresztes B, Schneiker A, Ragupathy G, Tarczay G. Energetic processing of thioacetamide in cryogenic matrices. J Chem Phys 2024; 160:024310. [PMID: 38214387 DOI: 10.1063/5.0177587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Accepted: 12/11/2023] [Indexed: 01/13/2024] Open
Abstract
There is an ongoing debate on the apparent depletion of sulfur in the interstellar medium (ISM) compared to its universal abundance; therefore, the investigation of sulfurous compounds at low temperatures is of utmost importance. This work aims to study thioacetamide, H3C-C(=S)-NH2, in low-temperature inert Ar and para-H2 matrices by IR spectroscopy. The samples have been exposed to various sources of irradiation, such as Lyman-α or laser UV photons as well as energetic electrons. Using different host materials enabled assessing the matrix's impact on precursor decomposition. The response of the molecule to different types of irradiation has also been evaluated. The existence of three main decomposition channels were deduced: formation of (i) CH3, CH4, and HNCS; (ii) H2S and H2C=C=NH; and (iii) NH3 and H2C=C=S. The H3C-CN and H3C-NC isomers of H2C=C=NH could also be identified. Secondary products such as HNC and HCN were also detected in the quantum solid para-H2 in contrast to the more rigid Ar matrix. The listed decomposition products have been observed in the ISM, with the exception of H2C=C=NH and H3C-NC. The results point to the potential sensitivity of the precursor molecule to energetic radiation in space environments. Finally, the findings of this work will serve as a foundation for future irradiation experiments using the astrochemically more relevant pure thioacetamide ice.
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Affiliation(s)
- Sándor Góbi
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Barbara Keresztes
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Anita Schneiker
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Hevesy György PhD School of Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - Gopi Ragupathy
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
| | - György Tarczay
- MTA-ELTE Lendület Laboratory Astrochemistry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Laboratory of Molecular Spectroscopy, Institute of Chemistry, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
- Centre for Astrophysics and Space Science, ELTE Eötvös Loránd University, P.O. Box 32, H-1518 Budapest, Hungary
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Drabkin VD, Paczelt V, Eckhardt AK. Spectroscopic identification of interstellar relevant 2-iminoacetaldehyde. Chem Commun (Camb) 2023; 59:12715-12718. [PMID: 37814897 DOI: 10.1039/d3cc04192a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
Imines play a fundamental role in organic synthesis and some of them have been detected in space. However, the simplest imines are spectroscopically not well-characterized. Herein we present the infrared and UV/Vis spectroscopic characterization of 2-iminoacetaldehyde using cryogenic matrix isolation techniques. After UV irradiation of 2-azidoacetaldehyde in solid argon at 3 K we identified two conformers of 2-iminoacetaldehyde, which can be photochemically interconverted. Deuterium labelling experiments and high level ab initio coupled cluster calculations at the CCSD(T)/CBS level of theory provide further evidence for the formation of 2-iminoacetaldehyde.
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Affiliation(s)
- Vladimir D Drabkin
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44801, Germany.
| | - Viktor Paczelt
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44801, Germany.
| | - André K Eckhardt
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44801, Germany.
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Feldman VI. Astrochemically Relevant Radicals and Radical-Molecule Complexes: A New Insight from Matrix Isolation. Int J Mol Sci 2023; 24:14510. [PMID: 37833965 PMCID: PMC10572415 DOI: 10.3390/ijms241914510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/15/2023] [Accepted: 09/16/2023] [Indexed: 10/15/2023] Open
Abstract
The reactive open-shell species play a very important role in the radiation-induced molecular evolution occurring in the cold areas of space and presumably leading to the formation of biologically relevant molecules. This review presents an insight into the mechanism of such processes coming from matrix isolation studies with a main focus on the experimental and theoretical studies performed in the author's laboratory during the past decade. The radicals and radical cations produced from astrochemically relevant molecules were characterized by Fourier transform infrared (FTIR) and electron paramagnetic resonance (EPR) spectroscopy. Small organic radicals containing C, O, and N atoms are considered in view of their possible role in the formation of complex organic molecules (COMs) in space, and a comparison with earlier results is given. In addition, the radical-molecule complexes generated from isolated intermolecular complexes in matrices are discussed in connection with their model significance as the building blocks for COMs formed under the conditions of extremely restricted molecular mobility at cryogenic temperatures.
