A double-component Anderson-Weiss approach for describing NMR signals of mobile SIn units: Application to constant-time DIPSHIFT experiments

Autor(es)

Cobo, Marcio Fernando ^[1] ; Reichert, Detlef ^[2] ; Saalwaehter, Kay ^[2] ; deAzevedo, Eduardo Ribeiro ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Carlos, SP - Brazil

^[2] Univ Halle Wittenberg, Inst Phys NMR, D-06120 Halle - Germany

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF MAGNETIC RESONANCE; v. 248, p. 115-125, NOV 2014.
• Citações Web of Science: 4

Resumo

A composed Gaussian local field is proposed to describe the effect of molecular motions on NMR signals of SI units (e.g., CHn or NHn), based upon the well-know Anderson-Weiss (AW) approximation. The approach is exemplified on constant-time recoupled dipolar chemical-shift correlation (t(c)-recDIPSHIFT) experiments, providing an analytical formula that can be used as a fitting function in studies of intermediate-regime motions. By comparison of analytical tc-recDIPSHIFT curves and dynamic spin dynamics simulations, we show that for heteronuclear spin pairs (SI system), the AW treatment assuming the usual Gaussian local field is accurate. However, the approximation fails for the case of SIn spin systems for motional rates higher than a few kHz. Based on earlier work of Terao et al., who proposed a decomposition of CHn dipolar powder patterns into to 2(n) spin-pair-type patterns, we propose an AW approach based upon a double-Gaussian local field. We derive an analytical formula for t(c)-recDIPSHIFT signals, and demonstrate its accuracy by comparison with simulations of several motional geometries and rates, and with experimental results for a model sample. The approach is not limited to the t(c)-recDIPSHIFT experiment and should be of general use in dipolar-coupling based experiments probing (partially) mobile SIn molecular moieties. (C) 2014 The Authors. Published by Elsevier Inc. (AU)

• Processo FAPESP: 08/11675-0 - Métodos de RMN para estudos de materiais com alta mobilidade molecular: aplicações a polímeros eletroluminescentes e nanocompostos de intercalação
• Beneficiário: Márcio Fernando Cobo
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 09/18354-8 - Dinâmica e estrutura de sistemas poliméricos estudados por ressonância magnética nuclear
• Beneficiário: Eduardo Ribeiro de Azevedo
• Modalidade de apoio: Auxílio à Pesquisa - Regular