title: Measurement of 13C-1H dipolar couplings in solids by using ultra-fast magic-angle spinning NMR spectroscopy with symmetry-based sequences.
abstract: We show that (13)C-(1)H dipolar couplings in fully protonated organic solids can be measured by applying a Symmetry-based Resonance-Echo DOuble-Resonance (S-REDOR) experiment at ultra-fast Magic-Angle Spinning (MAS). The (13)C-(1)H dipolar couplings are recovered by using the R12 recoupling scheme, while the interference of (1)H-(1)H dipolar couplings are suppressed by the symmetry properties of this sequence and the use of high MAS frequency (65 kHz). The R12 method is especially advantageous for large (13)C-(1)H dipolar interactions, since the dipolar recoupling time can be incremented by steps as short as one rotor period. This allows a fine sampling for the rising part of the dipolar dephasing curve. We demonstrate experimentally that one-bond (13)C-(1)H dipolar coupling in the order of 22 kHz can be accurately determined. Furthermore, the proposed method allows a rapid evaluation of the dipolar coupling by fitting the S-REDOR dipolar dephasing curve with an analytical expression.
authors.affiliation: Unit of Catalysis and Chemistry of Solids, CNRS-8181, Lille North of France University, Villeneuve d'Ascq cedex, Lille, France.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Xingyu
authors.initials: X
authors.lastname: Lu
authors.forename: Olivier
authors.initials: O
authors.lastname: Lafon
authors.forename: Julien
authors.initials: J
authors.lastname: Trébosc
authors.forename: Feng
authors.initials: F
authors.lastname: Deng
authors.forename: Bingwen
authors.initials: B
authors.lastname: Hu
authors.forename: Qun
authors.initials: Q
authors.lastname: Chen
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Amoureux