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CHAWANANON S, Pirali O, Goubet M, ASSELIN P. Characterizing centrosymmetric two-ring PAHs using jet-cooled high resolution mid-infrared laser spectroscopy and anharmonic Quantum Chemical calculations. J Chem Phys 2022; 157:064301. [DOI: 10.1063/5.0096777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The presence of Polycyclic Aromatic Hydrocarbons (PAH) molecules in the interstellar medium, recently confirmed by the detection of cyano-naphthalenes, renews the interest of extensive spectroscopic and physical-chemistry studies about such large species. The present study reports the jet-cooled rovibrational IR study of three centrosymmetric two-ring PAH molecules, naphthalene (C10H8), [1,5] naphthyridine (C8H6N2) and biphenyl (C12H10) in the in-plane ring C-H bending (975-1035 cm-1) and C-C ring stretching (1580-1620 cm-1) regions. For the two most rigid PAHs, the accuracy of spectroscopic parameters derived in ground and several excited states (6 for naphthalene and 6 for [1,5] naphthyridine) has significantly improved the literature values. In addition, comparison between experiments and quantum chemical calculations confirms the predictive power of the corrected calculated rotational parameters. The more flexible structure of biphenyl makes particularly challenging the analysis of high resolution jet-cooled spectra of n19 and n23 modes recorded at about 1601 and 1013 cm-1 respectively. The presence of three torsional vibrations below 120 cm-1 together with small values of the rotational constants prevented us to determine the ground and v19=1 excited rotational constants independently. In the n23 band region, the presence of two bands rotationally resolved and separated by only 0.8 cm-1, raises the question of possible splittings due to a large amplitude motion, most probably the torsion of the aliphatic bond between the two phenyl rings.
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Gawrilow M, Suhm MA. Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters. Molecules 2021; 26:molecules26154523. [PMID: 34361676 PMCID: PMC8348275 DOI: 10.3390/molecules26154523] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 02/01/2023] Open
Abstract
The conformational preferences of the ester group have the potential to facilitate the large amplitude folding of long alkyl chains in the gas phase. They are monitored by Raman spectroscopy in supersonic jet expansions for the model system methyl butanoate, after establishing a quantitative relationship with quantum-chemical predictions for methyl methanoate. This requires a careful analysis of experimental details, and a simulation of the rovibrational contours for near-symmetric top molecules. The technique is shown to be complementary to microwave spectroscopy in quantifying coexisting conformations. It confirms that a C-O-C(=O)-C-C chain segment can be collapsed into a single all-trans conformation by collisional cooling, whereas alkyl chain isomerism beyond this five-membered chain largely survives the jet expansion. This sets the stage for the investigation of linear alkyl alkanoates in terms of dispersion-induced stretched-chain to hairpin transitions by Raman spectroscopy.
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Leach S, Jones NC, Hoffmann SV, Un S. Isoquinoline gas-phase absorption spectrum in the vacuum ultraviolet between 3.7 and 10.7 eV. New valence and Rydberg electronic states. RSC Adv 2019; 9:5121-5141. [PMID: 35514650 PMCID: PMC9060705 DOI: 10.1039/c8ra09725a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 02/05/2019] [Indexed: 12/25/2022] Open
Abstract
VUV photons from a synchrotron source were used to record the gas-phase absorption spectrum of isoquinoline over the range 3.5 to 10.7 eV. The rich spectrum exhibits both broad and sharp features, of varying intensities, that are analyzed into eight valence and eight Rydberg transitions. Previous data on the valence transitions of isoquinoline were essentially limited to solution spectra up to 5.4 eV. Our study increases their number considerably. The features in the 3.96 eV region are discussed in terms of vibronic coupling between the nπ* 11A′′ and ππ* 21A′ valence electronic states. The intensities of some spectral features are augmented by collective π-electron modes considered to be of plasmon-type. Assignments of the valence transitions were facilitated by our DFT calculations and by earlier Pariser–Parr–Pople MO calculations. The calculation results are compared and their relative value is