Low-Temperature Tunneling in the Spin-State Relaxation Dynamics of Iron(III) Spin-Crossover Compounds

1994 ◽  
Vol 116 (12) ◽  
pp. 5497-5498 ◽  
Author(s):  
Sabine Schenker ◽  
Andreas Hauser
Keyword(s):  
Low Temperature ◽  
Spin State ◽  
Spin Crossover ◽  
Relaxation Dynamics

Structural investigation of the photoinduced spin conversion in the dinuclear compound {[Fe(bt)(NCS)2]2(bpym)}: toward controlled multi-stepped molecular switches

2007 ◽  
Vol 40 (1) ◽  
pp. 158-164 ◽  
Author(s):  
Elzbieta Trzop ◽  
Marylise Buron-Le Cointe ◽  
Hervé Cailleau ◽  
Loïc Toupet ◽  
Gabor Molnar ◽  
...  
Keyword(s):  
Low Temperature ◽  
Excited States ◽  
Spin State ◽  
Spin Crossover ◽  
Structural Investigation ◽  
Laser Excitation ◽  
Molecular Switches ◽  
Excitation Wavelength ◽  
Photoinduced Change ◽  
Spin Conversion

The photocrystallographic investigation of the light-induced excited spin-state trapping effect in the dinuclear spin-crossover compound {[Fe(bt)(NCS)2]2(bpym)} is reported. In this system, each of the two Fe sites may be either in the high-spin (HS) or in the low-spin (LS) state, so that the molecule corresponds to a three-state system (LS–LS, HS–LS and HS–HS). At low temperature, the laser excitation wavelength controls the photoswitching from the stable LS–LS state to one of the metastable excited states (HS–LS or HS–HS), and also between these two excited states. Significant changes in the crystalline structure associated with the photoinduced change of spin state are detailed here. The low-temperature photoinduced states look similar to the corresponding states observed at thermal equilibrium within the unit-cell thermal contraction.

scholarly journals Elastic Modeling of Two-Step Transitions in Sterically Frustrated 1D Binuclear Spin-Crossover Chains

Symmetry ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1836
Author(s):  
Rachid Traiche ◽  
Hassane Oubouchou ◽  
Kamel Boukheddaden
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
Spin Transition ◽  
Large Family ◽  
Relaxation Dynamics ◽  
Thermal Dependence ◽  
Competing Interactions ◽  
Open Chain ◽  
Self Organized ◽  
Binuclear Unit

Among the large family of spin-crossover materials, binuclear systems play an important role due to their specific molecular configurations, allowing the presence of multi-step transitions and elastic frustration. Although this issue benefited from a significant number of spin-based theories, there is almost no elastic description of the spin transition phenomenon in binuclear systems. To overcome this deficiency, in this work we develop the first elastic modeling of thermal properties of binuclear spin-crossover solids. At this end, we investigated a finite spin-crossover open chain constituted of elastically coupled binuclear (A = B) blocks, ⋯A=B−A=B−A=B⋯, in which the considered equivalent A and B sites may occupy two configurations, namely low-spin (LS) and high-spin (HS) states. The sites of the binuclear unit interact via an intramolecular spring and couple to the neighboring binuclear units via other springs. The model also includes the change of length inside and between the binuclear units subsequent to the spin state changes. When injecting an elastic frustration inside the binuclear unit in the LS state, competing interactions between the intra- and the inter-binuclear couplings emerge. The latter shows that according to the intra- and inter-binuclear elastic constants and the strength of the frustration, multi-step transitions are derived, for which a specific self-organization of type (HS = HS)-(LS-LS)-(HS = HS)⋯ is revealed and discussed. Finally, we have also studied the relaxation of the metastable photoinduced HS states at low temperature, in which two relaxation regimes with transient self-organized states were identified when monitoring the elastic frustration rate or the ratio of intra- and intermolecular elastic interactions. These behaviors are reminiscent of the thermal dependence of the order parameters of the system. The present model opens several possibilities of extensions of elastic frustrations acting in polynuclear spin-crossover systems, which may lead to other types of spin-state self-organizations and relaxation dynamics.

Influence of ligand substituent conformation on the spin state of an iron(ii)/di(pyrazol-1-yl)pyridine complex

2021 ◽  
Vol 50 (10) ◽  
pp. 3464-3467
Author(s):  
Rafal Kulmaczewski ◽  
Mark J. Howard ◽  
Malcolm A. Halcrow
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
Solution Phase ◽  
Pyridine Complex

The temperature of the solution-phase spin-crossover equilibrium in iron(ii) complexes of 4-alkylsulfanyl-2,6-di{pyrazol-1-yl}pyridine (bppSR) complexes depends strongly on the alkylsulfanyl substituent.

scholarly journals Spin-state-dependent electrical conductivity in single-walled carbon nanotubes encapsulating spin-crossover molecules

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julia Villalva ◽  
Aysegul Develioglu ◽  
Nicolas Montenegro-Pohlhammer ◽  
Rocío Sánchez-de-Armas ◽  
Arturo Gamonal ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Spin State ◽  
Spin Crossover ◽  
Single Walled Carbon Nanotubes ◽  
Guest Molecules ◽  
Spintronic Devices ◽  
Single Walled Carbon ◽  
State Dependent ◽  
Lack Of Control ◽  
Walled Carbon Nanotubes

AbstractSpin crossover (SCO) molecules are promising nanoscale magnetic switches due to their ability to modify their spin state under several stimuli. However, SCO systems face several bottlenecks when downscaling into nanoscale spintronic devices: their instability at the nanoscale, their insulating character and the lack of control when positioning nanocrystals in nanodevices. Here we show the encapsulation of robust Fe-based SCO molecules within the 1D cavities of single-walled carbon nanotubes (SWCNT). We find that the SCO mechanism endures encapsulation and positioning of individual heterostructures in nanoscale transistors. The SCO switch in the guest molecules triggers a large conductance bistability through the host SWCNT. Moreover, the SCO transition shifts to higher temperatures and displays hysteresis cycles, and thus memory effect, not present in crystalline samples. Our results demonstrate how encapsulation in SWCNTs provides the backbone for the readout and positioning of SCO molecules into nanodevices, and can also help to tune their magnetic properties at the nanoscale.

