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Dynamics of Chloromethanes in Cryptophane-E Inclusion Complexes: A H-2 Solid State NMR and X-ray Diffraction Study
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
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2005 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 109, no 20, 4442-4451 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, we present a variable temperature 2H solid-state NMR investigation of cryptophane-E:chloroform and cryptophane-E:dichloromethane inclusion complexes. The 2H line shapes and nuclear spin relaxation rates were analyzed in terms of the distribution of C−D bond orientations and the time scale of the guest dynamics. It was found that encaged chloroform produces broad 2H spectra, and that its reorientation is relatively slow with a correlation time of 0.17 μs at 292 K. In contrast, the 2H line shapes of encaged dichloromethane are narrow and the motion of this guest molecule is fast with a correlation time of 1.4 ps at 283 K. The 2H NMR data were complemented by an X-ray diffraction study of the cryptophane-E:dichloromethane structure, which was utilized in the analysis of the NMR parameters.

Place, publisher, year, edition, pages
2005. Vol. 109, no 20, 4442-4451 p.
Keyword [en]
National Category
Chemical Sciences
URN: urn:nbn:se:su:diva-23552DOI: 10.1021/jp044884aOAI: diva2:192767
Available from: 2005-01-28 Created: 2005-01-28 Last updated: 2010-10-29Bibliographically approved
In thesis
1. NMR Investigations of Host-Guest Complexes and Their Dynamic Properties
Open this publication in new window or tab >>NMR Investigations of Host-Guest Complexes and Their Dynamic Properties
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[cs]
Studium "host-guest" komplexu a jejich dynamickeho chovani metodami NMR
Abstract [en]

This thesis discusses several different methods offered by solution and solid state nuclear magnetic resonance for investigation of host-guest complexes and their constituents. The presented methods were used especially (but not exclusively) to address rotational dynamics of the bound guest in different molecular systems.

The main part of this thesis presents results of a project that combines and compares solution and solid state NMR investigations of inclusion complexes of a spherical, cage-like molecule of cryptophane-E with small neutral guest molecules like chlorinated methanes. Strong and weak bonding of these host--guest systems is studied in solution using C-13 NMR relaxation and in the crystalline form, using advanced dipolar recoupling methods as well as deuterium NMR lineshape and spin relaxation analysis. Comparison of the results from all the techniques suggests very similar guest behaviour regardless of the physical state of the system. Residing inside the cavity, CHCl3 behaves almost as an integral part of cryptophane-E, whereas the reorientation of CH2Cl2 is influenced only slightly by weak interactions with its host.

Molecular flexibility of thiacalix[4]arenes, a new class of the very popular calixarene family, was also studied by C-13 NMR relaxation in solution. Calixarenes are widely used in supramolecular chemistry as building blocks of receptors to many guest molecules.

The thesis is completed with examination of a β-cyclodextrin (β-CD) inclusion complex with adamantanecarboxylic acid (AdCA) where changes of translational and rotational diffusion properties of the guest were monitored during complexation with the host. By means of C-13 NMR relaxation it was found that despite the high association constant (which suggests strong interactions between the two molecules) AdCA rotates fast around the β-CD symmetry axis inside the cavity. This motion is made possible by the spherical shape of the adamantyl moiety and the whole system resembles to a "molecular bearing".

Place, publisher, year, edition, pages
Stockholm: Institutionen för fysikalisk kemi, oorganisk kemi och strukturkemi, 2005. 61 p.
supramolecular chemistry, host-guest complexes, non-covalent interactions, nuclear magnetic resonance, molecular motion, C-13 relaxation, deuterium NMR, dipolar recoupling
National Category
Physical Chemistry
urn:nbn:se:su:diva-347 (URN)91-7265-998-X (ISBN)
Public defence
2005-02-18, Magnélisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 12 A, Stockholm, 13:00
Available from: 2005-01-28 Created: 2005-01-28Bibliographically approved

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Kowalewski, Jozef
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Department of Physical, Inorganic and Structural Chemistry
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