Special Issue "Nuclear Magnetic Resonance Spectroscopy"

A special issue of Magnetochemistry (ISSN 2312-7481).

Deadline for manuscript submissions: closed (31 October 2017)

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A printed edition of this Special Issue is available here.

Special Issue Editor

Guest Editor
Dr. Teresa Lehmann

Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA
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Phone: +1 307 766 2772
Fax: +1 307 766 2807
Interests: NMR; cancer drugs; malaria; solution structure determination; interfacial phenomena; colloidal dispersion gels

Special Issue Information

Dear Colleagues,

Nuclear Magnetic Resonance (NMR) spectroscopy is a nondestructive technique that can be used to characterize a wide variety of systems. Sustained development of both methodology and instrumentation have allowed NMR to hold a special place as a powerful technology with applications in pure sciences, medicine, drug development, and important branches of industry. NMR provides precise structural information down to each atom and bond in a molecule, and it is the only method for the determination of structures of molecules in solution. NMR can lead to chemical identification and conformational analysis of natural and synthetic chemicals. It is also a powerful technique used in the investigation of polymers in chemistry, and can provide information on the motional properties of molecules and compounds. This Special Issue of the open access journal, Magnetochemistry, devoted to NMR, furnishes researches in the field with the opportunity for authors to publish their most recent discoveries using this exciting technique.

Dr. Teresa Lehmann
Guest Editor

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Keywords

  • Diffusion in porous media

  • Diffusion probes for energy-related macromolecules (surfactants, polymers, organic acids, and asphaltenes)

  • Time-domain NMR

  • NMR applied to polymer dispersion and gels

  • NMR applied to locally ordered protein networks

  • NMR applied to molecular conformation and dynamics

  • Transport imaging

  • NMR in the solid state

  • Relaxometry

  • NMR applied to paramagnetic molecules

  • Characterization of synthetic organic and inorganic molecules through NMR

  • NMR in natural products and pharmaceutical chemistry

  • Structural analysis by two-dimensional NMR

  • Multidimensional NMR in liquids

Published Papers (22 papers)

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Editorial

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Open AccessEditorial Nuclear Magnetic Resonance Spectroscopy
Magnetochemistry 2018, 4(2), 20; https://doi.org/10.3390/magnetochemistry4020020
Received: 13 April 2018 / Revised: 16 April 2018 / Accepted: 16 April 2018 / Published: 20 April 2018
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(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available

