Magnetochemistry

Editorial

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4 pages, 167 KiB

Open AccessEditorial

Nuclear Magnetic Resonance Spectroscopy

by Teresa E. Lehmann

Magnetochemistry 2018, 4(2), 20; https://doi.org/10.3390/magnetochemistry4020020 - 20 Apr 2018

Cited by 2 | Viewed by 4420

Abstract

n/a Full article

(This article belongs to the Special Issue Nuclear Magnetic Resonance Spectroscopy)

Research

Jump to: Editorial, Review

18 pages, 5373 KiB

Open AccessCommunication

Nuclear Magnetic Resonance Spectroscopy Investigations of Naphthalene-Based 1,2,3-Triazole Systems for Anion Sensing

by Karelle Aiken, Jessica Bunn, Steven Sutton, Matthew Christianson, Domonique Winder, Christian Freeman, Clifford Padgett, Colin McMillen, Debanjana Ghosh and Shainaz Landge

Magnetochemistry 2018, 4(1), 15; https://doi.org/10.3390/magnetochemistry4010015 - 6 Feb 2018

Cited by 12 | Viewed by 9376

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)

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21 pages, 420 KiB

Open AccessArticle

Towards a Microscopic Theory of the Knight Shift in an Anisotropic, Multiband Type-II Superconductor

by Richard A. Klemm

Magnetochemistry 2018, 4(1), 14; https://doi.org/10.3390/magnetochemistry4010014 - 29 Jan 2018

Cited by 2 | Viewed by 3473

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) \approx 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)

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8 pages, 1191 KiB

Open AccessArticle

Solid-State NMR Study of New Copolymers as Solid Polymer Electrolytes

by Jean-Christophe Daigle, Alexandre A. Arnold, Ashok Vijh and Karim Zaghib

Magnetochemistry 2018, 4(1), 13; https://doi.org/10.3390/magnetochemistry4010013 - 18 Jan 2018

Cited by 11 | Viewed by 6925

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)

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12 pages, 810 KiB

Open AccessArticle

The Radiofrequency NMR Spectra of Lithium Salts in Water; Reevaluation of Nuclear Magnetic Moments for ⁶Li and ⁷Li Nuclei

by Włodzimierz Makulski

Magnetochemistry 2018, 4(1), 9; https://doi.org/10.3390/magnetochemistry4010009 - 10 Jan 2018

Cited by 10 | Viewed by 4749

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)μ_N and μ(⁷Li) = +3.256418(20)μ_N. 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)

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9 pages, 1552 KiB

Open AccessArticle

Spatially Resolved Measurements of Crosslinking in UV-Curable Coatings Using Single-Sided NMR

by Madeline Brass, Frances Morin and Tyler Meldrum

Magnetochemistry 2018, 4(1), 8; https://doi.org/10.3390/magnetochemistry4010008 - 9 Jan 2018

Cited by 5 | Viewed by 5252

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)

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3199 KiB

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

by Shelby E. Follett, Sally A. Murray, Azure D. Ingersoll, Teresa M. Reilly and Teresa E. Lehmann

Magnetochemistry 2018, 4(1), 4; https://doi.org/10.3390/magnetochemistry4010004 - 27 Dec 2017

Cited by 5 | Viewed by 4111

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)

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483 KiB

Open AccessCommunication

Application of NMR Screening Methods with ¹⁹F Detection to Fluorinated Compounds Bound to Proteins

by Kazuo Furihata, Moe Usui and Mitsuru Tashiro

Magnetochemistry 2018, 4(1), 3; https://doi.org/10.3390/magnetochemistry4010003 - 27 Dec 2017

Cited by 5 | Viewed by 3704

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)

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2891 KiB

Open AccessArticle

Accelerating NMR-Based Structural Studies of Proteins by Combining Amino Acid Selective Unlabeling and Fast NMR Methods

by Bankala Krishnarjuna, Kousik Chandra and Hanudatta S. Atreya

Magnetochemistry 2018, 4(1), 2; https://doi.org/10.3390/magnetochemistry4010002 - 26 Dec 2017

Cited by 2 | Viewed by 3939

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, ¹³C^α, ¹³C^β, 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)

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3150 KiB

Open AccessArticle

Calcium-Dependent Interaction Occurs between Slow Skeletal Myosin Binding Protein C and Calmodulin

by Tzvia I. Springer, Christian W. Johns, Jana Cable, Brian Leei Lin, Sakthivel Sadayappan and Natosha L. Finley

Magnetochemistry 2018, 4(1), 1; https://doi.org/10.3390/magnetochemistry4010001 - 21 Dec 2017

Cited by 4 | Viewed by 3967

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)

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5020 KiB

Open AccessFeature PaperArticle

Local and Average Structural Changes in Zeolite A upon Ion Exchange

by Lisa Price, Ka Ming Leung and Asel Sartbaeva

Magnetochemistry 2017, 3(4), 42; https://doi.org/10.3390/magnetochemistry3040042 - 12 Dec 2017

