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Pannacci G, Mancini L, Vanuzzo G, Liang P, Marchione D, Rosi M, Casavecchia P, Balucani N. A combined crossed molecular beam and theorerical study of the O( 3P, 1D) + acrylonitrile (CH 2CHCN) reactions and implications for combustion and extraterrestrial environments. Phys Chem Chem Phys 2023. [PMID: 37469256 DOI: 10.1039/d3cp01558k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/21/2023]
Abstract
Acrylonitrile (CH2CHCN) is ubiquitous in space (molecular clouds, solar-type star forming regions, and circumstellar envelopes) and is also abundant in the upper atmosphere of Titan. The reaction O(3P) + CH2CHCN can be of relevance in the chemistry of the interstellar medium because of the abundance of atomic oxygen. The oxidation of acrylonitrile is also important in combustion as the thermal decomposition of pyrrolic and pyridinic structures present in fuel-bound nitrogen generates many nitrogen-bearing compounds, including acrylonitrile. Despite its relevance, limited information exists on this reaction. We report a combined experimental and theoretical investigation of the reactions of acrylonitrile with both ground 3P and excited 1D atomic oxygen. From product angular and time-of-flight distributions in crossed molecular beam experiments with mass spectrometric detection at a collision energy, Ec, of 31.4 kJ mol-1, we have identified the primary reaction products and determined their branching fractions (BFs). Theoretical calculations of the relevant triplet and singlet potential energy surfaces (PESs) were performed to interpret the experimental results and elucidate the reaction mechanism. Adiabatic statistical calculations of product BFs for the decomposition of the main triplet and singlet intermediates have been carried out. Combining the experimental and theoretical results, we conclude that the O(3P) reaction leads to two main product channels: (i) CH2CNH (ketenimine) + CO (dominant with a BF of 0.87 ± 0.05), formed via efficient intersystem crossing from the entrance triplet PES to the underlying singlet PES, and (ii) HCOCHCN + H (minor, with a BF of 0.13 ± 0.05), occurring adiabatically on the triplet PES. Our study suggests the inclusion of this reaction as a possible destruction pathway of CH2CHCN and a possible formation route of CH2CNH in the interstellar medium. The O(1D) + CH2CHCN reaction mainly leads to the formation of CH2CNH + CO adiabatically on the singlet PES. This result can improve models related to the chemistry of interstellar ice and cometary comas, where O(1D) reactions can play a role. Overall, our results are expected to be useful for improving the models of combustion and extraterrestrial environments.
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Affiliation(s)
- Giacomo Pannacci
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Luca Mancini
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Pengxiao Liang
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Demian Marchione
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Marzio Rosi
- Dipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Perugia, Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Perugia, Italy.
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Liang P, de Aragão EVF, Giani L, Mancini L, Pannacci G, Marchione D, Vanuzzo G, Faginas-Lago N, Rosi M, Skouteris D, Casavecchia P, Balucani N. OH( 2Π) + C 2H 4 Reaction: A Combined Crossed Molecular Beam and Theoretical Study. J Phys Chem A 2023. [PMID: 37207281 DOI: 10.1021/acs.jpca.2c08662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The reaction between the ground-state hydroxyl radical, OH(2Π), and ethylene, C2H4, has been investigated under single-collision conditions by the crossed molecular beam scattering technique with mass-spectrometric detection and time-of-flight analysis at the collision energy of 50.4 kJ/mol. Electronic structure calculations of the underlying potential energy surface (PES) and statistical Rice-Ramsperger-Kassel-Marcus (RRKM) calculations of product branching fractions on the derived PES for the addition pathway have been performed. The theoretical results indicate a temperature-dependent competition between the anti-/syn-CH2CHOH (vinyl alcohol) + H, CH3CHO (acetaldehyde) + H, and H2CO (formaldehyde) + CH3 product channels. The yield of the H-abstraction channel could not be quantified with the employed methods. The RRKM results predict that under our experimental conditions, the anti- and syn-CH2CHOH + H product channels account for 38% (in similar amounts) of the addition mechanism yield, the H2CO + CH3 channel for ∼58%, while the CH3CHO + H channel is formed in negligible amount (<4%). The implications for combustion and astrochemical environments are discussed.