Research

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Open AccessCommunication Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing
Magnetochemistry 2018, 4(1), 15; https://doi.org/10.3390/magnetochemistry4010015
Received: 3 November 2017 / Revised: 11 December 2017 / Accepted: 13 December 2017 / Published: 6 February 2018
Cited by 2 | PDF Full-text (5373 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Detailed Nuclear Magnetic Resonance (NMR) spectroscopy investigations on a novel naphthalene-substituted 1,2,3-triazole-based fluorescence sensor provided evidence for the “turn-on” detection of anions. The one-step, facile synthesis of the sensors was implemented using the “Click chemistry” approach in good yield. When investigated
[...] Read more.
Detailed Nuclear Magnetic Resonance (NMR) spectroscopy investigations on a novel naphthalene-substituted 1,2,3-triazole-based fluorescence sensor provided evidence for the “turn-on” detection of anions. The one-step, facile synthesis of the sensors was implemented using the “Click chemistry” approach in good yield. When investigated for selectivity and sensitivity against a series of anions (F, Cl, Br, I, H2PO4, ClO4, OAc, and BF4), the sensor displayed the strongest fluorometric response for the fluoride anion. NMR and fluorescence spectroscopic studies validate a 1:1 binding stoichiometry between the sensor and the fluoride anion. Single crystal X-ray diffraction evidence revealed the structure of the sensor in the solid state. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Towards a Microscopic Theory of the Knight Shift in an Anisotropic, Multiband Type-II Superconductor
Magnetochemistry 2018, 4(1), 14; https://doi.org/10.3390/magnetochemistry4010014
Received: 24 November 2017 / Revised: 26 December 2017 / Accepted: 4 January 2018 / Published: 29 January 2018
Cited by 1 | PDF Full-text (420 KB) | HTML Full-text | XML Full-text
Abstract
A method is proposed to extend the zero-temperature Hall-Klemm microscopic theory of the Knight shift K in an anisotropic and correlated, multi-band metal to calculate K(T) at finite temperatures T both above and into its superconducting state. The transverse part
[...] Read more.
A method is proposed to extend the zero-temperature Hall-Klemm microscopic theory of the Knight shift K in an anisotropic and correlated, multi-band metal to calculate K ( T ) at finite temperatures T both above and into its superconducting state. The transverse part of the magnetic induction B ( t ) = B 0 + B 1 ( t ) causes adiabatic changes suitable for treatment with the Keldysh contour formalism and analytic continuation onto the real axis. We propose that the Keldysh-modified version of the Gor’kov method can be used to evaluate K ( T ) at high B 0 both in the normal state, and by quantizing the conduction electrons or holes with Landau orbits arising from B 0 , also in the entire superconducting regime for an anisotropic, multiband Type-II BCS superconductor. Although the details have not yet been calculated in detail, it appears that this approach could lead to the simple result K S ( T ) a ( B 0 ) b ( B 0 ) | Δ ( B 0 , T ) | 2 , where 2 | Δ ( B 0 , T ) | is the effective superconducting gap. More generally, this approach can lead to analytic expressions for K S ( T ) for anisotropic, multiband Type-II superconductors of various orbital symmetries that could aid in the interpretation of experimental data on unconventional superconductors. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes
Magnetochemistry 2018, 4(1), 13; https://doi.org/10.3390/magnetochemistry4010013
Received: 4 December 2017 / Revised: 8 January 2018 / Accepted: 11 January 2018 / Published: 18 January 2018
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Abstract
We report the analysis of comb-like polymers by solid-state NMR. The polymers were previously evaluated as solid-polymer-electrolytes (SPE) for lithium-polymer-metal batteries that have suitable ionic conductivity at 60 °C. We propose to develop a correlation between 13C solid-state NMR measurements and phase
[...] Read more.
We report the analysis of comb-like polymers by solid-state NMR. The polymers were previously evaluated as solid-polymer-electrolytes (SPE) for lithium-polymer-metal batteries that have suitable ionic conductivity at 60 °C. We propose to develop a correlation between 13C solid-state NMR measurements and phase segregation. 13C solid-state NMR is a perfect tool for differentiating polymer phases with fast or slow motions. 7Li was used to monitor the motion of lithium ions in the polymer, and activation energies were calculated. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle The Radiofrequency NMR Spectra of Lithium Salts in Water; Reevaluation of Nuclear Magnetic Moments for 6Li and 7Li Nuclei
