Magnetochemistry

16 pages, 7565 KiB

Open AccessArticle

Preparation of the New Magnetic Nanoadsorbent Fe₃O₄@SiO₂-yl-VP and Study on the Adsorption Properties of Hg (II) and Pb (II) in Water

by Dun Chen, Jianxin Chen, Wanyong Zhou and Amatjan Sawut

Magnetochemistry 2024, 10(12), 105; https://doi.org/10.3390/magnetochemistry10120105 - 13 Dec 2024

Abstract

This article reports the preparation of a novel functionalized magnetic nanoadsorbent through an addition reaction between Fe₃O₄ nanoparticles coated with allyl silica gel and 4-pyridinyl ethylene. A detailed characterization of Fe₃O₄@SiO₂-yl-VP was conducted. Among [...] Read more.

This article reports the preparation of a novel functionalized magnetic nanoadsorbent through an addition reaction between Fe₃O₄ nanoparticles coated with allyl silica gel and 4-pyridinyl ethylene. A detailed characterization of Fe₃O₄@SiO₂-yl-VP was conducted. Among them, in the infrared spectrum, we can easily see that the absorption peak of the C=C stretching vibration at 1660 cm⁻¹ in the raw material disappears after the addition reaction, indicating the successful grafting of polymer on the surface of silica gel. The appearance of N element in the EDS spectrum also proves the successful completion of the addition reaction and the successful synthesis of Fe₃O₄@SiO₂-yl-VP. At pH = 5 and pH = 7, it only takes half an hour for Fe₃O₄@SiO₂-yl-VP to achieve maximum adsorption capacities of 85.06 and 73.78 mg/g for Hg (II) and Pb (II), respectively. The adsorption process conforms to the Langmuir model and the pseudo-first- and pseudo-second-order kinetic models and can be reused 11 times, demonstrating excellent reusability. Full article

(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)

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18 pages, 2864 KiB

Open AccessArticle

Engineering Mononuclear Ln(III) Complexes with a Pseudo-Macrocyclic Hexadentate N₄O₂ Schiff Base Ligand Exhibiting Slow Magnetic Relaxation

by Ismael Francisco Diaz-Ortega, Yating Ye, Jesus Jover, Eliseo Ruiz, Enrique Colacio and Juan Manuel Herrera

Magnetochemistry 2024, 10(12), 104; https://doi.org/10.3390/magnetochemistry10120104 - 12 Dec 2024

Abstract

We report here the synthesis of a series of nine coordinated mononuclear Ln^III complexes [LnL₁Cl₂(DMF)]Cl·2.5DMF and [LnL¹(L₂)₂]Cl·4CH₃OH (Ln^III = Gd^III, Dy^III, Er^III and Yb [...] Read more.

We report here the synthesis of a series of nine coordinated mononuclear Ln^III complexes [LnL₁Cl₂(DMF)]Cl·2.5DMF and [LnL¹(L₂)₂]Cl·4CH₃OH (Ln^III = Gd^III, Dy^III, Er^III and Yb^III, HL₂ = 9-anthracenecarboxylic acid), where L1 is a hexadentate N₄O₂ Schiff base ligand prepared from the condensation of 1,10-phenanthroline-2,9-dicarbaldehyde and semicarbazone. The X-ray crystal structures of these complexes show the Ln^III ions to possess LnN₄O₂Cl₂ and LnN₄O₄ coordination spheres, which can be considered to be derived from a hexagonal bipyramidal geometry, with the ligand in the equatorial plane and the anions (chloride or 9-antracenecarboxylate) in axial positions, which undergo distortion after coordination of either a molecule of DMF or a bidentate coordination of the 9-anthracenecarboxxylate ligand. All these compounds exhibit field-induced slow magnetization relaxation (SMR). The absence of SMR at zero field due to QTM, as well as the processes involved in the magnetic relaxation under a field of 0.1 T, have been justified on the basis of theoretical calculations and the distortion of the respective coordination spheres. The severe discrepancy between the calculated and experimental thermal energy barriers for the Dy^III complexes seems to indicate that the relaxation occurs with the contribution of spin–vibrational coupling, which is favored by the flexibility of the ligand. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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20 pages, 6567 KiB