discussed. The DFT calculations reproduce very well a number of experimentally determined properties of the ground state of isoquinoline, in particular its bond distances and angles, rotational constants, vibrational frequencies and dipole moment. No Rydberg series of isoquinoline have previously been observed. Three of the newly observed Rydberg series converge to the D0 electronic ground state of the ion, while two converge to the D1 and three to the D3 excited electronic states of the cation. Astrophysical applications of the VUV absorption spectrum of isoquinoline, in particular the measured absorption cross-sections, are briefly discussed. A comparison between the absorption spectra of isoquinoline and quinoline highlights their similarities and differences, related to their respective molecular orbitals. VUV photons from a synchrotron source were used to record the gas-phase absorption spectrum of isoquinoline over the range 3.5 to 10.7 eV.![]()
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Affiliation(s)
- Sydney Leach
- LERMA
- Observatoire de Paris
- PSL Research University
- CNRS
- Sorbonne Universités
| | - Nykola C. Jones
- ISA
- Department of Physics and Astronomy
- Aarhus University
- Denmark
| | | | - Sun Un
- Institute for Integrative Biology of the Cell (I2BC)
- Department of Biochemistry
- Biophysics and Structural Biology
- Université Paris-Saclay
- CEA
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Boudon V, Lamy M, Dugue-Boyé F, Pirali O, Gruet S, D'Accolti L, Fusco C, Annese C, Alikhani ME. Synthesis, High-Resolution Infrared Spectroscopy, and Vibrational Structure of Cubane, C8H8. J Phys Chem A 2016; 120:4418-28. [PMID: 27267150 DOI: 10.1021/acs.jpca.6b04323] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Carbon-cage molecules have generated a considerable interest from both experimental and theoretical points of view. We recently performed a high-resolution study of adamantane (C10H16), the smallest hydrocarbon cage belonging to the diamandoid family ( Pirali , O. ; et al. J. Chem. Phys. 2012 , 136 , 024310 ). There exist another family of hydrocarbon cages with additional interesting chemical properties: the so-called platonic hydrocarbons that comprise dodecahedrane (C20H20) and cubane (C8H8). Both possess C-C bond angles that deviate from the tetrahedral angle (109.8°) of the sp(3) hybridized form of carbon. This generates a considerable strain in the molecule. We report a new wide-range high-resolution study of the infrared spectrum of cubane. The sample was synthesized in Bari upon decarboxylation of 1,4-cubanedicarboxylic acid thanks to the improved synthesis of literature. Several spectra have been recorded at the AILES beamline of the SOLEIL synchrotron facility. They cover the 600-3200 cm(-1) region. Besides the three infrared-active fundamentals (ν10, ν11, and ν12), we could record many combination bands, all of them displaying a well-resolved octahedral rotational structure. We present here a preliminary analysis of some of the recorded bands, performed thanks the SPVIEW and XTDS software, based on the tensorial formalism developed in the Dijon group. A comparison with ab initio calculations, allowing to identify some combination bands, is also presented.
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Affiliation(s)
- V Boudon
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté , 9 avenue Alain Savary, BP 47870, F-21078 Dijon Cedex, France
| | - M Lamy
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté , 9 avenue Alain Savary, BP 47870, F-21078 Dijon Cedex, France
| | - F Dugue-Boyé
- Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303 CNRS-Université Bourgogne Franche-Comté , 9 avenue Alain Savary, BP 47870, F-21078 Dijon Cedex, France
| | - O Pirali
- Ligne AILES - Synchrotron SOLEIL, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France and Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay , F-91405 Orsay, France
| | - S Gruet
- Ligne AILES - Synchrotron SOLEIL, L'Orme des Merisiers, F-91192 Gif-sur-Yvette, France and Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay , F-91405 Orsay, France
| | - L D'Accolti
- Dipartimento di Chimica, Università di Bari A. Moro , I-70126 Bari, Italy.,Istituto di Chimica dei Composti Organometallici ICCOM , Bari Sect, I-70126 Bari, Italy
| | - C Fusco
- Dipartimento di Chimica, Università di Bari A. Moro , I-70126 Bari, Italy.,Istituto di Chimica dei Composti Organometallici ICCOM , Bari Sect, I-70126 Bari, Italy
| | - C Annese