Spin-crossover iron(II) long-chain complex with slow spin equilibrium at low temperature

2021 ◽  
Author(s):  
Qi Zhao ◽  
Jin-Peng Xue ◽  
Zhi-Kun Liu ◽  
Zi-Shuo Yao ◽  
Jun Tao
Keyword(s):  
Low Temperature ◽  
Single Crystal ◽  
Spin Crossover ◽  
Chain Complex ◽  
Mononuclear Complex ◽  
X Ray ◽  
Alkyl Chains ◽  
Long Chain

A mononuclear complex with long alkyl chains, [FeII(H2Bpz2)2(C9bpy)] (1; H2Bpz2 = dihydrobis(1-pyrazolyl)borate, C9bpy = 4,4'-dinonyl-2,2'-bipyridine), was synthesized. Single-crystal X-ray crystallographic studies revealed that - and - forms of the complex...

scholarly journals Spin Crossover in Nickel(II) Tetraphenylporphyrinate via Forced Axial Coordination at the Air/Water Interface

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4155
Author(s):  
Alexander V. Shokurov ◽  
Daria S. Kutsybala ◽  
Andrey P. Kroitor ◽  
Alexander A. Dmitrienko ◽  
Alexander G. Martynov ◽  
...  
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
High Spin State ◽  
Water Interface ◽  
Metal Centers ◽  
Axial Coordination ◽  
Vis Spectroscopy ◽  
Air Water Interface ◽  
Nickel Cation

Coordination-induced spin crossover (CISCO) in nickel(II) porphyrinates is an intriguing phenomenon that is interesting from both fundamental and practical standpoints. However, in most cases, realization of this effect requires extensive synthetic protocols or extreme concentrations of extra-ligands. Herein we show that CISCO effect can be prompted for the commonly available nickel(II) tetraphenylporphyrinate, NiTPP, upon deposition of this complex at the air/water interface together with a ruthenium(II) phthalocyaninate, CRPcRu(pyz)2, bearing two axial pyrazine ligands. The latter was used as a molecular guiderail to align Ni···Ru···Ni metal centers for pyrazine coordination upon lateral compression of the system, which helps bring the two macrocycles closer together and forces the formation of Ni–pyz bonds. The fact of Ni(II) porphyrinate switching from low- to high-spin state upon acquiring additional ligands can be conveniently observed in situ via reflection-absorption UV-vis spectroscopy. The reversible nature of this interaction allows for dissociation of Ni–pyz bonds, and thus, change of nickel cation spin state, upon expansion of the monolayer.

scholarly journals Programmable spin-state switching in a mixed-valence spin-crossover iron grid

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Takuto Matsumoto ◽  
Graham N. Newton ◽  
Takuya Shiga ◽  
Shinya Hayami ◽  
Yuta Matsui ◽  
...  
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
Mixed Valence ◽  
State Switching

Spin-State Ordering on One Sub-lattice of a Mononuclear Iron(III) Spin Crossover Complex Exhibiting LIESST and TIESST

2014 ◽  
Vol 20 (19) ◽  
pp. 5613-5618 ◽  
Author(s):  
Kevin D. Murnaghan ◽  
Chiara Carbonera ◽  
Loic Toupet ◽  
Michael Griffin ◽  
Marinela M. Dîrtu ◽  
...  
Keyword(s):  
Spin State ◽  
Spin Crossover ◽  
Mononuclear Iron

scholarly journals Stabilization of the Low-Spin State in a Mononuclear Iron(II) Complex and High-Temperature Cooperative Spin Crossover Mediated by Hydrogen Bonding

2015 ◽  
Vol 22 (1) ◽  
pp. 331-339 ◽  
Author(s):  
Sipeng Zheng ◽  
Niels R. M. Reintjens ◽  
Maxime A. Siegler ◽  
Olivier Roubeau ◽  
Elisabeth Bouwman ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
High Temperature ◽  
Spin State ◽  
Spin Crossover ◽  
Mononuclear Iron

scholarly journals Structural movies of the gradual spin-crossover in a molecular complex at various physical scales

2016 ◽  
Vol 18 (40) ◽  
pp. 28307-28315 ◽  
Author(s):  
S. Lakhloufi ◽  
M. H. Lemée-Cailleau ◽  
G. Chastanet ◽  
P. Rosa ◽  
N. Daro ◽  
...  
Keyword(s):  
Spin State ◽  
Molecular Complex ◽  
Spin Crossover ◽  
Structural Determination ◽  
Thermally Induced ◽  
Mononuclear Iron

The thermally induced Spin-CrossOver (SCO) undergone by the mononuclear iron(ii) complex [Fe(PM-AzA)2(NCS)2] (PM = N-2′-pyridylmethylene, AzA = 4-(phenylazo)aniline) is fully pictured by a quasi-continuous structural determination all along the spin-state modification within the sample.

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