Solid state nuclear magnetic resonance最新文献

{"title":"Indirect detection of wideline magic angle spinning solid-state NMR spectra of spin-5/2, −7/2, and −9/2 half-integer quadrupolar nuclei","authors":"Sujeewa N.S. Lamahewage ,&nbsp;Yuting Li ,&nbsp;Aaron D. Sadow ,&nbsp;Aaron J. Rossini","doi":"10.1016/j.ssnmr.2025.102032","DOIUrl":"10.1016/j.ssnmr.2025.102032","url":null,"abstract":"<div><div>Quadrupolar nuclei with a nuclear spin <em>I</em> &gt; 1/2 account for ∼73 % of all NMR-active nuclei. The quadrupolar interaction broadens solid-state NMR spectra, frequently resulting in low resolution and poor sensitivity. Here, we present a theoretical and experimental investigation of the use of magic angle spinning (MAS) ¹H{X} double-echo resonance-echo saturation-pulse double-resonance (DE-RESPDOR) pulse sequences for the indirect detection of NMR spectra of half-integer quadrupolar nuclei with spin &gt;3/2 (spin 5/2, 7/2, or 9/2 nuclei). In these experiments, a dephasing profile for the quadrupolar nucleus is created by plotting the observed dephasing of the detected spin as a function of the transmitter offset of the indirectly detected spin. Simulating the dephasing profile allows the quadrupolar coupling constant (<em>C</em>_Q) and the EFG tensor asymmetry parameter (η_Q) to be estimated. The achievable dephasing levels and the lineshapes of dephasing profiles of the indirectly detected nuclei were predicted using numerical simulations. We demonstrate ¹H detection of ¹²⁷I (<em>I</em> = 5/2), ¹³⁹La (<em>I</em> = 7/2), and ¹¹⁵In (<em>I</em> = 9/2) nuclei in BaI₂.2H₂O (barium iodide dihydrate), La(BH₄)₃(THF)₃ (tris(borohydride)tris(tetrahydrofuran)lanthanum(III)), and In(OH)₃ (indium(III) hydroxide), respectively. The observed improvements or reductions in sensitivity with indirect detection are related to the proportion of ¹H <em>T</em>₁ to quadrupolar nucleus <em>T</em>₁, alongside the quadrupolar nucleus's spin quantum number and gyromagnetic ratio (γ). Additionally, the indirect detection experiments confirm the existence of dipolar or scalar couplings between the detected nucleus and the quadrupolar nucleus of interest, providing important structural information. Numerical simulations suggest these methods are also potentially applicable to quadrupolar nuclei having <em>C</em>_Q larger than 100 MHz.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"139 ","pages":"Article 102032"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144879009","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}

{"title":"Experimental and computational 17O solid-state NMR investigation of Na- and K-(bi)carbonate salts","authors":"Austin Peach ,&nbsp;Nicolas Fabregue ,&nbsp;David Gajan ,&nbsp;Frédéric Mentink-Vigier ,&nbsp;Faith Scott ,&nbsp;Christel Gervais ,&nbsp;Danielle Laurencin","doi":"10.1016/j.ssnmr.2025.102020","DOIUrl":"10.1016/j.ssnmr.2025.102020","url":null,"abstract":"<div><div>The importance of (bi)carbonate salts cannot be understated. They are vital to the Earth's geology and ecosystems and are used as precursors by chemists for the synthesis of functional materials. Naturally, solid-state NMR (ssNMR) appears as the spectroscopic tool of choice to probe the atomic-level structure and dynamics of (bi)carbonate salts. Of the possible nuclei available as spectroscopic probes in carbonate and bicarbonate ions (<em>i.e.</em>, ¹H, ¹³C, and ¹⁷O), oxygen-17 is highly attractive. Yet, it is seldom employed, largely due to its low natural abundance (0.04 %) and lack of practical enrichment protocols. Recently, we reported an effective ¹⁷O-labeling strategy involving mechanochemistry of Na₂CO₃·H₂O, Na₂CO₃, NaHCO₃, K₂CO₃·1.5H₂O, and KHCO₃, and recorded their ¹⁷O NMR spectral fingerprints near room temperature. In this work, ultra-low temperature (<em>i.e.</em>, 100 K) ¹⁷O ssNMR spectra of these phases are acquired at two magnetic fields, 14.1 and 18.8 T, to extract the ¹⁷O NMR parameters <em>δ</em>_iso, <em>C</em>_Q, and η_Q for the different oxygen sites, and to further study the influence of dynamics on the spectra. We compare the experimental ¹⁷O NMR parameters to those computed with GIPAW-DFT calculations both on static models, and after averaging by molecular dynamics (MD) simulations. This approach was taken to aid in analyzing the structure-spectra relationships and shed light on the dynamics. Lastly, we report the static GIPAW-DFT calculations of ¹⁷O NMR parameters for a series of other carbonate salts of interest, further expanding upon current experimental ¹⁷O ssNMR results.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"139 ","pages":"Article 102020"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144621830","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}

