1
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Lang J, Foley CD, Thawoos S, Behzadfar A, Liu Y, Zádor J, Suits AG. Reaction dynamics of S( 3P) with 1,3-butadiene and isoprene: crossed-beam scattering, low-temperature flow experiments, and high-level electronic structure calculations. Faraday Discuss 2024; 251:550-572. [PMID: 38807494 DOI: 10.1039/d4fd00009a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Sulfur atoms serve as key players in diverse chemical processes, from astrochemistry at very low temperature to combustion at high temperature. Building upon our prior findings, showing cyclization to thiophenes following the reaction of ground-state sulfur atoms with dienes, we here extend this investigation to include many additional reaction products, guided by detailed theoretical predictions. The outcomes highlight the complex formation of products during intersystem crossing (ISC) to the singlet surfaces. Here, we employed crossed-beam velocity map imaging and high-level ab initio methods to explore the reaction of S(3P) with 1,3-butadiene and isoprene under single-collision conditions and in low-temperature flows. For the butadiene reaction, our experimental results show the formation of thiophene via H2 loss, a 2H-thiophenyl radical through H loss, and thioketene through ethene loss at a slightly higher collision energy compared to previous observations. Complementary Chirped-Pulse Fourier-Transform mmWave spectroscopy (CP-FTmmW) measurements in a uniform flow confirmed the formation of thioketene in the reaction at 20 K. For the isoprene reaction, we observed analogous products along with the 2H-thiophenyl radical arising from methyl loss and C3H4S (loss of ethene or H2 + acetylene). CP-FTmmW detected the formation of thioformaldehyde via loss of 1,3-butadiene, again in the 20 K flow. Coupled-cluster calculations on the pathways found by the automated kinetic workflow code KinBot support these findings and indicate ISC to the singlet surface, leading to the generation of various long-lived intermediates, including 5-membered heterocycles.
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Affiliation(s)
- Jinxin Lang
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Casey D Foley
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Shameemah Thawoos
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Abbas Behzadfar
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Yanan Liu
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
| | - Judit Zádor
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA.
| | - Arthur G Suits
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA.
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2
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Rap D, Schrauwen JGM, Redlich B, Brünken S. Noncovalent Interactions Steer the Formation of Polycyclic Aromatic Hydrocarbons. J Am Chem Soc 2024; 146:23022-23033. [PMID: 39110663 PMCID: PMC11345775 DOI: 10.1021/jacs.4c03395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 07/04/2024] [Accepted: 07/29/2024] [Indexed: 08/22/2024]
Abstract
Aromatic molecules play an important role in the chemistry of astronomical environments such as the cold interstellar medium (ISM) and (exo)planetary atmospheres. The observed abundances of (polycyclic) aromatic hydrocarbons such as benzonitrile and cyanonaphthalenes are, however, highly underestimated by astrochemical models. This demonstrates the need for more experimentally verified reaction pathways. The low-temperature ion-molecule reaction of benzonitrile•+ with acetylene is studied here using a multifaceted approach involving kinetics and spectroscopic probing of the reaction products. A fast radiative association reaction via an in situ experimentally observed prereactive complex shows the importance of noncovalent interactions in steering the pathway during cold ion-molecule reactions. Product structures of subsequent reactions are unambiguously identified using infrared action spectroscopy and reveal the formation of nitrogen-containing, linked bicyclic structures such as phenylpyridine•+ and benzo-N-pentalene+ structures. The results, contradicting earlier assumptions on the product structure, demonstrate the importance of spectroscopic probing of reaction products and emphasize the possible formation of linked bicyclic molecules and benzo-N-pentalene+ structures in astronomical environments.
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Affiliation(s)
- Daniël
B. Rap
- FELIX Laboratory, Institute
for Molecules and Materials, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Johanna G. M. Schrauwen
- FELIX Laboratory, Institute
for Molecules and Materials, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Britta Redlich
- FELIX Laboratory, Institute
for Molecules and Materials, Radboud University, Nijmegen 6525 ED, The Netherlands
| | - Sandra Brünken
- FELIX Laboratory, Institute
for Molecules and Materials, Radboud University, Nijmegen 6525 ED, The Netherlands
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3
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Suttle MD, Olbrich LF, Bays CL, Riches L. Rapid heating rates define the volatile emission and regolith composition of (3200) Phaethon. Nat Commun 2024; 15:7178. [PMID: 39168985 PMCID: PMC11339282 DOI: 10.1038/s41467-024-51054-w] [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: 04/16/2024] [Accepted: 07/29/2024] [Indexed: 08/23/2024] Open
Abstract
Asteroid (3200) Phaethon experiences extreme solar radiant heating ( ~ 750 °C) during perihelion (0.14 au), leading to comet-like activity. The regolith composition and mechanism of volatile emission are unknown but key to understanding JAXA's DESTINY+ mission data (fly-by in 2029) and the fate of near-Sun asteroids more generally. By subjecting CM chondrite fragments to fast, open system, cyclic heating (2-20 °C/min), simulating conditions on Phaethon we demonstrate that rapid heating rates combine with the low permeability, resulting in reactions between volatile gases and decomposing minerals. The retention of S-bearing gas limits the thermal decomposition of Fe-sulphides, allowing these minerals to survive repeated heating cycles. Slow escape of S-bearing gases provides a mechanism for repeated gas release from a thermally processed surface and, therefore the comet-like activity without requiring surface renewal to expose fresh material each perihelion cycle. We predict Phaethon regolith is composed of olivine, Fe-sulphides, Ca-sulphates and hematite.
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Affiliation(s)
- Martin D Suttle
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK.
- Planetary Materials Group, Natural History Museum, Cromwell Road, London, UK.
| | - Lorenz F Olbrich
- Department of Materials, University of Oxford, Parks Road, Oxford, UK
| | - Charlotte L Bays
- Planetary Materials Group, Natural History Museum, Cromwell Road, London, UK
- Department of Earth Sciences, Royal Holloway University of London, Surrey, UK
| | - Liza Riches
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK
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4
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Hrodmarsson HR, Garcia GA, Bourehil L, Nahon L, Gans B, Boyé-Péronne S, Guillemin JC, Loison JC. The isomer distribution of C 6H 6 products from the propargyl radical gas-phase recombination investigated by threshold-photoelectron spectroscopy. Commun Chem 2024; 7:156. [PMID: 38997498 PMCID: PMC11245511 DOI: 10.1038/s42004-024-01239-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2024] [Accepted: 07/02/2024] [Indexed: 07/14/2024] Open
Abstract
The resonance-stabilization of the propargyl radical (C3H3) makes it among the most important reactive intermediates in extreme environments and grants it a long enough lifetime to recombine in both terrestrial combustion media and cold molecular clouds in space. This makes the propargyl self-reaction a pivotal step in the formation of benzene, the first aromatic ring, to eventually lead to polycyclic aromatic hydrocarbons in a variety of environments. In this work, by producing propargyl radicals in a flow tube where propyne reacted with F atoms and probing the reaction products by mass-selected threshold-photoelectron spectroscopy (TPES), we identified eight C6H6 products in total, including benzene. On top of providing the first comprehensive measurements of the branching ratios of the eight identified C6H6 isomers in the propargyl self reaction products (4 mbar, 298 K conditions), this study also highlights the advantages and disadvantages of using isomer-selective TPES to identify and quantify reaction products.
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Affiliation(s)
- Helgi Rafn Hrodmarsson
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, F-91192, Gif sur Yvette, France.
- Univ Paris Est Créteil and Université Paris Cité, CNRS, LISA UMR 7583, 94010, Créteil, France.
| | - Gustavo A Garcia
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, F-91192, Gif sur Yvette, France
| | - Lyna Bourehil
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, F-91192, Gif sur Yvette, France
| | - Laurent Nahon
- Synchrotron SOLEIL, L'Orme des Merisiers, St. Aubin, F-91192, Gif sur Yvette, France
| | - Bérenger Gans
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, F-91405, Orsay, France
| | - Séverine Boyé-Péronne
- Université Paris-Saclay, CNRS, Institut des Sciences Moléculaires d'Orsay, F-91405, Orsay, France
| | - Jean-Claude Guillemin
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR - UMR6226, F-35000, Rennes, France
| | - Jean-Christophe Loison
- Institut des Sciences Moléculaires, CNRS, Université de Bordeaux, F-33400, Talence, France.
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5
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Goettl SJ, He C, Yang Z, Kaiser RI, Somani A, Portela-Gonzalez A, Sander W, Sun BJ, Fatimah S, Kadam KP, Chang AHH. Unconventional gas-phase synthesis of biphenyl and its atropisomeric methyl-substituted derivatives. Phys Chem Chem Phys 2024; 26:18321-18332. [PMID: 38912536 DOI: 10.1039/d4cp00765d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
The biphenyl molecule (C12H10) acts as a fundamental molecular backbone in the stereoselective synthesis of organic materials due to its inherent twist angle causing atropisomerism in substituted derivatives and in molecular mass growth processes in circumstellar environments and combustion systems. Here, we reveal an unconventional low-temperature phenylethynyl addition-cyclization-aromatization mechanism for the gas-phase preparation of biphenyl (C12H10) along with ortho-, meta-, and para-substituted methylbiphenyl (C13H12) derivatives through crossed molecular beams and computational studies providing compelling evidence on their formation via bimolecular gas-phase reactions of phenylethynyl radicals (C6H5CC, X2A1) with 1,3-butadiene-d6 (C4D6), isoprene (CH2C(CH3)CHCH2), and 1,3-pentadiene (CH2CHCHCHCH3). The dynamics involve de-facto barrierless phenylethynyl radical additions via submerged barriers followed by facile cyclization and hydrogen shift prior to hydrogen atom emission and aromatization to racemic mixtures (ortho, meta) of biphenyls in overall exoergic reactions. These findings not only challenge our current perception of biphenyls as high temperature markers in combustion systems and astrophysical environments, but also identify biphenyls as fundamental building blocks of complex polycyclic aromatic hydrocarbons (PAHs) such as coronene (C24H12) eventually leading to carbonaceous nanoparticles (soot, grains) in combustion systems and in deep space thus affording critical insight into the low-temperature hydrocarbon chemistry in our universe.
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Affiliation(s)
- Shane J Goettl
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Chao He
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Ankit Somani
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44801, Germany.
| | | | - Wolfram Sander
- Lehrstuhl für Organische Chemie II, Ruhr-Universität Bochum, Bochum 44801, Germany.
| | - Bing-Jian Sun
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Siti Fatimah
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Komal P Kadam
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
| | - Agnes H H Chang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan.
