Ikenna E. Ndukwe, Ian Black, Claudia A. Castro, Jiri Vlach, Christian Heiss, Caroline Roper, Parastoo Azadi
Current practices for structural analysis of extremely large-molecular-weight polysaccharides via solution-state nuclear magnetic resonance (NMR) spectroscopy incorporate partial depolymerization protocols that enable polysaccharide solubilization in suitable solvents. Non-specific depolymerization techniques utilized for glycosidic bond cleavage, such as chemical degradation or ultrasonication, potentially generate structural fragments that can complicate complete and accurate characterization of polysaccharide structures. Utilization of appropriate enzymes for polysaccharide degradation, on the other hand, requires prior structural knowledge and optimal enzyme activity conditions that are not available to an analyst working with novel or unknown compounds. Herein, we describe an application of a permethylation strategy that allows the complete dissolution of intact polysaccharides for NMR structural characterization. This approach is utilized for NMR analysis of Xylella fastidiosa extracellular polysaccharide (EPS), which is essential for the virulence of the plant pathogen that affects multiple commercial crops and is responsible for multibillion dollar losses each year.
{"title":"Permethylation as a strategy for high-molecular-weight polysaccharide structure analysis by nuclear magnetic resonance—Case study of Xylella fastidiosa extracellular polysaccharide","authors":"Ikenna E. Ndukwe, Ian Black, Claudia A. Castro, Jiri Vlach, Christian Heiss, Caroline Roper, Parastoo Azadi","doi":"10.1002/mrc.5413","DOIUrl":"10.1002/mrc.5413","url":null,"abstract":"<p>Current practices for structural analysis of extremely large-molecular-weight polysaccharides via solution-state nuclear magnetic resonance (NMR) spectroscopy incorporate partial depolymerization protocols that enable polysaccharide solubilization in suitable solvents. Non-specific depolymerization techniques utilized for glycosidic bond cleavage, such as chemical degradation or ultrasonication, potentially generate structural fragments that can complicate complete and accurate characterization of polysaccharide structures. Utilization of appropriate enzymes for polysaccharide degradation, on the other hand, requires prior structural knowledge and optimal enzyme activity conditions that are not available to an analyst working with novel or unknown compounds. Herein, we describe an application of a permethylation strategy that allows the complete dissolution of intact polysaccharides for NMR structural characterization. This approach is utilized for NMR analysis of <i>Xylella fastidiosa</i> extracellular polysaccharide (EPS), which is essential for the virulence of the plant pathogen that affects multiple commercial crops and is responsible for multibillion dollar losses each year.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5413","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138176530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The local structure and spin Hamiltonian parameters (SHPs) g factors (gx, gy, gz) and the hyperfine structure constants (Ax, Ay, Az) for Cu2+ doped in the LiTaO3 crystal are theoretically investigated by the perturbation formulas for a 3d9 ion under rhombically elongated octahedral based on the cluster approach. The impurity Cu2+ was assumed to occupy the host trigonally-distorted octahedral Li+ site and experience the Jahn–Teller (JT) distortion from the host trigonal octahedral [TaO6]10− to the impurity rhombically elongated octahedral [CuO6]10−. Based on the calculations, the impurity-ligand bond lengths parallel and perpendicular to the C2-axis are found to be R||(≈ 2.305 Å) and R⊥ (≈ 2.112 Å) for the studied [CuO6]10− cluster, with the planar bond angle θ (≈ 78.2°). Meanwhile, the ground-state wave function for Cu2+ center in LiTaO3 was also obtained. The calculated SHPs based on the above local lattice distortions agree well with the experimental data, and the results are discussed.
