Broadband adiabatic inversion cross-polarization to integer-spin nuclei with application to deuterium NMR,Magnetic Resonance in Chemistry

当前位置： X-MOL 学术 › Magn. Reson. Chem. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Broadband adiabatic inversion cross-polarization to integer-spin nuclei with application to deuterium NMR
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-02-26 , DOI: 10.1002/mrc.5145
Adam R Altenhof _{1,

2} , Sungsool Wi ₂ , Robert W Schurko _{1,

2}

Affiliation

Solid-state NMR (SSNMR) spectroscopy of integer-spin quadrupolar nuclei is important for the molecular-level characterization of a variety of materials and biological solids; of the integer spins, ²H (S = 1) is by far the most widely studied, due to its usefulness in probing dynamical motions. SSNMR spectra of integer-spin nuclei often feature very broad powder patterns that arise largely from the effects of the first-order quadrupolar interaction; as such, the acquisition of high-quality spectra continues to remain a challenge. The broadband adiabatic inversion cross-polarization (BRAIN-CP) pulse sequence, which is capable of cross-polarization (CP) enhancement over large bandwidths, has found success for the acquisition of SSNMR spectra of integer-spin nuclei, including ¹⁴N (S = 1), especially when coupled with Carr–Purcell/Meiboom–Gill pulse sequences featuring frequency-swept WURST pulses (WURST-CPMG) for T₂-based signal enhancement. However, to date, there has not been a systematic investigation of the spin dynamics underlying BRAIN-CP, nor any concrete theoretical models to aid in its parameterization for applications to integer-spin nuclei. In addition, the BRAIN-CP/WURST-CPMG scheme has not been demonstrated for generalized application to wideline or ultra-wideline (UW) ²H SSNMR. Herein, we provide a theoretical description of the BRAIN-CP pulse sequence for spin-1/2 → spin-1 CP under static conditions, featuring a set of analytical equations describing Hartmann–Hahn matching conditions and numerical simulations that elucidate a CP mechanism involving polarization transfer, coherence exchange, and adiabatic inversion. Several experimental examples are presented for comparison with theoretical models and previously developed integer-spin CP methods, demonstrating rapid acquisition of ²H NMR spectra from efficient broadband CP.

中文翻译：

应用于氘核磁共振的整数自旋核的宽带绝热反转交叉极化

整数自旋四极核的固态核磁共振 (SSNMR) 光谱对于各种材料和生物固体的分子级表征非常重要；在整数自旋中，² H ( S = 1) 是迄今为止研究最广泛的，因为它可用于探测动力学运动。整数自旋核的 SSNMR 光谱通常具有非常宽的粉末图案，这主要是由一阶四极相互作用的影响引起的。因此，获取高质量光谱仍然是一个挑战。宽带绝热反转交叉极化 (BRAIN-CP) 脉冲序列能够在大带宽上增强交叉极化 (CP)，已成功获取整数自旋核的 SSNMR 谱，包括¹⁴ N ( S = 1)，特别是当与 Carr-Purcell/Meiboom-Gill 脉冲序列结合使用时，该脉冲序列具有扫频 WURST 脉冲 (WURST-CPMG)，用于基于T ₂的信号增强。然而，迄今为止，还没有对 BRAIN-CP 的自旋动力学进行系统研究，也没有任何具体的理论模型来帮助其参数化以应用于整数自旋核。此外，BRAIN-CP/WURST-CPMG 方案尚未被证明可广泛应用于宽线或超宽线 (UW) ²H SSNMR。在此，我们提供了静态条件下自旋 1/2 → 自旋 1 CP 的 BRAIN-CP 脉冲序列的理论描述，具有一组描述 Hartmann-Hahn 匹配条件的解析方程和阐明 CP 机制的数值模拟，涉及极化转移、相干交换和绝热反转。提供了几个实验示例，用于与理论模型和先前开发的整数自旋 CP 方法进行比较，展示了从高效宽带 CP 中快速获取² H NMR 光谱。

更新日期：2021-02-26

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南