Magnetochemistry 2018, 4(1), 9; https://doi.org/10.3390/magnetochemistry4010009
Received: 2 December 2017 / Revised: 25 December 2017 / Accepted: 4 January 2018 / Published: 10 January 2018
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Abstract
LiCl and LiNO3 water solutions in the presence of small amounts of 3-helium have been investigated by means of multinuclear resonance spectroscopy. The resulting concentration dependences of the 3He, 6,7Li+, 14NO3 and 35Cl
[...] Read more.
LiCl and LiNO3 water solutions in the presence of small amounts of 3-helium have been investigated by means of multinuclear resonance spectroscopy. The resulting concentration dependences of the 3He, 6,7Li+, 14NO3 and 35Cl resonance radiofrequencies are reported in the infinite limit. This data along with new theoretical corrections of shielding lithium ions was analyzed by a known NMR relationship method. Consequently, the nuclear magnetic moments of 6Li and 7Li were established against that of the helium-3 dipole moment: μ(6Li) = +0.8220457(50)μN and μ(7Li) = +3.256418(20)μN. The new results were shown to be very close to the previously obtained values of the (ABMR) atomic beam magnetic resonance method. This experiment proves that our helium method is well suited for establishing dipole moments from NMR measurements performed in water solutions. This technique is especially valuable when gaseous substances of the needed element are not available. All shielding constants of species present in water solutions are consistent with new nuclear magnetic moments and these taken as a reference. Both techniques—NMR and ABMR—give practically the same results provided that all shielding corrections are properly made. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Spatially Resolved Measurements of Crosslinking in UV-Curable Coatings Using Single-Sided NMR
Magnetochemistry 2018, 4(1), 8; https://doi.org/10.3390/magnetochemistry4010008
Received: 21 November 2017 / Revised: 18 December 2017 / Accepted: 22 December 2017 / Published: 9 January 2018
Cited by 1 | PDF Full-text (1552 KB) | HTML Full-text | XML Full-text
Abstract
The UV-driven photocuring of coatings results in a crosslinked polymeric network. The degree of crosslinking in these coatings is typically assessed via optical spectroscopy; unfortunately, optical methods are typically limited in their maximum depth access. Alternatively, single-sided nuclear magnetic resonance (NMR) can be
[...] Read more.
The UV-driven photocuring of coatings results in a crosslinked polymeric network. The degree of crosslinking in these coatings is typically assessed via optical spectroscopy; unfortunately, optical methods are typically limited in their maximum depth access. Alternatively, single-sided nuclear magnetic resonance (NMR) can be used to probe the crosslinking of UV-curable coatings in a spatially sensitive manner. Relaxation measurements, which correlate with crosslinking, can be done with a spatial resolution on the order of microns throughout the depth dimension of the coating, regardless of optical transparency of the material. These results can be visualized via a relaxation cross-section that shows the depth at which a particular relaxation value is observed. These measurements are used to probe the effect of a scavenger molecule that is added to the coating mixture, allowing for efficient crosslinking despite the presence of atmospheric oxygen. This method may find purchase in evaluating systems whose crosslinking properties are intentionally varied throughout its thickness; using NMR, these systems, up to approximately one hundred microns thick, can be measured without repositioning or rastering. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessFeature PaperArticle Structural Changes of Zn(II)bleomycin Complexes When Bound to DNA Hairpins Containing the 5′-GT-3′ and 5′-GC-3′ Binding Sites, Studied through NMR Spectroscopy
Magnetochemistry 2018, 4(1), 4; https://doi.org/10.3390/magnetochemistry4010004
Received: 9 November 2017 / Revised: 8 December 2017 / Accepted: 12 December 2017 / Published: 27 December 2017
Cited by 1 | PDF Full-text (3199 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
We have previously investigated the diverse levels of disruption caused by Zn(II)BLMs with different C-termini to DNA hairpins containing 5′-GC-3′ and 5′-GT-3′ binding sites. The results of this investigation indicated that both the DNA-binding site and the bleomycin C-termini have an impact on
[...] Read more.