Open AccessArticle

Calixarene-like Lanthanide Single-Ion Magnets Based on Nd^III, Gd^III, Tb^III and Dy^III Oxamato Complexes

by Tamyris T. da Cunha, João Honorato de Araujo-Neto, Meiry E. Alvarenga, Felipe Terra Martins, Emerson F. Pedroso, Davor L. Mariano, Wallace C. Nunes, Nicolás Moliner, Francesc Lloret, Miguel Julve and Cynthia L. M. Pereira

Magnetochemistry 2024, 10(12), 103; https://doi.org/10.3390/magnetochemistry10120103 - 12 Dec 2024

Abstract

In this work, we describe the synthesis, crystal structures and magnetic properties of four air-stable mononuclear lanthanide(III) complexes with the N-(2,4,6-trimethylphenyl)oxamate (Htmpa) of formula: n-Bu₄N[Nd(Htmpa)₄(H₂O)]·4H₂O (1), n-Bu₄N[Gd(Htmpa)₄ [...] Read more.

In this work, we describe the synthesis, crystal structures and magnetic properties of four air-stable mononuclear lanthanide(III) complexes with the N-(2,4,6-trimethylphenyl)oxamate (Htmpa) of formula: n-Bu₄N[Nd(Htmpa)₄(H₂O)]·4H₂O (1), n-Bu₄N[Gd(Htmpa)₄(H₂O)]·3DMSO·2H₂O (2), n-Bu₄N[Tb(Htmpa)₄(H₂O)]·3DMSO·1H₂O (3) and n-Bu₄N[Dy(Htmpa)₄(H₂O)]·3DMSO·2H₂O (4) (n-Bu₄N⁺ = n-tetrabutylammonium; DMSO = dimethylsulfoxide). Their crystal structures reveal the occurrence of calixarene-type monoanionic species containing all-cis-disposed Htmpa ligands and one water molecule coordinated with the respective Ln^III ion (Ln = Nd, Gd, Tb and Dy), featuring a nine-coordinated environment with muffin (MFF-9) (1) or spherical-capped square antiprism (CSAPR-9) (2–4) geometry. The major difference between their crystal structures is related to the nature of crystallization solvent molecules, either water (1) or both DMSO and water (2–4). The intermolecular hydrogen bonds among the self-complementary Htmpa ligands in all four compounds mediated a 2 D supramolecular network in the solid state. Direct-current (dc) magnetic properties for 1–4 show typical behavior for the ground state terms of the Ln^III ions [⁴I_9/2 (Nd); ⁸S_7/2(Gd), ⁷F₆ (Tb), ⁶H^15/2 (Dy)]. Alternating-current (ac) magnetic measurements reveal the presence of slow magnetic relaxation without the presence of a dc field only for 4. In contrast, field-induced slow magnetic relaxation behavior was found in complexes 1, 2 and 3. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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13 pages, 5237 KiB

Open AccessArticle

A Trinuclear Co(II) Complex Based on the Tris-Dioxolene Triphenylene Non-Innocent Bridge: Complementary Redox, Magnetic Behavior and Theoretical Calculations

by Aristide Colin, Yiting Wang, François Lambert, Nathalie Bridonneau, Nicolas Suaud, Régis Guillot, Eric Rivière, Zakaria Halime, Nathalie Guihéry, Shin-ichi Ohkoshi and Talal Mallah

Magnetochemistry 2024, 10(12), 102; https://doi.org/10.3390/magnetochemistry10120102 - 11 Dec 2024

Abstract

A trinuclear Co(II)-containing complex was assembled using the non-innocent hexahydroxytriphenylene bridging ligand. Cyclovoltammetry and spectroelectrochemistry studies revealed that the central ligand sustained four reversible redox events, leading to different species with diverse optical behavior. Complementary analysis of the molecular structure confirmed by ab [...] Read more.