{"title":"Piezoelectric suppression for rapid detection of Methamphetamine Hydrochloride via 14N nuclear quadrupole resonance","authors":"Lewis Robertson,&nbsp;Richard Yong,&nbsp;David G. Miljak","doi":"10.1016/j.ssnmr.2025.102029","DOIUrl":"10.1016/j.ssnmr.2025.102029","url":null,"abstract":"<div><div>The ability to rapidly detect the presence of narcotic substances in baggage and on personnel is a prime requirement in airports, mail distribution centres and mass screening portals. Nuclear Quadrupole Resonance (NQR) is well-suited to detect selected narcotics as the resonances can be highly discriminating of a given substance due to the presence of narrow, non-overlapping spectral lines. Furthermore, the transparency of non-conductive materials to radio frequency (RF) magnetic fields allows for NQR to measure bulk volumes without any sample preparation. However, NQR as a spectroscopic technique is challenged by a relatively low signal-to-noise ratio (SNR) and the presence of interference sources like sample piezoelectric ringing. For NQR to be an effective tool for narcotics detection, these challenges must be overcome. Results of laboratory NQR measurements of the ¹⁴N <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mo>+</mo></mrow></msub></math></span> transition in methamphetamine hydrochloride are presented, occurring at 1.217<!--> <!-->MHz at room temperature. A confident detection of 200<!--> <!-->g of pure methamphetamine hydrochloride in a 20<!--> <!-->L sample coil was achieved in less than one second. In addition, the presence of piezoelectric interference in some smaller samples was investigated and successfully suppressed using electrostatic shielding techniques. The efficacy of the electrostatic shielding design was proven experimentally and further supported through simulation of the electric and magnetic fields within the sample coil.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"139 ","pages":"Article 102029"},"PeriodicalIF":2.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827037","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}

{"title":"A simple formulation of dynamic magic-angle spinning NMR derived from relaxation and Floquet theories","authors":"Jérôme Hirschinger","doi":"10.1016/j.ssnmr.2025.102017","DOIUrl":"10.1016/j.ssnmr.2025.102017","url":null,"abstract":"<div><div>A simple method proposed in an insightful paper by A. J. Vega [J. Magn. Reson. 65 (1985) 252–267] is applied for calculating the effects of chemical exchange on magic-angle spinning (MAS) NMR spectra in the case of a two-site rotational jump motion. This approach which only requires two basic expressions of <span><math><mrow><msub><mi>T</mi><mn>2</mn></msub></mrow></math></span> for the limiting cases of fast and slow exchange is compared with exact numerical calculations for arbitrary rates of motion and spinning frequencies. This comparison justifies the application of relaxation theory (RT) to calculate fast-exchange lineshapes but the slow-exchange <span><math><mrow><msub><mi>T</mi><mn>2</mn></msub></mrow></math></span> time constant originally derived by A. Schmidt and S. Vega [J. Chem. Phys. 87 (1987) 6895–6907] using Floquet-perturbation theory (FPT) fails to account for the differences in the spinning sideband linewidths. In this paper, the complete FPT (cFPT) expression of the MAS spectrum is shown to account for all details of differential sideband broadening observed in the slow-exchange regime. Moreover, the RT and cFPT solutions give insight into the effects of molecular dynamics on the MAS spectra and decrease dramatically the computation time. The calculation procedure using the RT and cFPT formulas yield lineshape simulations that are in very good agreement with exact numerical results except in the intermediate-exchange regime when the sideband linewidths become comparable with or larger than the MAS rate. This is a minor drawback in practice as fast relaxation then makes quantitative measurements difficult.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"138 ","pages":"Article 102017"},"PeriodicalIF":1.8,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144307767","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}

