Interstellar detection of the highly polar five-membered ring cyanocyclopentadiene

McCarthy, Michael; Lee, Kelvin; Loomis, Ryan A.; Burkhardt, Andrew M.; Shingledecker, Christopher N.; Charnley, Steven B.; Cordiner, Martin; Herbst, Eric; Kalenskii, S. V.; Willis, Eric R.; Xue, Ci; Remijan, Anthony J.; McGuire, Brett A.

doi:10.1038/s41550-020-01213-y

Cited by 114 publications

(108 citation statements)

References 39 publications

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“…The reaction between CH and butadiene (CH 2 CHCHCH 2 ) is calculated to produce c-C 5 H 6 with no barrier (McCarthy et al 2021). Adopting a rate coefficient of 10 −10 cm 3 s −1 for this reaction in our chemical model, based on Agúndez et al (2021) and assuming that c-C5H6 is mostly removed through reactions with C atoms and C + and H + ions, we calculate a peak abundance of ∼ 3 × 10 −13 relative to H 2 for c-C 5 H 6 .…”

Section: Cyclopentadiene (C-c 5 H 6 )mentioning

confidence: 99%

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Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene

Cernicharo

Agúndez

Cabezas

et al. 2021

A&A

181

161

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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 first cycle and similar values, in the range (1−2) × 1013 cm−2, for the second and third. 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, such as vinyl and allenyl acetylene (Agúndez et al. 2021, A&A, 647, L10; Cernicharo et al. 2021a, A&A, 647, L2; Cernicharo et al. 2021b, A&A, 647, L3), 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 five- and six-membered rings are formed under the cold conditions of a cloud such as TMC-1.

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Section: Cyclopentadiene (C-c 5 H 6 )mentioning

confidence: 99%

“…Theoretical studies on these reactions would help to evaluate their role in the synthesis of cyclopentadiene. Whatever the formation route to c-C 5 H 6 is, this hydrocarbon cycle is the most obvious precursor of the two cyanide derivatives of c-C 5 H 5 CN detected in TMC-1 (McCarthy et al 2021;Lee et al 2021).…”

Section: Cyclopentadiene (C-c 5 H 6 )mentioning

confidence: 99%

Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene

Cernicharo

Agúndez

Cabezas

et al. 2021

A&A

181

161

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“…The evermore increasing discovery of new and somewhat complex interstellar species, such as propargylimine (Bizzocchi et al, 2020), ethanolamine (Rivilla et al, 2021), glycolonitrile (Zeng et al, 2019), but also cyclopentadiene and indene (Cernicharo et al, 2021), benzonitrile (McGuire et al, 2018) together with larger species such as 1 and 2-cyanocylopentadiene McCarthy et al, 2021) or 1 and 2-cyanonaphthalene (McGuire et al, 2021), as well as chiral molecules like propylene oxide (McGuire et al, 2016), claims for a boost up on hypothetical formation routes of these species in the interstellar medium (ISM) and, more generally, for an intensification of the study of potential formation mechanisms for molecules of astrochemical interest.…”

Section: Introductionmentioning

confidence: 99%

“…The CN radical is the second species that has ever been detected in space (McKellar, 1940) even before its spectroscopic laboratory characterisation (Jefferts et al, 1970;McGuire, 2018) and is considered quite ubiquitous in the ISM (Savage et al, 2002;McGuire, 2018). Therefore, the reaction c-C 2 H 4 O + CN appears to be a promising reactive pathway, considering that the CN radical has been proved to be a good reactant for barrierless reactions being involved infor examplethe formation of formyl cyanide (Tonolo et al, 2020), cyanomethanimine (Vazart et al, 2015), benzonitrile (Woon, 2006;Cooke et al, 2020), and cyanocyclopentadiene (McCarthy et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Fate of the Gas-Phase Reaction Between Oxirane and the CN Radical in Interstellar Conditions

Alessandrini

Melosso

2021

Front. Astron. Space Sci.

