Size-Dependent Spin Switching in Robust Fe-triazole@SiO2 Spin-Crossover Nanoparticles with Ultrathin Shell

A familly of chemically robust hybrid [Fe(Htrz)2(trz)](BF4)@SiO2nanoparticles (NPs) presenting different sizes (from ca. 90 to 28 nm) and an ultrathin silica shell (< 3 nm) have been prepared. All NPs present a characteristic abrupt spin transition with a subsequent decrease in the width of the thermal hysteresis upon reducing the NP size.

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Downsizing of robust Fe-triazole@SiO2 spin-crossover nanoparticles with ultrathin shells

Dalton Transactions ◽

10.1039/c9dt02086a ◽

2019 ◽

Vol 48 (41) ◽

pp. 15465-15469 ◽

Cited By ~ 1

Author(s):

R. Torres-Cavanillas ◽

L. Lima-Moya ◽

F. D. Tichelaar ◽

H. W. Zandbergen ◽

M. Giménez-Marqués ◽

...

Keyword(s):

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

28 Nm

Robust hybrid [Fe(Htrz)2(trz)](BF4)@SiO2 nanoparticles with reduced sizes (from ca. 90 to 28 nm) and ultrathin silica shells (<3 nm) have been obtained, presenting abrupt spin transition and reduced thermal hysteresis.

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Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2011.12.011 ◽

2012 ◽

Vol 324 (8) ◽

pp. 1596-1600 ◽

Cited By ~ 39

Author(s):

Alexandru Atitoaie ◽

Radu Tanasa ◽

Cristian Enachescu

Keyword(s):

Monte Carlo ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Size Dependent

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Dynamical control of the spin transition inside the thermal hysteresis loop of a spin-crossover single crystal

Physica B Condensed Matter ◽

10.1016/j.physb.2015.09.054 ◽

2016 ◽

Vol 486 ◽

pp. 187-191 ◽

Cited By ~ 7

Author(s):

Kamel Boukheddaden ◽

Mouhamadou Sy ◽

Miguel Paez-Espejo ◽

Ahmed Slimani ◽

François Varret

Keyword(s):

Single Crystal ◽

Hysteresis Loop ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Thermal Hysteresis Loop ◽

Dynamical Control

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Compensation effects and relation between the activation energy of spin transition and the hysteresis loop width for an iron(ii) complex

Physical Chemistry Chemical Physics ◽

10.1039/c6cp01892k ◽

2016 ◽

Vol 18 (25) ◽

pp. 16690-16699 ◽

Cited By ~ 11

Author(s):

Mark B. Bushuev ◽

Denis P. Pishchur ◽

Elena B. Nikolaenkova ◽

Viktor P. Krivopalov

Keyword(s):

Hysteresis Loop ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Activation Barrier ◽

Spin Transition ◽

Hysteresis Loops ◽

High Activation ◽

Activation Barriers ◽

Spin Crossover Complexes ◽

Hysteresis Loop Width

Wide thermal hysteresis loops for iron(ii) spin crossover complexes are associated with high activation barriers: the higher the activation barrier, the wider the hysteresis loop for a series of related spin crossover systems.

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Mechanism of reversible spin transition with a thermal hysteresis loop in [FeIII(qsal)2][Ni(dmise)2]·2CH3CN: Selenium analogue of the precursor of an Fe(III) spin-crossover molecular conducting system

Polyhedron ◽

10.1016/j.poly.2008.11.047 ◽

2009 ◽

Vol 28 (9-10) ◽

pp. 1776-1781 ◽

Cited By ~ 30

Author(s):

Kazuyuki Takahashi ◽

Hatsumi Mori ◽

Hayao Kobayashi ◽

Osamu Sato

Keyword(s):

Hysteresis Loop ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Conducting System ◽

Thermal Hysteresis Loop

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Evidence of Photo-Thermal Effects on the First-Order Thermo-Induced Spin Transition of [{Fe(NCSe)(py)2}2(m-bpypz)] Spin-Crossover Material

Magnetochemistry ◽

10.3390/magnetochemistry5020021 ◽

2019 ◽

Vol 5 (2) ◽

pp. 21 ◽

Cited By ~ 1

Author(s):

Kamel Boukheddaden ◽

Houcem Fourati ◽

Yogendra Singh ◽

Guillaume Chastanet

Keyword(s):

Thermal Effects ◽

Spin Crossover ◽

Evolution Equations ◽

Thermal Hysteresis ◽

Magnetic Measurements ◽

Equations Of Motion ◽

Spin Transition ◽

Thermal Bath ◽

Trapping Region ◽

First Order

We have investigated by means of optical microscopy and magnetic measurements the first-order thermal spin transition of the [{Fe(NCSe)(py)2}2(m-bpypz)] spin-crossover compound under various shining intensities, far from the light-induced spin-state trapping region. We found evidence of photo-heating effects on the thermally-induced hysteretic response of this spin-crossover material, thus causing the shift of the thermal hysteresis to lower temperature regions. The experimental results are discussed in terms of the apparent crystal temperature and are analyzed theoretically using two evolution equations of motion, written on the high-spin (HS) fraction and heat balance between the crystal and the thermal bath. A very good qualitative agreement was found between experiment and theory in the stationary regime, explaining the experimental observations well and identifying the key factors governing these photo-thermal effects.