A trinuclear Co(II)-containing complex was assembled using the non-innocent hexahydroxytriphenylene bridging ligand. Cyclovoltammetry and spectroelectrochemistry studies revealed that the central ligand sustained four reversible redox events, leading to different species with diverse optical behavior. Complementary analysis of the molecular structure confirmed by ab initio theoretical calculations were consistent with the bridge in the tris-semiquinone (sq) state for the trinuclear complex. The exchange coupling among the electrons of the bridge resulted in a spin doublet (s = ½) localized close to one of the three Co²⁺ ions, as suggested by the experimental magnetic data. The central doublet underwent one large antiferromagnetic exchange coupling with one Co(II) and almost no coupling with the two other metal ions. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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12 pages, 6474 KiB

Open AccessArticle

A Novel Magnetic Flux Leakage Method Incorporating TMR Sensors for Detecting Zinc Dross Defects on the Surface of Hot-Dip Galvanized Sheets

by Bo Wang, San Zhang, Jie Wang, Liqin Jing and Feilong Mao

Magnetochemistry 2024, 10(12), 101; https://doi.org/10.3390/magnetochemistry10120101 - 10 Dec 2024

Abstract

Surface quality control of hot-dip galvanized sheets is a critical research topic in the metallurgical industry. Zinc dross, the most common surface defect in the hot-dip galvanizing process, significantly affects the sheet’s service performance. In this manuscript, a novel magnetic flux leakage (MFL) [...] Read more.

Surface quality control of hot-dip galvanized sheets is a critical research topic in the metallurgical industry. Zinc dross, the most common surface defect in the hot-dip galvanizing process, significantly affects the sheet’s service performance. In this manuscript, a novel magnetic flux leakage (MFL) detection method was proposed to detect zinc dross defects on the surface of hot-dip galvanized steel sheets. Instead of using exciting coils in traditional methods, a tiny permanent magnet with a millimeter magnitude was employed to reduce the size and weight of the equipment. Additionally, a high-precision tunnel magnetoresistance (TMR) sensor with a sensitivity of 300 mV/V/Oe was selected to achieve higher detection accuracy. The experimental setup was established, and the x-axis direction (sample movement direction) was determined as the best measurement axis by vector analysis through experiments and numerical simulation. The detection results indicate that this novel MFL detection method could detect industrial zinc dross with an equivalent size of 400 μm, with high signal repeatability and signal-to-noise ratio. In the range of 0–1200 mm/s, the detection speed has almost no effect on the measurement signal, which indicates that this novel method has higher adaptability to various conditions. The multi-path scanning method with a single probe was used to simulate the array measurement to detect a rectangular area of 30 × 60 mm. Ten zinc dross defects were detected across eight measurement paths with 4 mm intervals, and the positions of these zinc dross defects were successfully reconstructed. The research results indicate that this novel MFL detection method is simple and feasible. Furthermore, the implementation of array measurements provides valuable guidance for subsequent in-depth research and potential industrial applications in the future. Full article

(This article belongs to the Section Applications of Magnetism and Magnetic Materials)

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3 pages, 171 KiB

Open AccessEditorial

Advances in Magnetic Two Dimensional Materials

by Xiaoxi Li and Bo Li

Magnetochemistry 2024, 10(12), 100; https://doi.org/10.3390/magnetochemistry10120100 - 9 Dec 2024

Abstract

Since the discovery of graphene in 2004, two-dimensional (2D) van der Waals (vdW) layered materials have attracted extensive attention for their great potential for application in the electronic, optoelectronic, and electrochemical fields [...] Full article

(This article belongs to the Special Issue Advances in Magnetic Two Dimensional Materials)

12 pages, 3251 KiB

Open AccessArticle

Controlled Zn(II) to Co(II) Transmetalation in a Metal–Organic Framework Inducing Single-Ion Magnet Behavior

by Paula Escamilla, Nicolás Moliner, Donatella Armentano, Emilio Pardo, Jesús Ferrando-Soria and Thais Grancha

Magnetochemistry 2024, 10(12), 99; https://doi.org/10.3390/magnetochemistry10120099 - 6 Dec 2024

Abstract

The intrinsic characteristic features of metal–organic frameworks offer unique, great opportunities to develop novel materials with applications in very diverse fields. Aiming to take advantage of these, the application of post-synthetic methodologies has revealed itself to be a powerful approach to the isolation [...] Read more.