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The escalating identification of new complex molecules in the interstellar medium claims for potential formation routes of such species. In this regard, the present work considers the reaction between oxirane and the CN radical as a feasible formation mechanism of species having the C3H3NO molecular formula. Indeed, the compounds of this family are elusive in the interstellar medium and suggestions on which species could be formed at low temperature and low pressure conditions might aid their discovery. The c-C2H4O + CN reaction has been investigated from the thermodynamic and kinetic points of view. The thermodynamic has been studied by means of a double-hybrid density functional and revealed the presence of several mechanisms submerged with respect to the reactants energy, with the potential formation of oxazole and cyanoacetaldehyde. However, the kinetic results suggest that the main reaction pathway is the H-extraction, leading to 2-oxiranyl radical and HCN. The formation of cyanoacetaldehyde + H and of H2CCN + H2CO is also possible with smaller rate constants, while the production of oxazole is negligible due to the presence of a high energy barrier.

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“…Therefore, uracil and cytosine are more easily formed than thymine, which is consistent with the detection of uracil but not of thymine in meteorites. In 2019, (Oba et al, 2019) demonstrated that all DNA/RNA nucleobases, except guanine, can be also formed from a mixture of simple, abundant molecules (H 2 O, CO, NH 3 and CH 3 OH) exposed to UV photons at 10 K. So far, none of nucleobases have been detected in the interstellar medium (ISM), but other complex molecules exist in ISM, including two simplest nitrogen-bearing aromatic molecules: benzonitrile (c-C 6 H 5 CN) (McGuire et al, 2018) and 1-cyano-1,3-cyclopentadiene (c-C 5 H 5 CN) (McCarthy et al, 2021). Analysis of chemical composition and structure of any type of astrochemical "samples" (meteorites, comets, planetary atmosphere or soil, ISM) and search for prebiotic organic matter in extraterrestrial materials is a very challenging task (Callahan et al, 2011;Fornaro et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Identification of DNA Bases and Their Cations in Astrochemical Environments: Computational Spectroscopy of Thymine as a Test Case

Zhao

Hochlaf

Biczysko

2021

Front. Astron. Space Sci.

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Increased importance of vibrational fingerprints in the identification of molecular systems, can be highlighted by the upcoming interstellar medium (ISM) observations by the James Webb Space Telescope, or in a context of other astrochemical environments as meteorites or exoplanets, Mars robotic missions, such as instruments on board of Perseverance rover. These observations can be supported by combination of laboratory experiments and theoretical calculations, essential to verify and predict the spectral assignments. Astrochemical laboratory simulations have shown that complex organic molecules (COMs) can be formed from simple species by vacuum ultraviolet or X-ray irradiation expanding interest in searching for organic biological and prebiotic compounds. In this work an example of nucleobase, thymine, is selected as a test case for highlighting the utility of computational spectroscopic methods in astrochemical studies. We consider mid-infrared (MIR) and near-infrared (NIR) vibrational spectra of neutral (T) and cationic (T+) thymine ground states, and vibrationally-resolved photoelectron (PE) spectra in the far UV range from 8.7 to 9.4 eV. The theoretical framework is based on anharmonic calculations including overtones and combination bands. The same anharmonic wavenumbers are applied into the simulations of vibrationally-resolved photoelectron spectra based on Franck-Condon computations. The infrared and vibrationally-resolved photoelectron spectra are compared with the available experimental counterparts to verify their accuracy and provide assignment of the observed transitions. Finally, reliable predictions of spectra, going beyond currently available experimental data, either dealing with energy ranges, resolution or temperature, which can support astrochemistry studies are provided.

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Interstellar detection of the highly polar five-membered ring cyanocyclopentadiene

Cited by 114 publications

References 39 publications

Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene

Pure hydrocarbon cycles in TMC-1: Discovery of ethynyl cyclopropenylidene, cyclopentadiene, and indene

Fate of the Gas-Phase Reaction Between Oxirane and the CN Radical in Interstellar Conditions

Identification of DNA Bases and Their Cations in Astrochemical Environments: Computational Spectroscopy of Thymine as a Test Case

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