Structural Changes in Iron(II) Polymeric Complexes upon Thermally and Optically Induced Spin Transition Determined by EXAFS Spectroscopy

1998 ◽  
Vol 524 ◽  
Author(s):  
S. B. Erenburg ◽  
N. V. Bausk ◽  
L. G. Lavrenova ◽  
Yu. G. Shvedenkov ◽  
L. N. Mazalov
Keyword(s):  
High Spin ◽  
Structural Changes ◽  
Mutual Influence ◽  
Chemical Shifts ◽  
Spin Transition ◽  
High Spin State ◽  
Local Environment ◽  
Thermally Induced ◽  
Polymeric Complexes ◽  
Electronic And Spatial Structure

ABSTRACTChanges in the electronic and spatial structure of polymeric Fe(II) complexes with 1,2,4- triazoles and various anions upon spin transition was studied using EXAFS and XANES spectroscopy. Spin transition and structural changes were induced by variations of the anion, dilution with Zn, under heating or the action of light. In all complexes, the spin transition is accompanied by drastic changes in the local environment of Fe atoms. The increase in spin transition temperature for the complexes with variable anions CIO4-, I-, Br-, BF4-, NO3- was found to correlate with changes in the Fe-N distances and changes in bond covalence determined from the chemical shifts in Mössbauer spectra. High spin metastable long life states were detected and studied in the polymeric complex Fe(atrz)3(ClO4)2. It was established that the changes in structure of polymeric complexes upon the transition to a metastable high spin state under the action of light differ from those in the thermally induced spin transition. Such differences are determined by mutual influence of Fe atoms in high spin and low spin states in polymeric chains.

Iron(II) and Nickel(II) Complexes of 2,6-Di(thiazol-2-yl)pyridine and Related Ligands

1991 ◽  
Vol 44 (8) ◽  
pp. 1041 ◽  
Author(s):  
AT Baker ◽  
P Singh ◽  
V Vignevich
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Diethyl Acetal ◽  
Thermally Induced ◽  
Field Strengths

2,6-Di(thiazol-2-yl]pyridine (1a), 2,6-di(4-methylthiazol-2-yl)pyridine (1b) and 2,6-di(2-imid-azolin-2-yl)pyridine (3) have been prepared by the reaction of pyridine-2,6-dicarbothioamide with bromoacetaldehyde diethyl acetal, bromoacetone and ethylenediamine, severally. Bis ( ligand ) iron(II) and nickel(II) complexes of all ligands have been prepared. The bis ( ligand ) iron(II) complexes of (1a) and (3) are low-spin whereas that of (1b) is high-spin at room temperature and undergoes a thermally induced spin transition. The field strengths of the ligands , determined from the spectra of their nickel(II) complexes, correlate well with the observed magnetic behaviour of their iron(II) complexes. The field strengths of (1a) and (1b) are found to be marginally less than those of the isomeric ligands 2,6-di(thiazol-4-yl)pyridine (2a) and 2,6-di(2-methylthiazol-4-yl)pyridine (2b).

Optical Microscopy Imaging of the Thermally-Induced Spin Transition and Isothermal Multi-stepped Relaxation in a Low-Spin Stabilized Spin-Crossover Material

2021 ◽  
Author(s):  
Pradip Chakraborty ◽  
Mouhamadou Sy ◽  
Houcem Fourati ◽  
Maria Teresa Delgado Pérez ◽  
Mousumi Dutta ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
High Spin ◽  
Spin Relaxation ◽  
Spin Crossover ◽  
Spin Transition ◽  
Host Lattice ◽  
Microscopy Imaging ◽  
Thermally Induced ◽  
Optical Microscopy Imaging

The thermal spin transition and the photo-induced high-spin → low-spin relaxation of the prototypical [Fe(ptz)6](BF4)2 spin-crossover compound (ptz = 1-propyltetrazole) diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2, which stabilizes...

Demonstration of the thermally induced high spin–low spin transition for a transparent spin crossover complex film [Fe(II)(H-trz)3]-Nafion (trz=triazole)

Polyhedron ◽  
2005 ◽  
Vol 24 (16-17) ◽  
pp. 2909-2912 ◽  
Author(s):  
Akio Nakamoto ◽  
Norimichi Kojima ◽  
Liu XiaoJun ◽  
Yutaka Moritomo ◽  
Arao Nakamura
Keyword(s):  
High Spin ◽  
Spin Crossover ◽  
Spin Transition ◽  
Thermally Induced ◽  
Complex Film

Metal-Complexes of 1,10-Phenanthroline Derivatives. XV. Complexes of 2-(3,5-Dimethylpyrazol-1-yl)-1,10-phenanthroline