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Affiliation(s)
- Vladimir I Feldman
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
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Zasimov PV, Sanochkina EV, Tyurin DA, Feldman VI. Radiation-induced transformations of matrix-isolated ethanol molecules at cryogenic temperatures: an FTIR study. Phys Chem Chem Phys 2023; 25:21883-21896. [PMID: 37566409 DOI: 10.1039/d3cp02834h] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Ethanol (C2H5OH) is one of the most common alcohol molecules observed in various space media (molecular clouds, star formation regions, and, highly likely, interstellar ices), where it is exposed to light and ionizing radiation, leading to more complex organic molecules and eventually to the biologically important species. To better understand the radiation-induced evolution of ethanol molecules in icy media, we have examined the transformations of isolated C2H5OH and C2D5OH under the action of X-rays and vacuum ultraviolet (VUV) radiation in solid inert matrices (Ne, Ar, Kr, and Xe) at 4.4 K using Fourier transform infrared (FTIR) spectroscopy. The results obtained with X-ray irradiation demonstrate the formation of a variety of radiolysis products corresponding to dehydrogenation (CH3CHOH˙, CH3CHO, CH2CHOH, CH3CO˙, H2CCO-H2, H2CCO, HCCO˙, CCO) and C-C bond rupture (H2CO, HCO˙, CO, CH4, and CH3˙). The absorptions of the CH3CHOH˙ radical related to the CCO stretching (the bands at 1249.1, 1247.0, 1246.2, and 1245.1 cm-1, in Ne, Ar, Kr, and Xe, respectively) were first tentatively characterized on the basis of comparison with available computational data. In addition, the C2H2⋯H2O complex, which corresponds to dehydrogenation, was found followed by C-O bond cleavage. The results were confirmed by experiments with isotopic substitution. It was found that dehydrogenation strongly predominated in a xenon matrix, while skeleton bond rupture is more feasible in neon and argon. The matrix effect was attributed to a significant role of "hot" reaction channels in neon and argon, which are efficiently quenched due to relaxation in more polarizable xenon. The VUV photolysis (185 nm) in Ar and Xe matrices yields a similar set of products, except for CH3CHOH˙ and CH2CHOH, which were not found (the nonobservation of the former species may be explained by its efficient secondary photolysis). The plausible mechanisms of product formation and astrochemical implications of the results are discussed.
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Affiliation(s)
- Pavel V Zasimov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | | | - Daniil A Tyurin
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Vladimir I Feldman
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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Zasimov PV, Sanochkina EV, Tyurin DA, Feldman VI. An EPR study on the radiolysis of isolated ethanol molecules in solid argon and xenon: matrix control of radiation-induced generation of radicals in cryogenic media. Phys Chem Chem Phys 2023; 25:4624-4634. [PMID: 36723210 DOI: 10.1039/d2cp05356j] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
This paper addresses the basic question of the impact of a chemically inert environment on the radiation-induced transformations of isolated organic molecules in icy media at cryogenic temperatures with possible implications for astrochemical issues. The radicals produced by X-ray irradiation of isolated ethanol molecules (C2H5OH and CH3CD2OH) in solid argon and xenon matrices at 7 K were characterized by electron paramagnetic resonance (EPR) spectroscopy. It was shown that methyl (CH3˙) and formyl (HCO˙) radicals resulting from the C-C bond cleavage were mainly produced in the case of solid argon, which was attributed to the significant role of "hot" ionic fragmentation and inefficient energy dissipation to medium. In contrast, irradiation in xenon results in the predominant formation of α-hydroxyethyl radicals (CH3˙CHOH or CH3˙CDOH(D) in the cases of C2H5OH and CH3CD2OH, respectively). Remarkably, the experiments with selectively deuterated ethanol provide strong indirect evidence for the primary formation of ethoxy (CH3CD2O˙) radicals due to O-H bond cleavage, which convert to the α-hydroxyethyl radicals due to isomerization occurring at 7 K. The α-hydroxyethyl radicals adopt a specific rigid conformation with a non-rotating methyl group at low temperatures, which is an unusual effect for neutral CH3˙CHX species, and exhibit free rotation in solid xenon only at ca. 65 K.