We have previously investigated the diverse levels of disruption caused by Zn(II)BLMs with different C-termini to DNA hairpins containing 5′-GC-3′ and 5′-GT-3′ binding sites. The results of this investigation indicated that both the DNA-binding site and the bleomycin C-termini have an impact on the final conformation of the aforementioned hairpins in the drug-target complexes, as suggested by the different sets of intramolecular NOEs displayed by both oligonucleotides when bound to each Zn(II)BLM. The NMR signals elicited by 1H nuclei in the oligonucleotide bases and sugar moieties were also affected differently (shifted upfield or downfield in various patterns) depending on the BLM C-termini and the binding site in the oligonucleotides. The overall conclusion derived from the precedent research is that the spatial conformation of target DNA segments in DNA-Zn(II)BLM complexes could be forged by interactions between drug and DNA that are guided by the DNA binding site and the BLM C-termini. The present study focuses on the structural alterations exhibited by Zn(II)bleomycin-A2, -B2, -A5 and Zn(II)peplomycin molecules upon binding to the previously studied hairpins. Our main goal is to determine if different spatial conformations of the drugs in their DNA-bound forms are found in drug-DNA complexes that differ in the oligonucleotide binding site and BLM C-termini. Evidence that suggest that each Zn(II)bleomycin is structurally affected depending these two factors, as indicated by different sets of intramolecular NOE connectivities between drug protons and diverse patterns of shifting of their 1H-NMR signals, is provided. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessCommunication Application of NMR Screening Methods with 19F Detection to Fluorinated Compounds Bound to Proteins
Magnetochemistry 2018, 4(1), 3; https://doi.org/10.3390/magnetochemistry4010003
Received: 11 November 2017 / Revised: 7 December 2017 / Accepted: 21 December 2017 / Published: 27 December 2017
Cited by 1 | PDF Full-text (483 KB) | HTML Full-text | XML Full-text
Abstract
The combinational use of one-dimensional (1D) NMR-based screening techniques with 1H and 19F detections were applied to a human serum albumin–diflunisal complex. Since most NMR screening methods observe 1H spectra, the overlapped 1H signals were unavailable in the binding
[...] Read more.
The combinational use of one-dimensional (1D) NMR-based screening techniques with 1H and 19F detections were applied to a human serum albumin–diflunisal complex. Since most NMR screening methods observe 1H spectra, the overlapped 1H signals were unavailable in the binding epitope mapping. However, the NMR experiments with 19F detection can be used as an effective complementary method. For the purpose of identifying the 1H and 19F binding epitopes of diflunisal, this paper carries out a combinatorial analysis using 1H{1H} and 19F{1H} saturation transfer difference experiments. The differences of the 1H-inversion recovery rates with and without target irradiation are also analyzed for a comprehensive interpretation of binding epitope mapping. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Accelerating NMR-Based Structural Studies of Proteins by Combining Amino Acid Selective Unlabeling and Fast NMR Methods
Magnetochemistry 2018, 4(1), 2; https://doi.org/10.3390/magnetochemistry4010002
Received: 30 October 2017 / Revised: 4 December 2017 / Accepted: 7 December 2017 / Published: 26 December 2017
Cited by 1 | PDF Full-text (2891 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, there has been a growing interest in fast acquisition and analysis of nuclear magnetic resonance (NMR) spectroscopy data for high throughput protein structure determination. Towards this end, rapid data collection techniques and methods to simplify the NMR spectrum such as
[...] Read more.
In recent years, there has been a growing interest in fast acquisition and analysis of nuclear magnetic resonance (NMR) spectroscopy data for high throughput protein structure determination. Towards this end, rapid data collection techniques and methods to simplify the NMR spectrum such as amino acid selective unlabeling have been proposed recently. Combining these two approaches can speed up further the structure determination process. Based on this idea, we present three new two-dimensional (2D) NMR experiments, which together provide 15N, 1HN, 13Cα, 13Cβ, 13C′ chemical shifts for amino acid residues which are immediate C-terminal neighbors (i + 1) of residues that are selectively unlabeled. These experiments have high sensitivity and can be acquired rapidly using the methodology of G-matrix Fourier transform (GFT) NMR spectroscopy combined with non-uniform sampling (NUS). This is a first study involving the application of fast NMR methods to proteins samples prepared using a specific labeling scheme. Taken together, this opens up new avenues to using the method of selective unlabeling for rapid resonance assignment of proteins. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Calcium-Dependent Interaction Occurs between Slow Skeletal Myosin Binding Protein C and Calmodulin
