Potential and Limitations of 2D 1H–1H Spin-Exchange CRAMPS Experiments to Characterize Structures of Organic Solids |
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Authors: | Jiri Brus Hana Petříčková Jiri Dybal |
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Affiliation: | (1) Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Sq. 2, CZ-162 06 Prague 6, Czech Republic, CZ;(2) Institute of Chemical Technology, CZ-Prague, Technicka 5, 166 28 Prague 6, Czech Republic, CZ |
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Abstract: | Summary. A brief overview of our recent results concerning the application of 2D CRAMPS experiments to investigate a wide range of materials is presented. The abilities of the 2D 1H–1H spin-exchange technique to characterize the structure of organic solids as well as the limitations resulting from segmental mobility and from undesired coherence transfer are discussed. Basic principles of 1H NMR line-narrowing and procedures for analysis of the spin-exchange process are introduced. We focused to the qualitative and quantitative analysis of complex spin-exchange process leading to the determination of domain sizes and morphology in heterogeneous multicomponent systems as well as the characterization of clustering of surface hydroxyl groups in polysiloxane networks. Particular attention is devoted to the determination of the 1H–1H interatomic distances in the presence of local molecular motion. Finally we discuss limitations of the 13C–13C correlation mediated by 1H–1H spin exchange to obtain structural constraints. The application of Lee-Goldburg cross-polarization to suppress undesired coherence transfer is proposed. Corresponding author. E-mail: brus@imc.cas.cz Received May 28, 2002; accepted (revised) July 1, 2002 |
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Keywords: | . CRAMPS 2D solid-state NMR Lee-Goldburg Miscibility of polymers Clustering of surface silanols Molecular dynamics. |
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