Nanoparticles of iron(ii) spin-crossover

Forestier, Thibaut; Mornet, Stéphane; Daro, Nathalie; Nishihara, Taishi; Mouri, Shinichiro; Tanaka, Kōichiro; Fouché, Olivier; Freysz, É.; Létard, Jean‐François

doi:10.1039/b806347h

Cited by 182 publications

(121 citation statements)

References 18 publications

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“…They exhibit a very strong dependence of the spin transition temperature and the character of the transition on the type of the counter anions [2,10], the presence of hydrated water [11], and on the ligand substituent [12,13]. It has been shown that these SCO materials retain the cooperative character of their spin transition also as nanostructures [14][15][16][17][18][19][20][21]. This is important for the application of azole-bridged Fe(II)1D polymer complexes as materials for future molecular electronics and also provides an interesting challenge for theoretical modelling investigations.…”

Section: Introductionmentioning

confidence: 99%

Vibrational Coupling of Nearest Neighbors in 1-D Spin Crossover Polymers of Rigid Bridging Ligands. A Nuclear Inelastic Scattering and DFT Study

et al. 2016

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Abstract:The nuclear inelastic scattering signatures of the low-spin centers of the methanosulphonate, tosylate, and perchlorate salts of the spin crossover polymer ([Fe(II)(4-amino-1,2,4-triazole) 3 ] 2+ ) n have been compared for the low-spin phase, for the mixed high-spin and low-spin phases, as well as for Zn(II) diluted samples. Within this series a change in the vibrational pattern in the 320-500 cm´1 region is observed. Significant shifts and decreasing intensity of bands at~320 cm´1 and bands over 400 cm´1 are observed as the molar fraction of the low-spin (LS) centers decrease. Density functional theory calculations using Gaussian09 (B3LYP/CEP-31G) for pentameric, heptameric, and nonameric model molecules yielded the normal modes of several spin isomers: these include the all high-spin (HS) and the all low-spin (LS) configuration but also mixtures of LS and HS centers, with a special focus on those with LS centers in a HS matrix and vice versa. The calculations reproduce the observed spectral changes and show that they are caused by strain extorted on a LS Fe(II) center by its HS neighbors due to the rigid character of the bridging aminotriazole ligand. Additionally, the normal mode analysis of several spin isomers points towards a coupling of the vibrations of the iron centers of the same spin: the metal-ligand stretching modes of the all LS and the all HS spin isomers reveal a collective character: all centers of the same spin are involved in characteristic normal modes. For the isomers containing both LS and HS centers, the vibrational behavior corresponds to two different subsets (sublattices) the vibrational modes of which are not coupled. Finally, the calculation of nuclear inelastic scattering data of spin isomers containing a ca. 1:1 mixture of HS and LS Fe(II) points towards the formation of blocks of the same spin during the spin transition, rather than to alternate structures with a HS-LS-HS-LS-HS motif.

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Section: Introductionmentioning

confidence: 99%

Vibrational Coupling of Nearest Neighbors in 1-D Spin Crossover Polymers of Rigid Bridging Ligands. A Nuclear Inelastic Scattering and DFT Study

et al. 2016

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“…However, for fundamental studies as well as for practical applications, it still remains an experimental challenge to obtain precise control over the size and the shape of these switchable nanomaterials. Since the first descriptions in 2007 [19][20][21], a lot of works have been devoted to the influence of experimental synthesis parameters on the morphologies, sizes and properties of the [Fe(R-trz) 3 ].X 2 SCO materials: for example, parameters such as the surfactant nature [22,23], the surfactant ratio [23][24][25] and the Fe(II) concentration [26] have been considered. Despite these parameters appearing to influence the final size of the particles, no true rationalization of the synthesis has been done so far.…”

Section: Introductionmentioning

confidence: 99%

Rational Control of Spin-Crossover Particle Sizes: From Nano- to Micro-Rods of [Fe(Htrz)2(trz)](BF4)

et al. 2016

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Abstract:The spin-crossover (SCO) materials based on iron (II) and triazole ligands can change their spin state under an external perturbation such as temperature, pressure or light irradiation, exhibiting notably large hysteresis in their physical properties' transitions. If these aspects are investigated for decades, it is only in the recent years that the design of SCO particles has attracted the attention of the scientific community with increasing interest focusing on the possibility of getting wide ranges of sizes and shapes of nanoparticles. In this context, we rationalized the reverse-micellar synthesis, thanks to the scrutiny of the experimental parameters, to produce SCO particles with controlled size and shape. This approach has been performed for the reference one-dimensional (1D) polymeric spin-crossover compound of formula [Fe(Htrz) 2 (trz)](BF 4 ). A synergetic effect of both time and temperature is revealed as being of paramount importance to control the final particle size. Consequently, under well-defined experimental conditions, we can now offer rod-shaped SCO particles with lengths ranging from 75 to 1000 nm.

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“…This included the discovery of several new examples of SCO compounds [3,[9][10][11], the explanation of different types of SCO profiles [4,12] and the modification of SCO compounds to increase cooperativity and to direct their application into materials science [13]. Scientists have developed SCO networks [14][15][16], frameworks [17][18][19], gels [20][21][22], liquid crystals [23][24][25], nanoparticles and nanocrystals [26][27][28][29], nanowires [30], thin films [31][32][33] and have also applied patterning techniques to fabricate SCO devices [34]. Among complexes displaying SCO, [Fe(salEen) 2 ] + derivatives (salEen = N-ethyl-N-(2-aminoethyl)salicylaldiminate) are known to undergo thermal SCO sensitive to unit cell contents and supramolecular packing in the crystal [35].…”

Section: Introductionmentioning

confidence: 99%

Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands

Martinho

Vicente

Realista

et al. 2014

Journal of Organometallic Chemistry

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Nanoparticles of iron(ii) spin-crossover

Cited by 182 publications

References 18 publications

Vibrational Coupling of Nearest Neighbors in 1-D Spin Crossover Polymers of Rigid Bridging Ligands. A Nuclear Inelastic Scattering and DFT Study

Vibrational Coupling of Nearest Neighbors in 1-D Spin Crossover Polymers of Rigid Bridging Ligands. A Nuclear Inelastic Scattering and DFT Study

Rational Control of Spin-Crossover Particle Sizes: From Nano- to Micro-Rods of [Fe(Htrz)2(trz)](BF4)

Solution and solid state properties of Fe(III) complexes bearing N-ethyl-N-(2-aminoethyl)salicylaldiminate ligands

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