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DQ-DRENAR: A new NMR technique to measure site-resolved magnetic dipole-dipole interactions in multispin-1/2 systems: Theory and validation on crystalline phosphates
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10.1063/1.4801634
/content/aip/journal/jcp/138/16/10.1063/1.4801634
http://aip.metastore.ingenta.com/content/aip/journal/jcp/138/16/10.1063/1.4801634

Figures

Image of FIG. 1.
FIG. 1.

DQ-DRENAR pulse sequences. (a) Standard sequence, C′ means all the phases of pulses in (d) are 90° shifted. (b) DQ-DRENAR sequence with cross-polarization preparation and TPPM decoupling on the I channel used during acquisition, (c) Wideband DQ-DRENAR sequence; means all the phases of pulses in (d) are 180° shifted. (d) The pulse compositions of block C.

Image of FIG. 2.
FIG. 2.

(a) DQ-DRENAR curves of two-spin systems with different dipolar coupling constants. (b) Systematic error introduced by the approximate formula (9) as a function of data range analyzed. The simulations assume spinning rate to be 15 kHz.

Image of FIG. 3.
FIG. 3.

SIMPSON simulation results of Ij(Ik)n systems. (a) DQ-DRENAR curves of spin systems with different numbers of k spins n; (b) the difference between the value estimated by parabola fitting and the theoretical one for different system. The dipolar coupling constant bjk and the spinning rate are set to 400 Hz and 15 kHz, respectively. Tetrahedron geometry is taken. The dipolar interaction between Ik spins are taken into account.

Image of FIG. 4.
FIG. 4.

(a) Simulated DQ-DRENAR curves of the 3-spin system shown with different ratios of bik/bjk. Inset shows initial data ranges. (b) Systematic error introduced by dipolar truncation effects as a function of data range. Simulations assume bjk = bji = 400 Hz, νr = 15 kHz.

Image of FIG. 5.
FIG. 5.

(a) Simulated DQ-DRENAR curves for the linear 3-spin system shown with different ratios of bik/bjk. Inset shows initial data ranges. (b) Systematic error introduced by dipolar truncation effects as a function of data range. Simulations assume bjk = 400 Hz, νr = 15 kHz.

Image of FIG. 6.
FIG. 6.

Simulated DQ-DRENAR curves of the linear 3-spin system with the observe-spin Ij at the center, under variation of bji/bjk. Simulations assume bjk = 400 Hz, νr = 15 kHz.

Image of FIG. 7.
FIG. 7.

(a) Dependence of the DQ-DRENAR curves on the angle ß subtended by the two dipolar vectors in a 3-spin system; Simulations assume bjk = bji = 400 Hz, νr = 15 kHz and include dipolar truncation effects. (b) Dependence of the systematic error of the parabolic fitting procedure on the values as function of data range.

Image of FIG. 8.
FIG. 8.

(a) Simulated DQ-DRENAR curves of 4-spin systems Ij(Ik)n: Solid squares represent a pseudo-tetrahedral geometry; the angles between dipolar vectors are 109.47°. Solid circles reflect the configuration of an equilateral triangle with the observe-spin j at the center. Simulations assume bjk = 400 Hz, and a spinning rate of 15 kHz. The dipolar effects between different spins Ik are taken into account. (b) Dependence of the systematic error of the parabolic fitting procedure on the values as a function of data range.

Image of FIG. 9.
FIG. 9.

Effect of distance distributions on DQ-DRENAR data, simulated for a two-spin system with r = 3.667 Å. (a) Gaussian distance distributions considered (σ = 0.1, 0.2, and 0.3 Å, respectively). (b) Resultant dipolar coupling constant distributions, (c) calculated DQ-DRENAR curves (the inset showing the initial data range) and (d) dependence of the systematic error of the parabolic fitting procedure on the values as a function of data range, under different sigma values.

Image of FIG. 10.
FIG. 10.

CSA effect on the apparent dipolar coupling constant in two-spin systems. (a) Decay curves in the presence of CSA of different magnitudes; b jk = 400 Hz; (b) ratio b jk app /b jk predicted for different CSA values and dipolar coupling constants. Coincident dipolar and magnetic shielding tensors are assumed, but orientation effects were found unimportant. Simulations assume a spinning rate v r = 15 kHz.

Image of FIG. 11.
FIG. 11.

CSA effect on the apparent dipolar coupling constant in two-spin systems. (a) DQ-DRENAR sequence of Fig. 1(a) . (b) Sequence shown in Fig. 1(c) ; b jk = 400 Hz; b jk app /b jk predicted for different spinning rate. Coincident dipolar and magnetic shielding tensors are assumed.

Image of FIG. 12.
FIG. 12.

31P DQ-DRENAR curves, simplified spin-cluster simulations (dotted curves) and predicted parabolae (solid curves) based on Eq. (24) using from the crystal structures. First row: Na4P2O6·10H2O (left) and Rb2[(H2P2O6)(H4P2O6)] (middle, up and down triangles represent data for the signals at 13.8 and 12.8 ppm, respectively); CdPS3 (right). Second row: Ga(PO3)3 (left), KPO3 (middle, solid squares and empty circles represent data for signals at −18.4 and −20.2 ppm, respectively) and K2MoP2O9 (right, solid and empty circles represent data for signals −7.7 and −10.9 ppm, respectively); third row: (Ph2P)2C=C(C6F5)(B(C6F5)2 (left, solid star and triangles represent the data obtained for the resonances at 24.4 and −8.7 ppm, respectively. Spin-pair simulations including CSA are also shown as dotted curves). Ag7P3S11 (middle, squares, solid circles, and triangle symbols represent data for PS4 3− groups (103.2 ppm) and the two crystallographically inequivalent P atoms of the P2S7 4− group (101.4 and 92.0 ppm), respectively, for the latter, spin-pair simulations including CSA are also shown as dotted curves), and BPO4 (right); fourth row: Ag3PO4 (left), Ca5(PO4)3(OH) (middle) and H3Mo12O40P·13H2O (right, inset amplifies the initial data region).

Image of FIG. 13.
FIG. 13.

Performance comparison of the pulse sequences in Figs. 1(a) and 1(c) for two crystalline model compounds with moderately large CSAs: 31P DQ-DRENAR curves, and predicted parabola (solid curves) based on Eq. (24) using from the crystal structures. First row: Na5B2P3O13, left and right parts represent the data obtained from sequence 1(a) and 1(c); squares, solid circles, and triangle symbols represent data for signals centered at −0.2, −1.6 and −7.6 ppm, respectively. Second row: Na2PO3F, left and right represent the data obtained from sequence 1(a) and 1(c); squares and solid circles represent data for signals centered at 8.5 and 3.5 ppm, respectively.

Tables

Generic image for table
Table I.

31P isotropic chemical shifts (±0.5 ppm), CSA values Δσ (± 5 ppm), and experimental values of for the model compounds studied. Numbers in parentheses are theoretical values calculated from the crystal structures over a range of three times the closest P–P distance. CSAs are defined according to .

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/content/aip/journal/jcp/138/16/10.1063/1.4801634
2013-04-26
2014-04-23
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: DQ-DRENAR: A new NMR technique to measure site-resolved magnetic dipole-dipole interactions in multispin-1/2 systems: Theory and validation on crystalline phosphates
http://aip.metastore.ingenta.com/content/aip/journal/jcp/138/16/10.1063/1.4801634
10.1063/1.4801634
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