Pressure effect studies on spin crossover systems

Gütlich, Philipp; Ksenofontov, Vadim; Gaspar, Ana B.

doi:10.1016/j.ccr.2005.01.022

Cited by 223 publications

(219 citation statements)

References 55 publications

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“…Indeed, in past decades a variety of SCO behaviors under applied pressure have been reported in the literature, including "anomalous" phenomena such as increasing or nonmonotonously changing thermal hysteresis widths, a pressure-induced shift of the thermal transition curve without a change of its shape, stabilization of the HS phase, or a nonlinear shift of T c . 22,47 The reason behind this variety of behavior is that pressure is coupled to the order parameter by various mechanisms, which remain largely unexplored up to now. For example, coupling between structural phase transformations and SCO is often evoked in the literature, but the interpretation of the experimental observations has been at times compromised by the relatively poor and incomplete spectral and structural information provided by the detection methods or due to the experimental difficulties related to the need for hydrostatic conditions at low temperatures.…”

Section: Discussionmentioning

confidence: 99%

“…22,43 Clearly both hystereses broaden as pressure increases, which is contrary to the expectation from the standard theoretical models. 23 46,47 In the former, a crystallographic phase transition between the HS and LS states at ambient pressure was demonstrated by powder diffraction. 48 In the case of [Fe(PM-Bia) 2 (NCS) 2 ], at ambient pressure there is no difference in crystallographic symmetry between HS and LS states; however, the possibility of a second (pressure-induced) phase of this material that does show such a crystallographic transition between spin states has been postulated to explain the increase in width of the hysteresis above 6 kbar.…”

Section: Magnetometrymentioning

confidence: 99%

“…48 In the case of [Fe(PM-Bia) 2 (NCS) 2 ], at ambient pressure there is no difference in crystallographic symmetry between HS and LS states; however, the possibility of a second (pressure-induced) phase of this material that does show such a crystallographic transition between spin states has been postulated to explain the increase in width of the hysteresis above 6 kbar. 46,47 An alternative explanation for the increase in hysteresis width is that there is an increase in the particle size distribution, for example, in the case of [Fe(bipy) 2 (NCS) 2 ], where the widening and flattening of the hysteresis is attributed to the mechanical grinding of the sample. 44 Such an effect can be ruled out in the case of 1, as the hysteresis broadening is reversible, with hysteresis widths of 6 K and 21 K for the HS→IP and IP→LS transitions, respectively, after decompression to atmospheric pressure from 4.6 kbar, as shown in the electronic supplementary information (Fig.…”

Section: Magnetometrymentioning

confidence: 99%

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Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

et al. 2011

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We have used single-crystal x-ray diffraction, Raman spectroscopy, and magnetometry to investigate the effect of hydrostatic pressures up to 16 kbar on the molecular spin crossover complex [Fe II (bapbpy)(NCS) 2 ]. A stepped first-order transition from the high-spin (HS) to low-spin (LS) phase was observed upon compression of single-crystal samples. The intermediate phase (IP) is stable between 4 and 11 kbar at room temperature. This phase is characterized by supercell reflections and tripling of the c-axis of the unit cell (C2/c) due to the formation of a periodic [HS-LS-LS] structural motif, as seen in the thermal stepped transition. The pressure-temperature phase diagram reveals an anomalous increase of the thermal hysteresis widths with increasing pressure and the stabilization of the IP across the investigated P-T space.

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Section: Discussionmentioning

confidence: 99%

Section: Magnetometrymentioning

confidence: 99%

Section: Magnetometrymentioning

confidence: 99%

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Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

et al. 2011

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“…A few anomalous examples have already been reported in literature when the hysteresis width was found to increase under pressure [24,[37][38][39][40][41][42]. The most obvious explanation of this phenomenon can be a pressure induced additional structural change, since the sharp discontinuity in the phase diagram below 0.5 kbar, followed by a "regular" ClausiusClapeyron behaviour above 0.5 kbar is very difficult to explain in any other ways.…”

Section: Hs Lsmentioning

confidence: 99%

Temperature and pressure effects on the spin state of ferric ions in the [Fe(sal2-trien)][Ni(dmit)2] spin crossover complex

Szilágyi¹,

Dorbes²,

Molnár³

et al. 2008

Journal of Physics and Chemistry of Solids

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A c c e p t e d m a n u s c r i p t

