Polynuclear Iron(II)–Aminotriazole Spincrossover Complexes (Polymers) In Solution

Bräunlich, Irene; Sánchez‐Ferrer, Antoni; Schepper, Rahel; Knüsel, Philippe N.; Dshemuchadse, Julia; Mezzenga, Raffaele; Caseri, Walter

doi:10.1021/ic403035u

Cited by 29 publications

(38 citation statements)

References 42 publications

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“…1b). Noticeably, the molar ATrz/Fe 2+ ratio used for this synthesis was increased to 6 : 1 in order to promote the expected compound, [Fe(ATrz) 3 ]SO 4 , 45,46 due to the strong complexing ability of SO 4 2À anions for Fe(II)…”

Section: Resultsmentioning

confidence: 99%

Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites

et al. 2017

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Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites †T. Coradin * a and C. Roux* a One dimensional iron(II) coordination polymers formed from 1,2,4-triazole bridging ligands are a unique class of spin-crossover materials (SCO). The integration of those coordination polymers into devices for practical applications remains a major challenge. Using a nanocomposite approach based on the control of coordination polymer interactions with chemically engineered silica particles, we show that we can achieve in situ gelation, while preserving the SCO properties of the solid state. Tuning the interface between the two phases of a composite provides a unique way to synergistically adjust the material's structure and the cooperativity associated with its transition properties. The strategy described here should allow for bridging the gap between soft and crystalline functional inorganic materials.

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Section: Resultsmentioning

confidence: 99%

Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites

et al. 2017

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“…The syntheses of [Fe(H 2 O) 6 ](2ns) 2 and [Fe(NH 2 trz) 3 ] n (2ns) 2n were carried out as described earlier. 23…”

Section: Methodsmentioning

confidence: 99%

“…However, the alkyl-free soluble [Fe(NH 2 trz) 3 ](2ns) 2 is not suitable for preparing Langmuir-Blodgett lms because the complex is not amphiphilic in nature and gel-formation of [Fe(NH 2 trz) 3 ](2ns) 2 in DMF, the only good solvent found so far for this complex, is expected to proceed differently than in apolar solvents used for the alkyl-substituted compounds. 23 Therefore, this study deals with the formation of [Fe(NH 2 trz) 3 ](2ns) 2 spincrossover gels under different conditions and their drying, including CO 2 critical-point drying to minimize volume shrinkage and preserve the structure. Moreover, the formation of lms by solvent evaporation of the gels was studied as an alternative route for casting of solutions.…”

Section: Introductionmentioning

confidence: 99%

Gels, xerogels and films of polynuclear iron(ii)–aminotriazole spin-crossover polymeric complexes

et al. 2014

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The prominent polynuclear spin-crossover complex [Fe(NH 2 trz) 3 ](2ns) 2 (polymer) (NH 2 trz ¼ 4-amino-1,2,4-triazole, 2ns À ¼ 2-naphthalenesulfonate) as obtained from synthesis exists in a metastable state characterized by a columnar hexagonal packing (Col h) of polynuclear rigid-rod complexes, and shows considerable fluctuations in the spin-crossover temperature (between 22 and 41 C upon heating and between 14 and 25 C upon cooling). This structure is converted into a more stable columnar rectangular packing (Col r) by annealing this material at 250 C, which is accompanied by a shift of the spin-crossover towards higher temperatures ($52 C upon heating and $33 C upon cooling). Furthermore, solutions of [Fe(NH 2 trz) 3 ](2ns) 2 in dimethylformamide (DMF) can be converted into gels by increasing the concentration of [Fe(NH 2 trz) 3 ](2ns) 2 or by addition of toluene, while preserving the spincrossover behavior. Gels prepared by the latter method were converted into xerogels by CO 2 criticalpoint drying, or into transparent thermochromic films by slow evaporation of the solvent. For the xerogels an initial Col h packing is transformed into the more stable Col r packing by the same annealing procedure applied to the powders. On the other hand, the slow evaporation of solvent used for the manufacture of films allowed establishment of a Col r packing by annealing at lower temperatures (150 C). Polynuclear complexes of the type [Fe(Rtrz) 3 ] n X 2n (Rtrz ¼ 4-R-1,2,4-triazole) have attracted particular attention, not only due to their exceptional structure but also because their spincrossover temperature can be varied by applying differently substituted ligands and counter anions X À. 13-15 Thus, also materials with spin-crossover near room temperature can be fabricated. 16-18 Unfortunately, processing of those complexes is oen hampered due to lacking solubility or thermal stability (usually, decomposition takes place prior to melting). 19 One possibility to overcome the poor solubility is to attach long side chains at the ligands or counter anions. 20-22 However, introducing large Scheme 1 Schematic representation of the structure of the spincrossover complex [Fe(NH 2 trz) 3 ](2ns) 2 (NH 2 trz: 4-amino-1,2,4-triazole, 2ns À : 2-naphthalenesulfonate).

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“…However, there are a number of papers devoted to the investigation of such complexes in solutions. [10][11][12] Iron(II) complexes with polynitrogen-containing ligands are of particular interest, since the spin transitions in the most part of them is accompanied by thermochromism, which significantly extends the potentialities of their practical application. These complexes can be used in the development of systems for recording and storing information, thermochromic indicators and labels, electroluminescent devices, temperaturesensitive materials in magnetic resonance imaging (MRI) etc.…”

Section: Introductionmentioning

confidence: 99%

Studies on Sulfate Iron(II) Complex With Tris(pyrazol‐1‐yl)methane Exhibiting Spin Crossover in Aqueous Solutions

et al. 2019

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Using the methods of UV‐, VIS‐ and near‐IR spectrometry, potentiometry, static magnetic susceptibility and cyclic voltammetry, an iron(II) complex with tris(pyrazol‐1‐yl)methane (L) having the composition of [FeL2]SO4 is studied in aqueous solution. In the solid state this compound exhibits spin crossover 1A1 ↔ 5T2. The protonation constants of L (log K1H=2.53, log K2H=1.80) and stability constants of the complex (log β(FeL2+) ≈ 4, log β(FeL22+)=8.62) at t = 25° C, I=0.05 M have been determined. The studies on μeff(T) of [FeL2]SO4 in solution in the temperature range from 280 to 355 K have shown that the value of μeff exhibits an increase with increasing temperature. This indicates that with increasing temperature a transition occurs from the low spin (LS) state of the complex to the high spin (HS) state thereof.

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Polynuclear Iron(II)–Aminotriazole Spincrossover Complexes (Polymers) In Solution

Cited by 29 publications

References 42 publications

Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites

Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites

Gels, xerogels and films of polynuclear iron(ii)–aminotriazole spin-crossover polymeric complexes

Studies on Sulfate Iron(II) Complex With Tris(pyrazol‐1‐yl)methane Exhibiting Spin Crossover in Aqueous Solutions

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