{"title":"Theoretical studies on the local structure and spin Hamiltonian parameters for Cu2+ ions in LiTaO3 crystal","authors":"Yun Chen, Lu Tang, Houdao Cai, Meiyun Zhang, Xunjie Wang, Cuidi Feng, Wenbo Xiao, Huaming Zhang","doi":"10.1002/mrc.5414","DOIUrl":"10.1002/mrc.5414","url":null,"abstract":"<p>The local structure and spin Hamiltonian parameters (SHPs) <i>g</i> factors (<i>g</i><sub><i>x</i></sub>, <i>g</i><sub><i>y</i></sub>, <i>g</i><sub><i>z</i></sub>) and the hyperfine structure constants (<i>A</i><sub><i>x</i></sub>, <i>A</i><sub><i>y</i></sub>, <i>A</i><sub><i>z</i></sub>) for Cu<sup>2+</sup> doped in the LiTaO<sub>3</sub> crystal are theoretically investigated by the perturbation formulas for a 3d<sup>9</sup> ion under rhombically elongated octahedral based on the cluster approach. The impurity Cu<sup>2+</sup> was assumed to occupy the host trigonally-distorted octahedral Li<sup>+</sup> site and experience the Jahn–Teller (JT) distortion from the host trigonal octahedral [TaO<sub>6</sub>]<sup>10−</sup> to the impurity rhombically elongated octahedral [CuO<sub>6</sub>]<sup>10−</sup>. Based on the calculations, the impurity-ligand bond lengths parallel and perpendicular to the <i>C</i><sub>2</sub>-axis are found to be <i>R</i><sub>||</sub>(≈ 2.305 Å) and <i>R</i><sub>⊥</sub> (≈ 2.112 Å) for the studied [CuO<sub>6</sub>]<sup>10−</sup> cluster, with the planar bond angle θ (≈ 78.2°). Meanwhile, the ground-state wave function for Cu<sup>2+</sup> center in LiTaO<sub>3</sub> was also obtained. The calculated SHPs based on the above local lattice distortions agree well with the experimental data, and the results are discussed.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136398087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report high-quality solid-state 35/37Cl NMR spectra for chlorine atoms directly bonded to paramagnetic cobalt(II) ions (high spin S = 3/2) in powered samples of CoCl2, CoCl2·2H2O, CoCl2·6H2O, and CoCl2(terpy) (terpy = 2,2′:6′,2″-terpyridine). Because solid-state 35/37Cl NMR spectra for paramagnetic cobalt(II) compounds often cover an extremely wide spectral range, they were recorded in this work in the form of variable-offset cumulative spectra. Solid-state 35/37Cl NMR measurements were performed at three magnetic fields (11.7, 14.1, and 16.5 T) and analysis of data yielded information about 35/37Cl quadrupole coupling and hyperfine coupling tensors in these paramagnetic cobalt(II) compounds. Experimental 35/37Cl NMR tensors were found to be in reasonable agreement with quantum chemical calculations based on a periodic DFT method implemented in BAND.
{"title":"Solid-state 35/37Cl NMR detection of chlorine atoms directly bound to paramagnetic cobalt(II) ions in powder samples","authors":"Lukas Bauder, Gang Wu","doi":"10.1002/mrc.5407","DOIUrl":"10.1002/mrc.5407","url":null,"abstract":"<p>We report high-quality solid-state <sup>35/37</sup>Cl NMR spectra for chlorine atoms directly bonded to paramagnetic cobalt(II) ions (high spin <i>S</i> = 3/2) in powered samples of CoCl<sub>2</sub>, CoCl<sub>2</sub>·2H<sub>2</sub>O, CoCl<sub>2</sub>·6H<sub>2</sub>O, and CoCl<sub>2</sub>(terpy) (terpy = 2,2′:6′,2″-terpyridine). Because solid-state <sup>35/37</sup>Cl NMR spectra for paramagnetic cobalt(II) compounds often cover an extremely wide spectral range, they were recorded in this work in the form of variable-offset cumulative spectra. Solid-state <sup>35/37</sup>Cl NMR measurements were performed at three magnetic fields (11.7, 14.1, and 16.5 T) and analysis of data yielded information about <sup>35/37</sup>Cl quadrupole coupling and hyperfine coupling tensors in these paramagnetic cobalt(II) compounds. Experimental <sup>35/37</sup>Cl NMR tensors were found to be in reasonable agreement with quantum chemical calculations based on a periodic DFT method implemented in BAND.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5407","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72209861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many-body expansion (MBE) fragment approaches have been applied to accurately compute nuclear magnetic resonance (NMR) parameters in crystalline systems. Recent examples demonstrate that electric field gradient (EFG) tensor parameters can be accurately calculated for 14N and 17O. A key additional development is the simple molecular correction (SMC) approach, which uses two one-body fragment (i.e., isolated molecule) calculations to adjust NMR parameter values established using ‘benchmark’ projector augmented-wave (PAW) density functional theory (DFT) values. Here, we apply a SMC using the hybrid PBE0 exchange-correlation (XC) functional to see if this can improve the accuracy of calculated 35Cl EFG tensor parameters. We selected eight organic and two inorganic crystal structures and considered 15 chlorine sites. We find that this SMC improves the accuracy of computed values for both the 35Cl quadrupolar coupling constant (CQ) and the asymmetry parameter (