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Affiliation(s)
- Pengxiao Liang
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Emília Valença Ferreira de Aragão
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
- Master-Tec Srl, Via Sicilia, 41, Perugia 06128, Italy
| | - Lisa Giani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
- Université Grenoble Alpes, 621 Av. Centrale, Saint-Martin-d'Hères 38400, France
| | - Luca Mancini
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Giacomo Pannacci
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Demian Marchione
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Noelia Faginas-Lago
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
- Master-Tec Srl, Via Sicilia, 41, Perugia 06128, Italy
| | - Marzio Rosi
- Dipartimento di Ingegneria Civile Ed Ambientale, Università Degli Studi di Perugia, Perugia 06125, Italy
| | | | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università Degli Studi di Perugia, Perugia 06123, Italy
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3
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Liang P, de Aragão EVF, Pannacci G, Vanuzzo G, Giustini A, Marchione D, Recio P, Ferlin F, Stranges D, Lago NF, Rosi M, Casavecchia P, Balucani N. Reactions O( 3P, 1D) + HCCCN(X 1Σ +) (Cyanoacetylene): Crossed-Beam and Theoretical Studies and Implications for the Chemistry of Extraterrestrial Environments. J Phys Chem A 2023; 127:685-703. [PMID: 36638186 PMCID: PMC9884085 DOI: 10.1021/acs.jpca.2c07708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cyanoacetylene (HCCCN), the first member of the cyanopolyyne family (HCnN, where n = 3, 5, 7, ...), is of particular interest in astrochemistry being ubiquitous in space (molecular clouds, solar-type protostars, protoplanetary disks, circumstellar envelopes, and external galaxies) and also relatively abundant. It is also abundant in the upper atmosphere of Titan and comets. Since oxygen is the third most abundant element in space, after hydrogen and helium, the reaction O + HCCCN can be of relevance in the chemistry of extraterrestrial environments. Despite that, scarce information exists not only on the reactions of oxygen atoms with cyanoacetylene but with nitriles in general. Here, we report on a combined experimental and theoretical investigation of the reactions of cyanoacetylene with both ground 3P and excited 1D atomic oxygen and provide detailed information on the primary reaction products, their branching fractions (BFs), and the overall reaction mechanisms. More specifically, the reactions of O(3P, 1D) with HCCCN(X1Σ+) have been investigated under single-collision conditions by the crossed molecular beams scattering method with mass spectrometric detection and time-of-flight analysis at the collision energy, Ec, of 31.1 kJ/mol. From product angular and time-of-flight distributions, we have identified the primary reaction products and determined their branching fractions (BFs). Theoretical calculations of the relevant triplet and singlet potential energy surfaces (PESs) were performed to assist the interpretation of the experimental results and clarify the reaction mechanism. Adiabatic statistical calculations of product BFs for the decomposition of the main triplet and singlet intermediates have also been carried out. Merging together the experimental and theoretical results, we conclude that the O(3P) reaction is characterized by a minor adiabatic channel leading to OCCCN (cyanoketyl) + H (experimental BF = 0.10 ± 0.05), while the dominant channel (BF = 0.90 ± 0.05) occurs via intersystem crossing to the underlying singlet PES and leads to formation of 1HCCN (cyanomethylene) + CO. The O(1D) reaction is characterized by the same two channels, with the relative CO/H yield being slightly larger. Considering the recorded reactive signal and the calculated entrance barrier, we estimate that the rate coefficient for reaction O(3P) + HC3N at 300 K is in the 10-12 cm3 molec-1 s-1 range. Our results are expected to be useful to improve astrochemical and photochemical models. In addition, they are also relevant in combustion chemistry, because the thermal decomposition of pyrrolic and pyridinic structures present in fuel-bound nitrogen generates many nitrogen-bearing compounds, including cyanoacetylene.