Magnetochemistry 2018, 4(1), 1; https://doi.org/10.3390/magnetochemistry4010001
Received: 1 November 2017 / Revised: 12 December 2017 / Accepted: 15 December 2017 / Published: 21 December 2017
Cited by 1 | PDF Full-text (3150 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Myosin binding protein C (MyBP-C) is a multi-domain protein that participates in the regulation of muscle contraction through dynamic interactions with actin and myosin. Three primary isoforms of MyBP-C exist: cardiac (cMyBP-C), fast skeletal (fsMyBP-C), and slow skeletal (ssMyBP-C). The N-terminal region of
[...] Read more.
Myosin binding protein C (MyBP-C) is a multi-domain protein that participates in the regulation of muscle contraction through dynamic interactions with actin and myosin. Three primary isoforms of MyBP-C exist: cardiac (cMyBP-C), fast skeletal (fsMyBP-C), and slow skeletal (ssMyBP-C). The N-terminal region of cMyBP-C contains the M-motif, a three-helix bundle that binds Ca2+-loaded calmodulin (CaM), but less is known about N-terminal ssMyBP-C and fsMyBP-C. Here, we characterized the conformation of a recombinant N-terminal fragment of ssMyBP-C (ssC1C2) using differential scanning fluorimetry, nuclear magnetic resonance, and molecular modeling. Our studies revealed that ssC1C2 has altered thermal stability in the presence and absence of CaM. We observed that site-specific interaction between CaM and the M-motif of ssC1C2 occurs in a Ca2+-dependent manner. Molecular modeling supported that the M-motif of ssC1C2 likely adopts a three-helix bundle fold comparable to cMyBP-C. Our study provides evidence that ssMyBP-C has overlapping structural determinants, in common with the cardiac isoform, which are important in controlling protein–protein interactions. We shed light on the differential molecular regulation of contractility that exists between skeletal and cardiac muscle. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessFeature PaperArticle Local and Average Structural Changes in Zeolite A upon Ion Exchange
Magnetochemistry 2017, 3(4), 42; https://doi.org/10.3390/magnetochemistry3040042
Received: 21 August 2017 / Revised: 6 December 2017 / Accepted: 7 December 2017 / Published: 12 December 2017
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Abstract
The infamous ‘structure–property relationship’ is a long-standing problem for the design, study and development of novel functional materials. Most conventional characterization methods, including diffraction and crystallography, give us a good description of long-range order within crystalline materials. In recent decades, methods such as
[...] Read more.
The infamous ‘structure–property relationship’ is a long-standing problem for the design, study and development of novel functional materials. Most conventional characterization methods, including diffraction and crystallography, give us a good description of long-range order within crystalline materials. In recent decades, methods such as Solid State NMR (SS NMR) are more widely used for characterization of crystalline solids, in order to reveal local structure, which could be different from long-range order and sometimes hidden from long-range order probes. In particular for zeolites, this opens a great avenue for characterization through studies of the local environments around Si and Al units within their crystalline frameworks. In this paper, we show that some structural modifications occur after partially exchanging the extraframework Na + ions with monovalent, Li + , K + , Rb + and NH 4 + and divalent, Ca 2 + cations. Solid state NMR is deployed to study the local structure of exchanged materials, while average stricture changes can be observed by powder diffraction (PXRD). To corroborate our findings, we also employ Fourier Transform Infrared spectroscopy (FT-IR), and further characterization of some samples was done using Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray spectroscopy (EDX). Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Short-Chain Alkanethiol Coating for Small-Size Gold Nanoparticles Supporting Protein Stability
Magnetochemistry 2017, 3(4), 40; https://doi.org/10.3390/magnetochemistry3040040
Received: 30 October 2017 / Revised: 19 November 2017 / Accepted: 21 November 2017 / Published: 27 November 2017
Cited by 2 | PDF Full-text (3514 KB) | HTML Full-text | XML Full-text
Abstract
