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Cabezas C, Bermúdez C, Tercero B, Cernicharo J. The millimeter-wave spectrum and astronomical search for ethyl methyl sulfide. ASTRONOMY AND ASTROPHYSICS 2020; 639:A129. [PMID: 32724240 PMCID: PMC7115819 DOI: 10.1051/0004-6361/202038177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
CONTEXT Sulfur-containing molecules constitute only 8% of the molecules observed in the interstellar medium (ISM), in spite of the fact that sulfur has been shown to be an abundant element in the ISM. In order to understand the chemical behavior of the ISM and specific cases like the missing sulfur reservoir, a detailed chemical molecular composition in the ISM must be mapped out. AIMS Our goal is to investigate the rotational spectrum of ethyl methyl sulfide, CH3CH2SCH3, which ms to be a potential candidate for observation in the ISM since the simpler analogs, CH3SH and CH3CH2SH, have already been detected. Rotational spectrum of ethyl methyl sulfide has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the ISM. METHODS The rotational spectrum of ethyl methyl sulfide in the frequency range 72-116.5 GHz was measured using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches and identification of the vibrational excited states of ethyl methyl sulfide was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. RESULTS The rotational spectra for the trans and gauche conformers of ethyl methyl sulfide was analyzed, and a total of 172 and 259 rotational transitions were observed for each one, respectively. The observation of A - E internal rotation splittings allowed the experimental determination of the V 3 hindered internal rotation barrier height for both trans and gauche species. In addition, the vibrational excited states, resulting from the lowest frequency vibrational mode ν 30 were identified for both conformers. The new experimental rotational parameters were employed to search for ethyl methyl sulfide in the warm and cold molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30 m at 3 mm and 2 mm. CONCLUSIONS
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Affiliation(s)
- C. Cabezas
- Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/Serrano 123, 28006 Madrid, Spain
| | - C. Bermúdez
- Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/Serrano 123, 28006 Madrid, Spain
| | - B. Tercero
- Observatorio de Yebes (IGN), Cerro de la Palera s/n, 19141 Yebes, Guadalajara, Spain
- Observatorio Astronómico Nacional (OAN-IGN), C/Alfonso XII 3, 28014 Madrid, Spain
| | - J. Cernicharo
- Instituto de Física Fundamental (IFF-CSIC). Group of Molecular Astrophysics, C/Serrano 123, 28006 Madrid, Spain
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O’Brien RA, Mirjafari A, Mattson KM, Murray SM, Mobarrez N, Salter EA, Wierzbicki A, Davis JH, West KN. The Effect of the Sulfur Position on the Melting Points of Lipidic 1-Methyl-3-Thiaalkylimidazolium Ionic Liquids. J Phys Chem B 2014; 118:10232-9. [DOI: 10.1021/jp5058513] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Arsalan Mirjafari
- Department
of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, Florida 33965, United States
| | | | | | - Niloufar Mobarrez
- Department
of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, Florida 33965, United States
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Brédas J, Dufey M, Fripiat J, Andre J. Ab initio SCF-LCAO-MO study of conformational stability and internal rotation in n-butane, ethyl methyl ether and ethyl methyl sulphide. Mol Phys 2006. [DOI: 10.1080/00268978300102061] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- J.L. Brédas
- Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix , Rue de Bruxelles, 61, B-5000, Namur, Belgium
| | - M. Dufey
- Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix , Rue de Bruxelles, 61, B-5000, Namur, Belgium
| | - J.G. Fripiat
- Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix , Rue de Bruxelles, 61, B-5000, Namur, Belgium
| | - J.M. Andre
- Laboratoire de Chimie Théorique Appliquée, Facultés Universitaires Notre-Dame de la Paix , Rue de Bruxelles, 61, B-5000, Namur, Belgium
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Ohsaku M, Imamura A. Anab initioSCF MO study of conformational stability in ethyl methyl sulphide. Mol Phys 2006. [DOI: 10.1080/00268978500101361] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Vansteenkiste P, Pauwels E, Van Speybroeck V, Waroquier M. Rules for Generating Conformers and Their Relative Energies in n-Alkanes with a Heteroelement O or S: Ethers and Alcohols, or Sulfides and Thiols. J Phys Chem A 2005; 109:9617-26. [PMID: 16866415 DOI: 10.1021/jp051910b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With the aid of density functional theory calculations, all conformers of several single-chain alcohols, thiols, ethers, and sulfides are investigated. Starting from earlier computational works on n-alkanes, we construct an extended set of general rules for predicting the number and occurrence of conformers in these oxygen- or sulfur-containing compounds. In alcohols and thiols, it is found that only the conformers generated by internal rotations in the HXCH(2)CH(2)CH(2) (X = O or S) top are distinctive from those in n-alkanes. In ethers and sulfides, the primary influence of the heteroelement also extends up to three internal rotations, but many more conformers are possible. However, a number of double gauche sequences are forbidden, and therefore, several conformers can be eliminated. These exclusions in particular make up a set of rules for eventually deducing all possible conformers. Furthermore, on the basis of only an exact calculation of these gg conformations in addition to single gauche conformers, it is possible to make an accurate estimate of the relative energy. This two-dimensional approximation scheme constitutes an effective tool for adequately describing the relative energies of all possible conformers at a minimal computational cost.
