Control of the magnetic and optical properties in molecular compounds by electrochemical, photochemical and chemical methods

Osamu Sato, Shinya Hayami, Yasuaki Einaga, Zhong Ze Gu

Research output: Contribution to journalArticle

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Abstract

The electrochemical, photochemical and chemical control of the magnetic properties in molecular compounds is described. The preparation of various thin films of CrCr and FeFe Prussian blue on a conducting electrode allowed us to control the magnetic properties by varying the oxidation state of the component metals. The magnetic properties of CrCr Prussian blue show that the critical temperature and coercive field can be drastically modified by electrochemical treatment. That is, the compound, CrII1.29CrIII0.14 [CrIII(CN)6] has ferrimagnetic properties with Tc (critical temperature) = 240 K and Hc (coercive field) = 25 G, while the reduced form, KCrII1.29CrIII0.14 [CrII(CN)6], has Tc = 100 K and Hc = 220 G. Similarly, it was found that the critical temperature of FeFe Prussian blue shifts continuously from paramagnetic to magnetic with Tc = 12 K. These changes can be expressed as K4FeII4[FeII (CN)6]3 (paramagnetic) ⇆ FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.5 K) + 4 K+ + 4e- and FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.2 K) + 3Cl- - 3e- ⇆ FeIII4[FeIII(CN)6] 3(Cl)3 (Tc = 12 K). Furthermore, we have discovered that the FeCo Prussian blue and Co valence tautomeric compounds exhibit photo-reversible magnetization effects. The photoinduced magnetization in FeCo Prussian blue is expressed as Na0.4CoII-HS0.3CoIII-LS [FeII(CN)6] (paramagnetic) ⇆ Na0.4CoII-HS1.3[FeIII (CN)6] (ferrimagnetic, Tc = 26 K and Hc = 6000 G), where HS and LS denote high-spin and low-spin. An example of the photoinduced valence tautomeric behavior is expressed as [CoIII-LS(3,5-dbsq)(3,5-dbcat)(tmeda)] ⇆ [CoII-HS(3,5-dbsq)2(tmeda)], where tmeda, 3,5-dbsq and 3,5-dbcat represent N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. Additionally, we succeeded in tuning the phase transition temperature by varying the ligand field of the Co ions in the FeCo Prussian blue. Brief comments are also included regarding the first examples of light-induced excited spin state trapping observed in an FeIII complex, i.e. [FeIII-LS(pap)2]ClO4·H2O ⇆ [FeIII-HS(pap)2]- ClO4·H2O (pap = N-2-pyridylmethylidene-2-hydroxy-phenylaminato) and a photoinduced structural change observed in a CuII complex, [CuII(dieten)2](BF4)2 [dieten = bis(N,N-diethylethylenediamine)].

Original languageEnglish
Pages (from-to)443-470
Number of pages28
JournalBulletin of the Chemical Society of Japan
Volume76
Issue number3
DOIs
Publication statusPublished - Jan 1 2003
Externally publishedYes

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Magnetic properties
Optical properties
Magnetization
Temperature
ferric ferrocyanide
Tuning
Phase transitions
Metals
Ions
Ligands
Thin films
Oxidation
Electrodes

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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Control of the magnetic and optical properties in molecular compounds by electrochemical, photochemical and chemical methods. / Sato, Osamu; Hayami, Shinya; Einaga, Yasuaki; Gu, Zhong Ze.

In: Bulletin of the Chemical Society of Japan, Vol. 76, No. 3, 01.01.2003, p. 443-470.

Research output: Contribution to journalArticle

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abstract = "The electrochemical, photochemical and chemical control of the magnetic properties in molecular compounds is described. The preparation of various thin films of CrCr and FeFe Prussian blue on a conducting electrode allowed us to control the magnetic properties by varying the oxidation state of the component metals. The magnetic properties of CrCr Prussian blue show that the critical temperature and coercive field can be drastically modified by electrochemical treatment. That is, the compound, CrII1.29CrIII0.14 [CrIII(CN)6] has ferrimagnetic properties with Tc (critical temperature) = 240 K and Hc (coercive field) = 25 G, while the reduced form, KCrII1.29CrIII0.14 [CrII(CN)6], has Tc = 100 K and Hc = 220 G. Similarly, it was found that the critical temperature of FeFe Prussian blue shifts continuously from paramagnetic to magnetic with Tc = 12 K. These changes can be expressed as K4FeII4[FeII (CN)6]3 (paramagnetic) ⇆ FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.5 K) + 4 K+ + 4e- and FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.2 K) + 3Cl- - 3e- ⇆ FeIII4[FeIII(CN)6] 3(Cl)3 (Tc = 12 K). Furthermore, we have discovered that the FeCo Prussian blue and Co valence tautomeric compounds exhibit photo-reversible magnetization effects. The photoinduced magnetization in FeCo Prussian blue is expressed as Na0.4CoII-HS0.3CoIII-LS [FeII(CN)6] (paramagnetic) ⇆ Na0.4CoII-HS1.3[FeIII (CN)6] (ferrimagnetic, Tc = 26 K and Hc = 6000 G), where HS and LS denote high-spin and low-spin. An example of the photoinduced valence tautomeric behavior is expressed as [CoIII-LS(3,5-dbsq)(3,5-dbcat)(tmeda)] ⇆ [CoII-HS(3,5-dbsq)2(tmeda)], where tmeda, 3,5-dbsq and 3,5-dbcat represent N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. Additionally, we succeeded in tuning the phase transition temperature by varying the ligand field of the Co ions in the FeCo Prussian blue. Brief comments are also included regarding the first examples of light-induced excited spin state trapping observed in an FeIII complex, i.e. [FeIII-LS(pap)2]ClO4·H2O ⇆ [FeIII-HS(pap)2]- ClO4·H2O (pap = N-2-pyridylmethylidene-2-hydroxy-phenylaminato) and a photoinduced structural change observed in a CuII complex, [CuII(dieten)2](BF4)2 [dieten = bis(N,N-diethylethylenediamine)].",
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T1 - Control of the magnetic and optical properties in molecular compounds by electrochemical, photochemical and chemical methods