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“…2 This is because they can be switched between the two lowest-energy spin states, namely, the low-spin (LS) and the high-spin (HS) state, thermally, 3 by applying pressure, 4 in pulsed magnetic fields, 5 chemically, 6 as well as optically. 7 The latter has been achieved for the LS → HS conversion in the so-called LIESST effect (light-induced excited spin state trapping) at low temperatures for a large number of iron(II) spin-crossover systems.…”

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confidence: 99%

Persistent Bidirectional Optical Switching in the 2D High-Spin Polymer {[Fe(bbtr)₃](BF₄)₂}_∞

et al. 2012

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In the covalently linked 2D coordination network {[Fe(bbtr) 3 ](BF 4 ) 2 } ∞ , bbtr = 1,4-di(1,2,3-triazol-1-yl)butane, the iron(II) centers stay in the high-spin (HS) state down to 10 K. They can, however, be quantitatively converted to the low-spin (LS) state by irradiating into the near-IR spin allowed 5 dd band and back again by irradiating into the visible 1 dd band. The compound shows true light-induced bistability below 100 K, thus, having the potential for persistent bidirectional optical switching at elevated temperatures. Bidirectional switching between two states of a system is of importance for applications in a large number of fields, 1 and spin-crossover compounds of transition metal ions, in particular those of iron(II), have been considered prototypes for such switchable materials for more than a decade.2 This is because they can be switched between the two lowest-energy spin states, namely, the low-spin (LS) and the high-spin (HS) state, thermally, 3 by applying pressure, 4 in pulsed magnetic fields, 5 chemically, 6 as well as optically. 7 The latter has been achieved for the LS → HS conversion in the so-called LIESST effect (light-induced excited spin state trapping) at low temperatures for a large number of iron(II) spin-crossover systems. 7,8 Invariably, the light-induced HS state is, however, a metastable state, albeit in some cases with a very long lifetime below ∼50 K. 7,8 For iron(II) complexes with no low-energy metal−ligand charge transfer (MLCT) transitions, lightinduced HS → LS conversion (reverse-LIESST) is likewise possible through irradiation in the near-IR, 9 and Bousseksou et al. have demonstrated bidirectional switching by pulsed laser irradiation within the thermal hysteresis of a strongly cooperative iron(II) spin-crossover system near room temperature. 10Partial bidirectional switching was demonstrated in tetrazole based systems some 15 years ago, with memory effects up to ∼70 K. 11 In the present communication, we describe the photophysical properties of the 2D network {[Fe(bbtr) 3 ]-(BF 4 ) 2 } ∞ , bbtr = 1,4-di(1,2,3-triazol-1-yl)butane, in which, in contrast to the ClO 4 − derivative, 12 the iron(II) centers remain in the HS state down to 10 K, 13 but can quantitatively and reversibly be switched back and forth between the two states using energy-selective excitation in the near-IR and the visible, respectively. Strong cooperative effects result in a persistent light-induced bistability below 100 K. Figure 1 shows single crystal absorption spectra of a small crystal (∼300 × 300 × 75 μm , as proof that the iron(II) centers remain in the HS state down to 10 K. Prolonged irradiation at 12 050 cm −1 (830 nm) results in almost total bleaching of this band and replacement by a more intense band at 18 200 cm −1 readily attributed to the spin-allowed ligand-

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Pressure effect studies on spin crossover systems

Cited by 223 publications

References 55 publications

Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

Temperature and pressure effects on the spin state of ferric ions in the [Fe(sal2-trien)][Ni(dmit)2] spin crossover complex

Persistent Bidirectional Optical Switching in the 2D High-Spin Polymer {[Fe(bbtr)₃](BF₄)₂}_∞

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Pressure effect studies on spin crossover systems

Cited by 223 publications

References 55 publications

Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

Pressure-induced two-step spin transition with structural symmetry breaking: X-ray diffraction, magnetic, and Raman studies

Temperature and pressure effects on the spin state of ferric ions in the [Fe(sal2-trien)][Ni(dmit)2] spin crossover complex

Persistent Bidirectional Optical Switching in the 2D High-Spin Polymer {[Fe(bbtr)3](BF4)2}∞

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Product

Resources

About

Persistent Bidirectional Optical Switching in the 2D High-Spin Polymer {[Fe(bbtr)₃](BF₄)₂}_∞