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Affiliation(s)
- Pengxiao Liang
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Emilia V. F. de Aragão
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy,Master-Tec
srl, Via Sicilia 41, Perugia 06128, Italy
| | - Giacomo Pannacci
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Gianmarco Vanuzzo
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Andrea Giustini
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Demian Marchione
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Pedro Recio
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Francesco Ferlin
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Domenico Stranges
- Dipartimento
di Chimica, Università degli Studi
La Sapienza, Roma 00185, Italy
| | - Noelia Faginas Lago
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Marzio Rosi
- Dipartimento
di Ingegneria Civile e Ambientale, Università
degli Studi di Perugia, Perugia 06123, Italy
| | - Piergiorgio Casavecchia
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy,E-mail:
| | - Nadia Balucani
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, Perugia 06123, Italy,E-mail:
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Vanuzzo G, Marchione D, Mancini L, Liang P, Pannacci G, Recio P, Tan Y, Rosi M, Skouteris D, Casavecchia P, Balucani N. The N( 2D) + CH 2CHCN (Vinyl Cyanide) Reaction: A Combined Crossed Molecular Beam and Theoretical Study and Implications for the Atmosphere of Titan. J Phys Chem A 2022; 126:6110-6123. [PMID: 36053010 PMCID: PMC9483977 DOI: 10.1021/acs.jpca.2c04263] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The reaction of electronically excited nitrogen atoms,
N(2D), with vinyl cyanide, CH2CHCN, has been
investigated
under single-collision conditions by the crossed molecular beam (CMB)
scattering method with mass spectrometric detection and time-of-flight
(TOF) analysis at the collision energy, Ec, of 31.4 kJ/mol. Synergistic electronic structure calculations of
the doublet potential energy surface (PES) have been performed to
assist in the interpretation of the experimental results and characterize
the overall reaction micromechanism. Statistical (Rice–Ramsperger–Kassel–Marcus,
RRKM) calculations of product branching fractions (BFs) on the theoretical
PES have been carried out at different values of temperature, including
the one corresponding to the temperature (175 K) of Titan’s
stratosphere and at a total energy corresponding to the Ec of the CMB experiment. According to our theoretical
calculations, the reaction is found to proceed via barrierless addition
of N(2D) to the carbon–carbon double bond of CH2=CH–CN, followed by the formation of cyclic
and linear intermediates that can undergo H, CN, and HCN elimination.
In competition, the N(2D) addition to the CN group is also
possible via a submerged barrier, leading ultimately to N2 + C3H3 formation, the most exothermic of all
possible channels. Product angular and TOF distributions have been
recorded for the H-displacement channels leading to the formation
of a variety of possible C3H2N2 isomeric
products. Experimentally, no evidence of CN, HCN, and N2 forming channels was observed. These findings were corroborated
by the theory, which predicts a variety of competing product channels,
following N(2D) addition to the double bond, with the main
ones, at Ec = 31.4 kJ/mol, being six isomeric
H forming channels: c-CH(N)CHCN + H (BF = 35.0%), c-CHNCHCN + H (BF = 28.1%), CH2NCCN + H (BF =
26.3%), c-CH2(N)CCN(cyano-azirine) + H
(BF = 7.4%), trans-HNCCHCN + H (BF = 1.6%), and cis-HNCCHCN + H (BF = 1.3%), while C–C bond breaking
channels leading to c-CH2(N)CH(2H-azirine)
+ CN and c-CH2(N)C + HCN are predicted
to be negligible (0.02% and 0.2%, respectively). The highly exothermic
N2 + CH2CCH (propargyl) channel is also predicted
to be negligible because of the very high isomerization barrier from
the initial addition intermediate to the precursor intermediate able
to lead to products. The predicted product BFs are found to have,
in general, a very weak energy dependence. The above cyclic and linear
products containing an additional C–N bond could be potential
precursors of more complex, N-rich organic molecules that contribute
to the formation of the aerosols on Titan’s upper atmosphere.
Overall, the results are expected to have a significant impact on
the gas-phase chemistry of Titan’s atmosphere and should be
properly included in the photochemical models.