The application of gold nanoparticles (AuNPs) is emerging in many fields, raising the need for a systematic investigation on their safety. In particular, for biomedical purposes, a relevant issue are certainly AuNP interactions with biomolecules, among which proteins are the most abundant ones.
[...] Read more.
The application of gold nanoparticles (AuNPs) is emerging in many fields, raising the need for a systematic investigation on their safety. In particular, for biomedical purposes, a relevant issue are certainly AuNP interactions with biomolecules, among which proteins are the most abundant ones. Elucidating the effects of those interactions on protein structure and on nanoparticle stability is a major task towards understanding their mechanisms at a molecular level. We investigated the interaction of the 3-mercaptopropionic acid coating of AuNPs (MPA-AuNPs) with β2-microglobulin (β2m), which is a paradigmatic amyloidogenic protein. To this aim, we prepared and characterized MPA-AuNPs with an average diameter of 3.6 nm and we employed NMR spectroscopy and fluorescence spectroscopy to probe protein structure perturbations. We found that β2m interacts with MPA-AuNPs through a highly localized patch maintaining its overall native structure with minor conformational changes. The interaction causes the reversible precipitation of clusters that can be easily re-dispersed through brief sonication. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Early Stages of Biomineral Formation—A Solid-State NMR Investigation of the Mandibles of Minipigs
Magnetochemistry 2017, 3(4), 39; https://doi.org/10.3390/magnetochemistry3040039
Received: 27 October 2017 / Revised: 15 November 2017 / Accepted: 17 November 2017 / Published: 22 November 2017
Cited by 2 | PDF Full-text (1547 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Solid-state nuclear magnetic resonance (NMR) spectroscopy allows for the identification of inorganic species during the biomineral formation, when crystallite particles visible in direct imaging techniques have not yet been formed. The bone blocks surrounding dental implants in minipigs were dissected after the healing
[...] Read more.
Solid-state nuclear magnetic resonance (NMR) spectroscopy allows for the identification of inorganic species during the biomineral formation, when crystallite particles visible in direct imaging techniques have not yet been formed. The bone blocks surrounding dental implants in minipigs were dissected after the healing periods of two, four, and eight weeks, and newly formed tissues formed around the implants were investigated ex vivo. Two-dimensional 31P-1H heteronuclear correlation (HETCOR) spectroscopy is based on the distance-dependent heteronuclear dipolar coupling between phosphate- and hydrogen-containing species and provides sufficient spectral resolution for the identification of different phosphate minerals. The nature of inorganic species present at different mineralization stages has been determined based on the 31P chemical shift information. After a healing time of two weeks, pre-stages of mineralization with a rather unstructured distribution of structural motives were found. After four weeks, different structures, which can be described as nanocrystals exhibiting a high surface-to-volume ratio were detected. They grew and, after eight weeks, showed chemical structures similar to those of matured bone. In addition to hydroxyapatite, amorphous calcium phosphate, and octacalcium phosphate, observed in a reference sample of mature bone, signatures of ß-tricalcium phosphate and brushite-like structures were determined at the earlier stages of bone healing. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Separation of the α- and β-Anomers of Carbohydrates by Diffusion-Ordered NMR Spectroscopy
Magnetochemistry 2017, 3(4), 38; https://doi.org/10.3390/magnetochemistry3040038
Received: 31 October 2017 / Revised: 17 November 2017 / Accepted: 20 November 2017 / Published: 22 November 2017
Cited by 1 | PDF Full-text (1377 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This article describes the successful application of the DOSY method for the separation and analysis of the α- and β-anomers of carbohydrates with different diffusion coefficients. In addition, the DOSY method was found to effectively separate two kinds of glucopyranosides with similar aglycon
[...] Read more.
This article describes the successful application of the DOSY method for the separation and analysis of the α- and β-anomers of carbohydrates with different diffusion coefficients. In addition, the DOSY method was found to effectively separate two kinds of glucopyranosides with similar aglycon structures from a mixture. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle NMR-Assisted Structure Elucidation of an Anticancer Steroid-β-Enaminone Derivative
