Improved Magnetization Transfers among Quadrupolar Nuclei in Two-Dimensional Homonuclear Correlation NMR Experiments Applied to Inorganic Network Structures

We demonstrate that supercycles of previously introduced two-fold symmetry dipolar recoupling schemes may be utilized successfully in homonuclear correlation nuclear magnetic resonance (NMR) spectroscopy for probing proximities among half-integer spin quadrupolar nuclei in network materials undergoing magic-angle-spinning (MAS). These (SR2 [Formula: see text]) [Formula: see text] (SR2 [Formula: see text]) [Formula: see text] and (SR2 [Formula: see text])M recoupling sequences with [Formula: see text] and [Formula: see text] offer comparably efficient magnetization transfers in single-quantum–single-quantum (1Q–1Q) correlation NMR experiments under moderately fast MAS conditions, as demonstrated at 14.1 T and 24 kHz MAS in the contexts of [Formula: see text] B NMR on a Na [Formula: see text] O–CaO–B [Formula: see text] O [Formula: see text] –SiO [Formula: see text] glass and [Formula: see text] Al NMR on the open framework aluminophosphate AlPO-CJ19 [(NH [Formula: see text]) [Formula: see text] Al [Formula: see text] (PO [Formula: see text]) [Formula: see text] HPO [Formula: see text] H [Formula: see text] O]. Numerically simulated magnetization transfers in spin–3/2 pairs revealed a progressively enhanced tolerance to resonance offsets and rf-amplitude errors of the recoupling pulses along the series (SR2 [Formula: see text]) [Formula: see text] (SR2 [Formula: see text]) [Formula: see text] (SR2 [Formula: see text])M for increasing differences in chemical shifts between the two nuclei. Nonetheless, for scenarios of a relatively minor chemical-shift dispersions ([Formula: see text] kHz), the (SR2 [Formula: see text])M supercycles perform best both experimentally and in simulations.