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Affiliation(s)
- Pavel V Zasimov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | | | - Daniil A Tyurin
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | - Vladimir I Feldman
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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Zasimov PV, Sanochkina EV, Feldman VI. Radiation-induced transformations of acetaldehyde molecules at cryogenic temperatures: a matrix isolation study. Phys Chem Chem Phys 2021; 24:419-432. [PMID: 34897322 DOI: 10.1039/d1cp03999g] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Acetaldehyde is one of the key small organic molecules involved in astrochemical and atmospheric processes occurring under the action of ionizing and UV radiation. While the UV photochemistry of acetaldehyde is well studied, little is known about the mechanism of processes induced by high-energy radiation. This paper reports the first systematic study on the chemical transformations of CH3CHO molecules resulting from X-ray irradiation under the conditions of matrix isolation in different solid noble gases (Ne, Ar, Kr, and Xe) at 5 K. CO, CH4, H2CCO, H2CCO-H2, C2H2⋯H2O, CH2CHOH, CH3CO˙, CH3˙, HCCO˙, and CCO were identified as the main radiolysis products. The dominant pathway of acetaldehyde degradation involves C-C bond cleavage leading to the formation of carbon monoxide and methane. The second important channel is dehydrogenation resulting in the formation of ketene, a potentially highly reactive species. It was found that the matrix significantly affected both the decomposition efficiency and distribution of the reaction channels. Based on these observations, it was suggested that the formation of the methyl radical as well as vinyl alcohol and the C2H2⋯H2O complex presumably included a significant contribution of ionic pathways. The decomposition of acetyl radicals under photolysis with visible light leading to the CH3˙-CO radical-molecule pair was observed in all matrices, while the recovery of CH3CO˙ in the dark at 5 K was found only in Xe. This finding represents a prominent example of matrix-dependent chemical dynamics (probably, involving tunnelling), which deserves further theoretical studies. Probable mechanisms of acetaldehyde radiolysis and their implications for astrochemistry, atmospheric chemistry and low-temperature chemistry are discussed.
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Affiliation(s)
- Pavel V Zasimov
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
| | | | - Vladimir I Feldman
- Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russia.
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Volosatova AD, Lukianova MA, Zasimov PV, Feldman VI. Direct evidence for a radiation-induced synthesis of acetonitrile and isoacetonitrile from a 1 : 1 CH 4HCN complex at cryogenic temperatures: is it a missing link between inorganic and prebiotic astrochemistry? Phys Chem Chem Phys 2021; 23:18449-18460. [PMID: 34612385 DOI: 10.1039/d1cp01598b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Nitriles are important constituents of extraterrestrial media. Nitriles are supposed to play a crucial role in prebiotic chemistry occurring in the interstellar medium. In this work, we have investigated the low-temperature radiation-induced transformations of a 1 : 1 CH4HCN complex as a plausible precursor of the simplest nitriles using the matrix isolation approach with FTIR spectroscopic detection. The parent complexes isolated in a noble gas (Ng) matrix were obtained by deposition of the CH4/HCN/Ng gaseous mixture and characterized by comparison of experimental complexation-induced shifts of the HCN fundamentals with the results of the ab initio calculations. It was found that the X-ray irradiation of low-temperature matrices containing the isolated 1 : 1 CH4HCN complex resulted in the formation of acetonitrile (CH3CN) and isoacetonitrile (CH3NC) and it appears to be the first experimental evidence for the formation of C2 nitriles (acetonitrile and isoacetonitrile) from such a "building block". Additionally, a 1 : 1 CH4HNC complex was tentatively assigned to the irradiated Ar and Kr matrices. It is demonstrated that the matrix has a strong effect on the CH3CN/CH3NC yield ratio, which dramatically increases in the row Ar < Kr < Xe. Also, the efficiency of the radiation-induced formation of the CH4HNC complex was shown to decrease from Ar to Kr. It is believed that the proposed pathway for acetonitrile formation may be a significant step in the radiation-induced evolution leading to complex organic molecules and biomolecules under astrochemical conditions. Furthermore, the obtained results provide a prominent example of the impact of very weak intermolecular interactions on the radiation-induced transformations in cold media.
