Optimizing the searches for interstellar heterocycles

Etim, Emmanuel E.; Adelagun, R.O.A.; Andrew, Chrysanthus; Oladimeji, Enock

doi:10.1016/j.asr.2021.06.003

Cited by 10 publications

(13 citation statements)

References 28 publications

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“…In the case of the C 4 H 5 N group, the most stable isomer (pyrrole) and the isocyanide have been screened in different molecular clouds but no successful detection was reported. − Although pyrrole is more stable than isocyanide and 2-cyanopropene, it can adsorb more strongly in the interstellar dust grains, thereby reducing its abundance . The isocyanide should be less affected by this effect . This argument is corroborated by the column density measurements; i.e., pyrrole has a lower value than isocyanide. , On the other hand, 2-cyanopropene is more stable than isocyanide, it has a higher dipole moment, and it is less affected to the surface bonding effect .…”

Section: Introductionmentioning

confidence: 95%

“…36,40 On the other hand, 2-cyanopropene is more stable than isocyanide, it has a higher dipole moment, and it is less affected to the surface bonding effect. 39 These properties indicate that several low-energy isomers should be considered as detection candidates. 39 Therefore, the simulations of infrared (IR) spectra are imperative for band assignment of molecules detected in isolated matrices or ion traps for their unique identification.…”

Section: ■ Introductionmentioning

confidence: 99%

“…39 These properties indicate that several low-energy isomers should be considered as detection candidates. 39 Therefore, the simulations of infrared (IR) spectra are imperative for band assignment of molecules detected in isolated matrices or ion traps for their unique identification. 41−43 The vibrational spectra of C 4 H 3 N and C 4 H 5 N systems at neutral states were investigated under different experimental conditions.…”

Section: ■ Introductionmentioning

confidence: 99%

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Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

2023

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The relative stability of pyrrole derivatives were investigated by applying a global minimum (GM) search for the low-lying energy structures of C4H n N (n = 3–5) clusters at neutral, anionic, and cationic states. Several low-energy structures, previously not reported, were identified. The present results reveal a preference for cyclic and conjugated systems for the C4H5N and C4H4N compounds. In particular, the structures of the cationic and neutral C4H3N species are different from the anionic ones. For the neutrals and cations, cumulenic carbon chains were found, while for the anions, conjugated open chains were obtained. Of particular relevance, the GM candidates C4H4N+ and C4H4N are different from those reported previously. For the most stable structures, infrared spectra were simulated and the main vibrational bands were assigned. Also, a comparison with available laboratory data was done aiming to corroborate with experimental detection.

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Section: Introductionmentioning

confidence: 95%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

2023

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“…200 times faster than that of a carbon atom of benzene. They concluded that these findings are important not only for proving the potential role of these species in interstellar H 2 formation but also because the relatively fast H atom addition rate to furan may explain the absence of furan in the ISM. − …”

Section: Introductionmentioning

confidence: 97%

Potential Catalytic Role of Small Heterocycles in Interstellar H₂ Formation: A Laboratory Astrochemistry Study on Furan and Its Hydrogenated Forms

et al. 2022

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It is now well-accepted in astrochemistry that the formation of interstellar H 2 is taking place on the surface of interstellar grains. It has also been suggested a long time ago that polyaromatic hydrocarbons (PAHs) can catalyze this process by subsequent H atom addition and H abstraction reactions. Recent quantum chemical computations suggested that small heterocycles can be better catalysts than PAHs. In this study, the reaction of H atoms with furan, 2,3-and 2,5-dihydrofurans, and tetrahydrofuran were studied in solid para-H 2 at 3.1 K. The reactions were followed by Fourier transform infrared (FTIR) spectroscopy. By the analysis of spectra, 2-hydrofuran-3-yl, 3-hydrofuran-2-yl, 2,3,4-trihydrofuran-5-yl, and 2,3,5-trihydrofuran-4-yl radicals were identified among the products. The experiments revealed that all the possible H atom addition and H abstraction cycles connecting furan and tetrahydrofuran proceed effectively in both directions at a low temperature. This indicates the possible important role of small heterocycles in interstellar H 2 formation. Furthermore, it also indicates that, in the case of H atom excess, a quasi-equilibrium exists between the c-C 4 H x O (x = 4−8) species, and the ratios of these species in an astrophysical object are determined by the rate of the different H atom addition and H abstraction reaction steps.