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Elastic Origin of the Unsymmetrical Thermal Hysteresis in Spin Crossover Materials: Evidence of Symmetry Breaking

Symmetry ◽

10.3390/sym13050828 ◽

2021 ◽

Vol 13 (5) ◽

pp. 828

Author(s):

Mamadou Ndiaye ◽

Nour El Islam Belmouri ◽

Jorge Linares ◽

Kamel Boukheddaden

Keyword(s):

Symmetry Breaking ◽

High Spin ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Hysteresis Loops ◽

Point Of View ◽

Self Organization ◽

Spin States ◽

Heating And Cooling

The jungle of experimental behaviors of spin-crossover materials contains a tremendous number of unexpected behaviors, among which, the unsymmetrical hysteresis loops having different shapes on heating and cooling, that we often encounter in literature. Excluding an extra effect of crystallographic phase transitions, we study here these phenomena from the point of view of elastic modeling and we demonstrate that a simple model accounting for the bond lengths misfits between the high-spin and low-spin states is sufficient to describe the situation of unsymmetrical hysteresis showing plateaus at the transition only on cooling or on heating branches. The idea behind this effect relates to the existence of a discriminant elastic frustration in the lattice, which expresses only along the high-spin to low-spin transition or in the opposite side. The obtained two-step transitions showed characteristics of self-organization of the spin states under the form of stripes, which we explain as an emergence process of antagonist directional elastic interactions inside the lattice. The analysis of the spin state transformation inside the plateau on cooling in terms of two sublattices demonstrated that the elastic-driven self-organization of the spin states is accompanied with a symmetry breaking.

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Design of Bistable Gold@Spin-Crossover Core-Shell Nanoparticles Showing Large Electrical Responses for the Spin Switching

10.26434/chemrxiv.7543121 ◽

2019 ◽

Author(s):

Ramón Torres-Cavanillas ◽

Rocher Sanchis-Gual ◽

Julien Dugay ◽

Marc Coronado-Puchau ◽

Dr. Mónica Giménez Marqués ◽

...

Keyword(s):

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Hysteresis Loops ◽

Large Change ◽

Core Shell ◽

Shell Nanoparticles ◽

Simple Protocol ◽

Order Of Magnitude ◽

Core Shell Nanoparticles

A simple protocol to prepare core-shell gold@spin-crossover (Au@SCO) nanoparticles (NPs) based on the 1D spin-crossover [Fe(Htrz)2(trz)](BF4) coordination polymer is reported. The synthesis relies on a two-step approach consisting on a partial surface ligand substitution of the citrate-stabilized Au NPs followed by the controlled growth of a very thin layer of the SCO polymer. As a result, colloidally stable core@shell spherical NPs of 19 nm in size exhibiting a narrow distribution in sizes have been obtained, revealing a switchable SCOshell of ca.4 nm. Temperature-dependent charge transport measurements of an electrical device based on assemblies of these Au@SCO NPs display well-defined, reproducible and sharp thermal hysteresis loops in the conductance near room temperature. This device is characterized both, by a large change in conductance upon spin state switching, and a remarkable transition abruptness, as compared with other memory devices based on the pristine SCO NPs. As a result, the sensitivity of the device to the spin transition is dramatically improved, with values for the ON/OFF ratio which are an order of magnitude better than the best ones obtained in previous SCO devices.

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Five 2,6-Di(pyrazol-1-yl)pyridine-4-carboxylate Esters, and the Spin States of their Iron(II) Complexes

Magnetochemistry ◽

10.3390/magnetochemistry5010009 ◽

2019 ◽

Vol 5 (1) ◽

pp. 9 ◽

Cited By ~ 1

Author(s):

Iurii Galadzhun ◽

Rafal Kulmaczewski ◽

and Malcolm A. Halcrow

Keyword(s):

Room Temperature ◽

Spin Crossover ◽

Thermal Hysteresis ◽

Spin Transition ◽

Benzyl Ester ◽

The Other ◽

Spin States ◽

Phenyl Ester ◽

Coupling Reagent ◽

Complex Salts

Two phenyl ester and three benzyl ester derivatives have been synthesized from 2,6-di(pyrazol-1-yl)pyridine-4-carboxylic acid and the appropriate phenyl or benzyl alcohol using N,N’-dicyclohexylcarbodiimide as the coupling reagent. Complexation of the ligands with Fe[BF4]2·6H2O in acetone yielded the corresponding [FeL2][BF4]2 complex salts. Four of the new ligands and four of the complexes have been crystallographically characterised. Particularly noteworthy are two polymorphs of [Fe(L3)2][BF4]2·2MeNO2 (L3 = 3,4-dimethoxyphenyl 2,6-di{pyrazol-1-yl}pyridine-4-carboxylate), one of which is crystallographically characterised as high-spin while the other exhibits the onset of spin-crossover above room temperature. The other complexes are similarly low-spin at low temperature but exhibit gradual spin-crossover on heating, except for an acetone solvate of [Fe(L5)2][BF4]2 (L5 = benzyl 2,6-di{pyrazol-1-yl}pyridine-4-carboxylate), which exhibits a more abrupt spin-transition at T½ = 273 K with 9 K thermal hysteresis.

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