The advantageous characteristics attributed to the 19F19FT1T119F-labelled biological samples. We study the effect of Gd(DTPA) and Gd(DTPA-BMA) on 19FT1T2, and 13CT1T219F13C]-tryptophan-labelled protein via 19F-detected MAS NMR experiments. The observed paramagnetic relaxation enhancement substantially reduces measurement times of 19F12×39 kDa-large protein TET2 using a mutagenesis approach.
In addition to the development of various resonators, the concept of a probehead equipped with an additional low-noise amplifier (LNA) is becoming increasingly popular to enhance the sensitivity of electron paramagnetic resonance (EPR) spectrometers. The low-noise-detection amplifier makes it possible to measure pulsed EPR signals with high sensitivity. However, a strong reflected pulse signal can cause saturation and deterioration of the LNA characteristics, which requires protection of the LNA (for example, by using a protection switch in front of the LNA), which, in turn, reduces the signal-to-noise ratio. To overcome these limitations, we propose using an EPR probehead based on a bimodal cavity with strong isolation between the input and output ports in combination with a low-noise amplifier connected to the cavity output. The experiments demonstrate a 4-fold increase in the signal-to-noise ratio (SNR) of a bimodal probehead operating in transmission mode compared to its operation in reflection mode, which was achieved thanks to the additional use of LNA. The performance of the probe was also compared with the Bruker EN 5107D2 probe available in our laboratory, which showed an improvement that can be achieved by increasing the SNR by 2 times due to additional LNA and isolation of the detection channel from the input signal and by 3.3 times due to a larger sample volume in the bimodal probe (∼ 20 µL) at Q-band frequencies compared to the Bruker one (∼ 6 µL). The developed probehead can be used together with commercial Bruker ELEXYS EPR spectrometers without modification of the microwave bridge.
A connection between the symmetry of high-field nuclear magnetic resonance (NMR) spectra, including higher-order spectra, and the properties of the spin system has been established. It is shown that, for a spectrum to be symmetric about the mid-resonance frequency (ν0), two conditions must be satisfied: (1) the resonance frequencies of the spins must be symmetrically positioned about ν0, and (2) there must exist at least one spin ordering with a monotonic increase (or decrease) in resonance frequencies such that the spectrum is invariant under the reflection of the J-coupling matrix about its anti-diagonal (one way to satisfy this condition is for the J-coupling matrix to be explicitly persymmetric). The results were validated by calculating theoretical spectra for three-, four-, five-, and six-spin systems.
Bilinear rotations are essential building blocks in modern NMR spectroscopy. They allow the rotation of an isolated spin without couplings (i.e., bilinear interactions) in one way, while rotating spins with a matched coupling in another way. Different classes of rotations form the different bilinear rotations, with the acronyms BIRD, TANGO, BANGO, and BIG-BIRD. All original elements have in common hard pulses limiting bandwidths and defined rotations for coupled spins that are possible only for a narrow range of coupling constants. We recently introduced the COB-BIRD with a general optimization procedure to obtain robust bilinear rotations that are well compensated for couplings, offsets, and B1(Woordes et al., 2025). Here we show a fundamental principle on how the COB-BIRD can be used to construct all types of bilinear rotations, with the same improved robustness covering a coupling range of 120–250 Hz. In addition, a construction principle for universal rotation pulses is adapted to produce bilinear rotations from INEPT-type transfer elements, allowing the construction of bilinear rotations also for higher coupling ranges from, for example, COB3-INEPT, with coupling compensation in the range of 120–750 Hz. After introducing the two fundamental design principles, example sequences of the four classes of bilinear rotations and different degrees of robustness are derived and characterized in theory and experiment. In addition, a highly useful HMBC/ASAP-HSQC-IPE-COSY supersequence is introduced with a (COB-)BANGO element for Ernst-angle-type excitation. Finally, BIRD-decoupled J-resolved INEPT experiments with extreme compensation for partially aligned samples, with total couplings ranging from 47 Hz up to 434 Hz, are demonstrated.
Understanding spatially heterogeneous molecular diffusion in semicrystalline polymers is critical for elucidating interfacial dynamics in soft materials. This study employs static-gradient nuclear magnetic resonance (NMR) imaging to capture the depth-resolved translational motion of polymer chains in a polytetrafluoroethylene (PTFE) film. By focusing on spin–spin relaxation behavior in amorphous regions near crystalline lamellae, we identify multiple diffusion regimes consistent with Bloch–Torrey analysis. The results reveal that molecular mobility at the substrate interface of PTFE film, immobilized on a glass substrate using epoxy resin, is significantly constrained, likely due to interfacial pinning, while the air-side surface shows signs of enhanced mobility. Our findings highlight the utility of static-gradient field NMR for probing nanoscale dynamical heterogeneity in semicrystalline systems.
