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Baweja S, Antonelli E, Hussain S, Fernández-Ramos A, Kleiner I, Nguyen HVL, Sanz ME. Revealing Internal Rotation and 14N Nuclear Quadrupole Coupling in the Atmospheric Pollutant 4-Methyl-2-nitrophenol: Interplay of Microwave Spectroscopy and Quantum Chemical Calculations. Molecules 2023; 28:molecules28052153. [PMID: 36903397 PMCID: PMC10004196 DOI: 10.3390/molecules28052153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 02/17/2023] [Accepted: 02/17/2023] [Indexed: 03/02/2023] Open
Abstract
The structure and interactions of oxygenated aromatic molecules are of atmospheric interest due to their toxicity and as precursors of aerosols. Here, we present the analysis of 4-methyl-2-nitrophenol (4MNP) using chirped pulse and Fabry-Pérot Fourier transform microwave spectroscopy in combination with quantum chemical calculations. The rotational, centrifugal distortion, and 14N nuclear quadrupole coupling constants of the lowest-energy conformer of 4MNP were determined as well as the barrier to methyl internal rotation. The latter has a value of 106.4456(8) cm-1, significantly larger than those from related molecules with only one hydroxyl or nitro substituent in the same para or meta positions, respectively, as 4MNP. Our results serve as a basis to understand the interactions of 4MNP with atmospheric molecules and the influence of the electronic environment on methyl internal rotation barrier heights.
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Affiliation(s)
- Shefali Baweja
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Eleonore Antonelli
- Université Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
| | - Safia Hussain
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
| | - Antonio Fernández-Ramos
- Departamento de Química Física and Centro Singular de Investigación en Química Biolóxica e Materiais Moleculares (CIQUS), Jenaro de la Fuente s/n, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Isabelle Kleiner
- Université Paris Cité and Université Paris Est Créteil, CNRS, LISA, F-75013 Paris, France
| | - Ha Vinh Lam Nguyen
- Université Paris Est Créteil and Université Paris Cité, CNRS, LISA, F-94010 Créteil, France
- Institut Universitaire de France (IUF), 1 rue Descartes, F-75231 Paris, France
- Correspondence: (H.V.L.N.); (M.E.S.)
| | - M. Eugenia Sanz
- Department of Chemistry, King’s College London, Britannia House, 7 Trinity Street, London SE1 1DB, UK
- Correspondence: (H.V.L.N.); (M.E.S.)
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Nguyen T, Stahl W, Nguyen HVL, Kleiner I. Local vs global approaches to treat two equivalent methyl internal rotations and 14N nuclear quadrupole coupling of 2,5-dimethylpyrrole. J Chem Phys 2021; 154:204304. [PMID: 34241162 DOI: 10.1063/5.0049418] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The microwave spectrum of 2,5-dimethylpyrrole was recorded using a molecular jet Fourier transform microwave spectrometer operating in the frequency range from 2 to 26.5 GHz. Only one stable conformer was observed as expected and confirmed by quantum chemical calculations carried out to complement the experimental analysis. The two equivalent methyl groups cause each rotational transition to split into four torsional species, which is combined with the quadrupole hyperfine splittings in the same order of magnitude arising from the 14N nucleus. This results in a complicated spectrum feature. The spectral assignment was done separately for each torsional species. Two global fits were carried out using the XIAM code and the BELGI-C2v-2Tops-hyperfine code, a modified version of the BELGI-C2v-2Tops code, giving satisfactory root-mean-square deviations. The potential barriers to internal rotation of the two methyl groups were determined to be V3 = 317.208(16) cm-1. The molecular parameters were obtained with high accuracy, providing all necessary ground state information for further investigations in higher frequency ranges and on excited torsional-vibrational states.
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Affiliation(s)
- Thuy Nguyen
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, 61 avenue du Général de Gaulle, 94010 Créteil Cedex, France
| | - Wolfgang Stahl
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52074 Aachen, Germany
| | - Ha Vinh Lam Nguyen
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, 61 avenue du Général de Gaulle, 94010 Créteil Cedex, France
| | - Isabelle Kleiner
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, 61 avenue du Général de Gaulle, 94010 Créteil Cedex, France
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Nair KPR, Herbers S, Bailey WC, Obenchain DA, Lesarri A, Grabow JU, Nguyen HVL. Internal rotation and chlorine nuclear quadrupole coupling in 2-chloro-4-fluorotoluene explored by microwave spectroscopy and quantum chemistry. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2021; 247:119120. [PMID: 33189979 DOI: 10.1016/j.saa.2020.119120] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 10/11/2020] [Accepted: 10/13/2020] [Indexed: 06/11/2023]
Abstract
2-Chloro-4-fluorotoluene was investigated using a combination of molecular jet Fourier transform microwave spectroscopy in the frequency range from 5 to 21 GHz and quantum chemistry. The molecule experiences an internal rotation of the methyl group, which causes fine splittings of all rotational transitions into doublets with separation on the order of a few tens of kHz. In addition, hyperfine effects originating from the chlorine nuclear quadrupole moment coupling its nuclear spin to the end-over-end rotation of the molecule are observed. The torsional barrier was derived using both the rho and the combined-axis-method, giving a value of 462.5(41) cm-1. Accurate rotational constants and quadrupole coupling constants were determined for the 35Cl and 37Cl isotopologues and compared with Bailey's semi-experimental quantum chemical predictions. The gas phase molecular structure was deduced from the experimental rotational constants supplemented with those calculated by quantum chemistry at various levels of theory. The values of the methyl torsional barrier and chlorine nuclear quadrupole coupling constants were compared with the theoretical predictions and with those of other chlorotoluene derivatives.