The intrinsic characteristic features of metal–organic frameworks offer unique, great opportunities to develop novel materials with applications in very diverse fields. Aiming to take advantage of these, the application of post-synthetic methodologies has revealed itself to be a powerful approach to the isolation and structuration of metal ions, molecules, or more complex species, either within MOF channels or reticulated at their network, rendering novel and exciting MOFs with new or improved functionalities. Herein, we report the partial post-synthetic metal exchange of Zn(II) metal ions by Co(II) ones in water-stable three-dimensional CaZn₆-MOF 1, derived from the amino acid S-methyl-L-cysteine, allowing us to obtain two novel MOFs with increasing contents of the Co(II) ions Co_4%@1 and Co_8%@1. Remarkably, the presented post-synthetic metal exchange methodology has two relevant implications for us: (i) it allowed us to obtain two novel MOFs, which were not accessible by direct synthesis, and (ii) enabled us to transform physical properties within this family of isoreticular MOFs from the diamagnetic pristine MOF 1 to MOFs Co_4%@1 and Co_8%@1, exhibiting field-induced, frequency-dependent, alternating current magnetic susceptibility signals, which are characteristic features of single-molecule magnets. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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13 pages, 3122 KiB

Open AccessArticle

Fabrication of a Portable Magnetic Microcantilever Using Fe₄₀Ni₃₈Mo₄B₁₈ Amorphous Ribbon and Its Application as a Humidity Sensor by Coating with TiO₂ Nanotubes

by Selçuk Atalay, Sema Erdemoglu, Hatice Çağlar Yılmaz, Emine Mete, Orhan Orcun Inan and Veli Serkan Kolat

Magnetochemistry 2024, 10(12), 98; https://doi.org/10.3390/magnetochemistry10120098 - 5 Dec 2024

Abstract

Microcantilevers (MCs) are highly sensitive sensors capable of detecting mass changes on the surface at the nanogram and even picogram scale. In this study, microcantilevers were fabricated for the first time using the Sodick AP250L Wire electrical discharge machining (EDM) from amorphous 2826MB [...] Read more.

Microcantilevers (MCs) are highly sensitive sensors capable of detecting mass changes on the surface at the nanogram and even picogram scale. In this study, microcantilevers were fabricated for the first time using the Sodick AP250L Wire electrical discharge machining (EDM) from amorphous 2826MB (Fe₄₀Ni₃₈Mo₄B₁₈) ferromagnetic ribbons. This method is advantageous because it allows for the simultaneous production of a large number of microcantilevers, with about 100 MCs being produced in a single manufacturing process. Additionally, a straightforward and cost-effective measurement system was developed to measure the resonance frequency and frequency shift of the MC entirely through magnetic means, a technique not previously reported in the literature. To evaluate the performance of the MC, we employed it as a humidity sensor. For the TiO₂-NT-coated MC, a frequency shift of approximately 202 Hz was observed when the humidity level changed from 5% to 95% relative humidity (RH). Full article

(This article belongs to the Section Applications of Magnetism and Magnetic Materials)

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12 pages, 13760 KiB

Open AccessArticle

Phase Formation, Microstructure, and Permeability of Fe-Deficient Ni-Cu-Zn Ferrites (II): Effect of Oxygen Partial Pressure

by Christoph Priese and Jörg Töpfer

Magnetochemistry 2024, 10(12), 97; https://doi.org/10.3390/magnetochemistry10120097 - 3 Dec 2024

Abstract

We have investigated the phase formation, microstructure, and permeability of stoichiometric and Fe-deficient Ni-Cu-Zn ferrites of composition Ni_0.30Cu_0.20Zn_0.50+zFe_2−zO_4−(z/2) with 0 ≤ z ≤ 0.06 sintered at 1000 °C in various oxygen partial pressures p [...] Read more.

