Article
Chemistry, Multidisciplinary
Gogulan Karunanithy, Harold W. Mackenzie, D. Flemming Hansen
Summary: The study introduces a method of virtual decoupling using deep neural networks, which enhances the resolution of nuclear magnetic resonance experiments and reduces the phase cycles required for experiments. This approach successfully decouples various protein NMR spectra, offering a flexible and effective solution where traditional methods may fail.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Biochemical Research Methods
Chuang Yang, Jinyong Chen, Qing Zeng, Yao Luo, Zhong Chen, Yanqin Lin
Summary: Two-dimensional homonuclear correlation spectra play a vital role in analyzing coupling networks and delivering structural information of molecules. However, the challenges of resolution and efficiency need to be addressed. This study proposes a scheme to simultaneously obtain pure shift COSY and TOCSY or pure shift COSY and NOESY spectra in the indirect dimension, aiming to improve resolution, reduce sampling time, and enhance efficiency.
JOURNAL OF MAGNETIC RESONANCE
(2022)
Article
Chemistry, Physical
Coral Mycroft, Mathias Nilsson, Gareth A. Morris, Laura Castanar
Summary: A general pure shift method is presented for obtaining ultra-high resolution H-1 NMR spectra by suppressing both homonuclear and heteronuclear J-couplings. Its usefulness is demonstrated in the analysis of fluorine- and phosphorus-containing compounds of pharmaceutical and biochemical interest.
Article
Chemistry, Physical
Bruno Simoes de Almeida, Pinelopi Moutzouri, Gabriele Stevanato, Lyndon Emsley
Summary: The study on the internal spin interaction of two- and three-spin systems under fast MAS conditions reveals that the third-order Hamiltonian expression provides the best agreement with full numerical calculations. This information is crucial for obtaining rich structural information for organic solids from H-1 MAS spectra.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Dilek Eltemur, Peter Robatscher, Michael Oberhuber, Alberto Ceccon
Summary: NMR spectroscopy is a powerful analytical tool for identifying and quantifying natural compounds in food matrices. However, its low intrinsic sensitivity makes it challenging to detect adulterants or markers for authenticity at low concentrations. This study presents a simple solution to enhance the sensitivity of NMR and successfully applies it to the authentication of milk products.
Article
Chemistry, Physical
Sven Bodenstedt, Denis Moll, Stefan Gloeggler, Morgan W. Mitchell, Michael C. D. Tayler
Summary: The method demonstrated quantifies and manipulates nuclear spin decoherence mechanisms in zero to ultralow magnetic fields, including switching spin quantization axis and scalar pathways due to through-bond couplings. Scalar relaxation caused by H-2 near zero field can significantly limit nuclear spin polarization lifetimes. Robust trains of pulsed dc magnetic fields can switch the effective symmetry of the nuclear spin Hamiltonian, broadening the scope of hyperpolarized biomedical contrast-agent compounds used near zero field.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Jacqueline Tognetti, W. Trent Franks, Jozef R. Lewandowski, Steven P. Brown
Summary: This study demonstrates enhanced decoupling in H-1 magic-angle spinning solid-state NMR, as well as good performance of windowed decoupling in H-1 spin-echo experiments. The findings have implications for N-15-H-1 cross polarization experiments.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Evgeny Nimerovsky, Eszter E. Najbauer, Kumar Tekwani Movellan, Kai Xue, Stefan Becker, Loren B. Andreas
Summary: Homonuclear dipolar recoupling is a commonly used method in magic-angle spinning NMR-based structure determination. However, it is only capable of detecting short proton-proton distances in fully protonated samples. To address this limitation, a selective pulse sequence called MODIST is introduced in this study, which selectively records correlations between amide protons. Compared to other methods, MODIST demonstrates up to twice the intensity for proton-proton correlations while maintaining a good retention of total signal.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Tianyu Qiu, Amir Jahangiri, Xiao Han, Dmitry Lesovoy, Tatiana Agback, Peter Agback, Adnane Achour, Xiaobo Qu, Vladislav Orekhov
Summary: Nuclear magnetic resonance (NMR) spectroscopy is an important tool in biochemistry and medicine. This study introduces a new approach for achieving broadband heteronuclear decoupling using the low-rank method, by using a specific coupling value and the Hankel property of the exponential NMR signal. The results show that this method effectively enhances resolution, maintains sensitivity, and suppresses spectral artifacts, and can be combined with non-uniform sampling to further improve resolution without extra acquisition time.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Lia Zaharani, Nader Ghaffari Khaligh, Mohd Rafie Johan
Summary: The acid-base reaction of piperazine and sulfuric acid was conducted to obtain a new molten salt, whose structure was elucidated using FTIR, NMR, and mass spectrometry. Contrary to expectations, no characteristic signal was detected for the existence of hydrogen sulfate anion in 1H NMR of the molten salt in DMSO-d(6). The formation of 1H,4H-piperazineN,N'-diium dication was supported by NMR studies of its bromide derivative.
