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Magnetochemistry, Volume 10, Issue 11 (November 2024) – 11 articles

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18 pages, 7841 KiB  
Article
Macroscopic and Microscopic Levels of Methylene Blue Adsorption on a Magnetic Bio-Based Adsorbent: In-Depth Study Using Experiments, Advanced Modeling, and Statistical Thermodynamic Analysis
by Mohamed A. Ali, Aliaa M. Badawy, Ali Q. Seliem, Hazem I. Bendary, Eder C. Lima, M. Al-Dossari, N. S. Abd EL-Gawaad, Glaydson S. dos Reis, Mohamed Mobarak, Ali M. Hassan and Moaaz K. Seliem
Magnetochemistry 2024, 10(11), 91; https://doi.org/10.3390/magnetochemistry10110091 - 20 Nov 2024
Viewed by 514
Abstract
A magnetic bio-based adsorbent derived from H2O2-activated zeolite and turmeric carbohydrate polymer was fabricated, characterized, and utilized in removing methylene blue (MB) dye at pH 8.0 and temperatures between 25 and 55 °C. To understand the molecular-scale adsorption mechanism, [...] Read more.
A magnetic bio-based adsorbent derived from H2O2-activated zeolite and turmeric carbohydrate polymer was fabricated, characterized, and utilized in removing methylene blue (MB) dye at pH 8.0 and temperatures between 25 and 55 °C. To understand the molecular-scale adsorption mechanism, a range of advanced statistical physics models were employed in conjunction with conventional equilibrium models. The as-synthesized biosorbent presented high maximum capacities according to the Langmuir model, with values ranging from 268.67 to 307.73 mg/g. The double-layer equation yielded the best-fitting results to the MB experimental data among the applied statistical physics models. The number of MB molecules ranged from 1.14 to 1.97, suggesting a multi-molecular mechanism with a non-parallel orientation. The main factor affecting the effectiveness of this adsorbent was the density of its functional groups, which varied from 27.7 to 142.1 mg/g. Adsorption energies in the range of 19.22–21.69 kJ/mol were obtained, representing the existence of physical forces like hydrogen bonds and electrostatic interactions. To complete the macroscopic examination of the MB adsorption mechanism, thermodynamic parameters such as entropy, Gibbs free energy, and internal energy were considered. The adsorption/desorption outcomes up to five cycles displayed the stability of the magnetic biosorbent and its potential for decontaminating industrial effluents. Overall, this work increases our understanding of the MB adsorption mechanism onto the produced biosorbent at the molecular level. Full article
(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)
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23 pages, 1964 KiB  
Review
Recent Insights into Magneto-Structural Properties of Co(II) Dicyanamide Coordination Compounds
by Anna Świtlicka
Magnetochemistry 2024, 10(11), 90; https://doi.org/10.3390/magnetochemistry10110090 - 18 Nov 2024
Viewed by 508
Abstract
In recent decades, the chemistry of transition metal coordination compounds has undergone continuous development at both scientific and application levels. The diversity of metal(II) complexes, along with their structural features and physicochemical properties, makes them attractive for a wide range of applications. The [...] Read more.
In recent decades, the chemistry of transition metal coordination compounds has undergone continuous development at both scientific and application levels. The diversity of metal(II) complexes, along with their structural features and physicochemical properties, makes them attractive for a wide range of applications. The dicyanamide ion (N(CN)2) has the ability to form various transition metal compounds characterized by different architectures and topologies. The interaction of π-electrons from the nitrile groups with the π-system of the central nitrogen may enable electron delocalization, potentially facilitating electron transfer between the metal centers through the bridging dicyanamide (dca) ligand. This review focuses on dca–Co(II) compounds and, after a brief introduction, the structural aspects and magnetic properties are analyzed in detail. Full article
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12 pages, 1800 KiB  
Article
A Bifurcated Reconnecting Current Sheet in the Turbulent Magnetosheath
by Shimou Wang, Rongsheng Wang, Kai Huang and Jin Guo
Magnetochemistry 2024, 10(11), 89; https://doi.org/10.3390/magnetochemistry10110089 - 11 Nov 2024
Viewed by 536
Abstract
We report the Magnetospheric Multiscale (MMS) observation of a bifurcated reconnecting current sheet in Earth’s dayside magnetosheath. Typical signatures of the ion diffusion region, including sub-Alfvénic demagnetized ion outflow, super-Alfvénic electron flows, Hall magnetic fields, electron heating, and energy dissipation, were found when [...] Read more.