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6
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Nixon CA. The Composition and Chemistry of Titan's Atmosphere. ACS EARTH & SPACE CHEMISTRY 2024; 8:406-456. [PMID: 38533193 PMCID: PMC10961852 DOI: 10.1021/acsearthspacechem.2c00041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 11/02/2023] [Accepted: 02/02/2024] [Indexed: 03/28/2024]
Abstract
In this review I summarize the current state of knowledge about the composition of Titan's atmosphere and our current understanding of the suggested chemistry that leads to that observed composition. I begin with our present knowledge of the atmospheric composition, garnered from a variety of measurements including Cassini-Huygens, the Atacama Large Millimeter/submillimeter Array, and other ground- and space-based telescopes. This review focuses on the typical vertical profiles of gases at low latitudes rather than global and temporal variations. The main body of the review presents a chemical description of how complex molecules are believed to arise from simpler species, considering all known "stable" molecules-those that have been uniquely identified in the neutral atmosphere. The last section of the review is devoted to the gaps in our present knowledge of Titan's chemical composition and how further work may fill those gaps.
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Affiliation(s)
- Conor A. Nixon
- Planetary Systems Laboratory, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, Maryland 20771, United
States
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7
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Medvedkov IA, Nikolayev AA, Yang Z, Goettl SJ, Mebel AM, Kaiser RI. Elucidating the chemical dynamics of the elementary reactions of the 1-propynyl radical (CH 3CC; X 2A 1) with 2-methylpropene ((CH 3) 2CCH 2; X 1A 1). Phys Chem Chem Phys 2024; 26:6448-6457. [PMID: 38319693 DOI: 10.1039/d3cp05872g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Exploiting the crossed molecular beam technique, we studied the reaction of the 1-propynyl radical (CH3CC; X2A1) with 2-methylpropene (isobutylene; (CH3)2CCH2; X1A1) at a collision energy of 38 ± 3 kJ mol-1. The experimental results along with ab initio and statistical calculations revealed that the reaction has no entrance barrier and proceeds via indirect scattering dynamics involving C7H11 intermediates with lifetimes longer than their rotation period(s). The reaction is initiated by the addition of the 1-propynyl radical with its radical center to the π-electron density at the C1 and/or C2 position in 2-methylpropene. Further, the C7H11 intermediate formed from the C1 addition either emits atomic hydrogen or undergoes isomerization via [1,2-H] shift from the CH3 or CH2 group prior to atomic hydrogen loss preferentially leading to 1,2,4-trimethylvinylacetylene (2-methylhex-2-en-4-yne) as the dominant product. The molecular structures of the collisional complexes promote hydrogen atom loss channels. RRKM results show that hydrogen elimination channels dominate in this reaction, with a branching ratio exceeding 70%. Since the reaction of the 1-propynyl radical with 2-methylpropene has no entrance barrier, is exoergic, and all transition states involved are located below the energy of the separated reactants, bimolecular collisions are feasible to form trimethylsubstituted 1,3-enyne (p1) via a single collision event even at temperatures as low as 10 K prevailing in cold molecular clouds such as G+0.693. The formation of trimethylsubstituted vinylacetylene could serve as the starting point of fundamental molecular mass growth processes leading to di- and trimethylsubstituted naphthalenes via the HAVA mechanism.
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Affiliation(s)
- Iakov A Medvedkov
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | | | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | - Shane J Goettl
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
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8
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Falkowski AG, da Costa RF, Lima MAP, de A Cadena A, Pocoroba R, Jones R, Mathur M, Childers JG, Khakoo MA, Kossoski F. Electron impact electronic excitation of benzene: Theory and experiment. J Chem Phys 2023; 159:194301. [PMID: 37966005 DOI: 10.1063/5.0173024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/03/2023] [Indexed: 11/16/2023] Open
Abstract
We report experimental differential cross sections (DCSs) for electron impact excitation of bands I to V of benzene at incident energies of 10, 12.5, 15, and 20 eV. They are compared to calculations using the Schwinger multichannel method while accounting for up to 437 open channels. For intermediate scattering angles, the calculations reveal that the most intense band (V) emerges from surprisingly similar contributions from all its underlying states (despite some preference for the dipole-allowed transitions). They further shed light on intricate multichannel couplings between the states of bands I to V and higher-lying Rydberg states. In turn, the measurements support a vibronic coupling mechanism for excitation of bands II and IV and also show an unexpected forward peak in the spin-forbidden transition accounting for band III. Overall, there is decent agreement between theory and experiment at intermediate angles and at lower energies and in terms of the relative DCSs of the five bands. Discrepancies between the present and previous experiment regarding bands IV and V draw attention to the need of additional experimental investigations. We also report measured DCSs for vibrational excitation of combined C-H stretching modes.
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Affiliation(s)
- Alan G Falkowski
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
| | - Romarly F da Costa
- Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo, Brazil
| | - Marco A P Lima
- Instituto de Física "Gleb Wataghin," Universidade Estadual de Campinas, Campinas, Brazil
| | - Alexi de A Cadena
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Ronald Pocoroba
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Regan Jones
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Mahak Mathur
- Troy High School, 2200 Dorothy Lane, Fullerton, California 92831, USA
| | - J G Childers
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Murtadha A Khakoo
- Physics Department, California State University, Fullerton, California 92831, USA
| | - Fábris Kossoski
- Laboratoire de Chimie et Physique Quantiques (UMR 5626), Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
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9
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Murakami T, Matsumoto N, Fujihara T, Takayanagi T. Possible Roles of Transition Metal Cations in the Formation of Interstellar Benzene via Catalytic Acetylene Cyclotrimerization. Molecules 2023; 28:7454. [PMID: 37959873 PMCID: PMC10649463 DOI: 10.3390/molecules28217454] [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: 10/12/2023] [Revised: 10/28/2023] [Accepted: 11/03/2023] [Indexed: 11/15/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous interstellar molecules. However, the formation mechanisms of PAHs and even the simplest cyclic aromatic hydrocarbon, benzene, are not yet fully understood. Recently, we reported the statistical and dynamical properties in the reaction mechanism of Fe+-catalyzed acetylene cyclotrimerization, whereby three acetylene molecules are directly converted to benzene. In this study, we extended our previous work and explored the possible role of the complex of other 3d transition metal cations, TM+ (TM = Sc, Ti, Mn, Co, and Ni), as a catalyst in acetylene cyclotrimerization. Potential energy profiles for bare TM+-catalyst (TM = Sc and Ti), for TM+NC--catalyst (TM = Sc, Ti, Mn, Co, and Ni), and for TM+-(H2O)8-catalyst (TM = Sc and Ti) systems were obtained using quantum chemistry calculations, including the density functional theory levels. The calculation results show that the scandium and titanium cations act as efficient catalysts in acetylene cyclotrimerization and that reactants, which contain an isolated acetylene and (C2H2)2 bound to a bare (ligated) TM cation (TM = Sc and Ti), can be converted into a benzene-metal-cation product complex without an entrance barrier. We found that the number of electrons in the 3d orbitals of the transition metal cation significantly contributes to the catalytic efficiency in the acetylene cyclotrimerization process. On-the-fly Born-Oppenheimer molecular dynamics (BOMD) simulations of the Ti+-NC- and Ti+-(H2O)8 complexes were also performed to comprehensively understand the nuclear dynamics of the reactions. The computational results suggest that interstellar benzene can be produced via acetylene cyclotrimerization reactions catalyzed by transition metal cation complexes.
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Affiliation(s)
- Tatsuhiro Murakami
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (N.M.); (T.F.)
- Department of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
| | - Naoki Matsumoto
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (N.M.); (T.F.)
| | - Takashi Fujihara
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (N.M.); (T.F.)
- Comprehensive Analysis Center for Science, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama City 338-8570, Japan; (N.M.); (T.F.)
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10
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Vaneeva EE, Lepeshkin SV, Oganov AR. Prediction and Rationalization of Abundant C-N-H Molecules in Different Environments. J Phys Chem Lett 2023; 14:8367-8375. [PMID: 37705151 DOI: 10.1021/acs.jpclett.3c01753] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The extreme chemical diversity of CmNnHk molecules is at the same time very important (central in organic chemistry) and difficult to rationalize in the sense that some molecules are abundant and easy to synthesize, while others are rare and difficult to make. Using the recently developed criteria of molecular "magicity", combined with evolutionary structure prediction and quantum-chemical calculations, we study these molecules in a wide range of compositions (0 ≤ m ≤ 13, 0 ≤ n ≤ 4, and 0 ≤ k ≤ 14). "Magic" molecules are defined as those that are lower in energy than any isochemical mixture of molecules with the nearest compositions. The predicted "magic" molecules are in good agreement with compounds found in versatile environments (interstellar and circumstellar media, Titan's lower atmosphere, and crude oil fractions) and in experimental chemistry. This work shows the predictive power of our approach, capable of predicting and explaining stable molecules in complex systems.
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Affiliation(s)
- Elizaveta E Vaneeva
- Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, 121205 Moscow, Russian Federation
| | - Sergey V Lepeshkin
- Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, 121205 Moscow, Russian Federation
- Lebedev Physical Institute, Russian Academy of Sciences, Leninsky Ave. 53, 119991 Moscow, Russian Federation
- Vernadsky Institute of Geochemistry and Analytical Chemistry Russian Academy of Sciences, Kosygin St. 19, 119991 Moscow, Russian Federation
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Bolshoy Boulevard 30, bld. 1, 121205 Moscow, Russian Federation
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11
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Yang Z, Galimova GR, He C, Goettl SJ, Paul D, Lu W, Ahmed M, Mebel AM, Li X, Kaiser RI. Gas-phase formation of the resonantly stabilized 1-indenyl (C 9H 7•) radical in the interstellar medium. SCIENCE ADVANCES 2023; 9:eadi5060. [PMID: 37682989 PMCID: PMC10491290 DOI: 10.1126/sciadv.adi5060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 08/07/2023] [Indexed: 09/10/2023]
Abstract
The 1-indenyl (C9H7•) radical, a prototype aromatic and resonantly stabilized free radical carrying a six- and a five-membered ring, has emerged as a fundamental molecular building block of nonplanar polycyclic aromatic hydrocarbons (PAHs) and carbonaceous nanostructures in deep space and combustion systems. However, the underlying formation mechanisms have remained elusive. Here, we reveal an unconventional low-temperature gas-phase formation of 1-indenyl via barrierless ring annulation involving reactions of atomic carbon [C(3P)] with styrene (C6H5C2H3) and propargyl (C3H3•) with phenyl (C6H5•). Macroscopic environments like molecular clouds act as natural low-temperature laboratories, where rapid molecular mass growth to 1-indenyl and subsequently complex PAHs involving vinyl side-chained aromatics and aryl radicals can occur. These reactions may account for the formation of PAHs and their derivatives in the interstellar medium and carbonaceous chondrites and could close the gap of timescales of their production and destruction in our carbonaceous universe.