Magnetochemistry 2017, 3(4), 37; https://doi.org/10.3390/magnetochemistry3040037
Received: 31 October 2017 / Revised: 15 November 2017 / Accepted: 17 November 2017 / Published: 21 November 2017
Cited by 1 | PDF Full-text (2397 KB) | HTML Full-text | XML Full-text
Abstract
The fortuitous modification of a quinoline-proline-piperazine side chain linked to a steroid in the presence of lithium (trimethylsilyl) acetylide has generated an unknown product that is more active than its precursor. After having characterized two β-enaminones (two-carbon homologation compounds) that were generated from
[...] Read more.
The fortuitous modification of a quinoline-proline-piperazine side chain linked to a steroid in the presence of lithium (trimethylsilyl) acetylide has generated an unknown product that is more active than its precursor. After having characterized two β-enaminones (two-carbon homologation compounds) that were generated from a simplified model side chain, we have identified the unknown product as being the β-enaminone steroid derivative 1. NMR analysis, especially two-dimensional (2D) experiments (correlation spectroscopy (COSY), NOE spectroscopy (NOESY), heteronuclear single-quantum correlation (HSQC) and heteronuclear multiple-bond correlation (HMBC)) provided crucial information that was found essential in the characterization of enaminone 1. We also proposed a mechanism to rationalize the formation of this biologically active compound. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Quantification of Squalene in Olive Oil Using 13C Nuclear Magnetic Resonance Spectroscopy
Magnetochemistry 2017, 3(4), 34; https://doi.org/10.3390/magnetochemistry3040034
Received: 11 October 2017 / Revised: 26 October 2017 / Accepted: 31 October 2017 / Published: 6 November 2017
Cited by 1 | PDF Full-text (1320 KB) | HTML Full-text | XML Full-text
Abstract
In the course of our ongoing work on the chemical characterization of Corsican olive oil, we have developed and validated a method for direct quantification of squalene using 13C Nuclear Magnetic Resonance (NMR) spectroscopy without saponification, extraction, or fractionation of the investigated
[...] Read more.
In the course of our ongoing work on the chemical characterization of Corsican olive oil, we have developed and validated a method for direct quantification of squalene using 13C Nuclear Magnetic Resonance (NMR) spectroscopy without saponification, extraction, or fractionation of the investigated samples. Good accuracy, linearity, and precision of the measurements have been observed. The experimental procedure was applied to the quantification of squalene in 24 olive oil samples from Corsica. Squalene accounted for 0.35–0.83% of the whole composition. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessArticle Low Field NMR Determination of pKa Values for Hydrophilic Drugs for Students in Medicinal Chemistry
Magnetochemistry 2017, 3(3), 29; https://doi.org/10.3390/magnetochemistry3030029
Received: 6 September 2017 / Revised: 15 September 2017 / Accepted: 19 September 2017 / Published: 20 September 2017
Cited by 1 | PDF Full-text (1020 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
For an interdisciplinary approach on different topics of medicinal and analytical chemistry, we applied a known experimental pKa value determination method on the field of the bench top nuclear magnetic resonance (NMR) spectrometry of some known biologically active pyridine-based drugs, i.e., pyridoxine
[...] Read more.
For an interdisciplinary approach on different topics of medicinal and analytical chemistry, we applied a known experimental pKa value determination method on the field of the bench top nuclear magnetic resonance (NMR) spectrometry of some known biologically active pyridine-based drugs, i.e., pyridoxine hydrochloride, isoniazid, and nicotine amide. The chemical shifts of the aromatic ring protons in the 1H NMR spectrum change depending on the protonation status. The data were analyzed on dependence of the chemical shifts by different pH (pD) environments and then the pKa values were calculated. The pKa values obtained were in agreement with the literature data for the compounds, searched by the students on web programs available at our university. The importance of the pKa values in protein-ligand interactions and distribution etc. of drugs was brought up to the students’ attention. In addition, by the use of a free web application for pKa values prediction, students calculated the predicted modeled pKa value. The experimental and in-silico approaches enhance the tool box for undergraduate students in medicinal chemistry. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Review

