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Satterthwaite L, Koumarianou G, Carroll PB, Sedlik RJ, Wang I, McCarthy MC, Patterson D. Low-Temperature Gas-Phase Kinetics of Ethanol-Methanol Heterodimer Formation. J Phys Chem A 2023; 127:4096-4102. [PMID: 37119198 PMCID: PMC10184117 DOI: 10.1021/acs.jpca.3c01312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
The structures of gas-phase noncovalently bound clusters have long been studied in supersonic expansions. This method of study, while providing a wealth of information about the nature of noncovalent bonds, precludes observation of the formation of the cluster, as the clusters form just after the orifice of the pulsed valve. Here, we directly observe formation of ethanol-methanol dimers via microwave spectroscopy in a controlled cryogenic environment. Time profiles of the concentration of reagents in the cell yielded gas-phase reaction rate constants of kMe-g = (2.8 ± 1.4) × 10-13 cm3 molecule-1 s-1 and kMe-t = (1.6 ± 0.8) × 10-13 cm3 molecule-1 s-1 for the pseudo-second-order ethanol-methanol dimerization reaction at 8 K. The relaxation cross section between the gauche and trans conformers of ethanol was also measured using the same technique. In addition, thermodynamic relaxation between conformers of ethanol over time allowed for selection of conformer stoichiometry in the ethanol-methanol dimerization reaction, but no change in the ratio of dimer conformers was observed with changing ethanol monomer stoichiometry.
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Affiliation(s)
- Lincoln Satterthwaite
- Department of Chemistry and Biochemistry, Building 232, University of California, Santa Barbara, California 93106, United States
| | - Greta Koumarianou
- Department of Chemistry and Biochemistry, Building 232, University of California, Santa Barbara, California 93106, United States
| | - P Brandon Carroll
- Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - Robert J Sedlik
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
| | - Irene Wang
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
| | - Michael C McCarthy
- Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, Massachusetts 02138, United States
| | - David Patterson
- Physics Department, Broida Hall, University of California, Santa Barbara, California 93106, United States
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Schramm HM, Tamadate T, Hogan CJ, Clowers BH. Ion-neutral clustering alters gas-phase hydrogen-deuterium exchange rates. Phys Chem Chem Phys 2023; 25:4959-4968. [PMID: 36722872 DOI: 10.1039/d2cp04388b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The rates and mechanisms of chemical reactions that occur at a phase boundary often differ considerably from chemical behavior in bulk solution, but remain difficult to quantify. Ion-neutral interactions are one such class of chemical reactions whose behavior during the nascent stages of solvation differs from bulk solution while occupying critical roles in aerosol formation, atmospheric chemistry, and gas-phase ion separations. Through a gas-phase ion separation technique utilizing a counter-current flow of deuterated vapor, we quantify the degree of hydrogen-deuterium exchange (HDX) and ion-neutral clustering on a series of model chemical systems (i.e. amino acids). By simultaneously quantifying the degree of vapor association and HDX, the effects of cluster formation on reaction kinetics are realized. These results imply that cluster formation cannot be ignored when modeling complex nucleation processes and biopolymer structural dynamics.
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Affiliation(s)
- Haley M Schramm
- Department of Chemistry, Washington State University, Pullman, WA 99163, USA.
| | - Tomoya Tamadate
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Christopher J Hogan
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brian H Clowers
- Department of Chemistry, Washington State University, Pullman, WA 99163, USA.
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Zamir A, Stein T. Isomerization of hydrogen cyanide and hydrogen isocyanide in a cluster environment: quantum chemical study. J Chem Phys 2022; 156:054307. [DOI: 10.1063/5.0077000] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Alon Zamir
- Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Tamar Stein
- Fritz Haber Research Center for Molecular Dynamics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
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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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Molecular dynamics reveals formation path of benzonitrile and other molecules in conditions relevant to the interstellar medium. Proc Natl Acad Sci U S A 2021; 118:2101371118. [PMID: 33941678 DOI: 10.1073/pnas.2101371118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Polycyclic aromatic hydrocarbons and polycyclic aromatic nitrogen heterocycles are believed to be widespread in different areas of the interstellar medium. However, the astronomical detection of specific aromatic molecules is extremely challenging. As a result, only a few aromatic molecules have been identified, and very little is known about how they are formed in different areas of the interstellar medium. Recently, McGuire et al. [Science 359, 202-205 (2018)] detected the simple aromatic molecule benzonitrile in Taurus Molecular Cloud-1. Although benzonitrile has been observed, the molecular mechanism for its formation is still unknown. In this study, we use quantum chemistry and ab initio molecular dynamics to model ionization processes of van der Waals clusters containing cyanoacetylene and acetylene molecules. We demonstrate computationally that the clusters' ionization leads to molecular formation. For pure cyanoacetylene clusters, we observe bond formation among two and three monomer units, whereas in mixed clusters, bond formation can also occur in up to four units. We show that the large amount of energy available to the system after ionization can lead to barrier crossing and the formation of complex molecules. Our study reveals the rich chemistry that is observed upon ionization of the clusters, with a wide variety of molecules being formed. Benzonitrile is among the observed molecules, and we study the potential energy path for its formation. These results also offer insights that can guide astronomers in their search for aromatic molecules in the interstellar medium.
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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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