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Affiliation(s)
- Zhenghai Yang
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Galiya R. Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Chao He
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Shane J. Goettl
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Dababrata Paul
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Xiaohu Li
- Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China
- Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, HI 96822, USA
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12
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García-Abenza A, Lozano AI, Álvarez L, Oller JC, Rosado J, Blanco F, Limão-Vieira P, García G. Evaluated electron scattering cross section dataset for gaseous benzene in the energy range 0.1-1000 eV. Phys Chem Chem Phys 2023. [PMID: 37470102 DOI: 10.1039/d3cp01908j] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
In this study, a complete and self-consistent cross section dataset for electron transport simulations through gaseous benzene in the energy range 0.1-1000 eV has been critically compiled. Its reliability has been evaluated through a joint experimental and computational procedure. To accomplish this, the compiled dataset has been used as input for event-by-event Monte Carlo simulations of the magnetically confined electron transport through gaseous benzene, and the simulated transmitted intensity has been compared with the experimental one for different incident energies and benzene gas pressures.
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Affiliation(s)
- A García-Abenza
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
| | - A I Lozano
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - L Álvarez
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
| | - J C Oller
- Centro de Investigaciones Energéticas Mediambientales y Tecnológicas - CIEMAT, 28040 Madrid, Spain
| | - J Rosado
- Departamento de Estructura de la Materia, Física Térmica y Electrónica e IPARCOS, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - F Blanco
- Departamento de Estructura de la Materia, Física Térmica y Electrónica e IPARCOS, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - P Limão-Vieira
- Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - G García
- Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
- Centre for Medical Radiation Physics, University of Wollongong, NSW, Australia
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13
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Ru B, Sanov A. Photoelectron Spectra of Hot Polyatomic Ions: A Statistical Treatment of Phenide. J Phys Chem A 2022; 126:9423-9439. [DOI: 10.1021/acs.jpca.2c07361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Beverly Ru
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721, United States
| | - Andrei Sanov
- Department of Chemistry and Biochemistry, The University of Arizona, Tucson, Arizona85721, United States
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14
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Murakami T, Takayanagi T. Interstellar Benzene Formation Mechanisms via Acetylene Cyclotrimerization Catalyzed by Fe + Attached to Water Ice Clusters: Quantum Chemistry Calculation Study. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27227767. [PMID: 36431867 PMCID: PMC9693163 DOI: 10.3390/molecules27227767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/07/2022] [Accepted: 11/09/2022] [Indexed: 11/16/2022]
Abstract
Benzene is the simplest building block of polycyclic aromatic hydrocarbons and has previously been found in the interstellar medium. Several barrierless reaction mechanisms for interstellar benzene formation that may operate under low-temperature and low-pressure conditions in the gas phase have been proposed. In this work, we studied different mechanisms for interstellar benzene formation based on acetylene cyclotrimerization catalyzed by Fe+ bound to solid water clusters through quantum chemistry calculations. We found that benzene is formed via a single-step process with one transition state from the three acetylene molecules on the Fe+(H2O)n (n = 1, 8, 10, 12 and 18) cluster surface. Moreover, the obtained mechanisms differed from those of single-atom catalysis, in which benzene is sequentially formed via multiple steps.
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Affiliation(s)
- Tatsuhiro Murakami
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama 338-8570, Japan
- Department of Materials & Life Sciences, Faculty of Science & Technology, Sophia University, 7-1 Kioicho, Chiyoda-ku, Tokyo 102-8554, Japan
- Correspondence: (T.M.); (T.T.); Tel.: +81-48-858-9113 (T.M. & T.T.)
| | - Toshiyuki Takayanagi
- Department of Chemistry, Saitama University, Shimo-Okubo 255, Sakura-ku, Saitama 338-8570, Japan
- Correspondence: (T.M.); (T.T.); Tel.: +81-48-858-9113 (T.M. & T.T.)
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15
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Ismail I, Chantreau Majerus R, Habershon S. Graph-Driven Reaction Discovery: Progress, Challenges, and Future Opportunities. J Phys Chem A 2022; 126:7051-7069. [PMID: 36190262 PMCID: PMC9574932 DOI: 10.1021/acs.jpca.2c06408] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 09/22/2022] [Indexed: 11/29/2022]
Abstract
Graph-based descriptors, such as bond-order matrices and adjacency matrices, offer a simple and compact way of categorizing molecular structures; furthermore, such descriptors can be readily used to catalog chemical reactions (i.e., bond-making and -breaking). As such, a number of graph-based methodologies have been developed with the goal of automating the process of generating chemical reaction network models describing the possible mechanistic chemistry in a given set of reactant species. Here, we outline the evolution of these graph-based reaction discovery schemes, with particular emphasis on more recent methods incorporating graph-based methods with semiempirical and ab initio electronic structure calculations, minimum-energy path refinements, and transition state searches. Using representative examples from homogeneous catalysis and interstellar chemistry, we highlight how these schemes increasingly act as "virtual reaction vessels" for interrogating mechanistic questions. Finally, we highlight where challenges remain, including issues of chemical accuracy and calculation speeds, as well as the inherent challenge of dealing with the vast size of accessible chemical reaction space.
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Affiliation(s)
- Idil Ismail
- Department of Chemistry, University
of Warwick, CoventryCV4 7AL, United Kingdom
| | | | - Scott Habershon
- Department of Chemistry, University
of Warwick, CoventryCV4 7AL, United Kingdom
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16
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Galimova GR, Mebel AM, Goettl SJ, Yang Z, Kaiser RI. A crossed molecular beams and computational study on the unusual reactivity of banana bonds of cyclopropane (c-C 3H 6; ) through insertion by ground state carbon atoms (C( 3P j)). Phys Chem Chem Phys 2022; 24:22453-22463. [PMID: 36102937 DOI: 10.1039/d2cp03293g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism and chemical dynamics of the reaction of ground electronic state atomic carbon C(3Pj) with cyclopropane c-C3H6 have been explored by combining crossed molecular beams experiments with electronic structure calculations of the pertinent triplet C4H6 potential energy surface and statistical computations of product branching ratios under single-collision conditions. The experimental findings suggest that the reaction proceeds via indirect scattering dynamics through triplet C4H6 reaction intermediate(s) leading to C4H5 product(s) plus atomic hydrogen via a tight exit transition state, with the overall reaction exoergicity evaluated as 231 ± 52 kJ mol-1. The calculations indicate that C(3Pj) can easily insert into one of the three equivalent C-C 'banana' bonds of cyclopropane overcoming a low barrier of only 2 kJ mol-1 following the formation of a van der Waals reactant complex stabilized by 15 kJ mol-1. The carbon atom insertion into one of the six C-H bonds is also feasible via a slightly higher barrier of 5 kJ mol-1. These results highlight an unusual reactivity of cyclopropane's banana C-C bonds, which behave more like unsaturated C-C bonds with a π-character than saturated σ C-C bonds, which are known to be generally unreactive toward the ground electronic state atomic carbon such as in ethane (C2H6). The statistical theory predicts the overall product branching ratios at the experimental collision energy as 50% for 1-butyn-4-yl, 33% for 1,3-butadien-2-yl, i-C4H5, and 11% for 1,3-butadien-1-yl, n-C4H5, with i-C4H5 (230 kJ mol-1 below the reactants) favored by the C-C insertion providing the best match with the experimentally observed reaction exoergicity. The C(3Pj) + c-C3H6 reaction is predicted to be a source of C4H5 radicals under the conditions where its low entrance barriers can be overcome, such as in planetary atmospheres or in circumstellar envelopes but not in cold molecular clouds. Both i- and n-C4H5 can further react with acetylene eventually producing the first aromatic ring and hence, the reaction of the atomic carbon with c-C3H6 can be considered as an initial step toward the formation of benzene.
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Affiliation(s)
- Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Shane J Goettl
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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17
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Triple ionization and fragmentation of benzene trimers following ultrafast intermolecular Coulombic decay. Nat Commun 2022; 13:5335. [PMID: 36088449 PMCID: PMC9464219 DOI: 10.1038/s41467-022-33032-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 08/25/2022] [Indexed: 11/25/2022] Open
Abstract
Intermolecular interactions involving aromatic rings are ubiquitous in biochemistry and they govern the properties of many organic materials. Nevertheless, our understanding of the structures and dynamics of aromatic clusters remains incomplete, in particular for systems beyond the dimers, despite their high presence in many macromolecular systems such as DNA and proteins. Here, we study the fragmentation dynamics of benzene trimer that represents a prototype of higher-order aromatic clusters. The trimers are initially ionized by electron-collision with the creation of a deep-lying carbon 2s−1 state or one outer-valence and one inner-valence vacancies at two separate molecules. The system can thus relax via ultrafast intermolecular decay mechanisms, leading to the formation of C\documentclass[12pt]{minimal}
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\begin{document}$${}_{6}{{{{{{{{{\rm{H}}}}}}}}}_{6}}^{+}\cdot$$\end{document}6H6+⋅C\documentclass[12pt]{minimal}
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\begin{document}$${}_{6}{{{{{{{{{\rm{H}}}}}}}}}_{6}}^{+}$$\end{document}6H6+ trications and followed by a concerted three-body Coulomb explosion. Triple-coincidence ion momentum spectroscopy, accompanied by ab-initio calculations and further supported by strong-field laser experiments, allows us to elucidate the details on the fragmentation dynamics of benzene trimers. Higher-order aromatic clusters are prevalent in biochemical systems, but a full understanding of their structural and dynamical properties is lacking. Here, the authors demonstrate that inner-valence ionization can induce ultrafast relaxation and further fragmentation mechanisms in benzene trimers.