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Feldman VI, Ryazantsev SV, Kameneva SV. Matrix isolation in laboratory astrochemistry: state-of-the-art, implications and perspective. RUSSIAN CHEMICAL REVIEWS 2021. [DOI: 10.1070/rcr4995] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Lukianova MA, Volosatova AD, Drabkin VD, Sosulin IS, Kameneva SV, Feldman VI. Radiation-induced transformations of HCN⋯C2H2, HCN⋯C2H4 and HCN⋯C2H6 complexes in noble gas matrices: Synthesis of C3HxN molecules in cryogenic media. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109232] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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10
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Zasimov PV, Belousov AV, Baranova IA, Feldman VI. Quantitative assessment of the absorbed dose in cryodeposited noble-gas films under X-ray irradiation: Simulation vs. experiment. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.109084] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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11
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Radiation-induced transformations of isolated toluene molecules in low-temperature matrices: Towards better understanding of molecular radiation chemistry in condensed phases. Radiat Phys Chem Oxf Engl 1993 2020. [DOI: 10.1016/j.radphyschem.2020.109022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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12
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Ryazantsev SV, Zasimov PV, Feldman VI. Radiation-induced synthesis of formic acid in the H2O–CO system: A matrix isolation study. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137540] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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13
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Yang K, Li K, Pan L, Luo X, Xing J, Wang J, Wang L, Wang R, Zhai Y, Chen Z. Effect of Ozone and Electron Beam Irradiation on Degradation of Zearalenone and Ochratoxin A. Toxins (Basel) 2020; 12:toxins12020138. [PMID: 32102304 PMCID: PMC7076874 DOI: 10.3390/toxins12020138] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 02/15/2020] [Accepted: 02/21/2020] [Indexed: 11/25/2022] Open
Abstract
Zearalenone (ZEN) and ochratoxin A (OTA) are key concerns of the food industry because of their toxicity and pollution scope. This study investigated the effects of ozone and electron beam irradiation (EBI) on the degradation of ZEN and OTA. Results demonstrated that 2 mL of 50 μg/mL ZEN was completely degraded after 10 s of treatment by 2.0 mg/L ozone. The degradation rate of 1 μg/mL ZEN by 16 kGy EBI was 92.76%. Methanol was superior to acetonitrile in terms of degrading ZEN when the irradiation dose was higher than 6 kGy. The degradation rate of 2 mL of 5 μg/mL OTA by 50 mg/L ozone at 180 s was 34%, and that of 1 μg/mL OTA by 16 kGy EBI exceeded 90%. Moreover, OTA degraded more rapidly in acetonitrile. Ozone performed better in the degradation of ZEN, whereas EBI was better for OTA. The conclusions provide theoretical and practical bases for the degradation of different fungal toxins.
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Affiliation(s)
- Kai Yang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Ke Li
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Lihong Pan
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Xiaohu Luo
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China;
- College of Food and Pharmaceutical Science, Ningbo University, Ningbo 315000, China
- Research Institute of Gang Yagou Healthy Food and Biotechnology, Ningbo 315205, China
- Correspondence: (X.L.); (Z.C.)
| | - Jiali Xing
- Ningbo Institute for Food Control, Ningbo 315048, China;
| | - Jing Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing 100048, China;
| | - Li Wang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Ren Wang
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Yuheng Zhai
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
| | - Zhengxing Chen
- National Engineering Laboratory for Cereal Fermentation Technology, Jiangnan University, Wuxi 214122, China; (K.Y.); (K.L.); (L.P.); (L.W.); (R.W.); (Y.Z.)
- Correspondence: (X.L.); (Z.C.)
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Lukianova MA, Sanochkina EV, Feldman VI. Radiation-Induced Transformations of C 6H 6 Molecules in Solid Noble-Gas Matrices: Is Benzene Intrinsically Resistant in Condensed Media? J Phys Chem A 2019; 123:5199-5205. [PMID: 31150245 DOI: 10.1021/acs.jpca.9b01137] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The radiation resistance of aromatic compounds is one of the key concepts of basic and applied radiation chemistry in condensed phases. Usually, it is attributed to the intrinsic radiation stability of the benzene ring. In this work, we have demonstrated for the first time that the isolated benzene molecules undergo rather efficient radiation-induced degradation in rigid inert media at cryogenic temperatures (comparable to that of aliphatic hydrocarbons), and their stability is essentially determined by the intermolecular relaxation correlating with matrix polarizability. The principal primary products of benzene radiolysis in matrices are phenyl radicals and fulvene. The matrix environment strongly affects the proportion of these species because of external heavy atom effect on the intersystem crossing, which may trigger further reaction pathways. The obtained results may have important implications for the prediction of radiation stability of complex organic systems and polymers. Furthermore, they may contribute to a better understanding of the radiation-induced evolution of aromatic species in cold interstellar media.
