Expected Radial Column Density of Methylcyanopolyynes in CW Leonis (IRC+10216)
Affiliation(s)
1 Centre for Environmental Sciences and Department of Chemistry Faculty of Sciences, Universidad de Chile, Santiago, Chile. 2 Department of Chemistry, Faculty of Basic Sciences Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile.
1 Centre for Environmental Sciences and Department of Chemistry Faculty of Sciences, Universidad de Chile, Santiago, Chile. 2 Department of Chemistry, Faculty of Basic Sciences Universidad Metropolitana de Ciencias de la Educación, Santiago, Chile.
ABSTRACT
Methylcyanopolyynes (CH3-[C≡C]n-CN) are a particular kind of linear molecular wires, where the first three oligomers have been detected in the interstellar medium, particularly in CW Leonis (IRC + 10216), as well as in the envelopes of carbon-rich stars in a similar way to the unsubstituted cyanopolyynes. Based on the projected natural distribution in cold clouds under LTE, we have determined the radial column density of new expected methylcyanopolyynes to be present in CW Leonis (IRC + 10216). By following, we have made use of the inner molecular resistances of the internal charge transfer process presenting in these oligomeric species in order to determine the reactivity trends between them. Therefore, geometrical parameters and dipole moments determinations for these methylcyanopolyynes involving the n = 1 to 14 molecular species were obtained from Ab initio molecular orbital calculations by means of a GAUSSIAN Program, using a restricted Hartree-Fock approach and 6-311G* basis set. Our results present a similar behavior observed in cyanopolyynes, where this series reaches a saturation level at the 14th oligomer with a maximum dipole moment of 8.21 ± 0.01 (Debyes). Thus, this molecular wire model permits us to comprehend how these methylcyanopolyynes reach a maximum length in such chemical environment, in agreement to the astronomical observations and cosmological chemical models. The following CH3C9N and CH3C11N oligomers in CW Leonis should be expected near to 3.52 × 1010 [cm2] and 1.82 × 1010 [cm2], respectively.
Methylcyanopolyynes (CH3-[C≡C]n-CN) are a particular kind of linear molecular wires, where the first three oligomers have been detected in the interstellar medium, particularly in CW Leonis (IRC + 10216), as well as in the envelopes of carbon-rich stars in a similar way to the unsubstituted cyanopolyynes. Based on the projected natural distribution in cold clouds under LTE, we have determined the radial column density of new expected methylcyanopolyynes to be present in CW Leonis (IRC + 10216). By following, we have made use of the inner molecular resistances of the internal charge transfer process presenting in these oligomeric species in order to determine the reactivity trends between them. Therefore, geometrical parameters and dipole moments determinations for these methylcyanopolyynes involving the n = 1 to 14 molecular species were obtained from Ab initio molecular orbital calculations by means of a GAUSSIAN Program, using a restricted Hartree-Fock approach and 6-311G* basis set. Our results present a similar behavior observed in cyanopolyynes, where this series reaches a saturation level at the 14th oligomer with a maximum dipole moment of 8.21 ± 0.01 (Debyes). Thus, this molecular wire model permits us to comprehend how these methylcyanopolyynes reach a maximum length in such chemical environment, in agreement to the astronomical observations and cosmological chemical models. The following CH3C9N and CH3C11N oligomers in CW Leonis should be expected near to 3.52 × 1010 [cm2] and 1.82 × 1010 [cm2], respectively.
KEYWORDS
Methylcyanopolyynes, Dipole Moments, Inner Molecular Resistances, Organic Molecular Wires, ISM Radial Column Density
Methylcyanopolyynes, Dipole Moments, Inner Molecular Resistances, Organic Molecular Wires, ISM Radial Column Density
Cite this paper
Morales, R. and Hernández, C. (2015) Expected Radial Column Density of Methylcyanopolyynes in CW Leonis (IRC+10216). International Journal of Astronomy and Astrophysics, 5, 141-147. doi: 10.4236/ijaa.2015.53018.