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18
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Kaiser RI, Zhao L, Lu W, Ahmed M, Evseev MM, Azyazov VN, Mebel AM, Mohamed RK, Fischer FR, Li X. Gas-phase synthesis of racemic helicenes and their potential role in the enantiomeric enrichment of sugars and amino acids in meteorites. Phys Chem Chem Phys 2022; 24:25077-25087. [PMID: 36056687 DOI: 10.1039/d2cp03084e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular origins of homochirality on Earth is not understood well, particularly how enantiomerically enriched molecules of astrobiological significance like sugars and amino acids might have been synthesized on icy grains in space preceding their delivery to Earth. Polycyclic aromatic hydrocarbons (PAHs) identified in carbonaceous chondrites could have been processed in molecular clouds by circularly polarized light prior to the depletion of enantiomerically enriched helicenes onto carbonaceous grains resulting in chiral islands. However, the fundamental low temperature reaction mechanisms leading to racemic helicenes are still unknown. Here, by exploiting synchrotron based molecular beam photoionization mass spectrometry combined with electronic structure calculations, we provide compelling testimony on barrierless, low temperature pathways leading to racemates of [5] and [6]helicene. Astrochemical modeling advocates that gas-phase reactions in molecular clouds lead to racemates of helicenes suggesting a pathway for future astronomical observation and providing a fundamental understanding for the origin of homochirality on early Earth.
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Affiliation(s)
- Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA.
| | - Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, Hawaii, 96822, USA.
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
| | | | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA.
| | - Rana K Mohamed
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Felix R Fischer
- Department of Chemistry, University of California, Berkeley, CA 94720, USA.,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Kavli Energy Nano Sciences Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Xiaohu Li
- Xinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China.,Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, Urumqi, Xinjiang 830011, P. R. China.
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19
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Graham HV, Elsila JE, Dworkin JP, Sandford SA, Aponte JC. Deuterium Isotope Fractionation of Polycyclic Aromatic Hydrocarbons in Meteorites as an Indicator of Interstellar/Protosolar Processing History. Life (Basel) 2022; 12:life12091368. [PMID: 36143402 PMCID: PMC9502081 DOI: 10.3390/life12091368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 08/01/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
The stable isotope composition of soluble and insoluble organic compounds in carbonaceous chondrites can be used to determine the provenance of organic molecules in space. Deuterium enrichment in meteoritic organics could be a residual signal of synthetic reactions occurring in the cold interstellar medium or an indicator of hydrothermal parent-body reactions. δD values have been measured in grains and bulk samples for a wide range of meteorites; however, these reservoirs are highly variable and may have experienced fractionation during thermal and/or aqueous alteration. Among the plethora of organic compounds in meteorites are polycyclic aromatic hydrocarbons (PAHs), which are stable and abundant in carbonaceous chondrites, and their δD ratio may preserve evidence about their formation environment as well as the influence of parent-body processes. This study tests hypotheses about the potential links between PAHs-deuteration concentrations and their formation conditions by examining the δD ratio of PAHs in three CM carbonaceous chondrites representing an aqueous alteration gradient. We use deuterium enrichments in soluble 2–5-ring PAHs as an indicator of either photon-driven deuteration due to unimolecular photodissociation in warm regions of space, gas-phase ion–molecule reactions in cold interstellar regions of space, or UV photolysis in ices. We also test hypothesized reaction pathways during parent-body processing that differ between partially and fully aromatized PAHs. New methodological approaches were developed to extract small, volatile PAHs without fractionation. Our results suggest that meteoritic PAHs could have formed through reactions in cold regions, with possible overprinting of deuterium enrichment during aqueous parent-body alteration, but the data could not rule out PAH alteration in icy mantles as well.
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Affiliation(s)
- Heather V. Graham
- Solar System Exploration Division, NASA Goddard Space Flight Center, MS-691, Greenbelt, MD 20771, USA
- Correspondence:
| | - Jamie E. Elsila
- Solar System Exploration Division, NASA Goddard Space Flight Center, MS-691, Greenbelt, MD 20771, USA
| | - Jason P. Dworkin
- Solar System Exploration Division, NASA Goddard Space Flight Center, MS-691, Greenbelt, MD 20771, USA
| | - Scott A. Sandford
- Space Science and Astrobiology Division, NASA Ames Research Center, MS 245-6, Moffett Field, CA 94035, USA
| | - Jose C. Aponte
- Solar System Exploration Division, NASA Goddard Space Flight Center, MS-691, Greenbelt, MD 20771, USA
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20
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Lepeshkin SV, Baturin VS, Naumova AS, Oganov AR. "Magic" Molecules and a New Look at Chemical Diversity of Hydrocarbons. J Phys Chem Lett 2022; 13:7600-7606. [PMID: 35950980 DOI: 10.1021/acs.jpclett.2c02098] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We address the question why among the multitude of imaginable CnHm compositions some are easily synthesizable and abundant in nature, while others are not. To shed light on this problem we borrow approaches from nanocluster study, where stability with respect to neighboring compositions is used as a criterion of "magic" (particularly stable) clusters. By merging this criterion with predictions of lowest-energy structures of all CnHm molecules in a wide range of compositions (n ≤ 20, m ≤ 42) we provide guidelines for predicting the presence or absence of certain hydrocarbon molecules in various environments, their relative abundance and reactivity/inertness. The resulting maps of stability show the increased stability of C2nH2 compounds, polyaromatic hydrocarbons, and diamondoids, which is supported by experimental studies of the interstellar medium, flames, and petroleum fractions. This approach can be applied to any other molecular system, rationalizing the diversity of known compounds and predicting new potentially synthesizable molecules.
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Affiliation(s)
- Sergey V Lepeshkin
- Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygina, 19, Moscow, 119991, Russia
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 121205, Russia
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Leninskii prosp. 53, Moscow, Russia
| | - Vladimir S Baturin
- Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Kosygina, 19, Moscow, 119991, Russia
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 121205, Russia
| | - Anastasia S Naumova
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 121205, Russia
- Lebedev Physical Institute, Russian Academy of Sciences, 119991 Leninskii prosp. 53, Moscow, Russia
| | - Artem R Oganov
- Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, Moscow 121205, Russia
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21
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He C, Thomas AM, Dangi BB, Yang T, Kaiser RI, Lee HC, Sun BJ, Chang AHH. Formation of the Elusive Silylenemethyl Radical (HCSiH 2; X 2B 2) via the Unimolecular Decomposition of Triplet Silaethylene (H 2CSiH 2; a 3A″). J Phys Chem A 2022; 126:3347-3357. [PMID: 35584043 DOI: 10.1021/acs.jpca.2c01853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated the formation of small organosilicon molecules─potential precursors to silicon-carbide dust grains ejected by dying carbon-rich asymptotic giant branch stars─in the gas phase via the reaction of atomic carbon (C) in its 3P electronic ground state with silane (SiH4; X1A1) using the crossed molecular beams technique. The reactants collided under single collision conditions at a collision energy of 13.0 ± 0.2 kJ mol-1, leading to the formation of the silylenemethyl radical (HCSiH2; X2B2) via the unimolecular decomposition of triplet silaethylene (H2CSiH2; a3A″). The silaethylene radical was formed via hydrogen migration of the triplet silylmethylene (HCSiH3; X3A″) radical, which in turn was identified as the initial collision complex accessed via the barrierless insertion of atomic carbon into the silicon-hydrogen bond of silane. Our results mark the first observation of the silylenemethyl radical, where previously only its thermodynamically more stable methylsilylidyne (CH3Si; X2A″) and methylenesilyl (CH2SiH; X2A') isomers were observed in low-temperature matrices. Considering the abundance of silane and the availability of atomic carbon in carbon-rich circumstellar environments, our results suggest that future astrochemical models should be updated to include contributions from small saturated organosilicon molecules as potential precursors to pure gaseous silicon-carbides and ultimately to silicon-carbide dust.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Beni B Dangi
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Tao Yang
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Huan-Cheng Lee
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
| | - Bing-Jian Sun
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
| | - Agnes H H Chang
- Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
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22
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Kumar S, Izadi F, Ončák M, Limão-Vieira P, Denifl S. Hexachlorobenzene-negative ion formation in electron attachment experiments. Phys Chem Chem Phys 2022; 24:13335-13342. [PMID: 35608112 DOI: 10.1039/d2cp01360f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In this contribution, we report a comprehensive study on the formation of hexachlorobenzene (C6Cl6) negative ions probed by low-energy electron interactions from 0 up to 12 eV in a gas-phase crossed beam experiment. The anionic yields as a function of the electron energy reveal a rich fragmentation pattern of the dissociative electron attachment process, yet the most intense ion has been assigned to the non-dissociated parent anion that survives long enough within the detection time window. Other less intense fragment anions have been assigned as Cl-, Cl2-, C6Cl4-, and C6Cl5-. The experimental results are accompanied by quantum chemical calculations at various levels of accuracy, providing an insight into the electronic structure, thermochemical thresholds, electron affinities and structures of neutral and anionic molecular species. The electron attachment process induces a considerable geometry change in the temporary-negative ion relative to the neutral molecule, where the most intense fragment anion assigned to Cl- can be formed solely through a curve crossing involving a π*/σ* coupling. The yield of chlorine anions shows a signature of vibrational excitation reminiscent of a Jahn-Teller distortion.
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Affiliation(s)
- S Kumar
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - F Izadi
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
| | - M Ončák
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
| | - P Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
| | - S Denifl
- Institute for Ion Physics and Applied Physics, University of Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
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23
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Meyer KS, Westerfield JH, Johansen SL, Keane J, Wannenmacher AC, Crabtree KN. Rotational and Vibrational Spectra of the Pyridyl Radicals: A Coupled-Cluster Study. J Phys Chem A 2022; 126:3185-3197. [PMID: 35549287 DOI: 10.1021/acs.jpca.2c01761] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Pyridyl is a prototypical nitrogen-containing aromatic radical that may be a key intermediate in the formation of nitrogen-containing aromatic molecules under astrophysical conditions. On meteorites, a variety of complex molecules with nitrogen-containing rings have been detected with nonterrestrial isotopic abundances, and larger nitrogen-containing polycyclic aromatic hydrocarbons (PANHs) have been proposed to be responsible for certain unidentified infrared emission bands in the interstellar medium. In this work, the three isomers of pyridyl (2-, 3-, and 4-pyridyl) have been investigated with coupled cluster methods. For each species, structures were optimized at the CCSD(T)/cc-pwCVTZ level of theory and force fields were calculated at the CCSD(T)/ANO0 level of theory. Second-order vibrational perturbation theory (VPT2) was used to derive anharmonic vibrational frequencies and vibrationally corrected rotational constants, and resonances among vibrational states below 3500 cm-1 were treated variationally with the VPT2+K method. The results yield a complete set of spectroscopic parameters needed to simulate the pure rotational spectrum of each isomer, including electron-spin, spin-spin, and nuclear hyperfine interactions, and the calculated hyperfine parameters agree well with the limited available data from electron paramagnetic resonance spectroscopy. For the handful of experimentally measured vibrational frequencies determined from photoelectron spectroscopy and matrix isolation spectroscopy, the typical agreement is comparable to experimental uncertainty. The predicted parameters for rotational spectroscopy reported here can guide new experimental investigations into the yet-unobserved rotational spectra of these radicals.
