Journal of Magnetic Resonance Open最新文献

Pushing the sensitivity boundaries of X-band EPR cryoprobe using a fast microwave switch

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-04-03 DOI: 10.1016/j.jmro.2025.100196

Uršulė Tarvydytė , Vidmantas Kalendra , Gediminas Usevičius , James O’Sullivan , Adam Brookfield , Alice M. Bowen , Jūras Banys , John J.L. Morton , Mantas Šimėnas

{"title":"Pushing the sensitivity boundaries of X-band EPR cryoprobe using a fast microwave switch","authors":"Uršulė Tarvydytė , Vidmantas Kalendra , Gediminas Usevičius , James O’Sullivan , Adam Brookfield , Alice M. Bowen , Jūras Banys , John J.L. Morton , Mantas Šimėnas","doi":"10.1016/j.jmro.2025.100196","DOIUrl":"10.1016/j.jmro.2025.100196","url":null,"abstract":"<div><div>We present a new design of an X-band EPR cryoprobe based on a fast microwave switch and a cryogenic low-noise microwave amplifier that are placed close to the sample in the same cryostat. The probehead supports high-power (100 W) pulsed EPR experiments and is compatible with standard EPR resonators and samples. In contrast to the directional coupler design of the EPR cryoprobe reported previously, the fast microwave switch fully isolates the microwave amplifier from input thermal noise without microwave power suppression allowing us to approach the sensitivity limit of cryoprobes for pulsed EPR experiments. We benchmark the performance of our cryoprobe setup against a standard commercial EPR instrument revealing a significant sensitivity improvement, which reduces the measurement time by a factor of about <span><math><mrow><mn>250</mn><mo>×</mo></mrow></math></span> at 6 K sample temperature. We also show that the sensitivity of our new X-band cryoprobe design matches that of a standard Q-band setup for double electron–electron resonance experiments.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100196"},"PeriodicalIF":2.624,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143768066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Probing cation dynamics and phase transition in hybrid organic-inorganic perovskites by 13C solid-state NMR spectroscopy at very high resolution

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-28 DOI: 10.1016/j.jmro.2025.100197

Yue Dou , Qing Wang , Hengxing Ji , Haiming Liu

{"title":"Probing cation dynamics and phase transition in hybrid organic-inorganic perovskites by 13C solid-state NMR spectroscopy at very high resolution","authors":"Yue Dou , Qing Wang , Hengxing Ji , Haiming Liu","doi":"10.1016/j.jmro.2025.100197","DOIUrl":"10.1016/j.jmro.2025.100197","url":null,"abstract":"<div><div>The spatial dynamics of cations have a significant impact on the photodynamic behavior of excited states in high-performance hybrid organic-inorganic perovskites. Multinuclear (<sup>1</sup>H, <sup>2</sup>H, and <sup>14</sup>N) solid-state NMR (SSNMR) spectroscopy has traditionally been utilized to study the motion of methylammonium (MA) cations in methylammonium lead (II) halides MAPbX<sub>3</sub> (X = I, Br, Cl). NMR methods based on spin-lattice relaxation or quadrupolar line shape analysis over a limited temperature range demonstrate rapid MA reorientation, but the cation dynamics in a wider temperature range covering phase transition of all major crystallographic phases is lacking. Due to its low sensitivity, <sup>13</sup>C NMR is rarely used to assess MA dynamics in these perovskites. Herein, we adopte variable-temperature (VT) <sup>13</sup>C MAS NMR at very high resolution and dipolar-coupled transverse relaxation analysis as a new tool for dynamical characterization without isotopic enrichment, and systematically investigated MA dynamics in MAPbX<sub>3</sub> across phase transitions. This new approach enables retrieval of activation energy of MA reorientation and assessment of motion regimes. We propose a generalized “Camel model” that describes the common trend of cation dynamics for MAPbX<sub>3</sub>, suggesting possible complicated reorientation modes. Furthermore, we discover the evolution of multiple MA sites in orthorhombic MAPbCl<sub>3</sub>, consistent with X-ray crystallography, demonstrating its unique advantage in resolving and characterizing multi-cation dynamics. The VT <sup>13</sup>C SSNMR effectively probes organic ion motions and phase transitions in hybrid perovskites, helpful for further elucidating the structure-property relationship in photovoltaic conversion mechanisms.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100197"},"PeriodicalIF":2.624,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143738290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Paramagnetic relaxation: Direct and Raman relaxation of spin S=12

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-12 DOI: 10.1016/j.jmro.2025.100193

