35Cl–1H Heteronuclear correlation magic-angle spinning nuclear magnetic resonance experiments for probing pharmaceutical salts,Magnetic Resonance in Chemistry

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35Cl–1H Heteronuclear correlation magic-angle spinning nuclear magnetic resonance experiments for probing pharmaceutical salts
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-07-01 , DOI: 10.1002/mrc.5188
Dinu Iuga ₁ , Emily K Corlett ₁ , Steven P Brown ₁

Affiliation

Heteronuclear multiple-quantum coherence (HMQC) pulse sequences for establishing heteronuclear correlation in solid-state nuclear magnetic resonance (NMR) between ³⁵Cl and ¹H nuclei in chloride salts under fast (60 kHz) magic-angle spinning (MAS) and at high magnetic field (a ¹H Larmor frequency of 850 MHz) are investigated. Specifically, recoupling of the ³⁵Cl–¹H dipolar interaction using rotary resonance recoupling with phase inversion every rotor period or the symmetry-based SR4²₁ pulse sequences are compared. In our implementation of the population transfer (PT) dipolar (D) HMQC experiment, the satellite transitions of the ³⁵Cl nuclei are saturated with an off-resonance WURST sweep, at a low nutation frequency, over the second spinning sideband, whereby the WURST pulse must be of the same duration as the recoupling time. Numerical simulations of the ³⁵Cl–¹H MAS D-HMQC experiment performed separately for each crystallite orientation in a powder provide insight into the orientation dependence of changes in the second-order quadrupolar-broadened ³⁵Cl MAS NMR lineshape under the application of dipolar recoupling. Two-dimensional ³⁵Cl–¹H PT-D-HMQC MAS NMR spectra are presented for the amino acids glycine·HCl and l-tyrosine·HCl and the pharmaceuticals cimetidine·HCl, amitriptyline·HCl and lidocaine·HCl·H₂O. Experimentally observed ³⁵Cl lineshapes are compared with those simulated for ³⁵Cl chemical shift and quadrupolar parameters as calculated using the gauge-including projector-augmented wave (GIPAW) method: the calculated quadrupolar product (P_Q) values exceed those measured experimentally by a factor of between 1.3 and 1.9.

中文翻译：

35Cl-1H异核相关魔角自旋核磁共振实验探测药盐

异核多量子相干 (HMQC) 脉冲序列，用于在快速 (60 kHz) 魔角旋转 (MAS) 和高转速下，在氯化物盐中的³⁵ Cl 和¹ H 核之间建立固态核磁共振 (NMR) 中的异核相关性磁场（850 MHz的¹ H 拉莫尔频率）进行了研究。具体而言，比较了使用旋转共振重新耦合与每个转子周期的相位反转或基于对称性的 SR4 ²₁脉冲序列重新耦合的³⁵ Cl– ¹ H 偶极相互作用。在我们实施人口转移 (PT) 偶极 (D) HMQC 实验中，³⁵Cl 原子核在第二个旋转边带上以低章动频率通过偏共振 WURST 扫描饱和，因此 WURST 脉冲的持续时间必须与重新耦合时间相同。对粉末中每个微晶取向分别进行的³⁵ Cl– ¹ H MAS D-HMQC 实验的数值模拟提供了在偶极再耦合应用下二阶四极加宽³⁵ Cl MAS NMR 线形变化的取向依赖性的洞察. 二维³⁵ Cl– ¹ H PT-D-HMQC MAS NMR 光谱显示氨基酸甘氨酸·HCl 和l-酪氨酸·HCl 以及药物西咪替丁·HCl、阿米替林·HCl 和利多卡因·HCl·H₂ O. 将实验观察到的³⁵ Cl 线形与使用包括投影仪增强波 (GIPAW) 方法计算的³⁵ Cl 化学位移和四极参数模拟的那些进行比较：计算的四极乘积 ( P _Q ) 值超过了实验测量的值1.3 到 1.9 之间的系数。

更新日期：2021-09-07

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