We have investigated the phase formation, microstructure, and permeability of stoichiometric and Fe-deficient Ni-Cu-Zn ferrites of composition Ni_0.30Cu_0.20Zn_0.50+zFe_2−zO_4−(z/2) with 0 ≤ z ≤ 0.06 sintered at 1000 °C in various oxygen partial pressures p_O2, which range from 0.21 atm down to 10⁻⁵ atm. The density of the sintered samples is almost independent of the p_O2, whereas the grain size of the Fe-deficient ferrites decreases in more reducing atmospheres. Stoichiometric ferrites show a regular growth of single-phase ferrite grains if sintered in air. Sintering at p_O2 ≤ 10⁻² atm leads to the formation of a small amount of Cu₂O at grain boundaries and triple points. Fe-deficient compositions (z > 0) form Cu-poor stoichiometric ferrites, which coexist with a minority CuO phase homogeneously distributed between the grains after sintering in air. At p_O2 ≤ 10⁻² atm, the CuO grain boundary phase starts to transform into Cu₂O, which concentrates at some triple points at p_O2 = 10⁻² atm, and it is more homogeneously distributed between the ferrite grains at the lower p_O2. Formation of the Cu oxide second phases is investigated using XRD, SEM, and EDX. The permeability at 1 MHz of the stoichiometric ferrites (z = 0) is between µ′ = 200 and µ′ = 300 within the studied range of the p_O2. The permeability at 1 MHz of the Fe-deficient samples decreases with the p_O2, e.g., from µ′ = 750 at p_O2 = 0.21 atm to µ′ = 320 at p_O2 = 10⁻⁵ atm for z = 0.02, respectively. Full article

(This article belongs to the Special Issue Design and Applications of Advanced Magnetic Ceramic Materials: New Insights)

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12 pages, 1933 KiB

Open AccessArticle

Metallacrown of Ce^IIICu^II₅: Synthesis, Structural Characterization and Insights for Nanoparticles

by Jésio D. Tempesta, Fábio Faria Paiva, Leonildo A. Ferreira, Rafaela M. R. da Silva, Luckerman D. G. Botelho, Iara M. L. Rosa, Caio Cesar Candido, Angelo Marcio Gomes, Wallace C. Nunes, Guilherme P. Guedes and Maria Vanda Marinho

Magnetochemistry 2024, 10(12), 96; https://doi.org/10.3390/magnetochemistry10120096 - 30 Nov 2024

Abstract

The heterobimetallic 15-MC-5 metallacrown of formula [CeCu₅(5mpzHA)₅(NO₃)(H₂O)₇]·2NO₃·7H₂O, designated MC-Ce, was synthesized using 5-methyl-2-pyrazinehydroxamic acid (5mpzHA) as a linker, reacting with Ce^III and Cu^II salts under mild [...] Read more.

The heterobimetallic 15-MC-5 metallacrown of formula [CeCu₅(5mpzHA)₅(NO₃)(H₂O)₇]·2NO₃·7H₂O, designated MC-Ce, was synthesized using 5-methyl-2-pyrazinehydroxamic acid (5mpzHA) as a linker, reacting with Ce^III and Cu^II salts under mild conditions. Single-crystal X-ray diffraction analysis reveals a crown-like [Cu₅Ce(5mpzHA)₅] core, characteristic of a 15-MC-5 system, with five Cu^II atoms at the rim of the crown and the Ce^III ion occupying the dome of the crown, with water molecules, oxygen atoms and one nitrate anion filling the nine-coordination sphere around the Ce^III ion, which exhibits a distorted spherical tricapped trigonal prism geometry. The thermogravimetric analysis evidences successive mass losses due to the removal of water molecules and decomposition of the structure after 217 °C, whereas the PXRD analysis of the thermal decomposition residue reveals the presence of copper and copper/cerium oxide particles. These nanocomposite materials were also synthesized using the metallacrown MC-Ce under a hydrothermal method in the presence of multi-walled carbon nanotubes (MWCNTs), affording insights that this metallacrown can act as a source precursor for the synthesis of these mixed cerium/copper oxide nanomaterials. The experimental χMT value in MC-Ce at room temperature is 3.175 cm³ mol⁻¹ K, which is higher than the calculated one for one magnetically isolated Ce^III plus five Cu^II ions, probably due to the antiferromagnetic interactions among Cu^II ions within the metallacrown hoop plus the thermal depopulation of JZ sublevels of Ce^III ground state (5/2), which exhibit a small splitting under the anisotropic ligand field effects. The χMT decreases continuously until it reaches the value of 0.80 cm³ mol⁻¹ K at 10 K, reinforcing the presence of intramolecular antiferromagnetic interactions. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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22 pages, 4049 KiB