JOURNAL OF MOLECULAR STRUCTURE
(2021)
Article
Chemistry, Physical
Haolin Zhan, Mengyou Hao, Ye Feng, Shuohui Cao, Zhikai Ni, Yuqing Huang, Zhong Chen
Summary: Diffusion-ordered NMR spectroscopy (DOSY) is a noninvasive method for studying intact mixtures and identifying individual components based on their diffusion behaviors. The strategy of spatially selective pure shift-based DOSY can help eliminate inhomogeneous line broadening and extract pure shift singlets, facilitating diffusion analyses on complex mixtures and potentially monitoring electrochemical reactions. This study demonstrates the potential of DOSY in complex mixture analysis and its applications in various fields.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Review
Chemistry, Multidisciplinary
Sahil Ahlawat, Kaustubh R. Mote, Nils-Alexander Lakomek, Vipin Agarwal
Summary: In the past two decades, solid-state nuclear magnetic resonance (ssNMR) spectroscopy has evolved from investigating small molecules and industrial polymers to decrypting complex biological systems. This transformation is due to improvements in hardware design, sample preparation, and sensitivity. This review discusses state-of-the-art ssNMR methods and recent developments in signal filtering, proton methodologies, and data acquisition speed in fast magic-angle spinning (MAS) systems.
Article
Chemistry, Analytical
Adilah Bahadoor, Andreas Brinkmann, Jeremy E. Melanson
Summary: Quantitative H-1 nuclear magnetic resonance (qHNMR) is an established method for determining purity in organic compounds, relying on careful selection of integrals and decoupling C-13 satellites to avoid interferences. Two decoupling schemes, GARP and bilevel adiabatic broadband decoupling, were explored, highlighting benefits and drawbacks of each. qH{C-13}NMR provides added clarity about the presence of impurities and tautomers, making it advantageous for accurate measurements compared to qHNMR.
ANALYTICAL CHEMISTRY
(2021)
Article
Chemistry, Physical
Andrea Simion, Tobias Schubeis, Tanguy Le Marchand, Mihai Vasilescu, Guido Pintacuda, Anne Lesage, Claudiu Filip
Summary: A new heteronuclear decoupling pulse sequence called ROSPAC is introduced, which enhances decoupling efficiency by using a large pattern of radio-frequencies and minimizing cross-effects. ROSPAC performs well for a wide range of chemical shifts and low radio-frequency powers, making it suitable for ultra-fast magic-angle spinning (MAS) conditions.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Manuel Cordova, Pinelopi Moutzouri, Bruno Simoes de Almeida, Daria Torodii, Lyndon Emsley
Summary: A deep learning approach is introduced to determine pure isotropic proton spectra from a two-dimensional set of magic-angle spinning spectra acquired at different spinning rates. The model is applied to 8 organic solids, yielding high-resolution H-1 solid-state NMR spectra with isotropic linewidths in the 50-400 Hz range.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Inorganic & Nuclear
Ross Davidson, Yu-Ting Hsu, Mark A. Fox, Juan A. Aguilar, Dmitry Yufit, Andrew Beeby
Summary: This study investigates the emission behavior of Ir(ppy)2(acac) complexes with OPE3 motifs and finds that the complexes containing OPE3 structures have long emission lifetimes, which can be achieved through intramolecular reversible electronic energy transfer (REET) with even longer-lived localized OPE3 states. This finding is important for oxygen sensing and cellular imaging applications.
INORGANIC CHEMISTRY
(2023)
Article
Biochemical Research Methods
Runchao Li, Laura Castanar, Mathias Nilsson, Gareth A. Morris
Summary: Quantitative NMR is widely used, but the errors introduced by soft pulses are not well understood. This study shows that relaxation on resonance during shaped soft refocusing pulses can be represented by biexponential decay, allowing for correction of relaxational losses in experiments.
