Magnetochemistry

15 pages, 2106 KB

Open AccessArticle

Quantitative Analysis of the Components of Rotigotine Prolonged-Release Microspheres for Injection Using Solvent-Suppressed ¹H NMR

by Xiaoli Zhou, Zengxin Li, Xue Ni, Wanhui Liu and Lihui Yin

Magnetochemistry 2025, 11(9), 79; https://doi.org/10.3390/magnetochemistry11090079 - 4 Sep 2025

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Abstract

We developed a solvent-suppressed ¹H nuclear magnetic resonance (NMR) method for the quantitative analysis of the components of rotigotine prolonged-release microspheres prepared for injection. Dimethyl terephthalate was used as an internal standard and dimethylsulfoxide -d₆ as the solvent. The analysis [...] Read more.

We developed a solvent-suppressed ¹H nuclear magnetic resonance (NMR) method for the quantitative analysis of the components of rotigotine prolonged-release microspheres prepared for injection. Dimethyl terephthalate was used as an internal standard and dimethylsulfoxide -d₆ as the solvent. The analysis was performed using a Bruker Avance III HD 600 MHz NMR spectrometer, employing the noesygppr1d pulse sequence at a controlled temperature of 25 °C. Nuclear magnetic resonance spectra were acquired with a relaxation delay time (D1) of 40 s to simultaneously determine the content of rotigotine and the excipients mannitol and stearic acid in the rotigotine prolonged-release microspheres. Using the proposed approach, we successfully quantified the active pharmaceutical ingredient rotigotine and excipients in the prolonged-release microspheres. This method demonstrated excellent linearity, high precision, and strong repeatability. The solvent-suppressed ¹H NMR method developed in this study allows for the simultaneous quantification of rotigotine and the key excipients mannitol and stearic acid in the prolonged-release microspheres. This approach is accurate, simple, efficient, and environmentally friendly. Full article

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12 pages, 3515 KB

Open AccessArticle

Magnetic Properties and Coercivity Mechanism of Nanocrystalline Rare-Earth-Free Co₇₄Zr₁₆Mo₄Si₃B₃ Alloys

by Aida Miranda and Israel Betancourt

Magnetochemistry 2025, 11(9), 78; https://doi.org/10.3390/magnetochemistry11090078 - 2 Sep 2025

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Abstract

The microstructure and magnetic properties of rare-earth-free, melt-spun Co₇₄Zr₁₆Mo₄Si₃B₃ alloys were investigated to enhance their hard magnetic response and elucidate their coercivity mechanism. The alloys exhibit a polycrystalline microstructure composed of randomly oriented, equiaxed [...] Read more.

The microstructure and magnetic properties of rare-earth-free, melt-spun Co₇₄Zr₁₆Mo₄Si₃B₃ alloys were investigated to enhance their hard magnetic response and elucidate their coercivity mechanism. The alloys exhibit a polycrystalline microstructure composed of randomly oriented, equiaxed grains, predominantly comprising the rhombohedral hard magnetic Co₁₁Zr₂ phase (92.4 wt.%). These materials display a favorable combination of magnetic properties, with coercive fields up to 581 kA/m, maximum magnetization reaching 0.30 T, and Curie temperatures as high as 751 K. An interpretation of the results, based on microstructural features, intrinsic magnetic parameters, and micromagnetic simulations, indicates that the coercivity mechanism of these melt-spun alloys can be attributed to the nucleation of reverse magnetic domains. Full article

(This article belongs to the Section Magnetic Materials)

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26 pages, 10898 KB

Open AccessReview

Molecular Nanomagnets with Photomagnetic Properties: Design Strategies and Recent Advances

by Xiaoshuang Gou, Xinyu Sun, Peng Cheng and Wei Shi

Magnetochemistry 2025, 11(9), 77; https://doi.org/10.3390/magnetochemistry11090077 - 31 Aug 2025

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Abstract

The magnetic properties of molecular nanomagnets can be finely modulated by light, which provides great potential in optical switches, smart sensors, and data storage devices. Light-induced spin transition, structure changes, and radical formation could tune the static and dynamic magnetic properties of molecular [...] Read more.