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Affiliation(s)
- Mariia A Lukianova
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia
| | | | - Vladimir I Feldman
- Department of Chemistry , Lomonosov Moscow State University , Moscow 119991 , Russia
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15
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Custer T, Szczepaniak U, Gronowski M, Piétri N, Couturier-Tamburelli I, Guillemin JC, Turowski M, Kołos R. Isomerization of cyanopropyne in solid argon. Phys Chem Chem Phys 2019; 21:13668-13678. [PMID: 31190036 DOI: 10.1039/c8cp06739b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyanopropyne, CH3-C[triple bond, length as m-dash]C-CN, is a simple molecule whose photochemistry is still unexplored. Here we investigate the UV photolysis of this astrophysically significant nitrile trapped in solid argon. The FTIR study was assisted with 15N-isotopic substitution data and with DFT-level computations including the analyses of ground- and excited-state potential energy surfaces. Cyanopropyne was found to decay mainly via a two-step isomerization process. Infrared absorption spectra evolved to show signals from allenyl cyanide, CH2[double bond, length as m-dash]C[double bond, length as m-dash]CH-CN, which then further convert into propargyl cyanide, H-C[triple bond, length as m-dash]C-CH2-CN. Some evidence for the presence of allenyl isocyanide, propargyl isocyanide, 3-cyanocyclopropene, and 1,2,3-butatrien-1-imine under particular experimental conditions was also observed. Although cyano/isocyano interconversion has been observed during photolysis of other closely related species in solid argon matrices, including H-C[triple bond, length as m-dash]C-CN, no evidence could be found for production of 1-isocyano-1-propyne, CH3-C[triple bond, length as m-dash]C-NC for these experiments.
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Affiliation(s)
- Thomas Custer
- Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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16
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Volosatova AD, Kameneva SV, Feldman VI. Formation and interconversion of CCN and CNC radicals resulting from the radiation-induced decomposition of acetonitrile in solid noble gas matrices. Phys Chem Chem Phys 2019; 21:13014-13021. [PMID: 31166329 DOI: 10.1039/c8cp07896c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Acetonitrile and the species resulting from its dehydrogenation play an important role in the radiation-induced evolution of organic matter in the space environment. In this work, we report on FTIR spectroscopic studies of the degradation of isolated CH3CN and CD3CN molecules induced by prolonged X-ray irradiation in solid noble gas matrices at 5 K. The principal products observed at high conversion degree of the parent acetonitrile molecules (70-90%) are CCN and CNC radicals, which result from prompt or two-step dehydrogenation of the corresponding precursors, H2CN and CH2NC radicals, respectively. CHCN and CHNC were also found as products of dehydrogenation at high absorbed doses, whereas the fragmentation products (CH3, CN, HCN, and HNC) were detected only in minor amounts over the whole dose range studied. CCN and CNC are produced in nearly equal amounts at high absorbed doses. Selective isomerization of CCN to CNC was observed under the illumination with visible light (460-470 nm), while subsequent action of the UV light (254 nm) induced reverse transformation leading to a photostationary state with the relative population of CNC/CCN being ca. 0.7. The astrochemical implications of the obtained results are discussed in connection with the recent discovery of CCN in extraterrestrial objects.
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17
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Zapała J, Custer T, Guillemin JC, Gronowski M. Photochemistry of XCH 2CN (X = -Cl, -SH) in Argon Matrices. J Phys Chem A 2019; 123:3818-3830. [PMID: 30974940 DOI: 10.1021/acs.jpca.9b01983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report infrared spectra and photochemical behavior of the potentially astrochemically significant species, mercaptoacetonitrile (HS-CH2C≡N) and, for comparison purposes, chloroacetonitrile (Cl-CH2C≡N), both suspended in an argon matrix at 6 K. Photolytic formation of the isocyano products HS-CH2-NC and Cl-CH2-NC were observed as well as CH3NSC and CH3SCN (in HS-CH2CN photolysis). While no dissociation products were observed for Cl-CH2-CN, photolysis of HS-CH2-CN produced compounds necessitating the loss of the CN group to form CH2═S, the SH group to form H2C-CN and HC-CN, or both CN and SH to form CH3 and CH4. Observation of emission spectra upon annealing indicates the presence of free sulfur atom in matrices of photolyzed HS-CH2-CN.
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Affiliation(s)
- Joanna Zapała
- Institute of Physical Chemistry , Polish Academy of Sciences , Kasprzaka 44/52 , PL-01-224 Warsaw , Poland
| | - Thomas Custer
- Institute of Physical Chemistry , Polish Academy of Sciences , Kasprzaka 44/52 , PL-01-224 Warsaw , Poland
| | - Jean-Claude Guillemin
- Université Rennes , Ecole Nationale Supérieure de Chimie de Rennes , CNRS, ISCR-UMR6226 , F-35000 Rennes , France
| | - Marcin Gronowski
- Institute of Physical Chemistry , Polish Academy of Sciences , Kasprzaka 44/52 , PL-01-224 Warsaw , Poland
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Ryazantsev SV, Zasimov PV, Feldman VI. X-ray radiolysis of C2 hydrocarbons in cryogenic media. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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