title: High-resolution heteronuclear multi-dimensional NMR spectroscopy in magnetic fields with unknown spatial variations.
abstract: Heteronuclear NMR spectroscopy is an extremely powerful tool for determining the structures of organic molecules and is of particular significance in the structural analysis of proteins. In order to leverage the method's potential for structural investigations, obtaining high-resolution NMR spectra is essential and this is generally accomplished by using very homogeneous magnetic fields. However, there are several situations where magnetic field distortions and thus line broadening is unavoidable, for example, the samples under investigation may be inherently heterogeneous, and the magnet's homogeneity may be poor. This line broadening can hinder resonance assignment or even render it impossible. We put forth a new class of pulse sequences for obtaining high-resolution heteronuclear spectra in magnetic fields with unknown spatial variations based on distant dipolar field modulations. This strategy's capabilities are demonstrated with the acquisition of high-resolution 2D gHSQC and gHMBC spectra. These sequences' performances are evaluated on the basis of their sensitivities and acquisition efficiencies. Moreover, we show that by encoding and decoding NMR observables spatially, as is done in ultrafast NMR, an extra dimension containing J-coupling information can be obtained without increasing the time necessary to acquire a heteronuclear correlation spectrum. Since the new sequences relax magnetic field homogeneity constraints imposed upon high-resolution NMR, they may be applied in portable NMR sensors and studies of heterogeneous chemical and biological materials.
authors.affiliation: Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Yuqing
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Pieter E S
authors.initials: PE
authors.lastname: Smith
authors.affiliation: Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Kaiyu
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China.
authors.forename: Shuhui
authors.initials: S
authors.lastname: Cai
authors.affiliation: Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian 361005, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen, Fujian 361005, China. Electronic address: chenz@xmu.edu.cn.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001704:Biopolymers / Q000032:analysis* / Q000737:chemistry*; D060526:Magnetic Fields; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D001704:Biopolymers
keywords: Distant dipolar field; Heteronuclear multidimensional NMR; High-resolution spectroscopy; Inhomogeneous fields; Three-dimensional acquisition; Ultrafast acquisition