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38 pages, 16698 KiB

Open AccessArticle

Laudatio: Miguel Julve and Francisco Lloret, a Friendly Pair of Two Exceptional Coordination Chemists in Molecular Magnetism

by Michel Verdaguer

Magnetochemistry 2025, 11(2), 6; https://doi.org/10.3390/magnetochemistry11020006 - 21 Jan 2025

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Abstract

This laudatio is dedicated to Professors Miguel Julve Olcina and Francisco Lloret Pastor on the occasion of their retirement in 2024. The first part deals with the scientific trajectory of the Coordination Chemistry team at the University of Valencia, within the Department of [...] Read more.

This laudatio is dedicated to Professors Miguel Julve Olcina and Francisco Lloret Pastor on the occasion of their retirement in 2024. The first part deals with the scientific trajectory of the Coordination Chemistry team at the University of Valencia, within the Department of Inorganic Chemistry on the Burjassot campus and then in the Paterna Institute of Molecular Science. The second part relates some of the more salient results of the heritage left by our two colleagues in molecular magnetism, where they developed, in their own way, a rational approach to designing, creating and understanding a wealth of brand new systems from the simplest to Multifunctional Molecule-based Magnetic Materials. The robust and friendly links between our two colleagues are emphasized in the third part. 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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14 pages, 2876 KiB

Open AccessArticle

Slow Relaxation of the Magnetisation in a Two-Dimensional Metal–Organic Framework with a Layered Square Lattice

by Samia Benmansour, Christian Cerezo-Navarrete and Carlos J. Gómez-García

Magnetochemistry 2025, 11(1), 1; https://doi.org/10.3390/magnetochemistry11010001 - 26 Dec 2024

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Abstract

Herein, we present the synthesis and structural characterisation of two layered MOFs with the asymmetric ligand 3-chloro,6-cyano-2,5-dihydroxy-1,4-benzoquinone dianion (C₆O₄(CN)Cl²⁻ = chlorocyananilato). These compounds, formulated as (H₃O)[Eu(C₆O₄(CN)Cl)₂(H₂O)]·34H₂O [...] Read more.

Herein, we present the synthesis and structural characterisation of two layered MOFs with the asymmetric ligand 3-chloro,6-cyano-2,5-dihydroxy-1,4-benzoquinone dianion (C₆O₄(CN)Cl²⁻ = chlorocyananilato). These compounds, formulated as (H₃O)[Eu(C₆O₄(CN)Cl)₂(H₂O)]·34H₂O (1) and (H₃O)[Dy(C₆O₄(CN)Cl)₂(H₂O)]·44H₂O (2), are isostructural and show a (4,4)-layered square structure with the crystallisation water molecules located between the layers. The lanthanoid ions are surrounded by four bis-bidentate chlorocyananilato ligands that connect each Ln^III centre with other four, giving rise to square cavities formed by Ln^III centres in the vertices and chlorocyananilato ligands as the sides. There is an additional coordinated water molecule that occupies the caped position of the capped square antiprismatic coordination geometry around the Ln^III centres. The magnetic properties show the presence of a field-induced slow relaxation of the magnetisation in the Dy^III derivative at low temperatures that follows Direct and Orbach relaxation mechanisms with an energy barrier of 36(3) K. 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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19 pages, 11321 KiB

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Uncovering the Mechanisms of Long-Range Magnetic Order in [Mn(mal)(H₂O)]_n: Insights from Microscopic and Macroscopic Magnetic Analysis

by Fernando S. Delgado, Laura Cañadillas-Delgado, Juan Rodríguez-Carvajal, Óscar Fabelo and Jorge Pasán

Magnetochemistry 2024, 10(12), 109; https://doi.org/10.3390/magnetochemistry10120109 - 20 Dec 2024

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Abstract

In this study, we investigate the magnetic properties of the molecular compound [Mn(mal)(H₂O)]ₙ (mal = dianion of malonic acid) by integrating microscopic and macroscopic characterization, combining unpolarized neutron diffraction and magnetometry measurements. Neutron diffraction, though non-commonly applied to molecular compounds, proved [...] Read more.

In this study, we investigate the magnetic properties of the molecular compound [Mn(mal)(H₂O)]ₙ (mal = dianion of malonic acid) by integrating microscopic and macroscopic characterization, combining unpolarized neutron diffraction and magnetometry measurements. Neutron diffraction, though non-commonly applied to molecular compounds, proved essential for fully resolving the magnetic structure, as well as overcoming challenges such as hydrogen-related incoherent scattering and difficulties in accurately locating light atoms. Our neutron data provided critical structural details, including the precise location of hydrogen atoms, especially those associated with crystallization water molecules. By conducting low-temperature measurements below the magnetic ordering temperature, we identified the correct Shubnikov space group (Pc’a2₁’) and established a magnetic model consistent with the observed weak ferromagnetism. Our findings reveal that the compound presents a spin-canted structure with a weak ferromagnetic signal along the b-axis. This signal originates primarily from antisymmetric exchange interactions rather than single-ion anisotropy, consistent with the isotropic nature of the Mn(II) (⁶A₁g) ground state. The combined neutron diffraction and magnetometry results provide a comprehensive understanding of how structural and symmetry factors influence the magnetic properties of malonate-based manganese compounds. 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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18 pages, 2865 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