Jump to: Editorial, Research

Open AccessReview The NMR2 Method to Determine Rapidly the Structure of the Binding Pocket of a Protein–Ligand Complex with High Accuracy
Magnetochemistry 2018, 4(1), 12; https://doi.org/10.3390/magnetochemistry4010012
Received: 22 November 2017 / Revised: 25 December 2017 / Accepted: 4 January 2018 / Published: 22 January 2018
Cited by 1 | PDF Full-text (3568 KB) | HTML Full-text | XML Full-text
Abstract
Structural characterization of complexes is crucial for a better understanding of biological processes and structure-based drug design. However, many protein–ligand structures are not solvable by X-ray crystallography, for example those with low affinity binders or dynamic binding sites. Such complexes are usually targeted
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Structural characterization of complexes is crucial for a better understanding of biological processes and structure-based drug design. However, many protein–ligand structures are not solvable by X-ray crystallography, for example those with low affinity binders or dynamic binding sites. Such complexes are usually targeted by solution-state NMR spectroscopy. Unfortunately, structure calculation by NMR is very time consuming since all atoms in the complex need to be assigned to their respective chemical shifts. To circumvent this problem, we recently developed the Nuclear Magnetic Resonance Molecular Replacement (NMR2) method. NMR2 very quickly provides the complex structure of a binding pocket as measured by solution-state NMR. NMR2 circumvents the assignment of the protein by using previously determined structures and therefore speeds up the whole process from a couple of months to a couple of days. Here, we recall the main aspects of the method, show how to apply it, discuss its advantages over other methods and outline its limitations and future directions. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessReview Nuclear Magnetic Resonance, a Powerful Tool in Cultural Heritage
Magnetochemistry 2018, 4(1), 11; https://doi.org/10.3390/magnetochemistry4010011
Received: 28 December 2017 / Revised: 10 January 2018 / Accepted: 13 January 2018 / Published: 17 January 2018
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Abstract
In this paper five case studies illustrating applications of NMR (Nuclear Magnetic Resonance) in the field of cultural heritage, are reported. Different issues were afforded, namely the investigation of advanced cleaning systems, the quantitative mapping of moisture in historic walls, the investigation and
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In this paper five case studies illustrating applications of NMR (Nuclear Magnetic Resonance) in the field of cultural heritage, are reported. Different issues were afforded, namely the investigation of advanced cleaning systems, the quantitative mapping of moisture in historic walls, the investigation and evaluation of restoration treatments on porous stones, the stratigraphy of wall paintings, and the detection of CO2 in lapis lazuli. Four of these case studies deal with the use of portable NMR sensors which allow non-destructive and non-invasive investigation in situ. The diversity among cases reported demonstrates that NMR can be extensively applied in the field of cultural heritage. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessFeature PaperReview Multi-Quanta Spin-Locking Nuclear Magnetic Resonance Relaxation Measurements: An Analysis of the Long-Time Dynamical Properties of Ions and Water Molecules Confined within Dense Clay Sediments
Magnetochemistry 2017, 3(4), 35; https://doi.org/10.3390/magnetochemistry3040035
Received: 5 September 2017 / Revised: 27 October 2017 / Accepted: 31 October 2017 / Published: 14 November 2017
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Abstract
Solid/liquid interfaces are exploited in various industrial applications because confinement strongly modifies the physico-chemical properties of bulk fluids. In that context, investigating the dynamical properties of confined fluids is crucial to identify and better understand the key factors responsible for their behavior and
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Solid/liquid interfaces are exploited in various industrial applications because confinement strongly modifies the physico-chemical properties of bulk fluids. In that context, investigating the dynamical properties of confined fluids is crucial to identify and better understand the key factors responsible for their behavior and to optimize their structural and dynamical properties. For that purpose, we have developed multi-quanta spin-locking nuclear magnetic resonance relaxometry of quadrupolar nuclei in order to fill the gap between the time-scales accessible by classical procedures (like dielectric relaxation, inelastic and quasi-elastic neutron scattering) and obtain otherwise unattainable dynamical information. This work focuses on the use of quadrupolar nuclei (like 2H, 7Li and 133Cs), because quadrupolar isotopes are the most abundant NMR probes in the periodic table. Clay sediments are the confining media selected for this study because they are ubiquitous materials implied in numerous industrial applications (ionic exchange, pollutant absorption, drilling, waste storing, cracking and heterogeneous catalysis). Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessFeature PaperReview Orientational Glasses: NMR and Electric Susceptibility Studies
Magnetochemistry 2017, 3(4), 33; https://doi.org/10.3390/magnetochemistry3040033
Received: 3 October 2017 / Revised: 11 October 2017 / Accepted: 17 October 2017 / Published: 1 November 2017
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Abstract
We review the results of a wide range of nuclear magnetic resonance (NMR)measurements of the local order parameters and the molecular dynamics of solid ortho-para hydrogen mixtures and solid nitrogen-argon mixtures that form novel molecular orientational glass states at low temperatures. From the
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We review the results of a wide range of nuclear magnetic resonance (NMR)measurements of the local order parameters and the molecular dynamics of solid ortho-para hydrogen mixtures and solid nitrogen-argon mixtures that form novel molecular orientational glass states at low temperatures. From the NMR measurements, the distribution of the order parameters can be deduced and, in terms of simple models, used to analyze the thermodynamic measurements of the heat capacities of these systems. In addition, studies of the dielectric susceptibilities of the nitrogen-argon mixtures are reviewed in terms of replica symmetry breaking analogous to that observed for spin glass states. It is shown that this wide set of experimental results is consistent with orientation or quadrupolar glass ordering of the orientational degrees of freedom. Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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Open AccessReview Characterization of Halogen Bonded Adducts in Solution by Advanced NMR Techniques
Magnetochemistry 2017, 3(4), 30; https://doi.org/10.3390/magnetochemistry3040030
Received: 7 September 2017 / Revised: 16 September 2017 / Accepted: 20 September 2017 / Published: 25 September 2017
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Abstract
In the last 20 years, a huge volume of experimental work into halogen bonding (XB) has been produced. Most of the systems have been characterized by solid state X-ray crystallography, whereas in solution the only routine technique is titration (by using 1H
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In the last 20 years, a huge volume of experimental work into halogen bonding (XB) has been produced. Most of the systems have been characterized by solid state X-ray crystallography, whereas in solution the only routine technique is titration (by using 1H and 19F nuclear magnetic resonance (NMR), infrared (IR), ultraviolet–visible (UV–Vis) or Raman spectroscopies, depending on the nature of the system), with the aim of characterizing the strength of the XB interaction. Unfortunately, titration techniques have many intrinsic limitations and they should be coupled with other, more sophisticated techniques to provide an accurate and detailed description of the geometry and stoichiometry of the XB adduct in solution. This review will show how crucial information about XB adducts can be obtained by advanced NMR techniques, nuclear Overhauser effect-based spectroscopies (NOESY, ROESY, HOESY…) and diffusion NMR techniques (PGSE or DOSY). Full article
(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy) Printed Edition available
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