We report the Magnetospheric Multiscale (MMS) observation of a bifurcated reconnecting current sheet in Earth’s dayside magnetosheath. Typical signatures of the ion diffusion region, including sub-Alfvénic demagnetized ion outflow, super-Alfvénic electron flows, Hall magnetic fields, electron heating, and energy dissipation, were found when MMS traversed the current sheet. The weak ion exhaust at the current sheet center was bounded by two current peaks in which super-Alfvénic electron flow directed toward and away from the X line were observed, respectively. Both off-center current peaks were primarily carried by electrons, one of which was supported by field-aligned current, while the other was mainly supported by current driven by electric field drift. The two current peaks also exhibit other differences, including electron heating, electron pitch angle distributions, electron nongyrotropy, energy dissipation, and magnetic field curvature. An ion-scale magnetic flux rope was detected between the two current peaks where electrons showed field-aligned bidirectional distribution, in contrast to field-aligned distribution parallel to the magnetic field in two current peaks. The observed current sheet was embedded in a background shear flow. This shear flow worked together with the guide field and asymmetric field and density to affect the electron dynamics. Our results reveal the reconnection properties in this special plasma and field regime which may be common in turbulent environments. Full article
(This article belongs to the Special Issue New Insight into the Magnetosheath)
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15 pages, 3616 KiB  
Article
Polarizing Magnetic Field Effect on Some Electrical Properties of a Ferrofluid in Microwave Field
by Catalin N. Marin, Paul C. Fannin and Iosif Malaescu
Magnetochemistry 2024, 10(11), 88; https://doi.org/10.3390/magnetochemistry10110088 - 9 Nov 2024
Viewed by 708
Abstract
The complex dielectric permittivity, ε (f, H) = ε′ (f, H) − i ε″ (f, H), in the microwave frequency range f, of (0.1–3) GHz and polarizing field values H, [...] Read more.
The complex dielectric permittivity, ε (f, H) = ε′ (f, H) − i ε″ (f, H), in the microwave frequency range f, of (0.1–3) GHz and polarizing field values H, in the range of (0–135) kA/m, was measured for a kerosene-based ferrofluid with magnetite particles. A relaxation process attributed to interfacial type relaxation was highlighted, determining for the first time in the microwave field, the activation energy of the dielectric relaxation process in the presence of the magnetic field, EA(H), in relation to the activation energy in zero field, EA(H = 0). Based on the complex permittivity measurements and the Claussius–Mossotti equation, the dependencies on frequency (f), and magnetic field (H), of the polarizability (α) and electrical conductivity (σ), were determined. From the dependence of α(f,H), the electric dipolar moment, p, of the particles in the ferrofluid, was determined. The conductivity spectrum, σ(f,H), was found to be in agreement with Jonscher’s universal law and the electrical conduction mechanism in the ferrofluid was explained using both Mott’s VRH (variable range hopping) model and CBH (correlated barrier hopping) model. Based on these models and conductivity measurements, the hopping distance, Rh, of the charge carriers and the maximum barrier height, Wm, for the investigated ferrofluid was determined for the first time in the microwave field. Knowledge of these electrical properties of the ferrofluid in the microwave field is useful for explaining the mechanisms of polarization and control of electrical conductivity with an external magnetic field, in order to use ferrofluids in various technological applications in microwave field. Full article
(This article belongs to the Special Issue Ferrofluids - Electromagnetic Properties and Applications)
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24 pages, 10317 KiB  
Article
Magnetic CuFe2O4 Nanoparticles Immobilized on Modified Rice Husk-Derived Zeolite for Chlorogenic Acid Adsorption
by Tainara Ramos Neves, Letícia Ferreira Lacerda Schildt, Maria Luiza Lopes Sierra e Silva, Vannyla Viktória Viana Vasconcelos, Corrado Di Conzo, Francesco Mura, Marco Rossi, Gaspare Varvaro, Maryam Abdolrahimi, Simone Quaranta, Sandra Aparecida Duarte Ferreira and Elaine Cristina Paris
Magnetochemistry 2024, 10(11), 87; https://doi.org/10.3390/magnetochemistry10110087 - 4 Nov 2024
Viewed by 1276
Abstract
Adsorption has emerged as a promising method for removing polyphenols in water remediation. This work explores chlorogenic acid (CGA) adsorption on zeolite-based magnetic nanocomposites synthesized from rice husk waste. In particular, enhanced adsorbing materials were attained using a hydrothermal zeolite precursor (Z18) synthesized [...] Read more.