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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

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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

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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, 3251 KiB

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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

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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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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

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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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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

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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

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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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12 pages, 2875 KiB

Open AccessArticle

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

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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 (J_MnRad = −191 cm⁻¹, J_CoRad = −166 cm⁻¹ with H = −JS_MS_Rad). 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

(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, 2979 KiB

Open AccessArticle

[Mn^III₆Mn^IINa^I₂], [Mn^III₃Mn^IINa^I], and [Mn^III₃] Clusters Derived from Schiff Bases: Syntheses, Structures, and Magnetic Properties

by Johannes Löhr, Mercè Font-Bardia, Júlia Mayans and Albert Escuer

Magnetochemistry 2024, 10(10), 76; https://doi.org/10.3390/magnetochemistry10100076 - 10 Oct 2024

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Abstract

The reaction of manganese halides with polydentate Schiff bases obtained by the condensation of 3-ethoxysalicylaldehyde and different amino alcohols, resulting in a NO₃ set of donors, yielded a series of manganese clusters with {Mn^III₆Mn^IINa₂}, {Mn [...] Read more.

The reaction of manganese halides with polydentate Schiff bases obtained by the condensation of 3-ethoxysalicylaldehyde and different amino alcohols, resulting in a NO₃ set of donors, yielded a series of manganese clusters with {Mn^III₆Mn^IINa₂}, {Mn^III₃Mn^IINa}, and {Mn^III₃} metallic cores. The influence of the ligand substituents and the halide on the final nuclearity has been studied. Analysis of their static magnetic behaviour confirms the ground states of 19/2 for the {Mn^III₆Mn^IINa₂} complexes, 7/2 for the {Mn^III₃Mn^IINa} clusters, and 12/2 for the triangular {Mn^III₃} systems, and a weak field induced a slow relaxation of the magnetization for the trinuclear complexes. 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, 4862 KiB

Open AccessArticle

Theoretical Hints to Optimize Energy Dissipation and Cell–Cell Response in Quantum Cellular Automata Based on Tetrameric and Bidimeric Cells

by Andrew Palii, Shmuel Zilberg and Boris Tsukerblat

Magnetochemistry 2024, 10(10), 73; https://doi.org/10.3390/magnetochemistry10100073 - 30 Sep 2024

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Abstract

This article is largely oriented towards the theoretical foundations of the rational design of molecular cells for quantum cellular automata (QCA) devices with optimized properties. We apply the vibronic approach to the analysis of the two key properties of such molecular cells, namely [...] Read more.

This article is largely oriented towards the theoretical foundations of the rational design of molecular cells for quantum cellular automata (QCA) devices with optimized properties. We apply the vibronic approach to the analysis of the two key properties of such molecular cells, namely the cell–cell response and energy dissipation in the course of the non-adiabatic switching of the electric field acting on the cell. We consider two kinds of square planar cells, namely cells represented by a two-electron tetrameric mixed valence (MV) cluster and bidimeric cells composed of two one-electron MV dimeric half-cells. The model includes vibronic coupling of the excess electrons with the breathing modes of the redox sites, electron transfer, intracell interelectronic Coulomb repulsion, and also the interaction of the cell with the electric field of polarized neighboring cells. For both kinds of cells, the heat release is shown to be minimal in the case of strong delocalization of excess electrons (weak vibronic coupling and/or strong electron transfer) exposed to a weak electric field. On the other hand, such a parametric regime proves to be incompatible with a strong nonlinear cell–cell response. To reach a compromise between low energy dissipation and a strong cell–cell response, we suggest using weakly interacting MV molecules with weak electron delocalization as cells. From this point of view, bidimeric cells are advantageous over tetrameric ones due to their smaller number of electron transfer pathways, resulting in a lower extent of electron delocalization. The distinct features of bidimeric cells, such as their two possible mutual arrangements (“side-by-side” and “head-to-tail”), are discussed as well. Finally, we briefly discuss some relevant results from a recent ab initio study on electron transfer and vibronic coupling from the perspective of the possibility of controlling the key parameters of molecular QCA cells. 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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21 pages, 4971 KiB

Open AccessArticle

Manganese (III) Compounds Derived from R-Salicylaldoxime and 9-Anthracenecarboxylate Ligands: A Study of Their Synthesis and Structural, Magnetic, and Luminescent Properties

by Berta Casanovas, Ramon Vicente, Mercè Font-Bardía and Mohamed Salah El Fallah

Magnetochemistry 2024, 10(8), 55; https://doi.org/10.3390/magnetochemistry10080055 - 5 Aug 2024

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Abstract

The reaction of Mn(II) salts in the air with different R-salicylaldehyde oximes and the sodium or cesium salts of 9-anthracenecarboxylato (9-AC) allows for the isolation of new six polynuclear compounds: [Mn₃NaO(salox)₃(9-AC)₂(EtOH)₃H₂O]_n·2EtOH [...] Read more.