W.Th. Wenckebach

{"title":"Paramagnetic relaxation: Direct and Raman relaxation of spin S=12","authors":"W.Th. Wenckebach","doi":"10.1016/j.jmro.2025.100193","DOIUrl":"10.1016/j.jmro.2025.100193","url":null,"abstract":"<div><div>Paramagnetic relaxation in solids is a vast subject, about as vast as the range of manifestations of electron spin in matter. It is a complex subject as well: it is the interface between paramagnetic centres – be it transition metal ions, radicals or defects – and quantized vibrations: phonons. So it requires an understanding of both these phonons and those paramagnetic centres. Moreover, contrary to the case of integer spin, for half-integer spin the coupling between electron spins and phonons is indirect. Two interactions are needed, the spin–orbit interaction between the spin and the orbits of the paramagnetic centre and the orbit–phonon interaction between the latter and the phonons.</div><div>The present article is an effort to navigate the theory of this extensive subject for spin <span><math><mrow><mi>S</mi><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></math></span> and aims to derive the main properties of the two most important mechanisms: direct and red Raman relaxation. It tries to do so from first principles, that is, it includes a generalized, but fundamental description of the vibrational states, the orbital and spin states on the one hand, and the orbit–phonon and spin–orbit interaction on the other. Based on these descriptions it derives the transition matrix elements responsible for paramagnetic relaxation, following the original approach of Van Vleck for paramagnetic centres with spin <span><math><mrow><mi>S</mi><mo>=</mo><mfrac><mrow><mn>1</mn></mrow><mrow><mn>2</mn></mrow></mfrac></mrow></math></span>, a relatively weak spin–orbit interaction and embedded in an insulating, diamagnetic solid. Subsequently phonon statistics are included to derive the paramagnetic relaxation rates. No effort is done to review the vast body of experimental work on the subject.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100193"},"PeriodicalIF":2.624,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ultrafast 2D benchtop NMR spectroscopy enhanced by flow Overhauser dynamic nuclear polarization

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-10 DOI: 10.1016/j.jmro.2025.100195

Joris Mandral , Johnnie Phuong , Jonathan Farjon , Patrick Giraudeau , Kerstin Münnemann , Jean-Nicolas Dumez

{"title":"Ultrafast 2D benchtop NMR spectroscopy enhanced by flow Overhauser dynamic nuclear polarization","authors":"Joris Mandral , Johnnie Phuong , Jonathan Farjon , Patrick Giraudeau , Kerstin Münnemann , Jean-Nicolas Dumez","doi":"10.1016/j.jmro.2025.100195","DOIUrl":"10.1016/j.jmro.2025.100195","url":null,"abstract":"<div><div>Benchtop Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful analytical technique for the monitoring of reactions and processes due to its accessibility and lower cost compared to high-field NMR. However, benchtop NMR spectroscopy often suffers from limited sensitivity and resolution. In this work, we have combined ultrafast (UF) 2D NMR with Overhauser Dynamic Nuclear Polarization (ODNP) to tackle both problems. Compared to thermally polarized 1D NMR, UF 2D NMR provides improved spectral resolution in a single scan whereas ODNP boosts the NMR sensitivity. To demonstrate the possibility of combining UF 2D NMR with ODNP for process monitoring applications, experiments were carried out at different flow conditions. Our results show that ODNP at least compensated for the losses in sensitivity of UF 2D NMR that are normally induced by high flow velocities. Moreover, under certain flow conditions, ODNP brings additional sensitivity to UF 2D NMR spectra, with SNR increased by a factor of >3 compared to thermal equilibrium acquisitions. The methods developed in this article are expected to be beneficial for more informative and sensitive acquisitions in the context of process monitoring.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100195"},"PeriodicalIF":2.624,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Probing nanoparticle proximity effects on selective butadiene hydrogenation over Pd-Au/TiO2 with parahydrogen-induced polarization NMR

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-03 DOI: 10.1016/j.jmro.2025.100192

Bintian Lu , Weiyu Wang , Shuangqin Zeng , Xiuzhi Gao , Jun Xu , Feng Deng

{"title":"Probing nanoparticle proximity effects on selective butadiene hydrogenation over Pd-Au/TiO2 with parahydrogen-induced polarization NMR","authors":"Bintian Lu , Weiyu Wang , Shuangqin Zeng , Xiuzhi Gao , Jun Xu , Feng Deng","doi":"10.1016/j.jmro.2025.100192","DOIUrl":"10.1016/j.jmro.2025.100192","url":null,"abstract":"<div><div>Selective butadiene hydrogenation to butene is a crucial process in the petrochemical industry, however, a comprehensive understanding of the underlying structure-activity relationships remains elusive. This study explores the influence of supported metal nanoparticle proximity on butadiene hydrogenation using parahydrogen-induced polarization NMR spectroscopy. A sol-immobilization method was employed to systematically control the spacing between PdAu nanoparticles on Pd-Au/TiO<sub>2</sub> catalysts, while preserving their overall physicochemical properties. Experimental results demonstrate that denser PdAu nanoparticle arrangements lead to enhanced catalytic activity. This improved activity is coupled with accelerated isomerization of the semi-hydrogenated butene and over-hydrogenation to butane, facilitated by enhanced butene adsorption and subsequent conversion. Furthermore, increasing the hydrogen content significantly boosts butadiene conversion and butane formation, while having a less impact on butene isomerization. The addition of an inert support material, altering the spatial distribution of catalyst particles, positively affects both catalytic activity and butene selectivity. These findings highlight the critical role of nanoparticle proximity in controlling reaction pathways in butadiene hydrogenation.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100192"},"PeriodicalIF":2.624,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143577291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Robotic arms for hyperpolarization-enhanced NMR