The magnetic properties of molecular nanomagnets can be finely modulated by light, which provides great potential in optical switches, smart sensors, and data storage devices. Light-induced spin transition, structure changes, and radical formation could tune the static and dynamic magnetic properties of molecular nanomagnets with high spatial and temporal resolutions. Herein, we summarize the design strategies of photoresponsive molecular nanomagnets and review the recent advances in transition metal/lanthanide molecular nanomagnets with photomagnetic properties. The photoresponsive mechanism based on spin transition, photocyclization, and photogenerated radicals is discussed in detail, providing insights into the photomagnetic properties of molecular nanomagnets for advanced photoresponsive materials. Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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5 pages, 172 KB

Open AccessEditorial

Advances in Functional Magnetic Nanomaterials for Water Pollution Control

by Wei Ding and Huaili Zheng

Magnetochemistry 2025, 11(9), 76; https://doi.org/10.3390/magnetochemistry11090076 - 27 Aug 2025

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Abstract

The application of magnetism in water treatment processes has enhanced efficiency across various stages, including coagulation, flocculation, sedimentation, and filtration, representing a field with significant potential [...] Full article

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

12 pages, 2631 KB

Open AccessArticle

A Dy₂ Complex Constructed by TCNQ^·− Radical Anions with Slow Magnetic Relaxation Behavior

by Xirong Wang, Shijia Qin, Xiulan Li, Wenjing Zuo, Qinglun Wang, Licun Li, Yue Ma, Jinkui Tang and Bin Zhao

Magnetochemistry 2025, 11(9), 75; https://doi.org/10.3390/magnetochemistry11090075 - 26 Aug 2025

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Abstract

A centrosymmetric dinuclear complex, [Dy₂(H₂dapp)₂(μ-OH)₂(H₂O)₂]·4TCNQ·2CH₃OH, was synthesized using the TCNQ^·− radical anion (TCNQ = 7,7,8,8-tetracyanoquino-dimethane) and pentadentate nitrogen-containing Schiff base ligand (H₂dapp = 2,6-diacetylpyridine)-bis(2-pyridylhydrazone). [...] Read more.

A centrosymmetric dinuclear complex, [Dy₂(H₂dapp)₂(μ-OH)₂(H₂O)₂]·4TCNQ·2CH₃OH, was synthesized using the TCNQ^·− radical anion (TCNQ = 7,7,8,8-tetracyanoquino-dimethane) and pentadentate nitrogen-containing Schiff base ligand (H₂dapp = 2,6-diacetylpyridine)-bis(2-pyridylhydrazone). In the Dy₂ dimer, the two Dy^III ions adopt eight-coordinated geometries intermediate between D_4d and D_2d symmetries, linked by two OH⁻ groups, with ferromagnetic Dy-Dy interactions. The TCNQ^·− radical anions are uncoordinated, and they pack tightly into antiparamagnetic dimers to balance the system charge. Under zero field, weak magnetic relaxation was observed, with an approximate Δ_eff = 2.82 K and τ₀ = 6.88 × 10⁻⁶ s. This might be attributed to the short intermolecular Dy···Dy distance of 7.97 Å, which could enhance intermolecular dipolar interactions and quantum tunneling of magnetization (QTM). Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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13 pages, 1365 KB

Open AccessArticle

Effect of Microstructural Changes on the Magnetization Dynamics Mechanisms in Ferrofluids Subjected to Alternating Magnetic Fields

by Cristian E. Botez and Zachary Musslewhite

Magnetochemistry 2025, 11(9), 74; https://doi.org/10.3390/magnetochemistry11090074 - 24 Aug 2025

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Abstract

We investigated the effects of chemical and physical changes on the interplay between the Néel and Brown superspin relaxation mechanisms in ferrofluids containing 18 nm-diameter Co_0.2Fe_2.8O₄ magnetic nanoparticles. We attempted to tune the ferrofluid’s magnetization dynamics via three [...] Read more.

We investigated the effects of chemical and physical changes on the interplay between the Néel and Brown superspin relaxation mechanisms in ferrofluids containing 18 nm-diameter Co_0.2Fe_2.8O₄ magnetic nanoparticles. We attempted to tune the ferrofluid’s magnetization dynamics via three methods: (i) changing the carrier fluid from Isopar M to kerosene (ii) doubling the Co-doping level from x = 0.2 to x = 0.4, and (iii) diluting the Co_0.2Fe_2.8O₄/Isopar M nanomagnetic fluid from δ = 1 mg/mL to δ = 0.1 mg/mL. We used temperature-resolved ac-susceptibility measurements at different frequencies, χ″ vs. T|_f, to gain insight into the thermally driven superspin dynamics of the nanoparticles within the ferrofluid. Our data demonstrates that both increasing x and using a different carrier fluid quantitatively alter the temperature dependence of the Néel and Brown relaxation frequency (f_N vs. T and f_B vs. T) by changing the nanoparticles’ magnetic moments and the fluid’s viscosity. Yet, the two mechanisms remain decoupled, as indicated by the presence of two magnetic events (peaks in the χ″ vs. T|_f datasets) one corresponding to the Néel and the other to Brown relaxation. On the other hand, diluting the ferrofluid leads to a qualitative change in the collective superspin dynamics behavior. Indeed, there is just one χ″-peak in the data from the δ = 0.1 mg/mL nanofluid, and its f vs. T dependence is well-described by a model that includes coupled contributions from both the Néel and Brown relaxation:

f (T) = p \cdot \frac{T}{γ_{0}} \cdot e x p [- \frac{E^{'}}{k_{B} (T - T_{0}^{'})}] +

(1 − p)

f_{0} e x p [- \frac{E_{B}}{k_{B} (T - T_{0})}]

. This is a remarkable behavior that demonstrates the ability to control a ferrofluids magnetization dynamics through simple chemical and physical changes. Full article

(This article belongs to the Special Issue Ferrofluids: Electromagnetic Properties and Applications)

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13 pages, 4868 KB

Open AccessArticle

A Dinuclear Dysprosium(III) Single Molecule Magnet of Benzo[h]quinolin-10-ol

by Limin Zhou, Hongling Lv, Yuning Liang, Dongcheng Liu, Zaiheng Yao, Shuchang Luo and Zilu Chen

Magnetochemistry 2025, 11(9), 73; https://doi.org/10.3390/magnetochemistry11090073 - 24 Aug 2025

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Abstract

To develop single molecule magnets, a dinuclear complex [Dy₂(HOBQ)₄Cl₆] (1) was prepared from the reaction of DyCl₃ with benzo[h]quinolin-10-ol (HOBQ). Each Dy(III) ion shows a compressed octahedral geometry and the two Dy(III) [...] Read more.

To develop single molecule magnets, a dinuclear complex [Dy₂(HOBQ)₄Cl₆] (1) was prepared from the reaction of DyCl₃ with benzo[h]quinolin-10-ol (HOBQ). Each Dy(III) ion shows a compressed octahedral geometry and the two Dy(III) ions in 1 are bridged by two Cl⁻ ligands to construct a dinuclear structure with the four HOBQ ligands on the axial positions and six Cl⁻ ligands in the equatorial plane. Magnetic measurements showed that complex 1 is a field-induced single molecule magnet having an obvious magnetic hysteresis loop with an energy barrier of 71(2) K. These experimental results are corroborated by the ab initio complete active space self-consistent field (CASSCF) calculations which also interpret the magneto-structural correlation. It is a typical example to achieve Dy(III) SMM through regulating coordination geometry, i.e., lengthening equatorial coordination bonds and shortening axial ones to form a compressed octahedral geometry. Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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18 pages, 5350 KB

Open AccessArticle

Mössbauer Research and Magnetic Properties of Dispersed Microspheres from High-Calcium Fly Ash

by Elena V. Fomenko, Yuriy V. Knyazev, Galina V. Akimochkina, Sergey V. Semenov, Vladimir V. Yumashev, Leonid A. Solovyov, Natalia N. Anshits, Oleg A. Bayukov and Alexander G. Anshits

Magnetochemistry 2025, 11(9), 72; https://doi.org/10.3390/magnetochemistry11090072 - 23 Aug 2025

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Abstract

High-calcium fly ash (HCFA), produced from the lignite combustion, has emerged as a global concern due to its fine particle size and adverse environmental impacts. This study presents the characteristics of dispersed microspheres from HCFA obtained using modern techniques, such as XRD, SEM-EDS, [...] Read more.

High-calcium fly ash (HCFA), produced from the lignite combustion, has emerged as a global concern due to its fine particle size and adverse environmental impacts. This study presents the characteristics of dispersed microspheres from HCFA obtained using modern techniques, such as XRD, SEM-EDS, ⁵⁷Fe Mössbauer spectroscopy, DSC-TG, particle size analysis, and magnetic measurements. It is found that an increase in microsphere size is likely due to the growth of the silicate glass-like phase, while the magnetic crystalline phase content remains stable. According to the ⁵⁷Fe Mössbauer spectroscopy, there are two substituted Ca-based ferrites—CaFe₂O₄ and Ca₂Fe₂O₅ with a quite different magnetic behavior. Besides, the magnetic ordering temperature of the brownmillerite (Ca₂Fe₂O₅) phase increases with the average diameter of the microspheres. FORC analysis reveals enhanced magnetic interactions as microsphere size increases, indicating an elevation in the concentration of magnetic microparticles, primarily on the microsphere surface, as supported by electron microscopy data. The discovered the magnetic crystallographic phases distribution on the microsphere’s surface claims the accessibility for further enrichment of the magnetically active particles and the possible application of fly ashes as a cheap source for magnetic materials synthesis. Full article