Adsorption has emerged as a promising method for removing polyphenols in water remediation. This work explores chlorogenic acid (CGA) adsorption on zeolite-based magnetic nanocomposites synthesized from rice husk waste. In particular, enhanced adsorbing materials were attained using a hydrothermal zeolite precursor (Z18) synthesized from rice husk and possessing a remarkable specific surface area (217.69 m2 g−1). A composite material was prepared by immobilizing magnetic copper ferrite on Z18 (Z18:CuFe2O4) to recover the zeolite adsorbent. In addition, Z18 was modified (Z18 M) with a mixture of 3-aminopropyltriethoxysilane (APTES) and trimethylchlorosilane (TMCS) to improve the affinity towards organic compounds in the final nanocomposite system (Z18 M:CuFe2O4). While the unmodified composite demonstrated inconsequential CGA removal rates, Z18 M:CuFe2O4 could adsorb 89.35% of CGA within the first hour of operation. Z18 M:CuFe2O4 showed no toxicity for seed germination and achieved a mass recovery of 85% (due to a saturation magnetization of 4.1 emu g−1) when an external magnetic field was applied. These results suggest that adsorbing magnetic nanocomposites are amenable to CGA polyphenol removal from wastewater. Furthermore, the reuse, revalorization, and conversion into value-added materials of agro-industrial waste may allow the opportunity to implement sustainability and work towards a circular economy. Full article
(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)
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12 pages, 2875 KiB  
Article
Two New 2p–3d Metal Complexes with a Nitronyl-Nitroxide Ligand Derived from o-Vanillin: Synthesis, Crystals Structures and Magnetic Properties
by Cristian Andrei Spinu, Daniel O. T. A. Martins, Teodora Mocanu, Mihaela Hillebrand, Jean-Pascal Sutter, Floriana Tuna and Marius Andruh
Magnetochemistry 2024, 10(11), 86; https://doi.org/10.3390/magnetochemistry10110086 - 1 Nov 2024
Viewed by 944
Abstract
Two new 2p–3d complexes, (Et3NH)[ML(hfac)2], have been obtained using the nitronyl-nitroxide radical (HL) derived from 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (M = Mn 1; Co 2). The two compounds are isomorphous and their structures consist of anionic mononuclear species, [M(hfac)2 [...] Read more.
Two new 2p–3d complexes, (Et3NH)[ML(hfac)2], have been obtained using the nitronyl-nitroxide radical (HL) derived from 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (M = Mn 1; Co 2). The two compounds are isomorphous and their structures consist of anionic mononuclear species, [M(hfac)2L], M = Mn 1; Co 2, and triethylammonium cations, Et3NH+. The metal ions adopt an octahedral geometry, being coordinated by phenoxido and aminoxyl oxygen atoms from the ligand and four oxygen atoms from the hexafluoroacetylacetonato (hfac) ligand. The cryomagnetic behaviors of the two compounds reveal relatively strong antiferromagnetic M(II)-Rad interactions (JMnRad = −191 cm−1, JCoRad = −166 cm−1 with H = −JSMSRad). The EPR spectra (X- and Q-band) of compound 1 below 70 K show the characteristical features of a S = 2 spin system with zero field splitting terms of D = 0.26 cm−1 and E = 0.031 cm−1. Full article
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13 pages, 4372 KiB  
Article
Slow Magnetic Relaxation in a [Co4O4] Cubane Complex with Tridentate NNO-Schiff Base Ligands
by Yuki Suemitsu, Yoshitaka Amakusa, Haruka Yoshino, Masaaki Ohba and Masayuki Koikawa
Magnetochemistry 2024, 10(11), 85; https://doi.org/10.3390/magnetochemistry10110085 - 30 Oct 2024
Viewed by 536
Abstract
Two tetranuclear Co(II) complexes, [Co4(pmab)4Cl4] (1) and [Co4(pmab)4(OBz)2]Cl2 (2) [Hpmab = 2-{(p-pyridinylmethylene)amino}benzenemethanol], have been synthesized and characterized through single-crystal X-ray diffraction, IR and UV-VIS [...] Read more.
