Themed collection Recent progress and perspectives on spin transition compounds
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Introduction to the Dalton Transactions themed collection: recent progress and perspectives on spin transition compounds
Guest editors Shinya Hayami, Birgit Weber and Malcolm Halcrow introduce the Dalton Transactions themed collection on spin transitions.
Dalton Trans., 2024,53, 10036-10036
https://doi.org/10.1039/D4DT90083A
Spin crossover {[Fe(atrz)3](OTs)2}n monolith: a green synthesis approach for Robust switchable materials
We report a room-temperature synthesis of a {[Fe(atrz)3](OTs)2}n monolith following the green chemistry principles. This material exhibits a gradual spin crossover transition compared to bulk material, aligning with observations in smaller particles.
Dalton Trans., 2024,53, 9257-9261
https://doi.org/10.1039/D4DT00684D
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Soma–Iwamoto-type SCO complex Fe(quinazoline)2[Au(CN)2]2 using the quinazoline-type ligand
We have synthesized Fe(quinazoline)2[Au(CN)2]2 (1). Complex 1 shows the Soma–Iwamoto-type bilayer and a spin-crossover (SCO) phenomenon. Mononuclear complex with a hydrogen-bonding network Fe(H2O)2(quinazoline)2[Au(CN)2]2 has also been obtained.
Dalton Trans., 2024,53, 9248-9251
https://doi.org/10.1039/D4DT00458B
Thermal and protonation-induced electron transfer coupled spin transition in a discrete [Fe2Co3] Prussian blue analogue
The work presents a rationally designed cyanide bridged [Fe2Co3] pentanuclear complex integrated with protonation sites, where the electronic states can be triggered by both thermal and chemical stimuli. This provides a promising approach for multi-stimuli responsive switchable molecular materials.
Dalton Trans., 2024,53, 8910-8914
https://doi.org/10.1039/D4DT00593G
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Simultaneous manipulation of iron(II) spin crossover and LIESST behaviour using pressure, temperature and light
Single-crystal X-ray diffraction studies of a spin crossover coordination polymer under simultaneous control of temperature, pressure, and light.
Dalton Trans., 2024,53, 7677-7681
https://doi.org/10.1039/D4DT00509K
A tetravalent praseodymium complex with field-induced slow magnetic relaxation
A tetravalent praseodymium complex with field-induced slow magnetic relaxation is presented.
Dalton Trans., 2024,53, 5779-5783
https://doi.org/10.1039/D4DT00052H
Investigating the influence of oriented external electric fields on modulating spin-transition temperatures in Fe(II) SCO complexes: a theoretical perspective
Oriented external electric fields induce spin crossover in Fe(II) complexes, offering a novel pathway for temperature tuning, with potential applications in molecular electronics and sensing.
Dalton Trans., 2024, Advance Article
https://doi.org/10.1039/D4DT00808A
Above room temperature spin crossover in mononuclear iron(II) complexes featuring pyridyl-benzimidazole bidentate ligands adorned with aliphatic chains
The alkylated derivatives of bidentate pyridyl-benzimidazole ligands were employed in the synthesis of SCO active ferrous complexes, which were specifically designed for the preparation of molecular films.
Dalton Trans., 2024,53, 14037-14045
https://doi.org/10.1039/D4DT01338G
Orthogonal magnetic orbitals in high spin Cu–VO units: structure, magnetism and EPR study of anisotropic heterometallic complexes
High spin Cu–V units with orthogonal magnetic orbitals and anisotropy of a coupled system.
Dalton Trans., 2024,53, 13207-13215
https://doi.org/10.1039/D4DT01346H
Substituent effects on spin-crossover Fe(II)N4O2 pyrenylhydrazone complexes
By varying the substituents on the pyrenylhydrazone ligands, fluorescent Fe(II)N4O2 complexes show high spin, low spin or spin crossover (SCO) properties.
Dalton Trans., 2024, Advance Article
https://doi.org/10.1039/D4DT00904E
Tuning the spin-crossover properties of [Fe2] metal–organic cages
Electronic structure calculations on dinuclear Fe(II) spin-crossover systems unravel the effects that guest molecules have on tuning the transition temperature and the single or two-step behavior transition in such systems.
