Water-dependent charge-transfer-induced spin transition of Prussian blue analogues

2016 ◽  
Vol 45 (42) ◽  
pp. 16784-16788 ◽  
Author(s):  
Hitomi Ohmagari ◽  
Ryo Ohtani ◽  
Manabu Nakaya ◽  
Masaaki Ohba ◽  
Masaaki Nakamura ◽  
...  

Na0.46Co[Fe(CN)6]0.78(H2O)1.31 shows a water-dependent charge-transfer-induced spin transition behavior caused by a change in coordination geometry at Co centers.

2002 ◽  
Vol 41 (4) ◽  
pp. 678-684 ◽  
Author(s):  
Naonobu Shimamoto ◽  
Shin-ichi Ohkoshi ◽  
Osamu Sato ◽  
Kazuhito Hashimoto

2020 ◽  
Author(s):  
Jennifer Zimara ◽  
Hendrik Stevens ◽  
Rainer Oswald ◽  
Serhiy Demeshko ◽  
Sebastian Dechert ◽  
...  

The dynamics of photo-driven charge transfer-induced spin transition (CTIST) in two Fe/Co Prussian Blue Analogues (PBAs) is revealed by femtosecond IR and UV/vis pump-probe spectroscopy. Depending on temperature the known tetranuclear square-type complex [Co<sub>2</sub>Fe<sub>2</sub>(CN)<sub>6</sub>(tp*)<sub>2</sub>(4,4’-dtbbpy)<sub>4</sub>](PF<sub>6</sub>)<sub>2</sub> (<b>1</b>) exists in two electronic states. In acetonitrile solution at <240 K the low temperature (<b>LT</b>) phase is prevalent consisting of low-spin Fe(II) and low-spin Co(III), [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>LS</sub>]<sub>2</sub>. Temperature rise causes thermally induced CTIST towards the high temperature (<b>HT</b>) phase consisting of low-spin Fe(III) and high-spin Co(II), [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>]<sub>2</sub>, being prevalent at >300 K. Photo-excitation into the intervalence charge transfer (IVCT) band of the <b>LT</b> phase at 800 nm induces electron transfer in one Fe-Co edge of PBA <b>1</b> and produces a [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>LS</sub>] intermediate which by spin crossover (SCO) is stabilized within 400 fs to a long-lived (>1 ns) [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>]. In contrast, IVCT excitation of the <b>HT</b> phase at 400 nm generates a [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>HS</sub>] species with a lifetime of 3.6 ps. Subsequent back-electron transfer populates the vibrationally hot ground state, which thermalizes within 8 ps. The newly synthesized dinuclear PBA, [CoFe(CN)<sub>3</sub>(tp*)(pz*<sub>4</sub>Lut)]ClO<sub>4</sub> (<b>2</b>), provides a benchmark of the <b>HT</b> phase of <b>1</b>, i.e. [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>], as verified by variable temperature magnetic susceptibility measurements and <sup>57</sup>Fe Mößbauer spectroscopy. The photo-induced charge transfer dynamics of PBA <b>2</b> indeed is almost identical to that of the <b>HT</b> phase of phase of PBA <b>1</b> with a lifetime of the excited [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>HS</sub>] species of 3.8 ps.


2020 ◽  
Author(s):  
Jennifer Zimara ◽  
Hendrik Stevens ◽  
Rainer Oswald ◽  
Serhiy Demeshko ◽  
Sebastian Dechert ◽  
...  

The dynamics of photo-driven charge transfer-induced spin transition (CTIST) in two Fe/Co Prussian Blue Analogues (PBAs) is revealed by femtosecond IR and UV/vis pump-probe spectroscopy. Depending on temperature the known tetranuclear square-type complex [Co<sub>2</sub>Fe<sub>2</sub>(CN)<sub>6</sub>(tp*)<sub>2</sub>(4,4’-dtbbpy)<sub>4</sub>](PF<sub>6</sub>)<sub>2</sub> (<b>1</b>) exists in two electronic states. In acetonitrile solution at <240 K the low temperature (<b>LT</b>) phase is prevalent consisting of low-spin Fe(II) and low-spin Co(III), [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>LS</sub>]<sub>2</sub>. Temperature rise causes thermally induced CTIST towards the high temperature (<b>HT</b>) phase consisting of low-spin Fe(III) and high-spin Co(II), [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>]<sub>2</sub>, being prevalent at >300 K. Photo-excitation into the intervalence charge transfer (IVCT) band of the <b>LT</b> phase at 800 nm induces electron transfer in one Fe-Co edge of PBA <b>1</b> and produces a [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>LS</sub>] intermediate which by spin crossover (SCO) is stabilized within 400 fs to a long-lived (>1 ns) [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>]. In contrast, IVCT excitation of the <b>HT</b> phase at 400 nm generates a [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>HS</sub>] species with a lifetime of 3.6 ps. Subsequent back-electron transfer populates the vibrationally hot ground state, which thermalizes within 8 ps. The newly synthesized dinuclear PBA, [CoFe(CN)<sub>3</sub>(tp*)(pz*<sub>4</sub>Lut)]ClO<sub>4</sub> (<b>2</b>), provides a benchmark of the <b>HT</b> phase of <b>1</b>, i.e. [Fe<sup>III</sup><sub>LS</sub>Co<sup>II</sup><sub>HS</sub>], as verified by variable temperature magnetic susceptibility measurements and <sup>57</sup>Fe Mößbauer spectroscopy. The photo-induced charge transfer dynamics of PBA <b>2</b> indeed is almost identical to that of the <b>HT</b> phase of phase of PBA <b>1</b> with a lifetime of the excited [Fe<sup>II</sup><sub>LS</sub>Co<sup>III</sup><sub>HS</sub>] species of 3.8 ps.


