Magnetochemistry

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 34 | Viewed by 6064

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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7654 KiB

Open AccessArticle

Understanding Chemistry and Unique NMR Characters of Novel Amide and Ester Leflunomide Analogues

by Morkos A. Henen, Abdelrahman Hamdi, Abdelbasset A. Farahat and Mohammed A. M. Massoud

Magnetochemistry 2017, 3(4), 41; https://doi.org/10.3390/magnetochemistry3040041 - 05 Dec 2017

Cited by 2 | Viewed by 4325

Abstract

A series of diverse substituted 5-methyl-isoxazole-4-carboxylic acid amides, imide and esters in which the benzene ring is mono or disubstituted was prepared. Spectroscopic and conformational examination was investigated and a new insight involving steric interference and interesting downfield deviation due to additional diamagnetic [...] Read more.

A series of diverse substituted 5-methyl-isoxazole-4-carboxylic acid amides, imide and esters in which the benzene ring is mono or disubstituted was prepared. Spectroscopic and conformational examination was investigated and a new insight involving steric interference and interesting downfield deviation due to additional diamagnetic anisotropic effect of the amidic carbonyl group and the methine protons in 2,6-diisopropyl-aryl derivative (2) as conformationaly restricted analogues Leflunomide was discussed. Individual substituent electronic effects through π resonance of p-substituents and most stable conformation of compound (2) are discussed. Full article

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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 7907

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 3791

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 5 | Viewed by 5446

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 4346

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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1222 KiB

Open AccessArticle

Analysis of the Anisotropic Magnetocaloric Effect in RMn₂O₅ Single Crystals

by Mohamed Balli, Saber Mansouri, Serge Jandl, Patrick Fournier and Dimitre Z. Dimitrov

Magnetochemistry 2017, 3(4), 36; https://doi.org/10.3390/magnetochemistry3040036 - 21 Nov 2017

Cited by 9 | Viewed by 3502

Abstract

Thanks to the strong magnetic anisotropy shown by the multiferroic RMn₂O₅ (R = magnetic rare earth) compounds, a large adiabatic temperature change can be induced (around 10 K) by rotating them in constant magnetic fields instead of the standard magnetization-demagnetization [...] Read more.

Thanks to the strong magnetic anisotropy shown by the multiferroic RMn₂O₅ (R = magnetic rare earth) compounds, a large adiabatic temperature change can be induced (around 10 K) by rotating them in constant magnetic fields instead of the standard magnetization-demagnetization method. Particularly, the TbMn₂O₅ single crystal reveals a giant rotating magnetocaloric effect (RMCE) under relatively low constant magnetic fields reachable by permanent magnets. On the other hand, the nature of R³⁺ ions strongly affects their RMCEs. For example, the maximum rotating adiabatic temperature change exhibited by TbMn₂O₅ is more than five times larger than that presented by HoMn₂O₅ in a constant magnetic field of 2 T. In this paper, we mainly focus on the physics behind the RMCE shown by RMn₂O₅ multiferroics. We particularly demonstrate that the rare earth size could play a crucial role in determining the magnetic order, and accordingly, the rotating magnetocaloric properties of RMn₂O₅ compounds through the modulation of exchange interactions via lattice distortions. This is a scenario that seems to be supported by Raman scattering measurements. Full article

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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 4552

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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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 - 06 Nov 2017

Cited by 16 | Viewed by 3989

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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958 KiB

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 - 01 Nov 2017

Cited by 1 | Viewed by 4179

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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2844 KiB

Open AccessArticle

SERS Detection of Penicillin G Using Magnetite Decorated with Gold Nanoparticles

by Paula C. Pinheiro, Sara Fateixa and Tito Trindade

Magnetochemistry 2017, 3(4), 32; https://doi.org/10.3390/magnetochemistry3040032 - 23 Oct 2017

Cited by 18 | Viewed by 5300

Abstract

Sensitive and reliable procedures for detecting vestigial antibiotics are of great relevance for water quality monitoring due to the occurrence of such emergent pollutants in the aquatic environment. As such, we describe here research concerning the use of multifunctional nanomaterials combining magnetic and [...] Read more.

Sensitive and reliable procedures for detecting vestigial antibiotics are of great relevance for water quality monitoring due to the occurrence of such emergent pollutants in the aquatic environment. As such, we describe here research concerning the use of multifunctional nanomaterials combining magnetic and plasmonic components. These nanomaterials have been prepared by decorating magnetite nanoparticles (MNP) with colloidal gold nanoparticles (Au NPs) of distinct particle size distributions. Several analytical conditions were investigated in order to optimize the surface enhanced Raman scattering (SERS) detection of penicillin G (PG) dissolved in water. In particular, the dependence of the SERS signal by using distinct sized Au NPs adsorbed at the MNP was investigated. Additionally, microscopic methods, including Raman confocal microscopy, were employed to characterize the SERS substrates and then to qualitatively detect penicillin G using such substrates. For example, magnetic–plasmonic nanocomposites can be employed for magnetically concentrate analyte molecules and their removal from solution. As a proof of concept, we applied magneto-plasmonic nanosorbents in the removal of aqueous penicillin G and demonstrate the possibility of SERS sensing this antibiotic. Full article

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536 KiB

Open AccessArticle

The Role of Self-Interaction Corrections, Vibrations, and Spin-Orbit in Determining the Ground Spin State in a Simple Heme

by Der-you Kao, Mark R. Pederson, Torsten Hahn, Tunna Baruah, Simon Liebing and Jens Kortus

Magnetochemistry 2017, 3(4), 31; https://doi.org/10.3390/magnetochemistry3040031 - 17 Oct 2017

Cited by 19 | Viewed by 4448

Abstract

Without self-interaction corrections or the use of hybrid functionals, approximations to the density-functional theory (DFT) often favor intermediate spin systems over high-spin systems. In this paper, we apply the recently proposed Fermi–Löwdin-orbital self-interaction corrected density functional formalism to a simple tetra-coordinated Fe(II)-porphyrin molecule [...] Read more.

Without self-interaction corrections or the use of hybrid functionals, approximations to the density-functional theory (DFT) often favor intermediate spin systems over high-spin systems. In this paper, we apply the recently proposed Fermi–Löwdin-orbital self-interaction corrected density functional formalism to a simple tetra-coordinated Fe(II)-porphyrin molecule and show that the energetic orderings of the S = 1 and S = 2 spin states are changed qualitatively relative to the results of Generalized Gradient Approximation (developed by Perdew, Burke, and Ernzerhof, PBE-GGA) and Local Density Approximation (developed by Perdew and Wang, PW92-LDA). Because the energetics, associated with changes in total spin, are small, we have also calculated the second-order spin–orbit energies and the zero-point vibrational energies to determine whether such corrections could be important in metal-substituted porphins. Our results find that the size of the spin–orbit and vibrational corrections to the energy orderings are small compared to the changes due to the self-interaction correction. Spin dependencies in the Infrared (IR)/Raman spectra and the zero-field splittings are provided as a possible means for identifying the spin in porphyrins containing Fe(II). Full article

(This article belongs to the Special Issue Transition Metal Magnetism)

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3161 KiB

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 12 | Viewed by 6775

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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Magnetochemistry, Volume 3, Issue 4 (December 2017) – 13 articles

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