{"title":"A solid-state NMR approach for distinguishing between RNH2 and RNH3+ sites","authors":"Riley Nickles ,&nbsp;Emily C. Heider ,&nbsp;James K. Harper","doi":"10.1016/j.ssnmr.2025.102018","DOIUrl":"10.1016/j.ssnmr.2025.102018","url":null,"abstract":"<div><div>A necessary step in characterizing solid-phase organic materials is the accurate assignment of the ionization state at acidic and basic sites. Solution phase pK_a's are not always reliable reference points because local environments can significantly change pK_a values in solids. Herein, an approach for distinguishing R–NH₂ and R–NH₃⁺ is described based on experimental ¹⁵N chemical shift tensors principal values for a given site (i.e. <em>δ</em>₁₁, <em>δ</em>₂₂ and <em>δ</em>₃₃) from 18 model compounds. Those ¹⁵N sites that are present as R–NH₃⁺ have anisotropies between 5 and 15 ppm. In contrast, all R–NH₂ sites have anisotropies between 14 and 115 ppm. These R–NH₂ moieties can be further categorized into three subgroups. The differences observed are postulated to arise from differences in the symmetry of the intermolecular hydrogen bonding environment, or the direct attachment of the NH₂ to an aromatic ring.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"138 ","pages":"Article 102018"},"PeriodicalIF":1.8,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144335597","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}

{"title":"Practical aspects of Zeeman-perturbed NQR spectroscopy using an adjustable electromagnet","authors":"Alireza Nari,&nbsp;Patrick M.J. Szell,&nbsp;David L. Bryce","doi":"10.1016/j.ssnmr.2025.102014","DOIUrl":"10.1016/j.ssnmr.2025.102014","url":null,"abstract":"<div><div>Quadrupolar-perturbed solid-state NMR spectroscopy is a highly useful and well-established method for studying quadrupolar nuclei. This method relies on a high ratio of the Larmor frequency to the quadrupolar frequency and is limited, therefore, by the available magnetic field strengths suitable for NMR, which are on the order of 10¹ T. Nuclear quadrupole resonance (NQR) provides an approach to studying strongly quadrupolar isotopes, but there are technical challenges associated with measuring high-frequency transitions, and with measuring both the quadrupolar coupling constant, <em>C</em>_Q, and asymmetry parameter, <em>η</em>, with good precision. We describe here the technical and practical aspects of a modern implementation of Zeeman-perturbed NQR spectroscopy using an adjustable electromagnet, which overcomes the aforementioned challenges. This approach flips the quadrupolar-perturbed solid-state NMR method upside down, so that the quadrupolar interaction is dominant and the Zeeman interaction is the perturbation. ⁷⁹Br and ¹²⁷I Zeeman-perturbed NQR spectra are recorded for some solid bromo- and iodobenzene powders using applied magnetic fields on the order of 10⁻² T. Various experimental considerations are discussed, including the optimal magnetic field to be used, the optimization of the coil angle, frequency stepping, the simulation of spectra using an exact diagonalization of the Zeeman-quadrupolar Hamiltonian, and how to ensure high precision in the resulting quadrupolar parameters. As an example, a <em>C</em>_Q(¹²⁷) value of 2077.25 ± 1.49 MHz (with <em>η</em> = 0.114 ± 0.008) is measured for <em>sym</em>-triiodotrifluorobenzene in less than an hour at room temperature. The approach holds promise for studying strongly quadrupolar isotopes in a range of materials and obviates the need for ultrahigh magnetic fields in many situations of interest.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"138 ","pages":"Article 102014"},"PeriodicalIF":1.8,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144279234","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}

{"title":"Diverging errors: A comparison of DFT and machine-learning predictions of NMR shieldings","authors":"Ema Chaloupecká ,&nbsp;Ondřej Socha ,&nbsp;Martin Dračínský","doi":"10.1016/j.ssnmr.2025.102019","DOIUrl":"10.1016/j.ssnmr.2025.102019","url":null,"abstract":"<div><div>Accurate prediction of NMR parameters from first principles is essential for the structural characterization of molecular solids. Recent studies have shown that single-molecule correction schemes—based on hybrid DFT calculations—can significantly improve the accuracy of periodic DFT predictions of nuclear shieldings. Here, we evaluate the performance of this correction approach not only for periodic DFT calculations but also for ShiftML2, a machine-learning model trained on PBE-calculated NMR data. For ¹³C nuclei, the application of single-molecule PBE0 corrections to periodic PBE shieldings has reduced the root-mean-square deviation (RMSD) from 2.18 to 1.20 ppm, with negligible improvement observed for ¹H. When applied to ShiftML2 predictions, the corrections have yielded a smaller reduction in ¹³C RMSD (from 3.02 to 2.51 ppm); again, they have had minimal impact on ¹H predictions. Residual analysis has revealed weak correlation between DFT and ML errors, suggesting that while some sources of systematic deviation may be shared, others are likely distinct. These results demonstrate that DFT-specific correction schemes do not straightforwardly translate to machine-learning models, highlighting the need for ML-tailored post-processing or retraining strategies. The findings have important implications for the integration of machine learning into high-throughput NMR workflows and the development of more accurate predictive tools for solid-state spectroscopy.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"138 ","pages":"Article 102019"},"PeriodicalIF":1.8,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144514240","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}