JOURNAL OF MAGNETIC RESONANCE
(2023)
Article
Chemistry, Multidisciplinary
Coral Mycroft, Guilherme Dal Poggetto, Thaiis M. Barbosa, Claiudio F. Tormena, Mathias Nilsson, Gareth A. Morris, Laura Castanar
Summary: The NMR analysis of fluorine-containing molecules is important in pharmaceuticals and biochemistry, but faces challenges due to severe peak overlap. This study introduces a new method, IPAP-FESTA, that simplifies measurements of proton-fluorine couplings. Its usefulness is demonstrated in the structural study of the drug fluticasone propionate and in assessing solvent effects on fluorohydrin conformational equilibrium in a mixture.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Coral Mycroft, Marshall J. Smith, Mathias Nilsson, Gareth A. Morris, Laura Castanar
Summary: NMR measurements of molecules with sparse fluorine atoms are common in medicinal chemistry, but are complicated by homonuclear and heteronuclear scalar couplings. FESTA, a heteronuclear spectral editing method, simplifies 1H NMR spectra by obtaining only H-1 signals from the same spin system as a chosen F-19. However, signal overlap due to scalar couplings remains a problem in FESTA spectra.
MAGNETIC RESONANCE IN CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Marshall J. Smith, Jack E. Bramham, Mathias Nilsson, Gareth A. Morris, Laura Castanar, Alexander P. Golovanov
Summary: Fluorine is widely used in medicinal chemistry, both in drug molecules and molecular probes, due to its convenient monitoring capabilities by NMR spectroscopy in complex environments. However, NMR sensitivity is limited, especially at low concentrations of molecules.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Daniel A. Taylor, Peter Kiraly, Paul Bowyer, Mathias Nilsson, Laura Castanar, Gareth A. Morris, Ralph W. Adams
Summary: Selective 1D COSY can identify coupled spins but has limitations in selectivity and multiplet lineshapes. This study combines ultra-selective GEMSTONE excitation with CLIP-COSY to provide through-bond correlations for overlapping NMR signals. The method is demonstrated using the drugs lasalocid and cyclosporin.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Organic
Marshall J. J. Smith, Emma L. L. Gates, Goran Widmalm, Ralph W. W. Adams, Gareth A. A. Morris, Mathias Nilsson
Summary: Human milk oligosaccharides are bioactive molecules that have diverse effects on infant development. NMR provides important structural information about these oligosaccharides, but signal overlap in the spectra makes this information difficult to obtain. This study demonstrates the benefits of combining pure shift methods with the CASPER computational approach for resonance assignment in oligosaccharides.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Rafael Contreras-Montoya, James P. Smith, Stephen C. Boothroyd, Juan A. Aguilar, Marzieh Mirzamani, Martin A. Screen, Dmitry S. Yufit, Mark Robertson, Lilin He, Shuo Qian, Harshita Kumari, Jonathan W. Steed
Summary: The pathway complexity results in the formation of unique materials from the same components according to the assembly conditions. In this study, a chiral acyl-semicarbazide gelator forms three different gels and lyotropic liquid crystalline droplets depending on the assembly pathway. The gels have distinct morphologies and rheological properties due to the different conformers of the gelator. The emergence of different materials with contrasting properties is attributed to the emergent interactions during the assembly process.
Article
Chemistry, Multidisciplinary
Rafael Contreras-Montoya, James P. Smith, Stephen C. Boothroyd, Juan A. Aguilar, Marzieh Mirzamani, Martin A. Screen, Dmitry S. Yufit, Mark Robertson, Lilin He, Shuo Qian, Harshita Kumari, Jonathan W. Steed
Summary: Pathway complexity results in the formation of unique materials from the same components according to assembly conditions. A gelator in this study forms three different gels with contrasting morphology and rheological properties. The formation of a hyperhelical gel involves association with a non-gelling conformer. This research demonstrates the importance of pathway complexity in self-assembly processes.
Article
Chemistry, Multidisciplinary
Elsa Caytan, Howard M. Foster, Laura Castanar, Ralph W. Adams, Mathias Nilsson, Gareth A. Morris
Summary: This study reveals that practical pure shift NMR experiments using cryoprobes may result in signal loss, and proposes a simple adjustment to recover the lost signal.
CHEMICAL COMMUNICATIONS
(2023)
