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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Recoupled separated-local-field experiments and applications to study intermediate-regime molecular motions

Full text
Author(s):
Cobo, Marcio Fernando [1] ; Achilles, Anja [2] ; Reichert, Detlef [2] ; deAzevedo, Eduardo Ribeiro [1] ; Saalwaechter, Kay [2]
Total Authors: 5
Affiliation:
[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Paulo - Brazil
[2] Univ Halle Wittenberg, Inst Phys NMR, D-06120 Halle - Germany
Total Affiliations: 2
Document type: Journal article
Source: JOURNAL OF MAGNETIC RESONANCE; v. 221, p. 85-96, AUG 2012.
Web of Science Citations: 15
Abstract

A specific separated-local-field NMR experiment, dubbed Dipolar-Chemical-Shift Correlation (DIPSHIFT) is frequently used to study molecular motions by probing reorientations through the changes in XH dipolar coupling and T-2. In systems where the coupling is weak or the reorientation angle is small, a recoupled variant of the DIPSHIFT experiment is applied, where the effective dipolar coupling is amplified by a REDOR-like pi-pulse train. However, a previously described constant-time variant of this experiment is not sensitive to the motion-induced T-2 effect, which precludes the observation of motions over a large range of rates ranging from hundreds of Hz to around a MHz. We present a DIPSHIFT implementation which amplifies the dipolar couplings and is still sensitive to T-2 effects. Spin dynamics simulations, analytical calculations and experiments demonstrate the sensitivity of the technique to molecular motions, and suggest the best experimental conditions to avoid imperfections. Furthermore, an in-depth theoretical analysis of the interplay of REDOR-like recoupling and proton decoupling based on Average-Hamiltonian Theory was performed, which allowed explaining the origin of many artifacts found in literature data. (C) 2012 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 08/11675-0 - NMR methods for studying soft materials: application to eletroluminescent polymers and intercalation nanocomposites
Grantee:Márcio Fernando Cobo
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
FAPESP's process: 09/18354-8 - Dynamics and structure of polymer systems as studied by nuclear magnetic resonance
Grantee:Eduardo Ribeiro de Azevedo
Support Opportunities: Regular Research Grants