{"title":"Editorial: Solid-state NMR and DNP of heterogeneous biomaterials and cellular systems","authors":"Patrick C.A. van der Wel ,&nbsp;Tuo Wang","doi":"10.1016/j.ssnmr.2025.102003","DOIUrl":"10.1016/j.ssnmr.2025.102003","url":null,"abstract":"","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"137 ","pages":"Article 102003"},"PeriodicalIF":1.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143760051","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}

{"title":"Solid-state NMR observation of chitin in whole cells by indirect 15N detection with NC, NCC, CNC and CNCC polarization transfers","authors":"Loic Delcourte ,&nbsp;Mélanie Berbon ,&nbsp;Marion Rodriguez ,&nbsp;Laurence Delhaes ,&nbsp;Birgit Habenstein ,&nbsp;Antoine Loquet","doi":"10.1016/j.ssnmr.2025.102002","DOIUrl":"10.1016/j.ssnmr.2025.102002","url":null,"abstract":"<div><div>Chitin is the most important nitrogen-containing polysaccharide found on Earth. This polysaccharide is a polymer of an N-acetylglucosamine and it is a crucial structural component of fungal cell walls and crustaceans. Magic-angle spinning solid-state NMR is emerging as a powerful analytical approach to study polysaccharides in the context of intact cell walls and whole cells. The presence of an acetamido group in chitin is attractive for ¹⁵N solid-state NMR. Here we investigate the use of various multi-step polarization transfer experiments incorporating indirect ¹⁵N detection at moderate spinning frequency, adapted from pulse sequences commonly employed for residue resonance assignment in biosolid proteins. The ¹³C,¹⁵N chitin spin topology slightly differs from amino acids, and we discussed the use of frequency-selective ¹⁵N-¹³C cross-polarization transfers followed by broadband or frequency-selective homonuclear ¹³C–¹³C transfers to detect chitin resonances. Demonstrated here for chitin found in the cell wall of the fungus <em>Aspergillus fumigatus</em>, the use of indirect ¹⁵N detection through multi-step polarization transfers could be advantageous to investigate more complex nitrogen-containing polysaccharides found in whole cells and peptidoglycan samples.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"137 ","pages":"Article 102002"},"PeriodicalIF":1.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143675577","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}

{"title":"Dynamic nuclear polarization of TEMPO radical cross conjugated with a thioanisole scaffold","authors":"Renny Mathew ,&nbsp;Jagriti Gupta ,&nbsp;M.D. Devadarsan ,&nbsp;Sagar Mavi ,&nbsp;Mohammed Jasil ,&nbsp;Jerry A. Fereiro ,&nbsp;Benesh Joseph ,&nbsp;Keshaba N. Parida ,&nbsp;Brijith Thomas","doi":"10.1016/j.ssnmr.2025.102005","DOIUrl":"10.1016/j.ssnmr.2025.102005","url":null,"abstract":"<div><div>Nuclear magnetic resonance (NMR) spectroscopy is an important technique for molecular structure determination but is inherently limited by its low sensitivity. Recently, the Dynamic nuclear polarization (DNP) technique has emerged as a solution to overcome the intrinsic low sensitivity of NMR spectroscopy by transferring polarization from the unpaired electron spins to nuclear spins under microwave irradiation, achieving a theoretical sensitivity enhancement of up to 658-fold for the detection of ¹H. In this study, we report the synthesis and characterization of a series of TEMPO(2,2,6,6-tetramethylpiperidine-1-oxyl)-based radicals functionalized with a thioanisole scaffold, designed to facilitate self-assembled monolayers on gold surfaces. The radicals were investigated using electron paramagnetic resonance (EPR) and DNP NMR spectroscopy. These radicals demonstrated properties consistent with the standard TEMPO while maintaining stability and functionality. At 10 mM concentration in TCE (1,1,2,2-tetrachloroethane), Radical-Imine-1 yielded a DNP enhancement factor of 3.2 for ¹H nuclei and that of standard TEMPO is around 2.8 at 14.1 T. Relaxation measurements revealed that longitudinal relaxation times (T₁) decreased with radical concentration, while transverse relaxation times (T₂) remain largely unaffected, indicating minimal perturbation from paramagnetic quenching. The structural stability and surface-binding potential of the methyl thiol group make these derivatives suitable for surface-based DNP applications.</div></div>","PeriodicalId":21937,"journal":{"name":"Solid state nuclear magnetic resonance","volume":"137 ","pages":"Article 102005"},"PeriodicalIF":1.8,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143894297","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}