Morales, R. and Hernández, C. (2015) Expected Radial Column Density of Methylcyanopolyynes in CW Leonis (IRC+10216). International Journal of Astronomy and Astrophysics, 5, 141-147. doi: 10.4236/ijaa.2015.53018.
References
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http://dx.doi.org/10.1088/2041-8205/763/2/L38 [3] Jorgensen, J.K., Favre, C., Bisschop, S.E., Bourke, T.L., van Dishoeck, E.F. and Schmalzl, M. (2012) Detection of the Simplest Sugar, Glycolaldehyde, in a Solar-type Protostar with ALMA. Astrophysical Journal Letters, 757, L4-L9.
http://dx.doi.org/10.1088/2041-8205/757/1/L4 [4] Herbst, E. and van Dishoeck, E.F. (2009) Complex Organic Interstellar Molecules. Annual Review of Astronomy and Astrophysics, 47, 427-480.
http://dx.doi.org/10.1146/annurev-astro-082708-101654 [5] Pardo, J.R., Cernicharo, J. and Goicoechea, J.R. (2005) Observational Evidence of the Formation of Cyanopolyynes in CRL 618 through the Polymerization of HCN. Astrophysical Journal, 628, 275-282.
http://dx.doi.org/10.1086/430774 [6] Woods, P.M., Millar, T.J., Herbst, E. and Zijlstra, A.A. (2003) The Chemistry of Protoplanetary Nebulae. Astronomy and Astrophysics, 402, 189-199.
http://dx.doi.org/10.1051/0004-6361:20030215 [7] Millar, T.J., Herbst, E. and Bettens, R.P.A. (2000) Large Molecules in the Envelope Surrounding IRC+10o216. Monthly Notices of theRoyal Astronomical Society, 316, 195-203. [8] Cordiner, M.A. and Millar, T.J. (2009) Density-Enhanced Gas and Dust Shells in a New Chemical Model for IRC+10216. Astrophysical Journal, 697, 68-78.
http://dx.doi.org/10.1088/0004-637X/697/1/68 [9] Morales, R.G.E. and González-Rojas, C. (2005) Dipole Moments of Polyenic Oligomeric Systems. Part II. Molecular Organic Wire Resistivities: Polyacetylenes, Allenes and Polylines. Journal of Physical Organic Chemistry, 18, 941-944.
http://dx.doi.org/10.1002/poc.931 [10] McCarthy, M.C., Chen, W., Travers, M.J. and Thaddeus, P. (2000) Microwave Spectra of 11 Polyyne Carbon Chains. Astrophysical Journal, 129, 611-623.
http://dx.doi.org/10.1086/313428 [11] Bell, M.B., Feldman, P.A., Kwok, S. and Matthews, H.E. (1982) Detection of HC11N in IRC+10°216. Nature, 295, 389-391.
http://dx.doi.org/10.1038/295389a0 [12] Bell, M.B., Feldman, P.A., Travers, M.J., McCarthy, M.C., Gottlieband, C.A. and Thaddeus, P. (1997) Detection of HC11N in the Cold Dust Cloud TMC-1. Astrophysical Journal Letters, 483, L61-L64.
http://dx.doi.org/10.1086/310732 [13] Kroto, H.W., Kirby, C., Walton, R.M., Avery, L.W., Broten, N.W., MacLeod, J.M. and Oka, T. (1978) The Detection of Cyanohexatriyne, H(CC3)CN, in Heiles’ Cloud 2. Astrophysical Journal Letters, 219, L133-L137.
http://dx.doi.org/10.1086/182623 [14] Smith, D. (1992) The Ion Chemistry of Interstellar Clouds. Chemical Reviews, 92, 1473-1485.
http://dx.doi.org/10.1021/cr00015a001 [15] Carter, F.L. (1986) Molecular Electronic Devices. Marcel Dekker Inc., New York. [16] Joachim, C. and Roth, S. (1997) Atomic and Molecular Wires. Kluwer Academic Publishers, Alphen aan den Rijn.