Open AccessArticle

Synthesis of a Novel Magnetic Biochar from Lemon Peels via Impregnation-Pyrolysis for the Removal of Methyl Orange from Wastewater

by Samah Daffalla, Enshirah Da’na, Amel Taha and Mohamed R. El-Aassar

Magnetochemistry 2024, 10(12), 95; https://doi.org/10.3390/magnetochemistry10120095 - 29 Nov 2024

Abstract

This research examined the elimination of methyl orange (MO) utilizing a novel magnetic biochar adsorbent (MLPB) derived from lemon peels via an impregnation-pyrolysis method. Material characterization was conducted using SEM, XRD, TGA, FTIR, and nitrogen adsorption isotherms. SEM-EDX analysis indicates that MLPB is [...] Read more.

This research examined the elimination of methyl orange (MO) utilizing a novel magnetic biochar adsorbent (MLPB) derived from lemon peels via an impregnation-pyrolysis method. Material characterization was conducted using SEM, XRD, TGA, FTIR, and nitrogen adsorption isotherms. SEM-EDX analysis indicates that MLPB is a homogeneous and porous composite comprising Fe, O, and C, with iron oxide uniformly dispersed throughout the material. Also, MLPB is porous with an average pore diameter of 4.65 nm and surface area value (111.45 m²/g). This study evaluated pH, MO concentration, and contact time to analyze the adsorption process, kinetics, and isothermal behavior. Under optimal conditions, MLPB was able to remove MO dye from aqueous solutions with an efficiency of 90.87%. Results showed optimal MO removal at pH 4, suggesting a favorable electrostatic interaction between the adsorbent and dye. To ascertain the adsorption kinetics, the experimental findings were compared using several adsorption models, first- and second-orders, and intra-particle diffusion. According to the findings, the pseudo-second-order model described the adsorption kinetic promoting the formation of the chemisorption phase well. Modeling of intra-particle diffusion revealed that intra-particle diffusion is not the only rate-limiting step. A study involving isothermal systems showed that Langmuir is a good representation of experimental results; the maximum adsorption capacity of MLPB was 17.21 mg/g. According to the results, after four cycles of regeneration, the produced magnetic material regained more than 88% of its adsorption ability. Full article

(This article belongs to the Special Issue Applications of Magnetic Materials in Water Treatment)

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18 pages, 2757 KiB

Open AccessArticle

Building Up a Hexacopper(II)-Pyrazolate/Oxamate Magnetic Complex with Rare Ethane-1,2-Dioxide (–OCH₂CH₂O–) as a Bridge Between Copper(II) Units

by Willian X. C. Oliveira, Victor G. Araújo, Carlos B. Pinheiro, Miguel Julve and Cynthia L. M. Pereira

Magnetochemistry 2024, 10(12), 94; https://doi.org/10.3390/magnetochemistry10120094 - 29 Nov 2024

Abstract

The synthesis, structural, and magnetic characterization of a novel neutral copper(II) hexanuclear complex [Cu₆(en)₄(OCH₂CH₂O)₂(pyox)₄]·3eg·en·12H₂O (1) was investigated [en = ethylenediamine, eg = ethylene glycol, and H₂ [...] Read more.