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Affiliation(s)
- Kelly S Meyer
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - John H Westerfield
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Sommer L Johansen
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Jasmine Keane
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Anna C Wannenmacher
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
| | - Kyle N Crabtree
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616, United States
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24
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Goettl SJ, He C, Paul D, Nikolayev AA, Azyazov VN, Mebel AM, Kaiser RI. Gas-Phase Study of the Elementary Reaction of the D1-Ethynyl Radical (C 2D; X 2Σ +) with Propylene (C 3H 6; X 1A') under Single-Collision Conditions. J Phys Chem A 2022; 126:1889-1898. [PMID: 35289624 DOI: 10.1021/acs.jpca.2c00297] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bimolecular gas-phase reactions of the D1-ethynyl radical (C2D; X2Σ+) with propylene (C3H6; X1A') and partially substituted D3-3,3,3-propylene (C2H3CD3; X1A') were studied under single collision conditions utilizing the crossed molecular beams technique. Combining our laboratory data with electronic structure and statistical calculations, the D1-ethynyl radical is found to add without barrier to the C1 and C2 carbons of the propylene reactant, resulting in doublet C5H6D intermediate(s) with lifetime(s) longer than their rotational period(s). These intermediates undergo isomerization and unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming predominantly cis/trans-3-penten-1-yne ((HCC)CH═CH(CH3)) and, to a minor amount, 3-methyl-3-buten-1-yne ((HCC)C(CH3)═CH2) via overall exoergic reactions. Although the title reaction does not lead to the cyclopentadiene molecule (c-C5H6, X1A1), high-temperature environments can convert the identified acyclic C5H6 isomers through hydrogen atom assisted isomerization to cyclopentadiene (c-C5H6, X1A1). Since both the ethynyl radical and propylene reactants have been observed in cold interstellar environments such as TMC-1 and the reaction is exoergic and all barriers lie below the energy of the separated reactants, these C5H6 product isomers are predicted to form in those low-temperature regions.
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Affiliation(s)
- Shane J Goettl
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Chao He
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Dababrata Paul
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
| | - Anatoliy A Nikolayev
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation.,Samara National Research University, Samara 443086, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Ma̅noa, Honolulu, Hawaii 96822, United States
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25
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Reizer E, Viskolcz B, Fiser B. Formation and growth mechanisms of polycyclic aromatic hydrocarbons: A mini-review. CHEMOSPHERE 2022; 291:132793. [PMID: 34762891 DOI: 10.1016/j.chemosphere.2021.132793] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/18/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are mostly formed during the incomplete combustion of organic materials, but their importance and presence in materials science, and astrochemistry has also been proven. These carcinogenic persistent organic pollutants are essential in the formation of combustion generated particles as well. Due to their significant impact on the environment and human health, to understand the formation and growth of PAHs is essential. Therefore, the most important growth mechanisms are reviewed, and presented here from the past four decades (1981-2021) to initiate discussions from a new perspective. Although, the collected and analyzed observations are derived from both experimental, and computational studies, it is neither a systematic nor a comprehensive review. Nevertheless, the mechanisms were divided into three main categories, acetylene additions (e.g. HACA), vinylacetylene additions (HAVA), and radical reactions, and discussed accordingly.
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Affiliation(s)
- Edina Reizer
- Institute of Chemistry, University of Miskolc, H-3515, Miskolc, Miskolc-Egyetemváros, Hungary; Higher Education and Industrial Cooperation Centre, University of Miskolc, H-3515, Miskolc-Egyetemváros, Hungary
| | - Béla Viskolcz
- Institute of Chemistry, University of Miskolc, H-3515, Miskolc, Miskolc-Egyetemváros, Hungary; Higher Education and Industrial Cooperation Centre, University of Miskolc, H-3515, Miskolc-Egyetemváros, Hungary
| | - Béla Fiser
- Institute of Chemistry, University of Miskolc, H-3515, Miskolc, Miskolc-Egyetemváros, Hungary; Higher Education and Industrial Cooperation Centre, University of Miskolc, H-3515, Miskolc-Egyetemváros, Hungary; Ferenc Rákóczi II. Transcarpathian Hungarian College of Higher Education, UA, 90200, Beregszász, Transcarpathia, Ukraine.
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26
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Lukianova MA, Feldman VI. Radiation-induced closure of the second aromatic ring: Possible way to PAH starting from a styrene-acetylene complex. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2021.109847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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27
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Ideböhn V, Sterling AJ, Wallner M, Olsson E, Squibb RJ, Miniotaite U, Forsmalm E, Forsmalm M, Stranges S, Dyke JM, Duarte F, Eland JHD, Feifel R. Single photon double and triple ionization of allene. Phys Chem Chem Phys 2022; 24:786-796. [PMID: 34927639 DOI: 10.1039/d1cp04666g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Double and triple ionization of allene are investigated using electron-electron, ion-ion, electron-electron-ion and electron-electron-ion-ion (ee, ii, eei, eeii) coincidence spectroscopies at selected photon energies. The results provide supporting evidence for a previously proposed roaming mechanism in H3+ formation by double ionization. The lowest vertical double ionization energy is found to be 27.9 eV, while adiabatic double ionization is not accessed by vertical ionization at the neutral geometry. The triple ionization energy is found to be close to 50 eV in agreement with theoretical predictions. The doubly charged parent ion is stable up to about 2 eV above the threshold, after which dissociations by charge separation and by double charge retention occur with comparable intensities. Fragmentation to H+ + C3H3+ starts immediately above the threshold as a slow (metastable) decay with 130.5 ± 9.9 ns mean lifetime.
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Affiliation(s)
- Veronica Ideböhn
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Alistair J Sterling
- Department of Chemistry, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - Måns Wallner
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Emelie Olsson
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Richard J Squibb
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Ugne Miniotaite
- Department of Physics, Chalmers University of Technology, Kemigården 1, 412 96 Gothenburg, Sweden
| | - Emma Forsmalm
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Malin Forsmalm
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
| | - Stefano Stranges
- IOM-CNR Tasc, SS-14, Km 163.5 Area Science Park, Basovizza 34149, Trieste, Italy.,Dipartimento di Chimica e Tecnologie del Farmaco, Universitá Sapienza, Rome I-00185, Italy
| | - John M Dyke
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
| | - Fernanda Duarte
- Department of Chemistry, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | - John H D Eland
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK
| | - Raimund Feifel
- Department of Physics, University of Gothenburg, Origovägen 6B, 412 58 Gothenburg, Sweden.
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28
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Watson PD, Corkish TR, Haakansson CT, McKinley AJ, Wild DA. Halide–propene complexes: validated DSD-PBEP86-D3BJ calculations and photoelectron spectroscopy. Phys Chem Chem Phys 2022; 24:25842-25852. [DOI: 10.1039/d2cp03796c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Anion photoelectron spectroscopy has been used to determine the electron binding energies of the X−⋯C3H6 (X = Cl, Br, I) complexes.
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Affiliation(s)
- Peter D. Watson
- School of Molecular Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK
| | - Timothy R. Corkish
- School of Molecular Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
| | - Christian T. Haakansson
- School of Molecular Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
| | - Allan J. McKinley
- School of Molecular Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
| | - Duncan A. Wild
- School of Molecular Sciences, The University of Western Australia, Crawley, 6009, Western Australia, Australia
- School of Science, Edith Cowan University, Joondalup, 6027, Western Australia, Australia
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29
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He C, Yang Z, Doddipatla S, Thomas AM, Kaiser RI, Galimova GR, Mebel AM, Fujioka K, Sun R. Directed gas phase preparation of ethynylallene (H 2CCCHCCH; X 1A′) via the crossed molecular beam reaction of the methylidyne radical (CH; X 2Π) with vinylacetylene (H 2CCHCCH; X 1A′). Phys Chem Chem Phys 2022; 24:26499-26510. [DOI: 10.1039/d2cp04081f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The elementary reaction of the methylidyne radical with vinylacetylene leading to the predominant formation of ethynylallene and atomic hydrogen via indirect scattering dynamics.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Aaron M. Thomas
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Galiya R. Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Kazuumi Fujioka
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
| | - Rui Sun
- Department of Chemistry, University of Hawai‘i at Mānoa, Honolulu, HI 96822, USA
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30
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Caster KL, Selby TM, Osborn DL, Le Picard SD, Goulay F. Product Detection of the CH(X 2Π) Radical Reaction with Cyclopentadiene: A Novel Route to Benzene. J Phys Chem A 2021; 125:6927-6939. [PMID: 34374546 DOI: 10.1021/acs.jpca.1c03517] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of the methylidyne radical (CH(X2Π)) with cyclopentadiene (c-C5H6) is studied in the gas phase at 4 Torr and 373 K using a multiplexed photoionization mass spectrometer. Under multiple collision conditions, the dominant product channel observed is the formation of C6H6 + H. Fitting the photoionization spectrum using reference spectra allows for isomeric resolution of C6H6 isomers, where benzene is the largest contributor with a relative branching fraction of 90 (±5)%. Several other C6H6 isomers are found to have smaller contributions, including fulvene with a branching fraction of 8 (±5)%. Master Equation calculations for four different entrance channels on the C6H7 potential energy surface are performed to explore the competition between CH cycloaddition to a C═C bond vs CH insertion into C-H bonds of cyclopentadiene. Previous studies on CH addition to unsaturated hydrocarbons show little evidence for the C-H insertion pathway. The present computed branching fractions support benzene as the sole cyclic product from CH cycloaddition, whereas fulvene is the dominant product from two of the three pathways for CH insertion into the C-H bonds of cyclopentadiene. The combination of experiment with Master Equation calculations implies that insertion must account for ∼10 (±5)% of the overall CH + cyclopentadiene mechanism.