Two tetranuclear Co(II) complexes, [Co4(pmab)4Cl4] (1) and [Co4(pmab)4(OBz)2]Cl2 (2) [Hpmab = 2-{(p-pyridinylmethylene)amino}benzenemethanol], have been synthesized and characterized through single-crystal X-ray diffraction, IR and UV-VIS spectroscopy, and magnetic measurements. Structural analysis revealed that both complexes possess a [Co4O4] cubane-like metal core connected by μ3-alkoxo bridges. Magnetic measurements of Complex 1 indicate weak ferromagnetic interactions (J ~ +0.75 cm−1) within the tetranuclear core, while Complex 2 exhibits antiferromagnetic behavior due to the presence of syn-syn bridging benzoate ligands. Alternating current (AC) magnetic measurements suggest that Complex 1 exhibits slow magnetic relaxation behavior. Full article
(This article belongs to the Section Molecular Magnetism)
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11 pages, 2385 KiB  
Article
Radiation-Induced Paramagnetic Centers in Meso- and Macroporous Synthetic Opals from EPR and ENDOR Data
by Alexander Rodionov, Larisa Latypova, Georgy Mamin and Marat Gafurov
Magnetochemistry 2024, 10(11), 84; https://doi.org/10.3390/magnetochemistry10110084 - 30 Oct 2024
Viewed by 494
Abstract
The paramagnetic defects and radiation-induced paramagnetic centers (PCs) in silica opals can play a crucial role in determining the magnetic and electronic behavior of materials and serve as local probes of their electronic structure. Systematic investigations of paramagnetic defects are essential for advancing [...] Read more.
The paramagnetic defects and radiation-induced paramagnetic centers (PCs) in silica opals can play a crucial role in determining the magnetic and electronic behavior of materials and serve as local probes of their electronic structure. Systematic investigations of paramagnetic defects are essential for advancing both theoretical and practical aspects of material science. A series of silica opal samples with different geometrical parameters were synthesized and radiation-induced PCs were investigated by means of the conventional and pulsed X- and W-band electron paramagnetic resonance, and 1H/2H Mims electron-nuclear double resonance. Two groups of PCs were distinguished based on their spectroscopic parameters, electron relaxation characteristics, temperature and time stability, localization relative to the surface of silica spheres, and their origin. The obtained data demonstrate that stable radiation-induced E’ PCs can be used as sensitive probes for the hydrogen-containing fillers of the opal pores, for the development of compact radiation monitoring equipment, and for quantum technologies. Full article
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23 pages, 4716 KiB  
Review
Influence of Magnetic Field on Calcium Carbonate Precipitation: A Critical Review
by Fathi Alimi
Magnetochemistry 2024, 10(11), 83; https://doi.org/10.3390/magnetochemistry10110083 - 29 Oct 2024
Viewed by 839
Abstract
This review reports a critical study on the effect of magnetic fields on the precipitation process of calcium carbonate scale from hard water. Indeed, the harmful consequences of the water scaling phenomenon urged researchers to find effective solutions. One of the interesting antiscaling [...] Read more.
This review reports a critical study on the effect of magnetic fields on the precipitation process of calcium carbonate scale from hard water. Indeed, the harmful consequences of the water scaling phenomenon urged researchers to find effective solutions. One of the interesting antiscaling processes is the magnetic treatment of water, which triggers a reduction in the precipitation of calcium carbonate on the walls when in contact with hard water. In the present review, we discuss selected examples related to this process in a combined analysis of the latest advances and the mechanism of action of the magnetic field. Despite the diversity of studies investigating this phenomenon, the effectiveness of this treatment remains a controversial issue, and it is not possible to obtain a clear explanation of the phenomenon. This review proposes, finally, interesting hypotheses which can effectively explain the effect of magnetic treatment on the behavior of hard waters and the precipitation of calcium carbonate, which include magnetohydrodynamics and the hydration effect. Full article
(This article belongs to the Section Magnetic Field)
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15 pages, 6467 KiB  
Article
Strong Antiferromagnetic Interactions in the Binuclear Cobalt(II) Complex with a Bridged Nitroxide Diradical
by Vitaly A. Morozov, Eugenia V. Peresypkina, Wolfgang Wernsdorfer and Kira E. Vostrikova
Magnetochemistry 2024, 10(11), 82; https://doi.org/10.3390/magnetochemistry10110082 - 28 Oct 2024
Viewed by 807
Abstract
A binuclear cobalt–radical complex formed by the reaction of Co(hfac)2·2H2O (hfac = hexafluoroacetylacetonate) with the 2,2-bis(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolinyl) biradical (BR) has been synthesized. The complex {(hfac)CoII(BN)CoII(hfac)} crystallizes in the triclinic space group P1¯ :  C [...] Read more.