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Affiliation(s)
- P Vansteenkiste
- Center for Molecular Modeling, Laboratory of Theoretical Physics, Ghent University, Proeftuinstraat 86, B-9000 Gent, Belgium
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Butterfoss GL, Hermans J. Boltzmann-type distribution of side-chain conformation in proteins. Protein Sci 2003; 12:2719-31. [PMID: 14627733 PMCID: PMC2366981 DOI: 10.1110/ps.03273303] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2003] [Revised: 08/29/2003] [Accepted: 08/29/2003] [Indexed: 10/26/2022]
Abstract
We analyze packing imperfections in globular proteins as reflected in deviations of torsion angles from the equilibrium values for the isolated side chains. The distribution of conformations of methionine and lysine residues in a database of high-resolution structures is compared with energies of model compounds calculated with high-level quantum-mechanics. The distribution of the C-C and C-S torsion angles (chi(3)) correlates well with the Boltzmann factor of the torsion energy, exp(-betaE) of the model compounds C(2)H(5)-C(2)H(5) and C(2)H(5)-S-CH(3). An exponential relation was again found between the relative occurrence of g+, g- and t conformations for C(alpha)-C(beta) bonds in long side chains and the energy differences of rotamers of alpha-amino n-butyric acid, when dependence on backbone conformation was taken into account. The distribution of all 27 rotamers of methionine was correlated with the energy differences between the model's rotamers, corrected for clashes with nearby residues, the correlation being good for a set with backbone in the beta-conformation, but less clear for backbone alpha-conformation. In all correlations, the value of the coefficient beta corresponds to a temperature of circa 300 K. These results can be interpreted with a model that considers the structure of a folded protein as resulting from packing imperfectly complementary parts, with a requirement of an overall low energy. Compromises are required to optimize the fit of nonbonded contacts with surrounding groups, and side chains assume conformations away from the energy minimum. An exponential distribution is a most probable distribution, and this can be established easily under conditions other than thermal equilibrium.
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Affiliation(s)
- Glenn L Butterfoss
- Department of Biochemistry and Biophysics, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599-7260, USA
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Plusquellic DF, Suenram RD, Maté B, Jensen JO, Samuels AC. The conformational structures and dipole moments of ethyl sulfide in the gas phase. J Chem Phys 2001. [DOI: 10.1063/1.1385527] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Yokoyama Y, Ohashi Y. Crystal and Molecular Structures of Methoxy and Methylthio Compounds. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1999. [DOI: 10.1246/bcsj.72.2183] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Szász G, Kovács A, Hargittai I, Jeon I, Miller GP. Molecular Structure and Molecular Vibrations of 1,3,5,7,-Tetramethyl-2,4,6,8,9,10- Hexathiaadamantane. J Phys Chem A 1998. [DOI: 10.1021/jp972828m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Conformational energy profiles of n-butane, ethyl methyl ether and ethyl methyl sulfide Comparison of electron correlation correction procedures. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/0166-1280(96)04522-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Taccone R, Salinovich O. Semi-empirical calculations on bis-halomethyl sulfides. A comparison of the structures and other parameters by MNDO, AM1 and PM3 methods. J Fluor Chem 1995. [DOI: 10.1016/0022-1139(94)03082-b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Durig J, Phan H, Bergana M, Rollins M, Gulick J, Odom J, Hudson S. Infrared and Raman spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of ethyl methyl selenide. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0584-8539(94)80157-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Toyota S, Oki M. Structure of and Tetrahedral Character of the Boron Atom in 9-[2-(1-Ethylthiopentyl)phenyl]-9-borabicyclo[3.3.1]nonane. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1992. [DOI: 10.1246/bcsj.65.2857] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Durig J, Rollins M, Phan H. Conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of ethyl methyl sulfide. J Mol Struct 1991. [DOI: 10.1016/0022-2860(91)80059-d] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Allinger NL, Quinn M, Rahman M, Chen K. Molecular Mechanics (MM3) calculations on sulfides. J PHYS ORG CHEM 1991. [DOI: 10.1002/poc.610041102] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Molecular structure and conformation of diisopropyl sulfide in the vapor phase: reinvestigation by molecular orbital constrained electron diffraction. J Mol Struct 1990. [DOI: 10.1016/0022-2860(90)80505-e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Fausto R, Teixeira-Dias J, Carey P. A molecular mechanics force field for conformational analysis of alkanethiols and thioethers. J Mol Struct 1987. [DOI: 10.1016/0022-2860(87)85013-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Photoelectron spectra and electronic structure of (Alkylthiomethyl)trimethoxysilanes. Russ Chem Bull 1986. [DOI: 10.1007/bf00955367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Ultraviolet absorption spectra and electronic structure of dialkyl sulfides. J STRUCT CHEM+ 1986. [DOI: 10.1007/bf00748360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Tsuboyama A, Konaka S, Kimura M. Molecular structure of DI-t-butylsulphide as determined by gas electron diffraction. J Mol Struct 1985. [DOI: 10.1016/0022-2860(85)80151-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Sakakibara M, Yonemura Y, Tanaka Z, Matsumoto S, Fukuyama K, Matsuura H, Murata H. Vibrational spectra and crystal structure of ethyl methyl sulfide-mercury(II) chloride complex. J Mol Struct 1980. [DOI: 10.1016/0022-2860(80)85263-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Ohno K, Mitsui A, Murata H. Vibrational Spectra and Rotational Isomerism of Isopropyl Methyl Selenide and Diisopropyl Selenide. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1979. [DOI: 10.1246/bcsj.52.2178] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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