Acquisition of Wideline Solid-State NMR Spectra of Quadrupolar Nuclei

14N Solid‐State NMR Spectroscopy of Amino Acids

“…Individual subspectra of val at temperatures ranging from À81 to + 172 8Cs how the temperature dependence of the 14 NNMR signal resulting from an increased T 2 eff ( 14 N) (Figure S10 a). The subspectrum with the highest 14 NS /N (roughly two times that of the room temperature spectrum, T RT )o ccurs at at emperature of 130 8C( T max ), about 20 8Cl ower than that predicted by Equation (4). We note that discrepancies in the temperature values may arise from severalf actors, including the accuracy of T max of a-gly (which is the basis of our calculations),t he large temperature increments that we used, asw ell as the fact that there may not be an exact correspondence between the 1 Hr elaxation measurements of Andrew et al, [63,67,69] our T 2 eff ( 14 N) values, and the magnitudes of the rotational barriers and prefactors.…”

“…These ultra-wideline (UW) 14 Np owder patterns result in very low signal-tonoise (S/N) ratios due to the distribution of the signal intensity over broad frequency ranges. [3][4][5] Despite these seemingly unfavorable NMR properties, recently introduced methods for enhancing S/N in UW 14 NSSNMR spectra show promise for enabling routine investigations of structuralf eatures such as hydrogen bondinga nd polymorphism, as well as molecular dynamics andr elaxation processes, in aw idev ariety of nitrogencontaining systems. [6][7][8][9][10][11][12] The electric field gradients (EFGs) at the 14 Nn ucleusa re described with as econd-rank tensor that is traceless and symmetric, having three principal axis components: V 11 , V 22 ,a nd V 33 (j V 11 j j V 22 j j V 33 j).…”

“…[3,[29][30][31] Our group has proposed methodology for the acquisition of UW SSNMR spectra that has been successful for studying both spin-1 = 2 and quadrupolarn uclei (including 14 N). [6,8,12,[32][33][34] This methodology consists of three components: [4,5] 1) utilizing WURST (wideband, uniform rate, and smooth truncation) pulses [35,36] for uniform excitationo fb road powder patterns, [37] 2) using the WURST pulses in aC PMG (Carr-Purcell-Meiboom-Gill)-like sequence for transverse relaxation (T 2 )-based signal enhancement (i.e.,t he WURST-CPMG pulse sequence), [33] and 3) acquiring subspectra at evenly spaced transmitter frequency incrementsa cross the breadth of the powder pattern [i.e.,t he variable offset cumulative spectrum (VOCS) or frequency-stepped methods]. [38][39][40] We also demonstrated that WURSTp ulses may be utilized in the broadband adiabatic inversion cross-polarization( BRAIN-CP) sequence for broadband cross-polarization (BCP) from spin-1 = 2 nuclides (e.g., 1 H) to less receptive nuclei (both spin-1 = 2 and quadrupolar) under static (i.e., n rot = 0kHz) conditions [41] and have successfully appliedt his approach in the acquisition of severalU W 14 NSSNMR powder patternso fn itrogen-containing compounds.…”

High-field solid-state 35Cl NMR in selenium(IV) and tellurium(IV) hexachlorides

“…Because the breadth of the EFG-dominated powder patterns will scale inversely with the magnetic field B 0 , the higher magnetic field results in progressively narrower powder patterns thus making acquisition of such spectra more straightforward. Another limiting factor, the narrow excitation bandwidth of the square radiofrequency pulses, was recently circumvented by the introduction of WURST (Wideband Uniform Rate Smooth Truncation) pulses, which were found to be extremely helpful in recording ultra-wideline NMR spectra of not only quadrupolar but also spin-1/2 nuclei [12][13][14][15].…”

Solid-state NMR Study on Membrane Protein Structure in Biological Condition

“…Polarization is transferred during the spin locking period, (the contact time) and a π/2 pulse is only made on protons ( Figure 3). 15 CP is widely used in ssNMR spectroscopy and frequently combined with other technique, such as MAS (CP MAS) NMR, to provide high resolution spectra. Besides MAS and CP techniques, there are remarkable methodological improvements in ssNMR such as multiple-pulse sequence, hyperpolarization techniques and T 1 shortening experimental techniques.…”