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Affiliation(s)
- Kacee L Caster
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Talitha M Selby
- Department of Mathematics and Natural Sciences, University of Wisconsin-Milwaukee, West Bend, Wisconsin 53095, United States
| | - David L Osborn
- Combustion Research Facility, Sandia National Laboratories, Mail Stop 9055, Livermore, California 94551, United States
| | - Sebastien D Le Picard
- IPR (Institut de Physique de Rennes), UMR 6251, Univ Rennes, CNRS, F-35000 Rennes, France
| | - Fabien Goulay
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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31
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The Effect of Cluster Size on the Intra-Cluster Ionic Polymerization Process. Molecules 2021; 26:molecules26164782. [PMID: 34443370 PMCID: PMC8399435 DOI: 10.3390/molecules26164782] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 11/17/2022] Open
Abstract
Polyaromatic hydrocarbons (PAHs) are widespread in the interstellar medium (ISM). The abundance and relevance of PAHs call for a clear understanding of their formation mechanisms, which, to date, have not been completely deciphered. Of particular interest is the formation of benzene, the basic building block of PAHs. It has been shown that the ionization of neutral clusters can lead to an intra-cluster ionic polymerization process that results in molecular growth. Ab-initio molecular dynamics (AIMD) studies in clusters consisting of 3-6 units of acetylene modeling ionization events under ISM conditions have shown maximum aggregation of three acetylene molecules forming bonded C6H6+ species; the larger the number of acetylene molecules, the higher the production of C6H6+. These results lead to the question of whether clusters larger than those studied thus far promote aggregation beyond three acetylene units and whether larger clusters can result in higher C6H6+ production. In this study, we report results from AIMD simulations modeling the ionization of 10 and 20 acetylene clusters. The simulations show aggregation of up to four acetylene units producing bonded C8H8+. Interestingly, C8H8+ bicyclic species were identified, setting a precedent for their astrochemical identification. Comparable reactivity rates were shown with 10 and 20 acetylene clusters.
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32
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Cernicharo J, Agúndez M, Cabezas C, Tercero B, Marcelino N, Pardo JR, de Vicente P. Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene and indene. ASTRONOMY AND ASTROPHYSICS 2021; 649:L15. [PMID: 34257463 PMCID: PMC7611194 DOI: 10.1051/0004-6361/202141156] [Citation(s) in RCA: 66] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the detection for the first time in space of three new pure hydrocarbon cycles in TMC-1: c-C3HCCH (ethynyl cyclopropenylidene), c-C5H6 (cyclopentadiene) and c-C9H8 (indene). We derive a column density of 3.1 × 1011 cm-2 for the former cycle and similar values, in the range (1-2) × 1013 cm-2, for the two latter molecules. This means that cyclopentadiene and indene, in spite of their large size, are exceptionally abundant, only a factor of five less abundant than the ubiquitous cyclic hydrocarbon c-C3H2. The high abundance found for these two hydrocarbon cycles, together with the high abundance previously found for the propargyl radical (CH2CCH) and other hydrocarbons like vinyl and allenyl acetylene (Agúndez et al. 2021; Cernicharo et al. 2021a,b), start to allow us to quantify the abundant content of hydrocarbon rings in cold dark clouds and to identify the intermediate species that are probably behind the in situ bottom-up synthesis of aromatic cycles in these environments. While c-C3HCCH is most likely formed through the reaction between the radical CCH and c-C3H2, the high observed abundances of cyclopentadiene and indene are difficult to explain through currently proposed chemical mechanisms. Further studies are needed to identify how are five- and six-membered rings formed under the cold conditions of clouds like TMC-1.
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Affiliation(s)
- J. Cernicharo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/Serrano 121, 28006 Madrid, Spain
| | - M. Agúndez
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/Serrano 121, 28006 Madrid, Spain
| | - C. Cabezas
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/Serrano 121, 28006 Madrid, Spain
| | - B. Tercero
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
- Observatorio Astronómico Nacional (OAN, IGN), Madrid, Spain
| | - N. Marcelino
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/Serrano 121, 28006 Madrid, Spain
| | - J. R. Pardo
- Grupo de Astrofísica Molecular, Instituto de Física Fundamental (IFF-CSIC), C/Serrano 121, 28006 Madrid, Spain
| | - P. de Vicente
- Centro de Desarrollos Tecnológicos, Observatorio de Yebes (IGN), 19141 Yebes, Guadalajara, Spain
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33
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Zhao L, Lu W, Ahmed M, Zagidullin MV, Azyazov VN, Morozov AN, Mebel AM, Kaiser RI. Gas-phase synthesis of benzene via the propargyl radical self-reaction. SCIENCE ADVANCES 2021; 7:7/21/eabf0360. [PMID: 34020951 PMCID: PMC8139581 DOI: 10.1126/sciadv.abf0360] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 03/31/2021] [Indexed: 06/01/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) have been invoked in fundamental molecular mass growth processes in our galaxy. We provide compelling evidence of the formation of the very first ringed aromatic and building block of PAHs-benzene-via the self-recombination of two resonantly stabilized propargyl (C3H3) radicals in dilute environments using isomer-selective synchrotron-based mass spectrometry coupled to theoretical calculations. Along with benzene, three other structural isomers (1,5-hexadiyne, fulvene, and 2-ethynyl-1,3-butadiene) and o-benzyne are detected, and their branching ratios are quantified experimentally and verified with the aid of computational fluid dynamics and kinetic simulations. These results uncover molecular growth pathways not only in interstellar, circumstellar, and solar systems environments but also in combustion systems, which help us gain a better understanding of the hydrocarbon chemistry of our universe.
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Affiliation(s)
- Long Zhao
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA
| | - Wenchao Lu
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | | | - Valeriy N Azyazov
- Lebedev Physical Institute, Samara 443011, Russian Federation
- Samara National Research University, Samara 443086, Russian Federation
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
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34
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McGuire BA, Loomis RA, Burkhardt AM, Lee KLK, Shingledecker CN, Charnley SB, Cooke IR, Cordiner MA, Herbst E, Kalenskii S, Siebert MA, Willis ER, Xue C, Remijan AJ, McCarthy MC. Detection of two interstellar polycyclic aromatic hydrocarbons via spectral matched filtering. Science 2021; 371:1265-1269. [PMID: 33737489 DOI: 10.1126/science.abb7535] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Accepted: 02/04/2021] [Indexed: 11/02/2022]
Abstract
Unidentified infrared emission bands are ubiquitous in many astronomical sources. These bands are widely, if not unanimously, attributed to collective emissions from polycyclic aromatic hydrocarbon (PAH) molecules, yet no single species of this class has been identified in space. Using spectral matched filtering of radio data from the Green Bank Telescope, we detected two nitrile-group-functionalized PAHs, 1- and 2-cyanonaphthalene, in the interstellar medium. Both bicyclic ring molecules were observed in the TMC-1 molecular cloud. In this paper, we discuss potential in situ gas-phase PAH formation pathways from smaller organic precursor molecules.
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Affiliation(s)
- Brett A McGuire
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,National Radio Astronomy Observatory, Charlottesville, VA 22903, USA.,Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA 02138, USA
| | - Ryan A Loomis
- National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
| | - Andrew M Burkhardt
- Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA 02138, USA
| | - Kin Long Kelvin Lee
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA 02138, USA
| | - Christopher N Shingledecker
- Department of Physics and Astronomy, Benedictine College, Atchison, KS 66002, USA.,Center for Astrochemical Studies, Max Planck Institute for Extraterrestrial Physics, Garching, Germany.,Institute for Theoretical Chemistry, University of Stuttgart, Stuttgart, Germany
| | - Steven B Charnley
- Astrochemistry Laboratory and the Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - Ilsa R Cooke
- Université de Rennes, Centre National de la Recherche Scientifique, Institut de Physique de Rennes, Unité Mixte de Recherche 6251, F-35000 Rennes, France
| | - Martin A Cordiner
- Astrochemistry Laboratory and the Goddard Center for Astrobiology, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.,Institute for Astrophysics and Computational Sciences, Department of Physics, Catholic University of America, Washington, DC 20064, USA
| | - Eric Herbst
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA.,Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
| | - Sergei Kalenskii
- Astro Space Center, Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia
| | - Mark A Siebert
- Department of Astronomy, University of Virginia, Charlottesville, VA 22904, USA
| | - Eric R Willis
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Ci Xue
- Department of Chemistry, University of Virginia, Charlottesville, VA 22904, USA
| | - Anthony J Remijan
- National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
| | - Michael C McCarthy
- Center for Astrophysics, Harvard & Smithsonian, Cambridge, MA 02138, USA
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35
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McCarthy MC, McGuire BA. Aromatics and Cyclic Molecules in Molecular Clouds: A New Dimension of Interstellar Organic Chemistry. J Phys Chem A 2021; 125:3231-3243. [DOI: 10.1021/acs.jpca.1c00129] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Michael C. McCarthy
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
| | - Brett A. McGuire
- Center for Astrophysics
- Harvard & Smithsonian, 60 Garden Street, Cambridge Massachusetts 02138, United States
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
- National Radio Astronomy Observatory, Charlottesville, Virginia 22903, United States
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36
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Robertson C, Hyland R, Lacey AJD, Havens S, Habershon S. Identifying Barrierless Mechanisms for Benzene Formation in the Interstellar Medium Using Permutationally Invariant Reaction Discovery. J Chem Theory Comput 2021; 17:2307-2322. [DOI: 10.1021/acs.jctc.1c00046] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Ross Hyland
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Andrew J. D. Lacey
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Sebastian Havens
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Scott Habershon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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37
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Izadi ME, Bal KM, Maghari A, Neyts EC. Reaction mechanisms of C( 3P J) and C +( 2P J) with benzene in the interstellar medium from quantum mechanical molecular dynamics simulations. Phys Chem Chem Phys 2021; 23:4205-4216. [PMID: 33586718 DOI: 10.1039/d0cp04542j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
While spectroscopic data on small hydrocarbons in interstellar media in combination with crossed molecular beam (CMB) experiments have provided a wealth of information on astrochemically relevant species, much of the underlying mechanistic pathways of their formation remain elusive. Therefore, in this work, the chemical reaction mechanisms of C(3PJ) + C6H6 and C+(2P) + C6H6 systems using the quantum mechanical molecular dynamics (QMMD) technique at the PBE0-D3(BJ) level of theory is investigated, mimicking a CMB experiment. Both the dynamics of the reactions as well as the electronic structure for the purpose of the reaction network are evaluated. The method is validated for the first reaction by comparison to the available experimental data. The reaction scheme for the C(3PJ) + C6H6 system covers the literature data, e.g. the major products are the 1,2-didehydrocycloheptatrienyl radical (C7H5) and benzocyclopropenyl radical (C6H5-CH), and it reveals the existence of less common pathways for the first time. The chemistry of the C+(2PJ) + C6H6 system is found to be much richer, and we have found that this is because of more exothermic reactions in this system in comparison to those in the C(3PJ) + C6H6 system. Moreover, using the QMMD simulation, a number of reaction paths have been revealed that produce three distinct classes of reaction products with different ring sizes. All in all, at all the collision energies and orientations, the major product is the heptagon molecular ion for the ionic system. It is also revealed that the collision orientation has a dominant effect on the reaction products in both systems, while the collision energy mostly affects the charged system. These simulations both prove the applicability of this approach to simulate crossed molecular beams, and provide fundamental information on reactions relevant for the interstellar medium.