The synthesis, structural, and magnetic characterization of a novel neutral copper(II) hexanuclear complex [Cu₆(en)₄(OCH₂CH₂O)₂(pyox)₄]·3eg·en·12H₂O (1) was investigated [en = ethylenediamine, eg = ethylene glycol, and H₂pyox = 4-(1H-pyrazole-4-yl)phenylene-N-oxamic acid]. The crystal structure of 1, obtained by the single-crystal X-ray diffraction technique, revealed that the hexacopper(II) complex is built from two linear tricopper(II) complex subunits. Each subunit contains two [Cu(en)]²⁺ moieties connected to a [Cu(OCH₂CH₂O)] unit by two pyox²⁻ ligands acting as μ-κN:κN′ bridges, as well as a [OCH₂CH₂O]²⁻ ligand, which is ultimately found in the μ₃-κO,O′:κO:κO′ coordination form. The subunits are connected via the amide portion of the pyox²⁻ ligand, linked to copper atoms in the other subunit. They occupy the apical coordination positions, leading the trinuclear copper(II) segments to be almost perpendicular. The structural, chemical, and spectroscopic characterizations evidenced that ethylene glycol acted both as a solvent and a reactant upon deprotonation, forming the –OCH₂CH₂O– ligand due to the basic crystallization environment. DC magnetic studies revealed a strong antiferromagnetic interaction between the copper atoms within the trinuclear subunits, influenced by alkoxide and pyrazolate bridging ligands. Our findings offer new insights into the structural and magnetic properties of copper(II) complexes, enhancing the understanding of metal–ligand interactions in supramolecular chemistry. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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16 pages, 5155 KiB

Open AccessArticle

Mesoxalate-Bridged Heptanuclear Copper(II) Complexes: Structure and Magnetic Properties

by Beatriz Gil-Hernández, Simon Millan, Irina Gruber, Christoph Janiak, Carlos J. Gómez-García and Joaquín Sanchiz

Magnetochemistry 2024, 10(12), 93; https://doi.org/10.3390/magnetochemistry10120093 - 22 Nov 2024

Abstract

Two new compounds, (NH₄)₄[Cu₇(Hmesox)₆(H₂O)₈]∙10H₂O (1) and [Ru(bpy)₃]₄[Cu₇(Hmesox)₆Cl₂]Cl₂∙2CH₃CN∙12H₂O (2), were [...] Read more.

Two new compounds, (NH₄)₄[Cu₇(Hmesox)₆(H₂O)₈]∙10H₂O (1) and [Ru(bpy)₃]₄[Cu₇(Hmesox)₆Cl₂]Cl₂∙2CH₃CN∙12H₂O (2), were prepared and their structures were solved by single-crystal X-ray diffraction (mesoxalic acid = dihydroxypropanedioic acid, H₄mesox). The triply deprotonated mesoxalate anion acts as a chelating and bridging ligand with its carboxylate and alkoxide groups, forming the anionic heptanuclear copper(II) clusters [Cu₇(Hmesox)₆(H₂O)₈]⁴⁻ and [Cu₇(Hmesox)₆Cl₂]⁶⁻ in 1 and 2, respectively. Variable temperature magnetic studies revealed antiferromagnetic interactions in 1 and the coexistence of ferro and antiferromagnetic interactions in 2. The [Ru(bpy)₃]²⁺ cations provided luminescent properties to compound 2. Full article

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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4 pages, 179 KiB

Open AccessEditorial

Synthetic, Natural and Natural-Synthetic Hybrid Magnetic Structures: Technology and Application

by Kamil G. Gareev

Magnetochemistry 2024, 10(12), 92; https://doi.org/10.3390/magnetochemistry10120092 - 22 Nov 2024

Abstract

The magnetic properties of various types of structures based on iron oxides and the other ferri- or ferromagnets strongly correlate with their origin [...] Full article

(This article belongs to the Special Issue Synthetic, Natural and Natural-Synthetic Hybrid Magnetic Structures: Technology and Application)

18 pages, 7841 KiB

Open AccessArticle

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

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

Open AccessReview

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

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

(This article belongs to the Special Issue Magnetic Coordination Compounds and More... a Long and Successful Story: A Tribute to M. Julve and F. Lloret)

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12 pages, 1800 KiB

Open AccessArticle

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

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

Open AccessArticle

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

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, E_A(H), in relation to the activation energy in zero field, E_A(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, R_h, of the charge carriers and the maximum barrier height, W_m, 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

Open AccessArticle

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

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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