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-03 DOI: 10.1016/j.jmro.2025.100194

Kirill Sheberstov , Erik Van Dyke , Jingyan Xu , Raphael Kircher , Liubov Chuchkova , Yinan Hu , Sulaiman Alvi , Dmitry Budker , Danila A. Barskiy

引用次数: 0

Tribute to Alexander Pines (1945-2024)

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-03-01 DOI: 10.1016/j.jmro.2025.100185

Lucio Frydman , Jeffrey A. Reimer

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Introduction to average Hamiltonian theory. II. Advanced examples

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-02-16 DOI: 10.1016/j.jmro.2025.100191

Andreas Brinkmann

{"title":"Introduction to average Hamiltonian theory. II. Advanced examples","authors":"Andreas Brinkmann","doi":"10.1016/j.jmro.2025.100191","DOIUrl":"10.1016/j.jmro.2025.100191","url":null,"abstract":"<div><div>Where the first part of our tutorial <em>Introduction to average Hamiltonian theory</em> (Brinkmann, 2016) introduced in detail the basic concepts and demonstrated the application to two composite radio-frequency (rf) pulses in nuclear magnetic resonance (NMR) spectroscopy, this second part will present in a comprehensive but educational manner two, more advanced examples for the application of average Hamiltonian theory in solid-state NMR spectroscopy, both to analyse and design rf pulse sequences: (i) The Rotational-Echo Double Resonance (REDOR) sequence, which recouples the heteronuclear dipolar coupling during sample rotation around an axis at the magic-angle of <span><math><mrow><mn>54</mn><mo>.</mo><mn>7</mn><msup><mrow><mn>4</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span> with respect to the external static magnetic field. We will gradually increase the complexity of applying average Hamiltonian theory by first considering ideal, infinitesimally short rf pulses. Next, we will examine finite pulses with an rf phase of zero, and finally, we will explore finite pulses with arbitrary rf phases. In the latter case, if a first order average Hamiltonian proportional to heteronuclear longitudinal two-spin order (<span><math><mrow><mn>2</mn><msub><mrow><mi>I</mi></mrow><mrow><mi>z</mi></mrow></msub><msub><mrow><mi>S</mi></mrow><mrow><mi>z</mi></mrow></msub></mrow></math></span>) is desired, solutions for the choice of rf phases include the XY and MLEV type schemes. (ii) The Lee–Goldburg homonuclear dipolar decoupling sequence under static samples conditions and its improved successors, Flip-Flop Lee–Goldburg (FFLG) and Frequency-Switched Lee–Goldburg (FSLG).</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"23 ","pages":"Article 100191"},"PeriodicalIF":2.624,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

DNA Binding Mechanism of The Virulence Regulator SarA in Staphylococcus aureus

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-02-10 DOI: 10.1016/j.jmro.2025.100188

Dihong Fu , Xiaoyun Guo , Bo Duan , Bin Xia

{"title":"DNA Binding Mechanism of The Virulence Regulator SarA in Staphylococcus aureus","authors":"Dihong Fu , Xiaoyun Guo , Bo Duan , Bin Xia","doi":"10.1016/j.jmro.2025.100188","DOIUrl":"10.1016/j.jmro.2025.100188","url":null,"abstract":"<div><div><em>Staphylococcus aureus</em> infections have long been a significant challenge to public health, particularly due to the emergence of multiple drug-resistant strains. SarA is a critical global regulator in <em>S. aureus</em> which binds to AT-rich sequences in the promoter regions of various genes, but the DNA-binding mechanism of SarA remains unclear. Here, we determined the solution structures of a monomeric DNA binding domain of SarA (SarA<sup>ΔN19</sup>) and its complex with an AT-rich double-stranded DNA. The winged helix domain of SarA<sup>ΔN19</sup> binds to DNA in a classic way, with the α4 helix binding to the major groove of DNA, while the L5 loop binding to the minor groove, covering 10 AT base pairs. Residues L53, P65, and V68 of the α4 helix have hydrophobic interactions with thymine bases and sugar rings. The side chains of Arg90 and Arg84 from the wing are inserted into the minor groove, forming hydrogen bonds with A/T bases. Multiple positively charged or hydrophilic residues, including Lys54, Lys63, Lys69, Lys72, Lys82, and Gln64, interact with the phosphate groups on the DNA backbones. This complex structure provides an in-depth understanding of the molecular mechanism for SarA to bind DNA, and a better structure basis for future anti-bacterial drug design targeting SarA.</div></div>","PeriodicalId":365,"journal":{"name":"Journal of Magnetic Resonance Open","volume":"22 ","pages":"Article 100188"},"PeriodicalIF":2.624,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Chiral recognition of some D and L-amino acids by microcrystalline cellulose assisted diffusion-ordered NMR spectroscopy

IF 2.624

Journal of Magnetic Resonance Open Pub Date : 2025-02-01 DOI: 10.1016/j.jmro.2025.100189

Bowen Han , Jing He , Shaohua Huang

引用次数: 0