Dalton Trans., 2024, Advance Article
https://doi.org/10.1039/D4DT01213E
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Investigation of the spin crossover behaviour of a sublimable Fe(II)-qsal complex: from the bulk to a submonolayer on graphene/SiO2
Spin crossover Fe(II) molecules deposited on graphene/SiO2 as a submonolayer present a switching behavior within the whole temperature range from 350 to 4 K.
Dalton Trans., 2024,53, 12519-12526
https://doi.org/10.1039/D4DT01417K
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Accurate state energetics in spin-crossover systems using pure density functional theory
The outstanding challenge of the calculation of the energy difference between different spin states is targeted with a new family of KTBM functionals.
Dalton Trans., 2024,53, 11895-11902
https://doi.org/10.1039/D4DT00975D
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Spin dynamics phenomena of a cerium(III) double-decker complex induced by intramolecular electron transfer
By applying the IET to the spin dynamics of Ce porphyrinoid-based complexes, it is possible to investigate the effects of dynamic disorder on SMM properties.
Dalton Trans., 2024,53, 11664-11677
https://doi.org/10.1039/D4DT00436A
Iron(II) spin crossover complexes of tetradentate Schiff-bases: tuning T1/2 by choice of formyl-heterocycle component
Heterocycle choice in four structurally characterised solvent-free [FeII(Lheterocycle)(NCS)2] complexes of easily accessed Schiff base ligands strongly influences solid state spin crossover behaviour.
Dalton Trans., 2024,53, 10974-10981
https://doi.org/10.1039/D4DT00884G
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Lattice solvent- and substituent-dependent spin-crossover in isomeric iron(II) complexes
Studies on iron(II) complexes composed of isomeric ligands reveal that one of the complexes—1·CH3CN—undergoes bi-stable spin-state switching with T1/2 = 298 K and ΔT1/2 = 44 K.
Dalton Trans., 2024,53, 10851-10865
https://doi.org/10.1039/D4DT00429A
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Chiral spin-crossover complexes based on an enantiopure Schiff base ligand with three chiral carbon centers
Four enantiopure spin-crossover complexes have been prepared in which the unexpected incorporation of acetone leads to an additional chiral center.
Dalton Trans., 2024,53, 10637-10643
https://doi.org/10.1039/D4DT00924J
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Light-induced spin-state switching in Fe(II) spin-crossover complexes with thiazole-based chelating ligands
Three homoleptic Fe(II) complexes with bidentate thiazole-based ligands exhibit spin-crossover (SCO) at the metal center. Abrupt temperature-driven and light-induced spin transitions are observed due to cooperative interactions between SCO cations.
Dalton Trans., 2024,53, 10511-10520
https://doi.org/10.1039/D4DT00308J
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A combined theoretical and experimental approach to determine the right choice of co-ligand to impart spin crossover in Fe(II) complexes based on 1,3,4-oxadiazole ligands
It is discussed why for the Fe(II) complexes [Fe(LTetra-Py/Ph-ODA)(NCE)] with E = S, Se and BH3 only the latter revealed SCO.
Dalton Trans., 2024,53, 10303-10317
https://doi.org/10.1039/D4DT01141D
Magnetoelectric and MIESST effects in spin crossover materials exhibiting symmetry-breaking
Magnetoelectric coupling and magnetic-field-induced spin state trapping (MIESST) phenomena are discussed in the framework of a model based on the Landau theory for spin crossover materials with polar phases.
Dalton Trans., 2024,53, 10159-10167
https://doi.org/10.1039/D4DT00672K
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Spin crossover in dinuclear iron(II) complexes bridged by bis-bipyridine ligands: dimer effects on electronic structure, spectroscopic properties and spin-state switching
Two bipyridine-based bisbidentate ligands with an ethynyl- and a dimethoxy-phenylene bridge, respectively, are used to bridge two [Fe(H2B(pz)2)2] units (pz = pyrazolyl), leading to charge-neutral dinuclear iron(II) compounds.
Dalton Trans., 2024,53, 9909-9920
https://doi.org/10.1039/D4DT00707G
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Thermodynamics of spin crossover in a bis(terpyridine) cobalt(II) complex featuring a thioether functionality
A new cobalt(II) complex featuring a terpyridine ligand functionalized with a thioether group has been prepared, structurally and magnetically characterized, and the thermodynamics of its spin crossover behaviour investigated in solution.
Dalton Trans., 2024,53, 9933-9941
https://doi.org/10.1039/D4DT00574K
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Self-assembly of a supramolecular spin-crossover tetrahedron
A new mononuclear iron(II) SCO compound featuring H-bonding donor and acceptor units provides an entry to a purely supramolecular switchable {Fe4} tetrahedron that exhibits a singular magnetic behavior for each of the four Fe(II) centers.
