¹³C CP/MAS: Application to glycine

Abstract

ABSTRACT:In a previous article (Concepts Magn Reson May, 2004), the initial setup of the 13 C CP/MAS experiment was described. The advantages of the experiment over direct 13 C excitation were also given. In this article, the experiment is applied to three polymorphic structures of glycine. Temperature calibration of the experiment to investigate molecular dynamics as a function of temperature is also described. While the 13 C CP/MAS experiment is widely applicable, it can not be universally used. The 13 C CP/MAS experiment works at ambient temperature for both the α and γ polymorphic structures of glycine. However, the cross-polarization technique fails to provide a signal at low temperature from either polymorph. The failure of the technique for both polymorphs arises from the shortened 1 H T 1ρ at low temperatures. This shortened T 1ρ results from the hindered rotation of the -NH 3 group. The technique even fails at ambient temperature for β glycine. Again, the reason is a shortened 1 H T 1ρ .

Crystal growth and characterization of γ-glycine grown from potassium fluoride for photonic applications

“…The other peaks around 1335 and 1043 cm −1 have been attributed to CH 2 wagging and CN + stretching. The band appears at 3105 cm −1 attributed to N-H stretching for ␥-glycine, while the N-H stretching for ␣-glycine is at 3164 cm −1 and for ␤-glycine is at 3191 cm −1 has been reported in literature [18,19]. In the present investigation, the N-H stretching is observed at 3107 cm −1 which confirms the ␥-phase of glycine.…”

A solid-state 199Hg NMR study of mercury halides

“…The significantly long spin-relaxation times of these mercury materials in the solid state were measured by the saturation-recovery technique [29]. Temperature measurements were calibrated with the chemical shift of solid lead nitrate for both static [30] and MAS [31][32][33] experiments.…”

Revisiting HgCl2: A solution- and solid-state 199Hg NMR and ZORA–DFT computational study

“…The significantly longer spin-relaxation times in the solid state were measured by the saturation-recovery technique [21]. Temperature measurements for solution NMR were calibrated with ethylene glycol [22] while the chemical shift of lead nitrate was used to calibrate the solid-state measurements for static [23] and MAS [24][25][26] experiments.…”