Resolution enhancement in proton double quantum magic-angle spinning spectra by constant-time acquisition

Direct Identification of Zeolite Beta Polymorphs by Solid-State 29Si Nuclear Magnetic Resonance Spectroscopy

“…To solve this problem, we applied a “pure shift” pulse sequence, which suppresses either the left (α) or right (β) signal of the doublet and, therefore, results in a 2D spectrum with improved resolution. The “pure shift” sequence proposed is based on the INADEQUATE-CR (composite refocusing) sequence reported in 1995 for liquid samples, , which we modified by the introduction of the MAS synchronization, phase sensitivity, and constant-time block with two π pulses . The final constant-time pure-phase INADEQUATE with composite refocusing (CT-INADEQUATE-CR) sequence is shown in Figure S8 of the Supporting Information.…”

Proton-detected solid-state NMR spectroscopy of spin-1/2 nuclei with large chemical shift anisotropy

“…49 The trade-off between sensitivity and resolution is observed in many constant-time solid-state NMR experiments. [51][52][53][54][55][56] To demonstrate that AID D-HMQC is applicable for the indirect detection of a wide range of nuclei, we have performed 1 H{ 35 Cl} population transfer (PT) TONE D-HMQC-3 experiments with L-histidine⋅HCl⋅H2O. The addition of the AID t1-incrementation protocol did not introduce distortions in the second-order quadrupolar lineshape and resulted in improved sensitivity as compared to a constant-time experiment (Figure S2).…”

Ultrafast 1H MAS NMR Crystallography for Natural Abundance Pharmaceutical Compounds

“…Therefore, we used the SPC-5 3 sequence in multidimensional experiments. While it is generally anticipated that a constant time (CT) variation during the DQ evolution period 26 improves 1 H resolution, CT requires a long and fairly uniform transverse DQ spin relaxation, a condition hard to meet with only a few exceptions. In the case of histidine, the short T 2 relaxation times (Figure S3) caused a loss of several DQ−SQ correlations (Figure S4).…”

“…We examined the performance of several 2D and 3D experiments for crystalline U– 13 C, 15 N-histidine. Specifically, we assessed different double-quantum excitation schemes, including constant time variants, in homonuclear chemical shift correlation experiments and determined the optimum conditions for scalar coupling-based 13 C– 1 H correlation experiments. In addition, we also applied this approach to Posaconazole, a 700 Da antifungal agent .…”