Dalton Trans., 2024,53, 9792-9797
https://doi.org/10.1039/D4DT00578C
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Spin-crossover cobalt(II) complexes exhibiting temperature- and concentration-dependent optical changes in solution
Terpyridine-based cobalt(II) complexes with dynamic amine substituents have been found to exhibit not only solid-state spin-crossover behavior but also spectral changes associated with spin-state change in various organic solvents.
Dalton Trans., 2024,53, 9547-9553
https://doi.org/10.1039/D4DT00433G
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Binucleating Jäger-type {(N2O2)2}4− ligands: magnetic and electronic interactions of Fe(II), Ni(II) and Cu(II) across an in-plane TTF-bridge
The simultaneous presence of different electrophores provides an interesting playground for responsive materials.
Dalton Trans., 2024,53, 9092-9105
https://doi.org/10.1039/D4DT00479E
Valence tautomeric interconversion of bis-dioxolene cobalt complex with imino-pyridine functionalized by TEMPO moiety in solid solutions with isostructural nickel analogue: phase transitions and monocrystal destruction
Valence tautomeric interconversion taking place in the solid solutions of the cobalt complex in the inert nickel matrix maintains the hysteresis loop. All the crystals destruct upon cooling down to the transition temperature.
Dalton Trans., 2024,53, 9151-9160
https://doi.org/10.1039/D4DT00453A
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Unlocking room-temperature bistable spin transition at the nanoscale: the synthesis of core@shell [Fe(NH2trz)3(NO3)2]@SiO2 nanoparticles
In this study, we synthesize silica-coated core@shell nanoparticles based on the relatively unexplored [Fe(NH2trz)3](NO3)2. This enables the fabrication of water-stable spin-crossover nanoparticles exhibiting spin transition at room temperature.
Dalton Trans., 2024,53, 8764-8771
https://doi.org/10.1039/D4DT00911H
Design and characterization of Fe(II) complexes with tetradentate ligands exhibiting spin-crossover near room temperature
Fe(II) complexes with a customized N4 ligand exhibit spin-crossover near room temperature, suitable for molecular switch applications.
Dalton Trans., 2024,53, 8619-8625
https://doi.org/10.1039/D4DT00460D
Quantification of the thermodynamic effects of the low-spin – high-spin interaction in molecular crystals of a mononuclear iron(II) spin crossover complex.
A method is proposed to estimate the thermodynamic effects of neighbouring molecules on the spin transition of a mononuclear complex.
Dalton Trans., 2024,53, 8391-8397
https://doi.org/10.1039/D4DT00613E
Spin crossover of a Fe(II) mononuclear complex induced by intermolecular factors involving chloride and solvent ordering
Spin transition induced by chloride in a mononuclear tripodal Fe(II) complex.
Dalton Trans., 2024, Advance Article
https://doi.org/10.1039/D4DT00706A
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Rotational order–disorder and spin crossover behaviour in a neutral iron(II) complex based on asymmetrically substituted large planar ionogenic ligand
Room temperature spin crossover behaviour and LIESST effect synchronised with order–disorder at the 2-fluorophenyl substituent in a new neutral mononuclear FeII complex based on an asymmetric ionogenic tridentate planar ligand.
Dalton Trans., 2024,53, 8041-8049
https://doi.org/10.1039/D4DT00368C
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Hydrogen-bonded assemblies of iron(II) spin crossover complexes
Dehydration induces spin crossover in hydrogen-bonded metal–organic frameworks such as [Fe(bpp)2](ADC)·9H2O, a compound showing large channels of a Wheel-of-Mainz shape.
Dalton Trans., 2024,53, 7848-7856
https://doi.org/10.1039/D4DT00579A
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Spectroscopic and thermodynamic characterization of a cobalt-verdazyl valence tautomeric system. influence of crystal structure, solvent and counterion
Valence tautomerization in the cobalt bis verdazyl system [Co(dipyvd)2]2+ is associated with large ligand geometry changes. As a result the equilibrium is strongly dependent on intermolecular interaction in both solid and solution phases.