1988 ◽  
Vol 41 (6) ◽  
pp. 873 ◽  
Author(s):  
AS Abushamleh ◽  
HA Goodwin
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Spectral Data ◽  
High Spin ◽  
Nickel Complex ◽  
Spin Transition ◽  
Critical Value ◽  
Magnetic Data ◽  
Strong Temperature Dependence ◽  
Thermally Induced

Iron(II) and nickel(II) bis ( ligand ) complexes of 2-(3,5-dimethylpyrazol-1-yl)-1,10-phenanthroline (L) have been prepared. The field strength of L as determined from spectral data for the nickel complex is in the range encompassing the critical value at the singlet (1A1) ↔ quintet (5T2) crossover for iron(II). The magnetic properties of the iron(II) complex both in solution and in the solid state are anomalous, and indicative of the occurrence of a thermally induced spin transition. Mossbauer spectral data confirm this, and reveal separate contributions from the singlet and quintet species with a strong temperature-dependence of their relative intensities. Magnetic data for the complex in solution are consistent with a simple high spin ↔ low spin equilibrium, and lead to values of ΔH = 23�0.5 kJ mol-1 and ΔS = 66�5 J K-1 mol-1 for the low spin → high spin transformation.

scholarly journals Fluorescence modulation via photoinduced spin crossover switched energy transfer from fluorophores to FeII ions

2018 ◽  
Vol 9 (11) ◽  
pp. 2892-2897 ◽  
Author(s):  
Jun-Li Wang ◽  
Qiang Liu ◽  
Yin-Shan Meng ◽  
Xin Liu ◽  
Hui Zheng ◽  
...  
Keyword(s):  
Energy Transfer ◽  
High Spin ◽  
Spin State ◽  
Spin Crossover ◽  
Spin Transition ◽  
High Spin State ◽  
Fluorescence Modulation

Coupling between spin crossover and fluorescence was achieved by a thermal and light-induced Fe(ii) spin transition from the low spin state to the high spin state.

Cooperative spin transition and thermally quenched high-spin state in new polymorph of [Fe(qsal)2]I3

2011 ◽  
Vol 206 (1-3) ◽  
pp. 1-5 ◽  
Author(s):  
Kazuyuki Takahashi ◽  
Tetsuya Sato ◽  
Hatsumi Mori ◽  
Hiroyuki Tajima ◽  
Yasuaki Einaga ◽  
...  
Keyword(s):  
High Spin ◽  
Spin State ◽  
Spin Transition ◽  
High Spin State

Thermally Induced High-Spin Low-Spin Transition in Co[Cr0.5Ga1.5]S4 Spinel

2011 ◽  
Vol 170 ◽  
pp. 9-12
Author(s):  
J. Krok-Kowalski ◽  
Ewa Maciążek ◽  
Tadeusz Groń ◽  
Andrzej W. Pacyna ◽  
Tadeusz Mydlarz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
High Spin ◽  
Inflection Point ◽  
Spin Transition ◽  
Spin Frustration ◽  
Strong Suppression ◽  
Thermally Induced ◽  
Tetrahedral Sites ◽  
Curie Temperature Tc

A high spin (HS) – low spin (LS) transition has been discovered in the Co[Cr0.5Ga1.5]S4 spinel, where the Co ions occupy tetrahedral sites and the Cr and Ga ions octahedral ones. The latter are diluted by the non-magnetic Ga-ions. Application of magnetic fields revealed ferrimagnetic order with a Curie temperature TC = 126 K, a strong suppression of the magnetic susceptibility () and a slight shift of TC to lower temperatures. A cusp at 15.6 K on the ac (T) curve suggests a spin frustration of the re-entrant type. Characteristic for the HS-LS transition is an inflection point at 150 K on the 1/(T) curve, a lack of the Curie-Weiss region above TC and a small value of the magnetization, 4.76 emu/g at 4.4 K and at a magnetic field of 57.5 kOe.

scholarly journals Elastic coupling between spin-crossover particles and cellulose fibers

2016 ◽  
Vol 52 (75) ◽  
pp. 11267-11269 ◽  
Author(s):  
S. Rat ◽  
V. Nagy ◽  
I. Suleimanov ◽  
G. Molnár ◽  
L. Salmon ◽  
...  
Keyword(s):  
Composite Materials ◽  
Dynamic Mechanical Analysis ◽  
High Spin ◽  
Spin Crossover ◽  
Spin Transition ◽  
High Spin State ◽  
Cellulose Fibers ◽  
Mechanical Analysis ◽  
Elastic Coupling ◽  
Micro Particles

Composite materials made of cellulose fibers and spin crossover micro-particles investigated by dynamic mechanical analysis revealed an abrupt and reversible stiffening upon spin transition from the low spin to the high spin state.

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