Comparison of through-space homonuclear correlations between quadrupolar nuclei in solids

• Published in: Journal of magnetic resonance (1997) Vol. 348; p. 107388
• Main Authors: Gómez, Jennifer S., Trébosc, Julien, Tuan Duong, Nghia, Pourpoint, Frédérique, Lafon, Olivier, Amoureux, Jean-Paul
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2023; Elsevier
• Series: Journal of Magnetic Resonance
• Subjects: Catalysis; Chemical Sciences; Double-quantum coherences; Homonuclear correlation; Inorganic chemistry; Quadrupolar nuclei; Single-quantum coherences; Spatial proximity; Quadrupolar nuclei; Homonuclear correlation; Single-quantum coherences; Spatial proximity; Double-quantum coherences
• ISSN: 1090-7807; 1096-0856
• DOI: 10.1016/j.jmr.2023.107388

[Display omitted] •DQ-SQ, unlike SQ-SQ, allows observing species with close or identical frequencies.•With small chemical shift separation (≤4-5 kHz), [SR21/2] or [BR21/2] bracketed schemes are recommended.•With large chemical shift separation (>5 kHz), the BR21/2 scheme is recommended. Various two-dimensional (2D) homonuclear correlation experiments have been proposed to observe proximities between identical half-integer spin quadrupolar nuclei in solids. These experiments select either the single- or double-quantum coherences during the indirect evolution period, t1. We compare here the efficiency and the robustness of the 2D double-quantum to single-quantum (DQ-SQ) and SQ-SQ homonuclear correlations for two half-integer spin quadrupolar isotopes subject to small chemical shift anisotropy (CSA): 11B with a nuclear spin I = 3/2 and 27Al with I = 5/2. Such a comparison is performed using experiments on two model samples: Li2B4O7 for 11B and AlPO4-14 for 27Al. For both isotopes, the DQ-SQ homonuclear correlations are recommended since they allow probing the proximities between nuclei with close or identical frequencies. In the case of small or moderate isotropic chemical shift differences (e.g. 11B) the [SR221] or [BR221] bracketed DQ-SQ recoupling schemes are recommended; whereas it is the BR221 un-bracketed one otherwise (e.g. 27Al).