Center for Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States.
Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
J Phys Chem Lett. 2021 Sep 16;12(36):8897-8902. doi: 10.1021/acs.jpclett.1c02465. Epub 2021 Sep 9.
We report two- and three-dimensional (2D and 3D) C-O heteronuclear correlation solid-state NMR experiments under magic-angle spinning (MAS) conditions. These experiments utilize the D-RINEPT (Dipolar-mediated Refocused Insensitive Nuclei Enhanced by Polarization Transfer) scheme with symmetry-based SR4 recoupling blocks for coherence transfer between C and O nuclei. First, a 2D O → C correlation experiment was performed for the [1-C,O]-Gly/Gly·HCl cocrystal and [U-C, 1-O]-α/β-d-glucose samples. Second, a 2D O → C MQ-D-RINEPT correlation experiment where the indirect dimension incorporates the multiple-quantum MAS (MQMAS) scheme was tested for obtaining isotropic O resolution with [U-C, 1-O]-α/β-d-glucose. Third, a new 3D O → C → C correlation experiment was demonstrated where O → C and C → C correlations are achieved by D-RINEPT and DARR (Dipolar Assisted Rotational Resonance) sequences, respectively (thus termed as a 3D D-RINEPT/DARR OCC experiment). This new 3D O NMR experiment is implemented with the aim for site-resolved solid-state O NMR studies.
我们报告了在魔角旋转（MAS）条件下进行的二维（2D）和三维（3D）C-O 异核相关固态 NMR 实验。这些实验利用了基于对称性的 SR4 重聚块的 D-RINEPT（偶极介导的极化转移增强的非敏感核增强）方案，用于在 C 和 O 核之间进行相干转移。首先，我们对[1-C,O]-Gly/Gly·HCl 共晶和[U-C,1-O]-α/β-d-葡萄糖样品进行了二维 O→C 相关实验。其次，我们测试了二维 O→C MQ-D-RINEPT 相关实验，其中间接维度采用多量子 MAS（MQMAS）方案，以获得[U-C,1-O]-α/β-d-葡萄糖的各向同性 O 分辨率。第三，我们展示了一种新的 3D O→C→C 相关实验，其中 O→C 和 C→C 相关通过 D-RINEPT 和 DARR（偶极辅助旋转共振）序列分别实现（因此称为 3D D-RINEPT/DARR OCC 实验）。这个新的 3D O NMR 实验是为了进行基于位置分辨的固态 O NMR 研究而实施的。