- Dipartimento di Chimica, Università di Bari A. Moro , I-70126 Bari, Italy.,Istituto di Chimica dei Composti Organometallici ICCOM , Bari Sect, I-70126 Bari, Italy
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Gruet S, Pirali O, Goubet M, Tokaryk DW, Brechignac P. High-Resolution Far-Infrared Spectroscopy of N-Substituted Two-Ring Polycyclic Aromatic Hydrocarbons: An Extended Study. J Phys Chem A 2015; 120:95-105. [PMID: 26654581 DOI: 10.1021/acs.jpca.5b09626] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) and their N-substituted derivatives are among the largest species for which gas-phase high-resolution spectroscopy can be performed nowadays. In this paper we report the observation and analysis of spectra from several N-substituted two-ring PAHs, all taken in the "fingerprint" far-infrared region (<850 cm(-1)). Together with accurate measurements of their pure rotational transitions in the millimeter and submillimeter ranges, these synchrotron-based Fourier transform infrared (FTIR) measurements provide an accurate description of the rotational energy levels in the ground and low-energy excited vibrational states of these species. To complement the experimental data, anharmonic DFT calculations were performed to obtain relatively accurate rotational and vibrational parameters. The calculated results strongly support the rotational analysis and provide a good estimate of the equilibrium structures for each species. Extended measurements, analysis, and calculations are presented here for the far-IR bands of quinoline (C9H7N), isoquinoline (C9H7N), quinoxaline (C8H6N2), quinazoline (C8H6N2), [1,5]-naphthyridine (C8H6N2), [1,6]-naphthyridine (C8H6N2), and indole (C8H7N) molecules.
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Affiliation(s)
- S Gruet
- AILES beamline Synchrotron SOLEIL, L'Orme des Merisiers , 91190 Saint-Aubin, France.,Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS , Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - O Pirali
- AILES beamline Synchrotron SOLEIL, L'Orme des Merisiers , 91190 Saint-Aubin, France.,Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS , Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
| | - M Goubet
- Université Lille, CNRS , UMR 8523 - PhLAM - Physique des Lasers Atomes et Molécules, F-59000 Lille, France
| | - D W Tokaryk
- Physics Department, University of New Brunswick , Fredericton E3B 5A3, Canada
| | - P Brechignac
- Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS , Université Paris-Sud, Université Paris-Saclay, F-91405 Orsay, France
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Pirali O, Kisiel Z, Goubet M, Gruet S, Martin-Drumel MA, Cuisset A, Hindle F, Mouret G. Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species. J Chem Phys 2015; 142:104310. [DOI: 10.1063/1.4913750] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- O. Pirali
- AILES Beamline, Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette cedex, France
- Institut des Sciences Moléculaires d’Orsay, UMR8214 CNRS – Université Paris-Sud, Bât. 210, 91405 Orsay cedex, France
| | - Z. Kisiel
- Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - M. Goubet
- Laboratoire de Physique des Lasers, Atomes et Molécules, UMR 8523 CNRS - Université Lille 1, Bâtiment P5, F-59655 Villeneuve d’Ascq Cedex, France
| | - S. Gruet
- AILES Beamline, Synchrotron SOLEIL, l’Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette cedex, France
- Institut des Sciences Moléculaires d’Orsay, UMR8214 CNRS – Université Paris-Sud, Bât. 210, 91405 Orsay cedex, France
| | - M. A. Martin-Drumel
- Laboratoire de Physico-Chimie de l’Atmosphère, EA-4493, Université du Littoral – Côte d’Opale, 59140 Dunkerque, France
| | - A. Cuisset
- Laboratoire de Physico-Chimie de l’Atmosphère, EA-4493, Université du Littoral – Côte d’Opale, 59140 Dunkerque, France
| | - F. Hindle
- Laboratoire de Physico-Chimie de l’Atmosphère, EA-4493, Université du Littoral – Côte d’Opale, 59140 Dunkerque, France
| | - G. Mouret
- Laboratoire de Physico-Chimie de l’Atmosphère, EA-4493, Université du Littoral – Côte d’Opale, 59140 Dunkerque, France
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Gruet S, Goubet M, Pirali O. High resolution measurements supported by electronic structure calculations of two naphthalene derivatives: [1,5]- and [1,6]-naphthyridine—Estimation of the zero point inertial defect for planar polycyclic aromatic compounds. J Chem Phys 2014; 140:234308. [DOI: 10.1063/1.4882652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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