The reaction of Mn(II) salts in the air with different R-salicylaldehyde oximes and the sodium or cesium salts of 9-anthracenecarboxylato (9-AC) allows for the isolation of new six polynuclear compounds: [Mn₃NaO(salox)₃(9-AC)₂(EtOH)₃H₂O]_n·2EtOH (1), [Mn₃NaO(3-Me-salox)₃(9-AC)₂(EtOH)₃H₂O]_n·EtOH (2), [Mn₆O₂(salox)₆(9-AC)₂(EtOH)₂(H₂O)₂]·3EtOH (3), [Mn₃O(3-Me-salox)₃(9-AC)(EtOH)₃(H₂O)]·1.8EtOH·3H₂O (4), [Mn₆O₂(Me-salox)₆(9-AC)₂(EtOH)₄(H₂O)₂]·0.5H₂O (5), and [Mn₆O₂(Et-salox)₆(9-AC)₂(EtOH)₄(H₂O)₂]·3EtOH (6). H₂salox is a salicylaldehyde oxime, H₂(3-Me-salox) is a 3-methyl-salicylaldehyde oxime, H₂Me-salox is a 1-(2-hydroxyphenyl)ethan-1-one oxime and a H₂-Et-salox is 1-(2-hydroxyphenyl)propan-1-one oxime. Structurally, compounds 1 and 2 consist of chains of trinuclear {Mn^III₃(μ₃-O)(salox)₃}⁺ units connected by Na⁺ ions. Compounds 3, 5, and 6 are hexanuclear units formed by two parallel trinuclear units {Mn^III₃(μ₃-O)(salox)₃}⁺ or {Mn^III₃(μ₃-O)(Me-salox)₃}⁺ planes related through an inversion center. Compound 4 consists of two isolated [Mn₃O(3-Me-salox)₃(9-AC)(EtOH)₃(H₂O)] trinuclear molecules in the unit cell showing crystallographic differences. Magnetic studies reveal a set of antiferromagnetic interactions in compounds 1 and 2 and a combination of antiferromagnetic and ferromagnetic interactions in compounds 3, 5, and 6. In all cases, the magneto-structural correlation between the intramolecular Mn^III-N-O-Mn^III torsion angle and the magnetic exchange within these units have been confirmed. For compounds 5 and 6, ac magnetic measurements reveal the slow relaxation of magnetization with moderate energy barriers of 19.9 cm⁻¹ and 31.1 cm⁻¹, respectively. Absorbance and fluorescence measurements in solution show the transitions of the 9-anthracenecarboxylate chromophore for all the compounds. 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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Exploring Spin-Crossover Cobalt(II) Single-Ion Magnets as Multifunctional and Multiresponsive Magnetic Devices: Advancements and Prospects in Molecular Spintronics and Quantum Computing Technologies

by Renato Rabelo, Luminita M. Toma, Abdeslem Bentama, Salah-Eddine Stiriba, Rafael Ruiz-García and Joan Cano

Magnetochemistry 2024, 10(12), 107; https://doi.org/10.3390/magnetochemistry10120107 - 17 Dec 2024

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Abstract

Spin-crossover (SCO) and single-ion magnets (SIMs), or their mixed SCO-SIM derivatives, are a convenient solution in the evolution from molecular magnetism toward molecular spintronics and quantum computing. Herein, we report on the current trends and future directions on the use of mononuclear six-coordinate [...] Read more.

Spin-crossover (SCO) and single-ion magnets (SIMs), or their mixed SCO-SIM derivatives, are a convenient solution in the evolution from molecular magnetism toward molecular spintronics and quantum computing. Herein, we report on the current trends and future directions on the use of mononuclear six-coordinate Co^II SCO-SIM complexes with potential opto-, electro-, or chemo-active 2,6-pyridinediimine (PDI)- and 2,2′:6′,2′-terpyridine (TERPY)-type ligands as archetypical examples of multifunctional and multiresponsive magnetic devices for applications in molecular spintronics and quantum computing technologies. This unique class of spin-crossover cobalt(II) molecular nanomagnets is particularly well suited for addressing and scaling on different supports, like metal molecular junctions or carbon nanomaterials (CNMs) and metal–organic frameworks (MOFs) or metal-covalent organic frameworks (MCOFs), in order to measure the single-molecule electron transport and quantum coherence properties, which are two major challenges in single-molecule spintronics (SMS) and quantum information processing (QIP). 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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23 pages, 1964 KiB

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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

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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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