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Affiliation(s)
- Mohammad Ebrahim Izadi
- Department of Physical Chemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran
| | - Kristof M Bal
- Department of Chemistry, Research Group PLASMANT, NANOlab Center of Excellence, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
| | - Ali Maghari
- Department of Physical Chemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran
| | - Erik C Neyts
- Department of Chemistry, Research Group PLASMANT, NANOlab Center of Excellence, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
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38
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He C, Nikolayev AA, Zhao L, Thomas AM, Doddipatla S, Galimova GR, Azyazov VN, Mebel AM, Kaiser RI. Gas-Phase Formation of C 5H 6 Isomers via the Crossed Molecular Beam Reaction of the Methylidyne Radical (CH; X 2Π) with 1,2-Butadiene (CH 3CHCCH 2; X 1A'). J Phys Chem A 2021; 125:126-138. [PMID: 33397109 DOI: 10.1021/acs.jpca.0c08731] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The bimolecular gas-phase reaction of the methylidyne radical (CH; X2Π) with 1,2-butadiene (CH2CCHCH3; X1A') was investigated at a collision energy of 20.6 kJ mol-1 under single collision conditions. Combining our laboratory data with high-level electronic structure calculations, we reveal that this bimolecular reaction proceeds through the barrierless addition of the methylidyne radical to the carbon-carbon double bonds of 1,2-butadiene leading to doublet C5H7 intermediates. These collision adducts undergo a nonstatistical unimolecular decomposition through atomic hydrogen elimination to at least the cyclic 1-vinyl-cyclopropene (p5/p26), 1-methyl-3-methylenecyclopropene (p28), and 1,2-bis(methylene)cyclopropane (p29) in overall exoergic reactions. The barrierless nature of this bimolecular reaction suggests that these cyclic C5H6 isomers might be viable targets to be searched for in cold molecular clouds like TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | | | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
| | - Galiya R Galimova
- Samara National Research University, Samara 443086, Russian Federation.,Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Valeriy N Azyazov
- Samara National Research University, Samara 443086, Russian Federation.,Lebedev Physical Institute, Samara 443011, Russian Federation
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, United States
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39
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Doddipatla S, Galimova GR, Wei H, Thomas AM, He C, Yang Z, Morozov AN, Shingledecker CN, Mebel AM, Kaiser RI. Low-temperature gas-phase formation of indene in the interstellar medium. SCIENCE ADVANCES 2021; 7:7/1/eabd4044. [PMID: 33523847 PMCID: PMC7775774 DOI: 10.1126/sciadv.abd4044] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 11/04/2020] [Indexed: 06/07/2023]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are fundamental molecular building blocks of fullerenes and carbonaceous nanostructures in the interstellar medium and in combustion systems. However, an understanding of the formation of aromatic molecules carrying five-membered rings-the essential building block of nonplanar PAHs-is still in its infancy. Exploiting crossed molecular beam experiments augmented by electronic structure calculations and astrochemical modeling, we reveal an unusual pathway leading to the formation of indene (C9H8)-the prototype aromatic molecule with a five-membered ring-via a barrierless bimolecular reaction involving the simplest organic radical-methylidyne (CH)-and styrene (C6H5C2H3) through the hitherto elusive methylidyne addition-cyclization-aromatization (MACA) mechanism. Through extensive structural reorganization of the carbon backbone, the incorporation of a five-membered ring may eventually lead to three-dimensional PAHs such as corannulene (C20H10) along with fullerenes (C60, C70), thus offering a new concept on the low-temperature chemistry of carbon in our galaxy.
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Affiliation(s)
- Srinivas Doddipatla
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
- Samara National Research University, Samara 443086, Russia
| | - Hongji Wei
- Department of Physics and Astronomy, Benedictine College, Atchison, KS 66002, USA
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Chao He
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Zhenghai Yang
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA
| | - Alexander N Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA
| | | | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL, 33199, USA.
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Mānoa, Honolulu, HI 96822, USA.
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40
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Early Science from GOTHAM: Project Overview, Methods, and the Detection of Interstellar Propargyl Cyanide (HCCCH2CN) in TMC-1. ACTA ACUST UNITED AC 2020. [DOI: 10.3847/2041-8213/aba632] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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41
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Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C6H6. ACTA ACUST UNITED AC 2020. [DOI: 10.3847/2041-8213/ab7a9c] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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42
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He C, Thomas AM, Galimova GR, Mebel AM, Kaiser RI. Gas-Phase Formation of 1-Methylcyclopropene and 3-Methylcyclopropene via the Reaction of the Methylidyne Radical (CH; X 2Π) with Propylene (CH 3CHCH 2; X 1A'). J Phys Chem A 2019; 123:10543-10555. [PMID: 31718184 DOI: 10.1021/acs.jpca.9b09815] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed molecular beam reactions of the methylidyne radical (CH; X2Π) with propylene (CH3CHCH2; X1A') along with (partially) substituted reactants were conducted at collision energies of 19.3 kJ mol-1. Combining our experimental data with ab initio electronic structure and statistical calculations, the methylidyne radical is revealed to add barrierlessly to the carbon-carbon double bond of propylene reactant resulting in a cyclic doublet C4H7 intermediate with a lifetime longer than its rotation period. These adducts undergo a nonstatistical unimolecular decomposition via atomic hydrogen loss through tight exit transition states forming the cyclic products 1-methylcyclopropene and 3-methylcyclopropene with overall reaction exoergicities of 168 ± 25 kJ mol-1. These C4H6 isomers are predicted to exist even in low-temperature environments such as cold molecular clouds like TMC-1, since the reaction is barrierless and exoergic, all transition states are below the energy of the separated reactants, and both the methylidyne radical (CH; X2Π) and propylene reactant were detected in cold molecular clouds such as TMC-1.
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Affiliation(s)
- Chao He
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Aaron M Thomas
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States.,Samara National Research University , Samara 443086 , Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
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43
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A Barrierless Pathway Accessing the C 9H 9 and C 9H 8 Potential Energy Surfaces via the Elementary Reaction of Benzene with 1-Propynyl. Sci Rep 2019; 9:17595. [PMID: 31772216 PMCID: PMC6879741 DOI: 10.1038/s41598-019-53987-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/07/2019] [Indexed: 11/16/2022] Open
Abstract
The crossed molecular beams reactions of the 1-propynyl radical (CH3CC; X2A1) with benzene (C6H6; X1A1g) and D6-benzene (C6D6; X1A1g) were conducted to explore the formation of C9H8 isomers under single-collision conditions. The underlying reaction mechanisms were unravelled through the combination of the experimental data with electronic structure and statistical RRKM calculations. These data suggest the formation of 1-phenyl-1-propyne (C6H5CCCH3) via the barrierless addition of 1-propynyl to benzene forming a low-lying doublet C9H9 intermediate that dissociates by hydrogen atom emission via a tight transition state. In accordance with our experiments, RRKM calculations predict that the thermodynamically most stable isomer – the polycyclic aromatic hydrocarbon (PAH) indene – is not formed via this reaction. With all barriers lying below the energy of the reactants, this reaction is viable in the cold interstellar medium where several methyl-substituted molecules have been detected. Its underlying mechanism therefore advances our understanding of how methyl-substituted hydrocarbons can be formed under extreme conditions such as those found in the molecular cloud TMC-1. Implications for the chemistry of the 1-propynyl radical in astrophysical environments are also discussed.
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44
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He C, Zhao L, Thomas AM, Galimova GR, Mebel AM, Kaiser RI. A combined experimental and computational study on the reaction dynamics of the 1-propynyl radical (CH 3CC; X 2A 1) with ethylene (H 2CCH 2; X 1A 1g) and the formation of 1-penten-3-yne (CH 2CHCCCH 3; X 1A'). Phys Chem Chem Phys 2019; 21:22308-22319. [PMID: 31576858 DOI: 10.1039/c9cp04073k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The crossed molecular beam reactions of the 1-propynyl radical (CH3CC; X2A1) with ethylene (H2CCH2; X1A1g) and ethylene-d4 (D2CCD2; X1A1g) were performed at collision energies of 31 kJ mol-1 under single collision conditions. Combining our laboratory data with ab initio electronic structure and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations, we reveal that the reaction is initiated by the barrierless addition of the 1-propynyl radical to the π-electron density of the unsaturated hydrocarbon of ethylene leading to a doublet C5H7 intermediate(s) with a life time(s) longer than the rotation period(s). The reaction eventually produces 1-penten-3-yne (p1) plus a hydrogen atom with an overall reaction exoergicity of 111 ± 16 kJ mol-1. About 35% of p1 originates from the initial collision complex followed by C-H bond rupture via a tight exit transition state located 22 kJ mol-1 above the separated products. The collision complex (i1) can also undergo a [1,2] hydrogen atom shift to the CH3CHCCCH3 intermediate (i2) prior to a hydrogen atom release; RRKM calculations suggest that this pathway contributes to about 65% of p1. In higher density environments such as in combustion flames and circumstellar envelopes of carbon stars close to the central star, 1-penten-3-yne (p1) may eventually form the cyclopentadiene (c-C5H6) isomer via hydrogen atom assisted isomerization followed by hydrogen abstraction to the cyclopentadienyl radical (c-C5H5) as an important pathway to key precursors to polycyclic aromatic hydrocarbons (PAHs) and to carbonaceous nanoparticles.
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Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Long Zhao
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Aaron M Thomas
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA. and Samara National Research University, Samara 443086, Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA. and Samara National Research University, Samara 443086, Russia
| | - Ralf I Kaiser
- Department of Chemistry, University of Hawai'i at Manoa, Honolulu, Hawaii 96822, USA.