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“…Despite their prevalence in natural products, aromatic heterocycles with a permanent dipole moment have eluded all radioastronomical searches. − The feasibility of radioastronomical detection of a molecule depends upon its population in the source of interest, the intensity of its rotational transitions due to its dipole moment, and the quality of the measurements of its laboratory transition frequencies. The rotational spectrum − and high-resolution infrared spectrum of furan − have been well investigated, but, despite the available, high-quality laboratory spectra, this important heterocycle has eluded detection in the interstellar medium (ISM). ,, Furan ( c -C 4 H 4 O, C 2 v , κ = 0.916) is a near-oblate aromatic heterocycle with an a -axis dipole moment (μ a = 0.661(6) D) .…”

Section: Introductionmentioning

confidence: 99%

Millimeter-Wave and High-Resolution Infrared Spectroscopy of 2-Furonitrile─A Highly Polar Substituted Furan

et al. 2023

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The rotational spectrum of 2-furonitrile (2-cyanofuran) has been obtained from 140 to 750 GHz, capturing its most intense rotational transitions at ambient temperature. 2-Furonitrile is one of two isomeric cyano-substituted furan derivatives, both of which possess a substantial dipole moment due to the cyano group. The large dipole of 2-furonitrile allowed over 10 000 rotational transitions of its ground vibrational state to be observed and least-squares fit to partial octic, A-and S-reduced Hamiltonians with low statistical uncertainty (σ fit = 40 kHz). The high-resolution infrared spectrum, obtained at the Canadian Light Source, allowed for accurate and precise determination of the band origins of its three lowest-energy fundamental modes (ν 24 , ν 17 , and ν 23 ). Similar to other cyanoarenes, the first two fundamental modes (ν 24, A″, and ν 17 , A′, for 2-furonitrile) form an a-and b-axis Coriolis-coupled dyad. More than 7000 transitions from each of these fundamental states were fit to an octic A-reduced Hamiltonian (σ fit = 48 kHz), and the combined spectroscopic analysis determines fundamental energies of 160.1645522 (26) cm −1 and 171.9436561 (25) cm −1 for ν 24 and ν 17 , respectively. The least-squares fitting of this Coriolis-coupled dyad required 11 coupling terms,J , and F ac K . Using both the rotational and high-resolution infrared spectra, a preliminary least-squares fit was obtained for ν 23 , providing its band origin of 456.7912716 (57) cm −1 . The transition frequencies and spectroscopic constants provided in this work, when combined with theoretical or experimental nuclear quadrupole coupling constants, will provide the foundation for future radioastronomical searches for 2-furonitrile across the frequency range of currently available radiotelescopes.

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Optimizing the searches for interstellar heterocycles

Cited by 10 publications

References 28 publications

Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

Potential Catalytic Role of Small Heterocycles in Interstellar H₂ Formation: A Laboratory Astrochemistry Study on Furan and Its Hydrogenated Forms

Millimeter-Wave and High-Resolution Infrared Spectroscopy of 2-Furonitrile─A Highly Polar Substituted Furan

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Optimizing the searches for interstellar heterocycles

Cited by 10 publications

References 28 publications

Low Energy Isomers and Infrared Spectra Simulations of C4H3N, C4H4N, and C4H5N and Related Ions

Low Energy Isomers and Infrared Spectra Simulations of C4H3N, C4H4N, and C4H5N and Related Ions

Potential Catalytic Role of Small Heterocycles in Interstellar H2 Formation: A Laboratory Astrochemistry Study on Furan and Its Hydrogenated Forms

Millimeter-Wave and High-Resolution Infrared Spectroscopy of 2-Furonitrile─A Highly Polar Substituted Furan

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Product

Resources

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Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

Low Energy Isomers and Infrared Spectra Simulations of C₄H₃N, C₄H₄N, and C₄H₅N and Related Ions

Potential Catalytic Role of Small Heterocycles in Interstellar H₂ Formation: A Laboratory Astrochemistry Study on Furan and Its Hydrogenated Forms