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Affiliation(s)
- Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Demian Marchione
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Luca Mancini
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Pengxiao Liang
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Giacomo Pannacci
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Pedro Recio
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Yuxin Tan
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Marzio Rosi
- Dipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Perugia, 06125 Perugia, Italy
| | | | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
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5
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Marchione D, Mancini L, Liang P, Vanuzzo G, Pirani F, Skouteris D, Rosi M, Casavecchia P, Balucani N. Unsaturated Dinitriles Formation Routes in Extraterrestrial Environments: A Combined Experimental and Theoretical Investigation of the Reaction between Cyano Radicals and Cyanoethene (C 2H 3CN). J Phys Chem A 2022; 126:3569-3582. [PMID: 35640168 PMCID: PMC9189926 DOI: 10.1021/acs.jpca.2c01802] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
The reaction between
cyano radicals (CN, X2Σ+) and cyanoethene
(C2H3CN) has been
investigated by a combined approach coupling crossed molecular beam
(CMB) experiments with mass spectrometric detection and time-of-flight
analysis at a collision energy of 44.6 kJ mol–1 and
electronic structure calculations to determine the relevant potential
energy surface. The experimental results can be interpreted by assuming
the occurrence of a dominant reaction pathway leading to the two but-2-enedinitrile
(1,2-dicyanothene) isomers (E- and Z-NC–CH=CH–CN) in a H-displacement channel and,
to a much minor extent, to 1,1-dicyanoethene, CH2C(CN)2. In order to derive the product branching ratios under the
conditions of the CMB experiments and at colder temperatures, including
those relevant to Titan and to cold interstellar clouds, we have carried
out RRKM statistical calculations using the relevant potential energy
surface of the investigated reaction. We have also estimated the rate
coefficient at very low temperatures by employing a semiempirical
method for the treatment of long-range interactions. The reaction
has been found to be barrierless and fast also under the low temperature
conditions of cold interstellar clouds and the atmosphere of Titan.
Astrophysical implications and comparison with literature data are
also presented. On the basis of the present work, 1,2-dicyanothene
and 1,1-dicyanothene are excellent candidates for the search of dinitriles
in the interstellar medium.
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Affiliation(s)
- Demian Marchione
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Luca Mancini
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Pengxiao Liang
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Gianmarco Vanuzzo
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Fernando Pirani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | | | - Marzio Rosi
- Dipartimento di Ingegneria Civile ed Ambientale, Università degli Studi di Perugia, 06125 Perugia, Italy
| | - Piergiorgio Casavecchia
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
| | - Nadia Balucani
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, 06123 Perugia, Italy
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6
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Semiempirical Potential in Kinetics Calculations on the HC3N + CN Reaction. Molecules 2022; 27:molecules27072297. [PMID: 35408696 PMCID: PMC9000235 DOI: 10.3390/molecules27072297] [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: 02/15/2022] [Revised: 03/25/2022] [Accepted: 03/28/2022] [Indexed: 02/04/2023] Open
Abstract
The reaction between the cyano radical CN and cyanoacetylene molecule HC3N is of great interest in different astronomical fields, from star-forming regions to planetary atmospheres. In this work, we present a new synergistic theoretical approach for the derivation of the rate coefficient for gas phase neutral-neutral reactions. Statistic RRKM calculations on the Potential Energy Surface are coupled with a semiempirical analysis of the initial bimolecular interaction. The value of the rate coefficient for the HC3N + CN → H + NCCCCN reaction obtained with this method is compared with previous theoretical and experimental investigations, showing strengths and weaknesses of the new presented approach.
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Barone V, Lupi J, Salta Z, Tasinato N. Development and Validation of a Parameter-Free Model Chemistry for the Computation of Reliable Reaction Rates. J Chem Theory Comput 2021; 17:4913-4928. [PMID: 34228935 PMCID: PMC8359010 DOI: 10.1021/acs.jctc.1c00406] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
![]()
A recently developed
model chemistry (jun-Cheap) has been slightly
modified and proposed as an effective, reliable, and parameter-free
scheme for the computation of accurate reaction rates with special
reference to astrochemical and atmospheric processes. Benchmarks with
different sets of state-of-the-art energy barriers spanning a wide
range of values show that, in the absence of strong multireference
contributions, the proposed model outperforms the most well-known
model chemistries, reaching a subchemical accuracy without any empirical
parameter and with affordable computer times. Some test cases show
that geometries, energy barriers, zero point energies, and thermal
contributions computed at this level can be used in the framework
of the master equation approach based on the ab initio transition-state
theory for obtaining accurate reaction rates.