Dalton Trans., 2024,53, 7536-7545
https://doi.org/10.1039/D4DT00465E
Guest water-induced structural transformation and spin-crossover variation of a two-dimensional Hofmann-type compound
A two-dimensional Hofmann-type coordination polymer [FeII(o-NTrz)2PtII(CN)4]·H2O (o-NTrz = 4-(o-nitrobenzyl)imino-1,2,4-triazole) shows changes in spin-crossover behavior due to the loss of water molecules and consequent rotation of ligand o-NTrz.
Dalton Trans., 2024,53, 7522-7526
https://doi.org/10.1039/D4DT00435C
Memory effect in ferroelectric polyvinylidene fluoride (PVDF) films via spin crossover probes
A composite film combining a ferroelectric organic polymer with a spin crossover coordination polymer exhibits memory effect in their ferroelectric properties, with the appearance of thermal hysteresis in electric polarization and coercivity.
Dalton Trans., 2024,53, 7590-7595
https://doi.org/10.1039/D4DT00220B
Two-dimensional spin-crossover coordination polymers based on the 1,1,2,2-tetra(pyridin-4-yl)ethene ligand
Spin-crossover behaviors and guest effects were investigated in three Fe(II) two-dimensional coordination polymers based on the 1,1,2,2-tetra(pyridin-4-yl)ethene ligand.
Dalton Trans., 2024,53, 7470-7476
https://doi.org/10.1039/D4DT00204K
Exploring spin states and ligand field splitting in metal complexes: a theoretical analysis of spin–orbital interactions and magnetic properties
2D Spectrochemical series for predicting a magnitude of the ligand field splitting in six-coordinated octahedral metal complexes ML6.
Dalton Trans., 2024,53, 7175-7189
https://doi.org/10.1039/D4DT00329B
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Spin crossover in {Fe(pyrazine)[M(CN)4]} (M = Ni, Pt) thin films assembled on fused silica substrates
Thin films of the spin crossover compound {Fe(pyrazine)[μ4-M(CN)4]} (M = Ni, Pt) have been deposited on transparent fused silica substrates using a sequential assembly method with a scope for photonic and (opto)electronic applications.
Dalton Trans., 2024,53, 7197-7205
https://doi.org/10.1039/D4DT00454J
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Activating a high-spin iron(II) complex to thermal spin-crossover with an inert non-isomorphous molecular dopant
[Fe(bpp)2][ClO4]2 (bpp = 2,6-bis{pyrazol-1-yl}pyridine; monoclinic, C2/c) is high-spin between 5–300 K, and crystallises with a highly distorted molecular geometry that lies along the octahedral–trigonal prismatic distortion pathway.
Dalton Trans., 2024,53, 6983-6992
https://doi.org/10.1039/D4DT00443D
Reversible structural change of [Co2Fe2] complexes between diamagnetic hydrogen-bonded 1D chains and paramagnetic complexes within a layered structure of amphiphilic anions
In an alternating layered structure of an amphiphilic anion, the electron transfer-coupled spin transition of a [Co2Fe2] complex causes a reversible structural change between the hydrogen-bonded 1D chains and discrete complexes.
Dalton Trans., 2024,53, 7190-7196
https://doi.org/10.1039/D4DT00482E
Expanding the dimensionality of bis(tetrazolyl)alkane-based Fe(II) coordination polymers by the application of dinitrile coligands
Di(tetrazolyl)alkanes form with Fe(II) chains or layers which can be extended into spin-crossover 2D and 3D networks by applying dinitriles.
Dalton Trans., 2024,53, 7163-7174
https://doi.org/10.1039/D4DT00462K
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Room temperature spin crossover properties in a series of mixed-anion Fe(NH2trz)3(BF4)2−x(SiF6)x/2 complexes
A series of mixed-anion Fe(NH2trz)3(BF4)2−x(SiF6)x/2 complexes presenting abrupt spin crossover behaviour with a narrow hysteresis loop just above room temperature is obtained by coordination reaction or solid–liquid post synthetic modification.
Dalton Trans., 2024,53, 6830-6838
https://doi.org/10.1039/D4DT00267A
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Mononuclear Fe(III) complexes with 2,4-dichloro-6-((quinoline-8-ylimino)methyl)phenolate: synthesis, structure, and magnetic behavior
We synthesized three Fe(III) mononuclear complexes and investigated the effects of the functional group of qsal ligands and anions on spin crossover behaviors and the relaxation times of T1 and T2 in DMF solution.