2008 ◽  
Vol 10 (38) ◽  
pp. 5882 ◽  
Author(s):  
Sébastien Bonhommeau ◽  
Niko Pontius ◽  
Saioa Cobo ◽  
Lionel Salmon ◽  
Frank M. F. de Groot ◽  
...  

2020 ◽  
Vol 13 (1) ◽  
pp. 10-14
Author(s):  
Marco Cammarata ◽  
Serhane Zerdane ◽  
Lodovico Balducci ◽  
Giovanni Azzolina ◽  
Sandra Mazerat ◽  
...  

2017 ◽  
Vol 2018 (3-4) ◽  
pp. 272-277 ◽  
Author(s):  
Serhane Zerdane ◽  
Marco Cammarata ◽  
Lodovico Balducci ◽  
Roman Bertoni ◽  
Laure Catala ◽  
...  

Crystals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 112 ◽  
Author(s):  
Maria Zentkova ◽  
Marian Mihalik

We present the review of pressure effect on the crystal structure and magnetic properties of Cr(CN)6-based Prussian blue analogues (PBs). The lattice volume of the fcc crystal structure space group Fm 3 ¯ m in the Mn-Cr-CN-PBs linearly decreases for p ≤ 1.7 GPa, the change of lattice size levels off at 3.2 GPa, and above 4.2 GPa an amorphous-like structure appears. The crystal structure recovers after removal of pressure as high as 4.5 GPa. The effect of pressure on magnetic properties follows the non-monotonous pressure dependence of the crystal lattice. The amorphous like structure is accompanied with reduction of the Curie temperature (TC) to zero and a corresponding collapse of the ferrimagnetic moment at 10 GPa. The cell volume of Ni-Cr-CN-PBs decreases linearly and is isotropic in the range of 0–3.1 GPa. The Raman spectra can indicate a weak linkage isomerisation induced by pressure. The Curie temperature in Mn2+-CrIII-PBs and Cr2+-CrIII-PBs with dominant antiferromagnetic super-exchange interaction increases with pressure in comparison with decrease of TC in Ni2+-CrIII-PBs and Co2+-CrIII-PBs ferromagnets. TC increases with increasing pressure for ferrimagnetic systems due to the strengthening of magnetic interaction because pressure, which enlarges the monoelectronic overlap integral S and energy gap ∆ between the mixed molecular orbitals. The reduction of bonding angles between magnetic ions connected by the CN group leads to a small decrease of magnetic coupling. Such a reduction can be expected on both compounds with ferromagnetic and ferrimagnetic ordering. In the second case this effect is masked by the increase of coupling caused by the enlarged overlap between magnetic orbitals. In the case of mixed ferro–ferromagnetic systems, pressure affects μ(T) by a different method in Mn2+–N≡C–CrIII subsystem and CrIII–C≡N–Ni2+ subsystem, and as a consequence Tcomp decreases when the pressure is applied. The pressure changes magnetization processes in both systems, but we expect that spontaneous magnetization is not affected in Mn2+-CrIII-PBs, Ni2+-CrIII-PBs, and Co2+-CrIII-PBs. Pressure-induced magnetic hardening is attributed to a change in magneto-crystalline anisotropy induced by pressure. The applied pressure reduces saturated magnetization of Cr2+-CrIII-PBs. The applied pressure p = 0.84 GPa induces high spin–low spin transition of cca 4.5% of high spin Cr2+. The pressure effect on magnetic properties of PBs nano powders and core–shell heterostructures follows tendencies known from bulk parent PBs.


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