A binuclear cobalt–radical complex formed by the reaction of Co(hfac)2·2H2O (hfac = hexafluoroacetylacetonate) with the 2,2-bis(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolinyl) biradical (BR) has been synthesized. The complex {(hfac)CoII(BN)CoII(hfac)} crystallizes in the triclinic space group P1¯ :  C34H28Co2F24N4O12, a = 11.1513(5) Å, b = 12.8362(7) Å, c = 18.2903(8) Å, α = 103.061(1)°, β = 100.898(2)°, γ = 102.250(1)°, Z = 2. The compound consists of two non-equivalent pseudo-octahedral CoII ions, each bearing two hfac ancillary ligands bridged by the tetradentate bis-nitroxide (BN). The temperature dependence of the magnetic susceptibility indicates a strong antiferromagnetic exchange between each of the Co2+ ions and the nitroxyl biradical, as well as between the spins within the bridging ligand, forming a spin-frustrated system. Micro-squid investigations, performed on a single crystal of {(hfac)CoII(BN)CoII(hfac)}, reveal a peculiarity of the M(H) graph at temperatures below 0.4 K displaying a step that is a result of ground and first excited levels mixing by the applied magnetic field due to a small energy gap between them, as inferred from ab initio calculation. The latter was also carried out for two models of mononuclear Co2+ complexes in order to obtain a set of initial parameters for fitting the experimental magnetic curves using the Phi program. Moreover, direct CAS(12,10)/def2-TZVP calculations of the magnetic dependences χT(T) and M(H) were performed, which satisfactorily reproduced the experimental ones. Full article
(This article belongs to the Section Molecular Magnetism)
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16 pages, 7713 KiB  
Article
Digital Magnetic Sorting for Fractionating Cell Populations with Variable Antigen Expression in Cell Therapy Process Development
by Savannah Bshara-Corson, Andrew Burwell, Timothy Tiemann and Coleman Murray
Magnetochemistry 2024, 10(11), 81; https://doi.org/10.3390/magnetochemistry10110081 - 23 Oct 2024
Viewed by 982
Abstract
Cellular therapies exhibit immense potential in treating complex diseases with sustained responses. The manufacture of cell therapies involves the purification and engineering of specific cells from a donor or patient to achieve a therapeutic response upon injection. Magnetic cell sorting targeting the presence [...] Read more.
Cellular therapies exhibit immense potential in treating complex diseases with sustained responses. The manufacture of cell therapies involves the purification and engineering of specific cells from a donor or patient to achieve a therapeutic response upon injection. Magnetic cell sorting targeting the presence or absence of surface markers is commonly used for upfront purification. However, emerging research shows that optimal therapeutic phenotypes are characterized not only by the presence or absence of specific antigens but also by antigen density. Unfortunately, current cell purification tools like magnetic or fluorescence-activated cell sorting (FACS) lack the resolution to differentiate populations based on antigen density while maintaining scalability. Utilizing a technique known as digital magnetic sorting (DMS), we demonstrate proof of concept for a scalable, magnetic-based approach to fractionate cell populations based on antigen density level. Targeting CD4 on human leukocytes, DMS demonstrated fractionation into CD4Hi T cells and CD4Low monocytes and neutrophils as quantified by flow cytometry and single-cell RNA seq. DMS also demonstrated high throughput processing at throughputs 3–10× faster than FACS. We believe DMS can be leveraged and scaled to enable antigen density-based sorting in cell therapy manufacturing, leading to the production of more potent and sustainable cellular therapies. Full article
(This article belongs to the Section Applications of Magnetism and Magnetic Materials)
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