Dalton Trans., 2024,53, 6809-6817
https://doi.org/10.1039/D3DT04385A
Impact of flexible hexyl chain ordering in a mononuclear spin crossover iron(III) complex
Temperature-dependent variation of flexible hexyl groups in an iron(III) complex influences cation-to-cation and cation-to-anion interactions, leading to an unusual two-step SCO transition in the 400–10 K temperature range.
Dalton Trans., 2024,53, 5851-5860
https://doi.org/10.1039/D4DT00425F
Solvation/desolvation induced reversible distortion change and switching between spin crossover and single molecular magnet behaviour in a cobalt(II) complex
The cobalt(II) compound [Co(MeOphterpy)2](ClO4)2 shows reversible switching between SCO and SMM properties depending on solvation or desolvation.
Dalton Trans., 2024,53, 5861-5870
https://doi.org/10.1039/D3DT03936F
Nature of cyanoargentate bridges defining spin crossover in new 2D Hofmann clathrate analogues
Chemical composition is leading among the numerous factors that determine the spin transition properties of coordination compounds.
Dalton Trans., 2024,53, 4251-4259
https://doi.org/10.1039/D3DT04372J
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Low-spin to low-spin valence tautomeric transition in cobalt bis-dioxolenes
Intramolecular electron transfer without accompanying spin-crossover in cobalt bis-dioxolenes has been observed for the first time.
Dalton Trans., 2024,53, 4098-4107
https://doi.org/10.1039/D3DT03935H
Tuning valence tautomerism in a family of dinuclear cobalt complexes incorporating a conjugated bridging bis(dioxolene) ligand with weak communication
Judicious pairing of ancillary and redox-active ligands affords thermally-induced two-step valence tautomerism for a dinuclear cobalt complex bridged by a conjugated bis(dioxolene) ligand.
Dalton Trans., 2024,53, 3104-3117
https://doi.org/10.1039/D3DT04162J
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Photo-induced valence tautomerism and polarization switching in mononuclear cobalt complexes with an enantiopure chiral ligand
We report the discovery of a novel valence tautomeric cobalt mononuclear compound with a chiral ligand, which enhances the efficiency of light-induced polarization switching.
Dalton Trans., 2024,53, 2512-2516
https://doi.org/10.1039/D3DT03915C
X-ray crystallographic analysis of the antiferromagnetic low-temperature phase of galvinoxyl: investigating magnetic duality in organic radicals
Crystal structure of the low-temperature phase of galvinoxyl consists of a radical dimer with a significant overlap between the SOMOs.
Dalton Trans., 2024,53, 1961-1965
https://doi.org/10.1039/D3DT03601D
Spin-state versatility in FeII4L6 supramolecular cages with a pyridyl-hydrazone ligand scaffold modulated by solvents and counter anions
Discrete spin crossover (SCO) tetranuclear cages are a unique class of materials that have potential use in next-generation molecular recognition and sensing.
Dalton Trans., 2024,53, 1449-1459
https://doi.org/10.1039/D3DT02474A
Exploring a prototype for cooperative structural phase transition in cobalt(II) spin crossover compounds
Four structurally related Co(II) spin crossover compounds were prepared, which revealed that combining a rigid polymeric framework with flexible substituents may constitute to a prototype for cooperative SPT in cobalt(II) SCO systems.
Dalton Trans., 2024,53, 699-705
https://doi.org/10.1039/D3DT03529H
Improving spin crossover characteristics in heteroleptic [FeIII(qsal-5-I)(qsal-5-OMe)]A complexes
Heteroleptic iron(III) spin crossover complexes are reported with one of the compounds exhibiting a strongly hysteretic spin crossover that is superior to the homoleptic complexes.
Dalton Trans., 2023,52, 18148-18157
https://doi.org/10.1039/D3DT02503A
About this collection
The passing of Prof. Philipp Gütlich in September 2022, which is a great loss to the community of spin transition, has urged us to review the current status and development of this field. It was realized that, in many cases, the concept of spin transition is considered of secondary importance within the topics of molecule-based materials and molecular magnetism. Studies of spin transition, especially from the next generation of scientists, have yet to receive the attention they are due. These facts motivated us to produce this special issue which focuses on research of spin transition phenomena in a broad sense, including spin-crossover (SCO), valence tautomerism (VT), electron transfer (ET) and any other related topics. This themed collection showcases the recent progress and new viewpoints of spin transition materials from the perspective of compound synthesis, physical properties, and applications.