Observation of proximities between spin-1/2 and quadrupolar nuclei: which heteronuclear dipolar recoupling method is preferable?

We have recently shown that the dipolar-mediated heteronuclear multiple-quantum coherence (D-HMQC) method allows observing through-space proximities between spin-1/2 ((1)H, (13)C, (31)P...) and quadrupolar ((23)Na, (27)Al...) nuclei. However, the D-HMQC effectiveness depends on the choice of the het...

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Bibliographic Details
Published in:The Journal of chemical physics 2012-10, Vol.137 (14), p.144201-144201
Main Authors: Lu, X, Lafon, O, Trébosc, J, Tricot, G, Delevoye, L, Méar, F, Montagne, L, Amoureux, J P
Format: Article
Language:English
Subjects:
ALUMINIUM 27
CARBON 13
Chemical Sciences
CHEMICAL SHIFT
COMPUTERIZED SIMULATION
Construction
Crystal structure
FREQUENCY MODULATION
HAMILTONIANS
HYDROGEN 1
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
Material chemistry
Mathematical analysis
Mathematical models
NUCLEAR MAGNETIC MOMENTS
NUCLEAR PHYSICS AND RADIATION PHYSICS
Nuclei
OPTIMIZATION
PHOSPHORUS 31
Proximity
QUADRUPOLE MOMENTS
Robustness
SODIUM 23
SPIN
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Summary:We have recently shown that the dipolar-mediated heteronuclear multiple-quantum coherence (D-HMQC) method allows observing through-space proximities between spin-1/2 ((1)H, (13)C, (31)P...) and quadrupolar ((23)Na, (27)Al...) nuclei. However, the D-HMQC effectiveness depends on the choice of the heteronuclear dipolar recoupling sequence. Here, we compare the efficiency and the robustness of four rotor-synchronized sequences: the symmetry-based ones, R4(1)(2)R4(1)(-2) and its super-cycled version, SR4(1)(2), and two schemes based on simultaneous amplitude and frequency modulations, denoted SFAM-1 and SFAM-2. For the SFAM methods, we point out efficient recoupling conditions that facilitate their experimental optimization and we introduce analytical expressions for the buildup of D-HMQC signal in the case of an isolated spin pair. We show that the main differences between these four sequences lie in the number of adjustable parameters and in their robustness with respect to chemical shift and homonuclear dipolar interactions. The relative performances of these four recoupling sequences are analyzed using average Hamiltonian theory, numerical simulations, and (27)Al-{(31)P} D-HMQC experiments on crystalline aluminophosphate.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4753987