INVESTIGATION OF MOLECULAR INTERACTION BETWEEN PHENYLACETYLENE AND HEXAMETHYLPHOSPHORIC TRIAMIDE BY 13C NMR T1 RELAXATION TIME STUDIES AND AB INITIO QM CALCULATIONS

https://doi.org/10.22146/ijc.21668

Parsaoran Siahaan(1*), Cynthia L. Radiman(2), Susanto Imam Rahayu(3), Muhamad A. Martoprawiro(4), Dieter Ziessow(5)

(1) Chemistry Study Program, Faculty of Mathematics and Natural Sciences, Jl Ganesha 10 Bandung Indonesia
(2) Inorganic and Physical Chemistry, FMIPA ITB, Jl Ganesha 10 Bandung Indonesia
(3) Inorganic and Physical Chemistry, FMIPA ITB, Jl Ganesha 10 Bandung Indonesia
(4) Inorganic and Physical Chemistry, FMIPA ITB, Jl Ganesha 10 Bandung Indonesia
(5) Stranski Laboratory for Physical and Theoretical Chemistry TU Berlin, Germany
(*) Corresponding Author

Abstract


Intermolecular interactions and molecular translational and rotational mobility are key factors in molecular material sciences, e.g. liquid crystals. One of the important substructures is given by phenylacetylene, Ph-CºCH. Its rotational behavior in its pure form and in high dilution in hexamethylphosphoric triamide OP[N(CH3)2]3 (HMPA) has been studied by means 13C NMR T1 relaxation times at ambient temperature as measured by the inversion recovery method. HMPA is an exceptional solvent in that is has a quite large dipole moment but comparatively low relative dielectricity constant. From the molecular shape Ph-CºCH is expected to exhibit anisotropic rotational diffusion which in fact can be deduced from the measured set of T1 values of the ortho, meta and para carbon nuclei in the neat liquid as well as in the HMPA solution. This expected result rules the dominance of a linearly molecules pair Ph-CºCH...HMPA along their dipole moment axes as anticipated in view of the large HMPA dipole moment. In order to conform with the T1 data, a linear arrangement of Ph-CºCH via the interaction between its weakly acidic H-atom with negatively charge O-atom of HMPA molecules seems to lead to such an anisotropic rotational motion. This hypothesis is supported by ab initio QM calculations which come out with higher interaction energy for linear orientation than other geometries. These ab initio calculations were performed with the basis set of RHF/6-31G(d) for the single molecules of Ph-CºCH and HMPA as well as for their various geometries of the molecules pair. Molecular dynamics simulations need to be performed for further confirmation.


Keywords


Relaxation Times; HMPA; pheylacetylene; ab initio; intermolecular interaction; rotational diffusion

Full Text:

Full Text PDF


References

[1] Deitz, V. and Andrews, D.H., Kirchner, 1933, J. Chem. Phys., 1, 62-67.

[2] Woessner, D.E., 1962, J. Chem. Phys, 36(1), 1-4.

[3] Huntress Jr, W.T., 1967, J. Chem. Phys, 48(8), 3524-3533.

[4] Carrington, A. and McLachlan, A.D., 1967, Introduction to Magnetic Resonance: with Applications to Chemistry and Chemical Physics, New York, Harper & Row and John Weatherhill, Inc.

[5] Huntress Jr., W.T., 1970, The Study of Anisotropic Rotation of Molecules in Liquids by NMR Quadrupolar Relaxation, Advances in Magnetic Resonance, editor: John S. Waugh, Vol.4, New York, Academic Press.

[6] Davis Jr., J.C. and Deb, K.K., 1970, Analysis of Hydrogen Bonding and Related Association Equilibria by Nuclear Magnetic Resonance, Advances in Magnetic Resonance, editor: John S. Waugh, Vol.4, New York, Academic Press.

[7] Levy, G.C. (editor), 1974, Topics in Carbon-13 NMR Spectroscopy, Vol. 1, New York, John Wiley & Sons, Inc.

[8] Levy, G.C. (editor), 1976, Topics in Carbon-13 NMR Spectroscopy, Vol. 2, New York, John Wiley & Sons, Inc.

[9] Abragam, A., 1978, The Principles of Nuclear Magnetism, The International Series of Monographs on Physics, editors: W.C. Marshall and D.H., Wilkinson, Oxford, Oxford University Press.

[10] Yasukawa, T and Chachaty, C., 1976, Chem. Phys. Lett., 43(3), 565-567.

[11] Yasukawa, T and Chachaty, C., 1977, Chem. Phys. Lett., 51(2), 311-314.

[12] Kratochwill, A., Vold, R.L., Vold, R.R., 1979, J. Chem. Phys., 71(3), 1319-1324.

[13] Dölle, A. and Suhm, M.A., and Weingartner, H., 1991, J. Chem. Phys., 94, 3361-3365.

[14] Abseher, R., Lüdemann, S., Schreiber, H., and Stein hauser, O., 1994, J. Am. Chem. Soc., 116, 4006-4018.

[15] Kowalewski, J., and Widmalm, G., 1994, J. Phys. Chem., 98, 28-34.

[16] Martoprawiro, M.A. and Bacskay, G.B., 1995, Molecular Physics, 85(3), 573-585.

[17] Sass, M. and Ziessow, D., 1977, J. Mag. Res., 25, 263-276.



DOI: https://doi.org/10.22146/ijc.21668

Article Metrics

Abstract views : 864 | views : 846


Copyright (c) 2010 Indonesian Journal of Chemistry

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

 


Indonesian Journal of Chemistry (ISSN 1411-9420 / 2460-1578) - Chemistry Department, Universitas Gadjah Mada, Indonesia.

Web
Analytics View The Statistics of Indones. J. Chem.