Cited by 35 | Viewed by 6633

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)

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3514 KiB

Open AccessArticle

Short-Chain Alkanethiol Coating for Small-Size Gold Nanoparticles Supporting Protein Stability

by Cristina Cantarutti, Paolo Bertoncin, Alessandra Corazza, Sofia Giorgetti, P. Patrizia Mangione, Vittorio Bellotti, Federico Fogolari and Gennaro Esposito

Magnetochemistry 2017, 3(4), 40; https://doi.org/10.3390/magnetochemistry3040040 - 27 Nov 2017

Cited by 4 | Viewed by 8698

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)

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1547 KiB

Open AccessArticle

Early Stages of Biomineral Formation—A Solid-State NMR Investigation of the Mandibles of Minipigs

by Anastasia Vyalikh, Cindy Elschner, Matthias C. Schulz, Ronald Mai and Ulrich Scheler

Magnetochemistry 2017, 3(4), 39; https://doi.org/10.3390/magnetochemistry3040039 - 22 Nov 2017

Cited by 15 | Viewed by 4072

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)

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1377 KiB

Open AccessArticle

Separation of the α- and β-Anomers of Carbohydrates by Diffusion-Ordered NMR Spectroscopy

by Takashi Yamanoi, Yoshiki Oda and Kaname Katsuraya

Magnetochemistry 2017, 3(4), 38; https://doi.org/10.3390/magnetochemistry3040038 - 22 Nov 2017

Cited by 6 | Viewed by 6043

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)

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2397 KiB

Open AccessArticle

NMR-Assisted Structure Elucidation of an Anticancer Steroid-β-Enaminone Derivative

by Donald Poirier and René Maltais

Magnetochemistry 2017, 3(4), 37; https://doi.org/10.3390/magnetochemistry3040037 - 21 Nov 2017

Cited by 3 | Viewed by 4726

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)

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1320 KiB

Open AccessArticle

Quantification of Squalene in Olive Oil Using ¹³C Nuclear Magnetic Resonance Spectroscopy

by Anne-Marie Nam, Ange Bighelli, Félix Tomi, Joseph Casanova and Mathieu Paoli

Magnetochemistry 2017, 3(4), 34; https://doi.org/10.3390/magnetochemistry3040034 - 6 Nov 2017

Cited by 18 | Viewed by 4369

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)

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1020 KiB

Open AccessArticle

Low Field NMR Determination of pKa Values for Hydrophilic Drugs for Students in Medicinal Chemistry

by Aleksandra Zivkovic, Jan Josef Bandolik, Alexander Jan Skerhut, Christina Coesfeld, Miomir Raos, Nenad Zivkovic, Vlastimir Nikolic and Holger Stark

Magnetochemistry 2017, 3(3), 29; https://doi.org/10.3390/magnetochemistry3030029 - 20 Sep 2017

Cited by 9 | Viewed by 6863

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)

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Review

Jump to: Editorial, Research

14 pages, 3568 KiB

Open AccessReview

The NMR² Method to Determine Rapidly the Structure of the Binding Pocket of a Protein–Ligand Complex with High Accuracy

by Marielle Aulikki Wälti and Julien Orts

Magnetochemistry 2018, 4(1), 12; https://doi.org/10.3390/magnetochemistry4010012 - 22 Jan 2018

Cited by 11 | Viewed by 6470

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 [...] Read more.

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)

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22 pages, 5866 KiB

Open AccessReview

Nuclear Magnetic Resonance, a Powerful Tool in Cultural Heritage

by Noemi Proietti, Donatella Capitani and Valeria Di Tullio

Magnetochemistry 2018, 4(1), 11; https://doi.org/10.3390/magnetochemistry4010011 - 17 Jan 2018

Cited by 12 | Viewed by 5454

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 [...] Read more.

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)

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2384 KiB

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

by Patrice Porion and Alfred Delville

Magnetochemistry 2017, 3(4), 35; https://doi.org/10.3390/magnetochemistry3040035 - 14 Nov 2017

Cited by 4 | Viewed by 4846

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 [...] Read more.

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)

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Open AccessFeature PaperReview

Orientational Glasses: NMR and Electric Susceptibility Studies

by Neil Sullivan, Jaha Hamida, Khandker Muttalib, Subrahmanyam Pilla and Edgar Genio

Magnetochemistry 2017, 3(4), 33; https://doi.org/10.3390/magnetochemistry3040033 - 1 Nov 2017

Cited by 1 | Viewed by 4466

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 [...] Read more.

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)

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Open AccessReview

Characterization of Halogen Bonded Adducts in Solution by Advanced NMR Techniques

by Gianluca Ciancaleoni

Magnetochemistry 2017, 3(4), 30; https://doi.org/10.3390/magnetochemistry3040030 - 25 Sep 2017

Cited by 14 | Viewed by 7125

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 [...] Read more.

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)

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