We report the analysis of the structure and dynamics of the calix[4]arene bis-crown derivative (Dc3) and the host-guest system formed by Dc3 and acetonitrile in a chloroform solution. NMR spectral measurements, molecular mechanics, and molecular dynamics calculations have been used. Results showed that the host-guest complex in solution has chemical shift values that are considerably different from those of the pure compounds and from the Dc3-acetonitrile mixture. Molecular mechanics simulations showed that Dc3 has a cavity with an almost circular cone shape and that the CN group of acetonitrile in the host-guest complex pointed toward the outside of the cavity. This orientation appeared energetically favored. The value of the generalized order parameter (S2) from13C-NMR relaxation rates also showed that the methyl group of acetonitrile behaved as a free rotor in the Dc3 cavity with reorientational motion of almost two orders of magnitude faster than the aromatic carbons.

Analysis of the p-tert-butylcalix[4]arene bis-crown Derivative (DC3)-Acetonitrile Host-Guest Complexing Behavior by Nuclear Magnetic Resonance (NMR) Spectroscopy and Computational Methods / C., Bonechi; A., Donati; S., Martini; C., Rossi; Arduini, Arturo; Pochini, Andrea; B., Lonetti; P., Baglioni. - In: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL. - ISSN 1520-6106. - 108(2004), pp. 7603-7610. [10.1021/jp037464e]

Analysis of the p-tert-butylcalix[4]arene bis-crown Derivative (DC3)-Acetonitrile Host-Guest Complexing Behavior by Nuclear Magnetic Resonance (NMR) Spectroscopy and Computational Methods

ARDUINI, Arturo;POCHINI, Andrea;
2004

Abstract

We report the analysis of the structure and dynamics of the calix[4]arene bis-crown derivative (Dc3) and the host-guest system formed by Dc3 and acetonitrile in a chloroform solution. NMR spectral measurements, molecular mechanics, and molecular dynamics calculations have been used. Results showed that the host-guest complex in solution has chemical shift values that are considerably different from those of the pure compounds and from the Dc3-acetonitrile mixture. Molecular mechanics simulations showed that Dc3 has a cavity with an almost circular cone shape and that the CN group of acetonitrile in the host-guest complex pointed toward the outside of the cavity. This orientation appeared energetically favored. The value of the generalized order parameter (S2) from13C-NMR relaxation rates also showed that the methyl group of acetonitrile behaved as a free rotor in the Dc3 cavity with reorientational motion of almost two orders of magnitude faster than the aromatic carbons.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/2314320
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