AU - Sato, Osamu

AU - Hayami, Shinya

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AU - Gu, Zhong Ze

PY - 2003/1/1

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N2 - The electrochemical, photochemical and chemical control of the magnetic properties in molecular compounds is described. The preparation of various thin films of CrCr and FeFe Prussian blue on a conducting electrode allowed us to control the magnetic properties by varying the oxidation state of the component metals. The magnetic properties of CrCr Prussian blue show that the critical temperature and coercive field can be drastically modified by electrochemical treatment. That is, the compound, CrII1.29CrIII0.14 [CrIII(CN)6] has ferrimagnetic properties with Tc (critical temperature) = 240 K and Hc (coercive field) = 25 G, while the reduced form, KCrII1.29CrIII0.14 [CrII(CN)6], has Tc = 100 K and Hc = 220 G. Similarly, it was found that the critical temperature of FeFe Prussian blue shifts continuously from paramagnetic to magnetic with Tc = 12 K. These changes can be expressed as K4FeII4[FeII (CN)6]3 (paramagnetic) ⇆ FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.5 K) + 4 K+ + 4e- and FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.2 K) + 3Cl- - 3e- ⇆ FeIII4[FeIII(CN)6] 3(Cl)3 (Tc = 12 K). Furthermore, we have discovered that the FeCo Prussian blue and Co valence tautomeric compounds exhibit photo-reversible magnetization effects. The photoinduced magnetization in FeCo Prussian blue is expressed as Na0.4CoII-HS0.3CoIII-LS [FeII(CN)6] (paramagnetic) ⇆ Na0.4CoII-HS1.3[FeIII (CN)6] (ferrimagnetic, Tc = 26 K and Hc = 6000 G), where HS and LS denote high-spin and low-spin. An example of the photoinduced valence tautomeric behavior is expressed as [CoIII-LS(3,5-dbsq)(3,5-dbcat)(tmeda)] ⇆ [CoII-HS(3,5-dbsq)2(tmeda)], where tmeda, 3,5-dbsq and 3,5-dbcat represent N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. Additionally, we succeeded in tuning the phase transition temperature by varying the ligand field of the Co ions in the FeCo Prussian blue. Brief comments are also included regarding the first examples of light-induced excited spin state trapping observed in an FeIII complex, i.e. [FeIII-LS(pap)2]ClO4·H2O ⇆ [FeIII-HS(pap)2]- ClO4·H2O (pap = N-2-pyridylmethylidene-2-hydroxy-phenylaminato) and a photoinduced structural change observed in a CuII complex, [CuII(dieten)2](BF4)2 [dieten = bis(N,N-diethylethylenediamine)].

AB - The electrochemical, photochemical and chemical control of the magnetic properties in molecular compounds is described. The preparation of various thin films of CrCr and FeFe Prussian blue on a conducting electrode allowed us to control the magnetic properties by varying the oxidation state of the component metals. The magnetic properties of CrCr Prussian blue show that the critical temperature and coercive field can be drastically modified by electrochemical treatment. That is, the compound, CrII1.29CrIII0.14 [CrIII(CN)6] has ferrimagnetic properties with Tc (critical temperature) = 240 K and Hc (coercive field) = 25 G, while the reduced form, KCrII1.29CrIII0.14 [CrII(CN)6], has Tc = 100 K and Hc = 220 G. Similarly, it was found that the critical temperature of FeFe Prussian blue shifts continuously from paramagnetic to magnetic with Tc = 12 K. These changes can be expressed as K4FeII4[FeII (CN)6]3 (paramagnetic) ⇆ FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.5 K) + 4 K+ + 4e- and FeIII4[FeII(CN)6]3 (ferromagnetic, Tc = 4.2 K) + 3Cl- - 3e- ⇆ FeIII4[FeIII(CN)6] 3(Cl)3 (Tc = 12 K). Furthermore, we have discovered that the FeCo Prussian blue and Co valence tautomeric compounds exhibit photo-reversible magnetization effects. The photoinduced magnetization in FeCo Prussian blue is expressed as Na0.4CoII-HS0.3CoIII-LS [FeII(CN)6] (paramagnetic) ⇆ Na0.4CoII-HS1.3[FeIII (CN)6] (ferrimagnetic, Tc = 26 K and Hc = 6000 G), where HS and LS denote high-spin and low-spin. An example of the photoinduced valence tautomeric behavior is expressed as [CoIII-LS(3,5-dbsq)(3,5-dbcat)(tmeda)] ⇆ [CoII-HS(3,5-dbsq)2(tmeda)], where tmeda, 3,5-dbsq and 3,5-dbcat represent N,N,N′,N′-tetramethylethylenediamine, 3,5-di-tert-butyl-1,2-semiquinonate and 3,5-di-tert-butyl-1,2-catecholate, respectively. Additionally, we succeeded in tuning the phase transition temperature by varying the ligand field of the Co ions in the FeCo Prussian blue. Brief comments are also included regarding the first examples of light-induced excited spin state trapping observed in an FeIII complex, i.e. [FeIII-LS(pap)2]ClO4·H2O ⇆ [FeIII-HS(pap)2]- ClO4·H2O (pap = N-2-pyridylmethylidene-2-hydroxy-phenylaminato) and a photoinduced structural change observed in a CuII complex, [CuII(dieten)2](BF4)2 [dieten = bis(N,N-diethylethylenediamine)].

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