A 2D ³¹P MAS NMR Study of Polycrystalline Cd₃(PO₄)₂

Abstract

It is demonstrated on a polycrystalline powder sample of Cd3(PO4)2, given a known single-crystal X-ray structure, that two-dimensional 31P double-quantum single-quantum MAS correlation experiments allow unique assignment of multiple 31P resonances to specific P sites in the structure of such inorganic orthophosphates. The eigenvalues of the 31P and 113Cd shielding tensors of Cd3(PO4)2 are reported, the determination of which requires usage of a 2D MAS spinning sideband separation experiment.

The Stuffed Framework Structure of SrP2N4: Challenges to Synthesis and Crystal Structure Determination

“…In the literature some examples are reported [37][38][39][40] where such a combination of experiments could successfully validate structures from powder diffraction analysis. To the best of our knowledge, however, none of these examples deals with such a heavy spectral overlap (Figure 2a) of NMR resonances as it is given in SrP 2 N 4 .…”

Recent Advances in Solid‐State MAS NMR Methodology for Probing Structure and Dynamics in Polymeric and Supramolecular Systems

“…This article has highlighted the new insight into the structural and dynamic processes that determine the bulk properties of polymeric and supramolecular materials that can be obtained by novel 1 H, 2 H, 13 C, 15 N and 17 O solidstate MAS NMR methods that exploit the sensitivity to structure and dynamics (over a wide range of timescales) of the NMR chemical shift and quadrupolar coupling as well as the through-space dipolar coupling and throughbond J coupling. Notably, many of the presented methods are applicable to samples at natural abundance, i.e.…”

“…This shifting of the phases achieves a negation of the spin-part of the DQ Hamiltonian, which exactly compensates the negation of the spatial part caused by MAS. [7,13] The BABA sequence was used initially in the context of a heteronuclear 13 C-1 H MQ coherence experiment, [12] and was adapted for homonuclear 31 P DQ MAS experiments, [14,15] with modified two-and four-t R versions having been employed, which provide compensation with respect to offset and pulse imperfections. [16] The first application of the BABA recoupling sequence in 1 H DQ MAS spectroscopy coincided with the first 1 H DQ MAS experiments at 35 kHz MAS using a 2.5 mm MAS probe.…”

“…As an example, the two NH protons (d 1 For a L-histidine Á HCl Á H 2 O sample at natural abundance, Schnell and Saalwächter have shown that the NH distances can be determined from rotor-encoded spinning sidebands [8,70,122] observed in a 15 N-1 H two-dimensional experiment with TEDOR (transferred echo double resonance) magnetisation transfer and inverse ( 1 H) detection: [123] While the spectrum in Figure 8a displays correlation 15 N-1 H peaks corresponding to the directly bonded nitrogen-hydrogen resonances, rotor-encoded spinning sidebands are observed for each resonance in Figure 8b (the extracted patterns with best fits are shown in Figure 8c). The spectrum in Figure 8b was recorded in a split-t 1 fashion, where time periods corresponding to the evolution of both 15 N SQ coherence (t 1 ) and longitudinal 15 N-1 H two-spin order, I z S z (t 1 0 ) were incremented, with the t 1 evolution revealing the 15 N chemical shift, while the t 1 0 evolution causes the appearance of the rotor-encoded spinning-sidebands. Figure 8d corresponds to the experimental (and best-fit) rotor-encoded spinning sideband patterns observed for an experiment where only the t 1 0 evolution period was incremented.…”

“…[1][2][3] This article highlights novel solid-state NMR methods which are enabling new insight to be obtained into the structural and dynamic processes that determine the bulk properties of polymeric and supramolecular materials. The nuclei of most importance for NMR of organic molecules are considered, namely 1 H, 2 H, 13 C, 15 N and 17 O, specifically showcasing methods that exploit the sensitivity to structure and dynamics of the NMR chemical shift and quadrupolar coupling as well as the through-space dipolar coupling and through-bond J coupling. The article is organised into two parts that present new methods for probing, first, structure and, second, dynamics.…”