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45
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Ooi BG, Dutta D, Kazipeta K, Chong NS. Influence of the E-Cigarette Emission Profile by the Ratio of Glycerol to Propylene Glycol in E-Liquid Composition. ACS OMEGA 2019; 4:13338-13348. [PMID: 31460462 PMCID: PMC6705204 DOI: 10.1021/acsomega.9b01504] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 07/22/2019] [Indexed: 05/19/2023]
Abstract
The use of electronic cigarettes (E-cig) is popular because of the perception that they are less addictive and safer compared to the traditional cigarettes. Nevertheless, there are still harmful effects associated with chemicals emitted from E-cig. Identifying the sources of the emitted compounds can be challenging because of the differences in the design of E-cig devices and the variability in the composition of E-cig liquids used in these devices. In this study, the emission profiles from impurity-free E-liquids containing only propylene glycol and glycerol in various percentage ratios along with two commercially available E-liquids were evaluated using gas chromatography-mass spectrometry (GC-MS). This study approach allows the elucidation of the transformation pathways of the major emitted compounds without the confounding effects of existing impurities or flavor ingredients added to E-liquids. Analysis of the vapor phases of E-cig emissions detected toxicants such as acetaldehyde, acrolein, benzaldehyde, as well as benzene, toluene, ethylbenzene, and xylene (BTEX) compounds. The amount of glycerol in the E-liquids has a major effect on the concentration of these hazardous compounds emitted because the concentration of these chemicals increased with increasing glycerol percentage in the E-liquid. Acetaldehyde and acrolein increased by 175-fold and 28-fold, respectively, when the glycerol composition was increased from 0 to 80%. Benzaldehyde, naphthalene, diphenyl ether, and glycerol along with menthol and nicotine that were present in the commercial E-liquids were also detected in the aerosol condensates. The cascade impactor data on the distribution of the nicotine and menthol in different size fractions from >2.5 to <2.5 μm allow the estimates of the extent of toxicant deposition in different parts of the pulmonary system including the oropharynx region, the trachea as well as inside the alveoli and bronchioles. In summary, users of E-cig are exposed to harmful chemicals even if the E-liquids contain only propylene glycol and glycerol without flavorings, nicotine, or impurities. Furthermore, this study shows that E-liquids containing higher percentages of glycerol will produce higher levels of toxicants compared to E-liquids with similar percentages of propylene glycol. This finding has important implications to E-cigarette vendors and manufacturers, consumers, and regulatory agencies.
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Affiliation(s)
- Beng G. Ooi
- Department
of Chemistry, Middle Tennessee State University, P.O. Box 68, Murfreesboro, Tennessee 37132, United States
| | - Dibyendu Dutta
- Department
of Professional Science, Middle Tennessee
State University, P.O. Box 83, Murfreesboro, Tennessee 37132, United States
| | - Kavya Kazipeta
- Department
of Chemistry, Middle Tennessee State University, P.O. Box 68, Murfreesboro, Tennessee 37132, United States
| | - Ngee S. Chong
- Department
of Chemistry, Middle Tennessee State University, P.O. Box 68, Murfreesboro, Tennessee 37132, United States
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46
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Zdanovskaia MA, Esselman BJ, Woods RC, McMahon RJ. The 130-370 GHz rotational spectrum of phenyl isocyanide (C 6H 5NC). J Chem Phys 2019; 151:024301. [PMID: 31301709 DOI: 10.1063/1.5100805] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The analysis of phenyl isocyanide (C6H5NC, μa = 4.0 D) in its ground vibrational state and two lowest-energy excited vibrational states, ν22 (141 cm-1) and ν33 (155 cm-1), in the 130-370 GHz frequency region has been completed. Over 4500 new rotational transitions have been measured in the ground vibrational state for the most abundant isotopologue, resulting in the determination of the spectroscopic constants for a partial octic Hamiltonian with low error. The Coriolis-coupled ν22-ν33 dyad reported herein, containing over 3500 new transitions for each vibrational state, has been analyzed for the first time. The coupled-state least-squares fit utilizes seven coupling terms (Ga, Ga J, Ga K, Ga JJ, Ga JK, Fbc, and Fbc K) to address perturbation between the two vibrational states, including resonances and several nominal interstate transitions. This work results in precise determination of the energy separation between the two states, ΔE22,33 = 9.682 248(3) cm-1, and the Coriolis coupling coefficient, |ζ22,33 a| = 0.858(9). The precise rotational and distortion constants determined in this work provide the foundation for an astronomical search for phenyl isocyanide across the radio band.
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Affiliation(s)
- Maria A Zdanovskaia
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Brian J Esselman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - R Claude Woods
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Robert J McMahon
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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47
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Caster KL, Donnellan ZN, Selby TM, Goulay F. Kinetic Investigations of the CH (X2Π) Radical Reaction with Cyclopentadiene. J Phys Chem A 2019; 123:5692-5703. [PMID: 31194547 DOI: 10.1021/acs.jpca.9b03813] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kacee L. Caster
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Zachery N. Donnellan
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
| | - Talitha M. Selby
- Department of Mathematics and Natural Sciences, University of Wisconsin—Milwaukee, West Bend, Wisconsin 53095, United States
| | - F. Goulay
- C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506, United States
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48
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He C, Zhao L, Thomas AM, Morozov AN, Mebel AM, Kaiser RI. Elucidating the Chemical Dynamics of the Elementary Reactions of the 1-Propynyl Radical (CH3CC; X2A1) with Methylacetylene (H3CCCH; X1A1) and Allene (H2CCCH2; X1A1). J Phys Chem A 2019; 123:5446-5462. [DOI: 10.1021/acs.jpca.9b03746] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Chao He
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Long Zhao
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Aaron M. Thomas
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
| | - Alexander N. Morozov
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Alexander M. Mebel
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Ralf I. Kaiser
- Department of Chemistry, University of Hawai’i at Manoa, Honolulu, Hawaii 96822, United States
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49
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Thomas AM, He C, Zhao L, Galimova GR, Mebel AM, Kaiser RI. Combined Experimental and Computational Study on the Reaction Dynamics of the 1-Propynyl (CH 3CC)-1,3-Butadiene (CH 2CHCHCH 2) System and the Formation of Toluene under Single Collision Conditions. J Phys Chem A 2019; 123:4104-4118. [PMID: 31017790 DOI: 10.1021/acs.jpca.9b00092] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The crossed beams reactions of the 1-propynyl radical (CH3CC; X2A1) with 1,3-butadiene (CH2CHCHCH2; X1Ag), 1,3-butadiene- d6 (CD2CDCDCD2; X1Ag), 1,3-butadiene- d4 (CD2CHCHCD2; X1Ag), and 1,3-butadiene- d2 (CH2CDCDCH2; X1Ag) were performed under single collision conditions at collision energies of about 40 kJ mol-1. The underlying reaction mechanisms were unraveled through the combination of the experimental data with electronic structure calculations at the CCSD(T)-F12/cc-pVTZ-f12//B3LYP/6-311G(d,p) + ZPE(B3LYP/6-311G(d,p) level of theory along with statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. Together, these data suggest the formation of the thermodynamically most stable C7H8 isomer-toluene (C6H5CH3)-via the barrierless addition of 1-propynyl to the 1,3-butadiene terminal carbon atom, forming a low-lying C7H9 intermediate that undergoes multiple isomerization steps resulting in cyclization and ultimately aromatization following hydrogen atom elimination. RRKM calculations predict that the thermodynamically less stable isomers 1,3-heptadien-5-yne, 5-methylene-1,3-cyclohexadiene, and 3-methylene-1-hexen-4-yne are also synthesized. Since the 1-propynyl radical may be present in cold molecular clouds such as TMC-1, this pathway could potentially serve as a carrier of the methyl group incorporating itself into methyl-substituted (poly)acetylenes or aromatic systems such as toluene via overall exoergic reaction mechanisms that are uninhibited by an entrance barrier. Such pathways are a necessary alternative to existing high energy reactions leading to toluene that are formally closed in the cold regions of space and are an important step toward understanding the synthesis of polycyclic aromatic hydrocarbons (PAHs) in space's harsh extremes.
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Affiliation(s)
- Aaron M Thomas
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Chao He
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Long Zhao
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
| | - Galiya R Galimova
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States.,Samara National Research University , Samara 443086 , Russia
| | - Alexander M Mebel
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , United States
| | - Ralf I Kaiser
- Department of Chemistry , University of Hawai'i at Manoa , Honolulu , Hawaii 96822 , United States
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50
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Fioroni M, Savage RE, DeYonker NJ. On the formation of phosphorous polycyclic aromatics hydrocarbons (PAPHs) in astrophysical environments. Phys Chem Chem Phys 2019; 21:8015-8021. [PMID: 30931458 DOI: 10.1039/c9cp00547a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The formation of phosphorous-containing polycyclic aromatic hydrocarbons (PAPHs) in astrophysical contexts is proposed and analyzed by means of computational methods [B3LYP-D3BJ/ma-def2-TZVPP, MP2-F12, CCSD-F12b and CCSD(T)-F12b levels of theory]. A "bottom-up" approach based on a radical-neutral reaction scheme between acetylene (C2H2) and the CP radical was used investigating: (a) the synthesis of the first PAPH (C5H5P) "phosphinine"; (b) PAPH growth by addition of C2H2 to the C5H4P radical; (c) PAPH synthesis by addition reactions of one CP radical and nC2H2 to a neutral PAH. Results show: (I) the formation of the phosphinine radical has a strong thermodynamic tendency (-133.3 kcal mol-1) and kinetic barriers ≤5.4 kcal mol-1; (II) PAPH growth by nC2H2 addition on the radical phosphinine easily and exothermically produces radicals (1a- or 1-phospha-naphtalenes with kinetic barriers ≤7.1 kcal mol-1 and reaction free energies ≤-102.5 kcal mol-1); (III) the addition of a single CP + nC2H2 to a neutral benzene generates a complex chemistry where the main product is 2-phospha-naphtalene; (IV) because of the CP radical character, its barrierless addition to a PAH produces a resonant stabilized PAPH, becoming excellent candidates for addition reactions with neutral or radical hydrocarbons and PAHs; (V) the same energy trend between all four levels of theory continues a well-calibrated computational protocol to analyze complex organic reactions with astrochemical interest using electronic structure theory.
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Affiliation(s)
- Marco Fioroni
- 213 Smith Chemistry Building, The University of Memphis, Memphis, 38152, TN, USA.
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