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http://dx.doi.org/10.1021/j100147a016 [19] Morales, R.G.E. and Hernández, C. (2012) Cyanopolyynes as Organic Molecular Wires in the Interstellar Medium. International Journal of Astronomy and Astrophysics, 2, 230-235.
http://dx.doi.org/10.4236/ijaa.2012.24030 [20] Morales, R.G.E. and González-Rojas, C. (1998) Dipole Moments of Polyenic Oligomeric Systems. Part I. A One-Dimensional Molecular Wire Model. Journal of Physical Organic Chemistry, 11, 853-856.
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[1] M üller, H.S.P., Goicoechea, J.R., Cernicharo, J., Agúndez, M., Pety, J., Cuadrado, S., Gerin, M., Dumas, G. and Chapillon, E. (2014) Revised Spectroscopic Parameters of SH+ from ALMA and IRAM 30 m observations. Astronomy and Astrophysics, 569, L5-L9.
http://dx.doi.org/10.1051/0004-6361/201424756 [2] Kahane, C., Ceccarelli, C., Faure, A. and Caux, E. (2013) Detection of Formamide, the Simplest but Crucial Amide, in a Solar-type Protostar. Astrophysical Journal Letters, 763, L38-L42.
http://dx.doi.org/10.1088/2041-8205/763/2/L38 [3] Jorgensen, J.K., Favre, C., Bisschop, S.E., Bourke, T.L., van Dishoeck, E.F. and Schmalzl, M. (2012) Detection of the Simplest Sugar, Glycolaldehyde, in a Solar-type Protostar with ALMA. Astrophysical Journal Letters, 757, L4-L9.
http://dx.doi.org/10.1088/2041-8205/757/1/L4 [4] Herbst, E. and van Dishoeck, E.F. (2009) Complex Organic Interstellar Molecules. Annual Review of Astronomy and Astrophysics, 47, 427-480.
http://dx.doi.org/10.1146/annurev-astro-082708-101654 [5] Pardo, J.R., Cernicharo, J. and Goicoechea, J.R. (2005) Observational Evidence of the Formation of Cyanopolyynes in CRL 618 through the Polymerization of HCN. Astrophysical Journal, 628, 275-282.
http://dx.doi.org/10.1086/430774 [6] Woods, P.M., Millar, T.J., Herbst, E. and Zijlstra, A.A. (2003) The Chemistry of Protoplanetary Nebulae. Astronomy and Astrophysics, 402, 189-199.
http://dx.doi.org/10.1051/0004-6361:20030215 [7] Millar, T.J., Herbst, E. and Bettens, R.P.A. (2000) Large Molecules in the Envelope Surrounding IRC+10o216. Monthly Notices of theRoyal Astronomical Society, 316, 195-203. [8] Cordiner, M.A. and Millar, T.J. (2009) Density-Enhanced Gas and Dust Shells in a New Chemical Model for IRC+10216. Astrophysical Journal, 697, 68-78.
http://dx.doi.org/10.1088/0004-637X/697/1/68 [9] Morales, R.G.E. and González-Rojas, C. (2005) Dipole Moments of Polyenic Oligomeric Systems. Part II. Molecular Organic Wire Resistivities: Polyacetylenes, Allenes and Polylines. Journal of Physical Organic Chemistry, 18, 941-944.
http://dx.doi.org/10.1002/poc.931 [10] McCarthy, M.C., Chen, W., Travers, M.J. and Thaddeus, P. (2000) Microwave Spectra of 11 Polyyne Carbon Chains. Astrophysical Journal, 129, 611-623.
http://dx.doi.org/10.1086/313428 [11] Bell, M.B., Feldman, P.A., Kwok, S. and Matthews, H.E. (1982) Detection of HC11N in IRC+10°216. Nature, 295, 389-391.