Fast and accurate arbitrary waveform generators (AWGs) for generating shaped pulses in electron paramagnetic resonance (EPR) have been commercially available for over a decade now. However, while the use of chirp pulses as inversion pulses in pulsed electron double resonance (PELDOR) experiments has become common, their application for generating broadband phase-sensitive transverse magnetization is not widely adopted within the community. Here, we give a detailed insight into optimization procedures and instrumental challenges when using chirped pulses for broadband Fourier transform (FT) detection of electron spin echo signals, particularly the two-dimensional frequency-correlated single-frequency technique for refocusing (SIFTER) experiment. To better understand the influence of chirped pulses on the generation of broadband transverse magnetization, we investigated the phase and amplitude of chirped echoes for different time bandwidth products while varying the number of refocusing pulses, particularly under the influence of B1
Long-lived statesTLLST1. In this study, lifetimes TLLS(19F) have been measured in three different achiral per- and polyfluoroalkyl substances (PFAS) containing two or three consecutive CF2B0=11.7 T, the lifetimes TLLS(19F) exceed the longitudinal relaxation times T1(19F) by about a factor of 2. The lifetimes TLLS(19F) can be strongly affected by binding to macromolecules, a feature that can be exploited for the screening of fluorinated drugs. Both TLLS(19F) and T1(19F) should be longer at lower fields where relaxation due to the chemical shift anisotropy (CSA) of 19F is less effective, which is demonstrated here by running experiments at two fields of 11.7 and 7 T.
Using cell-free protein synthesis, the protein G B1 domain (GB1) was prepared with uniform high-level substitution of valine by (2S,3S)-4-fluorovaline, (2S,3R)-4-fluorovaline or 4,4'-difluorovaline. The 19F1H19F-NMR signals. For the singly fluorinated residues, the 13C chemical shifts of the remaining CH3γCH2F3JFCγ-gauche effect on 19F3JHF19F–19F
Conference travel contributes to the climate footprint of academic research. Here, we provide a quantitative estimate of the carbon emissions associated with conference attendance by analyzing travel data from participants of 10 international conferences in the field of magnetic resonance, namely EUROMAR, ENC and ICMRBS. We find that attending a EUROMAR conference produces, on average, more than 1 t CO2 eq.. For the analyzed conferences outside Europe, the corresponding value is about 2–3 times higher, on average, with intercontinental trips amounting to up to 5 t. We compare these conference-related emissions to other activities associated with research and show that conference travel is a substantial portion of the total climate footprint of a researcher in magnetic resonance. We explore several strategies to reduce these emissions, including the impact of selecting conference venues more strategically and the possibility of decentralized conferences. Through a detailed comparison of train versus air travel – accounting for both direct and infrastructure-related emissions – we demonstrate that train travel offers considerable carbon savings. These data may provide a basis for strategic choices of future conferences in the field and for individuals deciding on their conference attendance.
Combining high-resolution high-field nuclear magnetic resonance (NMR) with an evolution of spin systems at a low magnetic field offers many opportunities for the investigation of molecular motions and hyperpolarization and the exploration of field-dependent spin dynamics. Fast and reproducible transfer between high and low fields is required to minimize polarization losses due to longitudinal relaxation. Here, we introduce a new design of a sample shuttle that achieves remarkably high speeds (vmax ∼ 27 m s−1). This hybrid pneumatic–mechanical apparatus is compatible with conventional probes at the high-field center. We show applications in water relaxometry in solutions of paramagnetic ions, high-resolution proton relaxometry of a small molecule, and sample shuttling of a solution of a 42 kDa protein. Importantly, this fast sample shuttle (FSS) system is narrow, with a diameter of d = 6 mm for the sample shuttle container based on a standard 5 mm outer diameter glass tube, which should allow near access to the sample for magnetic manipulation at a low field.
Pulse-dipolar electron paramagnetic resonance (PD-EPR) has emerged as an effective tool in structural biology, enabling distance measurements between spin labels attached to biomolecules. The sensitivity and accessible distance range of these measurements are governed by the phase memory time (Tm) of the spin labels. Understanding the decoherence mechanisms affecting Tm2O
Additive manufacturing has enabled rapid prototyping of components with minimum investment in specific fabrication infrastructure. These tools allow for a fast iteration from design to functional prototypes within days or even hours. Such prototyping technologies exist in many fields, including three-dimensional mechanical components and printed electric circuit boards (PCBs) for electrical connectivity, to mention two. In the case of nuclear magnetic resonance (NMR) spectroscopy, one needs the combination of both fields; we need to fabricate three-dimensional electrically conductive tracks as coils that are wrapped around a sample container. Fabricating such structures is difficult (e.g., six-axis micro-milling) or simply not possible with conventional methods. In this paper, we modified an additive manufacturing method that is based on the extrusion of conductive ink to fast-prototype solenoidal coil designs for NMR. These NMR coils need to be as close to the sample as possible and, by their shape, have specific inductive values. The performance of the designs was first investigated using electromagnetic field simulations and circuit simulations. The coil found to have optimal parameters for NMR was fabricated by extrusion printing, and its performance was tested in a 1.05 T