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Affiliation(s)
- K P Rajappan Nair
- Institut für Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universität Hannover, Callinstraße 3A, 30167 Hannover, Germany; Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal 576104, India.
| | - Sven Herbers
- Institut für Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universität Hannover, Callinstraße 3A, 30167 Hannover, Germany
| | - William C Bailey
- Chemistry-Physics Department, Kean University, 1000 Morris Avenue, Union, NJ, USA
| | - Daniel A Obenchain
- Institut für Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universität Hannover, Callinstraße 3A, 30167 Hannover, Germany
| | - Alberto Lesarri
- Departamento de Química Física y Química Inorgánica - I.U. CINQUIMA, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid, Spain
| | - Jens-Uwe Grabow
- Institut für Physikalische Chemie und Elektrochemie, Gottfried-Wilhelm-Leibniz-Universität Hannover, Callinstraße 3A, 30167 Hannover, Germany
| | - Ha Vinh Lam Nguyen
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, 61 Avenue du Général de Gaulle, 94010 Créteil, France; Institut Universitaire de France (IUF), 1 rue Descartes, 75231 Paris Cedex 05, France.
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Pinacho P, Obenchain DA, Schnell M. New findings from old data: A semi-experimental value for the eQq of the nitrogen atom. J Chem Phys 2020; 153:234307. [DOI: 10.1063/5.0033071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Pablo Pinacho
- Deutsches Elektronen-Synchrotron (DESY), Notkestraβe 85, 22607 Hamburg, Germany
| | - Daniel A. Obenchain
- Deutsches Elektronen-Synchrotron (DESY), Notkestraβe 85, 22607 Hamburg, Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron (DESY), Notkestraβe 85, 22607 Hamburg, Germany
- Institute of Physical Chemistry, Christian-Albrechts-Universität zu Kiel, Max-Eyth-Straβe 1, 24118 Kiel, Germany
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Nguyen HVL, Kleiner I. Understanding (coupled) large amplitude motions: the interplay of microwave spectroscopy, spectral modeling, and quantum chemistry. PHYSICAL SCIENCES REVIEWS 2020. [DOI: 10.1515/psr-2020-0037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abstract
A large variety of molecules contain large amplitude motions (LAMs), inter alia internal rotation and inversion tunneling, resulting in tunneling splittings in their rotational spectrum. We will present the modern strategy to study LAMs using a combination of molecular jet Fourier transform microwave spectroscopy, spectral modeling, and quantum chemical calculations to characterize such systems by the analysis of their rotational spectra. This interplay is particularly successful in decoding complex spectra revealing LAMs and providing reference data for fundamental physics, astrochemistry, atmospheric/environmental chemistry and analytics, or fundamental researches in physical chemistry. Addressing experimental key aspects, a brief presentation on the two most popular types of state-of-the-art Fourier transform microwave spectrometer technology, i.e., pulsed supersonic jet expansion–based spectrometers employing narrow-band pulse or broad-band chirp excitation, will be given first. Secondly, the use of quantum chemistry as a supporting tool for rotational spectroscopy will be discussed with emphasis on conformational analysis. Several computer codes for fitting rotational spectra exhibiting fine structure arising from LAMs are discussed with their advantages and drawbacks. Furthermore, a number of examples will provide an overview on the wealth of information that can be drawn from the rotational spectra, leading to new insights into the molecular structure and dynamics. The focus will be on the interpretation of potential barriers and how LAMs can act as sensors within molecules to help us understand the molecular behavior in the laboratory and nature.
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Affiliation(s)
- Ha Vinh Lam Nguyen
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583 , Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace , 61 avenue du Général de Gaulle, F-94010 , Créteil , France
- Institut Universitaire de France (IUF) , 1 rue Descartes, F-75231 Paris cedex 05, France
| | - Isabelle Kleiner
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583 , Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace , 61 avenue du Général de Gaulle, F-94010 , Créteil , France
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Van V, Nguyen T, Stahl W, Nguyen HVL, Kleiner I. Coupled large amplitude motions: The effects of two methyl internal rotations and 14N quadrupole coupling in 4,5-dimethylthiazole investigated by microwave spectroscopy. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.127787] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hakiri R, Derbel N, Bailey WC, Nguyen HVL, Mouhib H. The heavy atom structures and 33S quadrupole coupling constants of 2-thiophenecarboxaldehyde: insights from microwave spectroscopy. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1728406] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Rihab Hakiri
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications, Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar, Tunis, Tunisia
- Laboratoire Modélisation et Simulation Multi Echelle (MSME), CNRS UMR 8208, Université Paris-Est Marne-la-Vallée, France
| | - Najoua Derbel
- Laboratoire de Spectroscopie Atomique, Moléculaire et Applications, Département de Physique, Faculté des Sciences de Tunis, University of Tunis El Manar, Tunis, Tunisia
| | | | - Ha Vinh Lam Nguyen
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Université Paris-Est Créteil, Université de Paris, Institut Pierre Simon Laplace, Créteil, France
| | - Halima Mouhib
- Laboratoire Modélisation et Simulation Multi Echelle (MSME), CNRS UMR 8208, Université Paris-Est Marne-la-Vallée, France
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