Rapid acquisition of wideline MAS solid-state NMR spectra with fast MAS, proton detection, and dipolar HMQC pulse sequences

Abstract

The solid-state NMR spectra of many NMR active elements are often extremely broad due to the presence of chemical shift anisotropy (CSA) and/or the quadrupolar interaction (for nuclei with spin I > 1/2). These NMR interactions often give rise to wideline solid-state NMR spectra which can span hundreds of kHz or several MHz. Here we demonstrate that by using fast MAS, proton detection and dipolar hetero-nuclear multiple-quantum (D-HMQC) pulse sequences, it is possible to rapidly acquire 2D spectra which correlate H chemical shifts to the indirectly detected wideline MAS powder patterns of dipolar coupled hetero-nuclei. The D-HMQC pulse sequence enables broadband excitation of the wideline hetero-nuclear NMR spectrum and provides higher sensitivity by detecting the narrower and more sensitiveH NMR signal. This approach is demonstrated for the rapid acquisition of 2D H detectedPt solid-state NMR spectra of cisplatin and transplatin and the Ga solid-state NMR spectrum of a self-assembled Ga coordination polymer of unconfirmed structure. This approach should be broadly applicable for the rapid acquisition of wideline MAS solid-state NMR spectra of moderately abundant NMR nuclei.

Ambient synthesis of nanomaterials by in situ heterogeneous metal/ligand reactions

“…To deduce the molecular structure of the nanobeams, we applied solid-state 1 H, 2 H, 13 C and 71/69 Ga magic angle spinning (MAS) multi-nuclear magnetic resonance (NMR) experiments. 31 The MAS 1 H solid-state NMR spectrum of nanobeams (MAS frequency = 50 kHz) is shown in the upper part of Fig. 3a, and depicts a single peak with an isotropic chemical shift of ca.…”

Enhanced 1H-X D-HMQC performance through improved 1H homonuclear decoupling

“…The D-HMQC experiment, in particular, has found widespread use for the acquisition of HETCOR spectra involving 14 N 41,43-54 and half-integer quadrupolar nuclei. 40,[55][56][57] More recently, its broadbandedness has also been exploited for the detection of correlations to ultra-wideline and isotropic spectra of heavy spin-1/2 nuclei 58,59 as well as satellite transitions of quadrupolar nuclei. 60,61 Despite the abovementioned advantages, the D-RINEPT and D-HMQC techniques are limited by the lack of radiofrequency (RF) power flexibility of non-γ-encoded heteronuclear dipolar recoupling sequences.…”

Solid‐state nuclear magnetic resonance and nuclear quadrupole resonance as complementary tools to study quadrupolar nuclei in solids

“…Multiple quantum magic angle spinning (MQMAS) is another alternative, which combines MAS with a multipulse sequence in order to obtain high‐resolution spectra . Additionally, new pulse sequences with the combination of fast MAS and indirect detection offer several advantages compared to the aforementioned techniques . It is also possible to gain information on the C Q indirectly through the SSNMR observation of neighboring nuclei.…”