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26 pages, 4255 KB

Open AccessReview

Application Progress of Magnetic Chitosan in Heavy Metal Wastewater Treatment

by Xiaotian Wang, Yan Zhuang, Kinjal J. Shah and Yongjun Sun

Magnetochemistry 2025, 11(9), 71; https://doi.org/10.3390/magnetochemistry11090071 - 22 Aug 2025

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Abstract

Wastewater containing heavy metals can come from a variety of sources and is extremely toxic and hard to break down. Conventional treatment methods can easily result in secondary pollution and are expensive. The research on magnetic chitosan composites, a new adsorbent in the [...] Read more.

Wastewater containing heavy metals can come from a variety of sources and is extremely toxic and hard to break down. Conventional treatment methods can easily result in secondary pollution and are expensive. The research on magnetic chitosan composites, a new adsorbent in the treatment of heavy metal wastewater, is methodically reviewed in this paper. It offers a theoretical foundation for the creation of more environmentally friendly and effective wastewater treatment technology by examining its preparation and modification technology, adsorption mechanism, and application performance. This paper provides a summary of the technology used to prepare and modify magnetic chitosan composites. Both the cross-linking and co-precipitation methods are thoroughly examined. A summary of the fundamental process of heavy metal ion adsorption is provided, along with information on the chemical and physical impacts. Of these, chemical adsorption has been shown to work well with the majority of heavy metal adsorption systems. According to application research, magnetic chitosan exhibits good adaptability in real-world industrial wastewater treatment and has outstanding adsorption performance for various heavy metal ion types and multi-metal coexistence systems (including synergistic/competitive effects). Lastly, the optimization of the material preparation and modification process, the mechanism influencing the various coexisting ion types, and the improvement of regeneration ability should be the main areas of future development. Full article

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

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16 pages, 1626 KB

Open AccessArticle

Enhanced Magnetocaloric Effect and Single-Molecule Magnet Behavior in a Series of Sulfur-Containing Ligand-Based Ln₉ Clusters (Ln = Gd, Tb, and Dy)

by Ya-Wei Geng, Tong Guo, Xiao-Qin Wang and Tian Han

Magnetochemistry 2025, 11(9), 70; https://doi.org/10.3390/magnetochemistry11090070 - 22 Aug 2025

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Abstract

As an important branch of lanthanide-based complexes, clusters show unique properties in magnetocaloric effect (MCE) and single-molecule magnets (SMMs) using O/N ligands, while research on heavy p-block elements (e.g., S atom) with larger atomic radii and more diffuse p valence orbitals as coordinating [...] Read more.

As an important branch of lanthanide-based complexes, clusters show unique properties in magnetocaloric effect (MCE) and single-molecule magnets (SMMs) using O/N ligands, while research on heavy p-block elements (e.g., S atom) with larger atomic radii and more diffuse p valence orbitals as coordinating atoms remains relatively scarce. Herein, using the sulfur-containing ligand of 2-pyridinethiol 1-oxide (HL), we successfully synthesized a series of hourglass-like Ln₉ clusters [Ln₉(L)₁₇(μ₃-OH)₉(μ₄-OH)]·nH₂O (1: Ln = Gd, n = 3; 2: Ln = Tb, n = 3; 3: Ln = Dy, n = 1). Magnetic data analysis reveals that cluster 1 shows a significant MCE, with the entropy change (−ΔS_m) reaching a maximum of 34.41 J kg⁻¹ K⁻¹ at 2 K under ΔH = 7 T. Cluster 3, meanwhile, exhibits distinct frequency- and temperature-dependent behavior, indicating its SMM characteristics. Interestingly, despite possessing the highest molar mass among reported Gd₉ clusters with MCE, 1 exhibits a competitive −ΔS_m value, highlighting the critical role of sulfur-containing ligand on the structure and even exchange interactions. This work offers new insights into synthesizing high-performance MCE materials and understanding magneto-structural relationships. Full article

(This article belongs to the Special Issue Molecular Magnetism: A Themed Issue in Honor of Professor Dai-Zheng Liao on the Occasion of His 85th Birthday)

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Magnetochemistry, Volume 11, Issue 9 (September 2025) – 10 articles

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