http://dx.doi.org/10.1038/295389a0 [12] Bell, M.B., Feldman, P.A., Travers, M.J., McCarthy, M.C., Gottlieband, C.A. and Thaddeus, P. (1997) Detection of HC11N in the Cold Dust Cloud TMC-1. Astrophysical Journal Letters, 483, L61-L64.
http://dx.doi.org/10.1086/310732 [13] Kroto, H.W., Kirby, C., Walton, R.M., Avery, L.W., Broten, N.W., MacLeod, J.M. and Oka, T. (1978) The Detection of Cyanohexatriyne, H(CC3)CN, in Heiles’ Cloud 2. Astrophysical Journal Letters, 219, L133-L137.
http://dx.doi.org/10.1086/182623 [14] Smith, D. (1992) The Ion Chemistry of Interstellar Clouds. Chemical Reviews, 92, 1473-1485.
http://dx.doi.org/10.1021/cr00015a001 [15] Carter, F.L. (1986) Molecular Electronic Devices. Marcel Dekker Inc., New York. [16] Joachim, C. and Roth, S. (1997) Atomic and Molecular Wires. Kluwer Academic Publishers, Alphen aan den Rijn.
http://dx.doi.org/10.1007/978-94-011-5882-4 [17] James, D.K. and Tour, J.M. (2005) Molecular Wires. Topics in Current Chemistry, 257, 33-62.
http://dx.doi.org/10.1007/b136066 [18] Hernández, C. and Morales, R.G.E. (1993) Bridge Effect in Charge-Transfer Photoconduction Channels. 1. Aromatic Carbonyl Compounds. Journal of Physical Chemistry, 97, 11649-11651.
http://dx.doi.org/10.1021/j100147a016 [19] Morales, R.G.E. and Hernández, C. (2012) Cyanopolyynes as Organic Molecular Wires in the Interstellar Medium. International Journal of Astronomy and Astrophysics, 2, 230-235.
http://dx.doi.org/10.4236/ijaa.2012.24030 [20] Morales, R.G.E. and González-Rojas, C. (1998) Dipole Moments of Polyenic Oligomeric Systems. Part I. A One-Dimensional Molecular Wire Model. Journal of Physical Organic Chemistry, 11, 853-856.
http://dx.doi.org/10.1002/(SICI)1099-1395(199812)11:12<853::AID-POC74>3.0.CO;2-Y [21] González, C. and Morales, R.G.E. (1999) Molecular Resistivities in Organic Polyenic Wires. I. A One-Dimensional Photoconduction Charge Transfer Model. Chemical Physics, 250, 279-284.
http://dx.doi.org/10.1016/S0301-0104(99)00335-3 [22] Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., Petersson, G.A., Nakatsuji, H., Caricato, M., Li, X., Hratchian, H.P., Izmaylov, A.F., Bloino, J., Zheng, G., Sonnenberg, J.L., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa, J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Vreven, T., Montgomery Jr., J.A. Peralta, J.E., Ogliaro, F., Bearpark, M., Heyd, J.J., Brothers, E., Kudin, K.N., Staroverov, V.N., Kobayashi, R., Normand, J., Raghavachari, K., Rendell, A., Burant, J.C., Iyengar, S.S., Tomasi, J., Cossi, M., Rega, N., Millam, J.M., Klene, M., Knox, J.E., Cross, J.B., Bakken, V., Adamo, C., Jaramillo, J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J.W., Martin, R.L., Morokuma, K., Zakrzewski, V.G., Voth, G.A., Salvador, P., Dannenberg, J.J., Dapprich, S., Daniels, A.D., Farkas, O., Foresman, J.B., Ortiz, J.V., Cioslowski, J. and Fox, D.J. (2009) Gaussian 09, Revision A.01. Gaussian, Inc., Wallingford.