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Affiliation(s)
- Vincenzo Barone
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Jacopo Lupi
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Zoi Salta
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
| | - Nicola Tasinato
- SMART Laboratory, Scuola Normale Superiore di Pisa, piazza dei Cavalieri 7, 56125 Pisa, Italy
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8
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Kruse FM, Teichert JS, Trapp O. Prebiotic Nucleoside Synthesis: The Selectivity of Simplicity. Chemistry 2020; 26:14776-14790. [PMID: 32428355 PMCID: PMC7756251 DOI: 10.1002/chem.202001513] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 05/10/2020] [Indexed: 12/29/2022]
Abstract
Ever since the discovery of nucleic acids 150 years ago,[1] major achievements have been made in understanding and decrypting the fascinating scientific questions of the genetic code.[2] However, the most fundamental question about the origin and the evolution of the genetic code remains a mystery. How did nature manage to build up such intriguingly complex molecules able to encode structure and function from simple building blocks? What conditions were required? How could the precursors survive the unhostile environment of early Earth? Over the past decades, promising synthetic concepts were proposed providing clarity in the field of prebiotic nucleic acid research. In this Minireview, we show the current status and various approaches to answer these fascinating questions.
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Affiliation(s)
- Florian M. Kruse
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
| | - Jennifer S. Teichert
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
- Max-Planck-Institute for AstronomyKönigstuhl 1769117HeidelbergGermany
| | - Oliver Trapp
- Department of ChemistryLudwig-Maximilians-University MunichButenandtstr. 5–13'81377MunichGermany
- Max-Planck-Institute for AstronomyKönigstuhl 1769117HeidelbergGermany
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9
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Gas phase reaction kinetics of complex organic molecules at temperatures of the interstellar medium: The OH + CH3OH case. ACTA ACUST UNITED AC 2020. [DOI: 10.1017/s1743921319006446] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractRecent experimental and theoretical works concerning gas-phase radical-neutral reactions involving Complex Organic Molecules are reviewed in the context of cold interstellar objects with a special emphasis on the OH + CH3OH reaction and its potential impact on the formation of CH3O.
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10
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Maioli LS, Kossoski F, Bettega MHF. Low-energy electron scattering by cyanamide: anion spectra and dissociation pathways. Phys Chem Chem Phys 2020; 22:7894-7902. [PMID: 32227067 DOI: 10.1039/d0cp00806k] [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 low-energy anion spectra of cyanamide and its rare tautomer carbodiimide were surveyed with elastic electron scattering calculations. Our assignments differ qualitatively and quantitatively from a previous theoretical report. We support that both tautomers present two π* and two shape resonances, while cyanamide should also display a dipole bound state and a shape resonance. Available dissociative electron attachment measurements have shown several structures for dehydrogenation below 4 eV, but no sharp peaks related to vibrational Feshbach resonances. The absence of these resonances is explained by the lack of a potential barrier for tunneling of the hydrogen atom, despite the coupling between dipole bound and states. We found that the π* resonances initiate the dynamics that lead to hydrogen loss at 1.5, 2.5 and 3 eV. The later two structures arise from the anion states of cyanamide, while carbodiimide should account for the lower-lying one. The rarity of the second tautomer would be offset by its larger dissociative electron attachment cross section, enough to leave a distinct signature in the measured ion yield spectra. Low-energy electrons should thus decompose carbodiimide much more efficiently than cyanamide.
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Affiliation(s)
- Leticia S Maioli
- Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba, Paraná, Brazil
| | | | - Márcio H F Bettega
- Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba, Paraná, Brazil
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