One-Dimensional and Two-Dimensional Anilate-Based Magnets with Inserted Spin-Crossover Complexes

The syntheses, structures, and magnetic properties of a family of bimetallic anilate-based compounds with inserted spin-crossover cationic complexes are reported. The structures of <b>1</b>–<b>4</b> present a two-dimensional anionic network formed by Mn­(II) and Cr­(III) ions linked through anilate ligands with inserted [Fe^III(sal₂-trien)]⁺ (<b>1</b>), [Fe^III(4-OH-sal₂-trien)]⁺ (<b>2</b>), [Fe^III(sal₂-epe)]⁺ (<b>3</b>), or [Fe^III(5-Cl-sal₂-trien)]⁺ (<b>4</b>) complexes. The structure of <b>5</b> is formed by anionic [Mn^IICl₂Cr^III(Cl₂An)₃]^3– chains surrounded by [Fe^II(tren­(imid)₃)]²⁺, Cl^–, and solvent molecules. The magnetic properties indicate that <b>1</b>–<b>4</b> undergo a long-range ferrimagnetic ordering at ca. 10 K. On the other hand, the inserted Fe­(III) cations remain in the low-spin (in <b>4</b>) or high-spin state (in <b>1</b>, <b>2</b>, and <b>3</b>). In the case of <b>5</b>, half of the inserted Fe­(II) cations undergo a complete and gradual spin crossover from 280 to 90 K that coexists with a magnetic ordering below 2.5 K

Patterning of Magnetic Bimetallic Coordination Nanoparticles of Prussian Blue Derivatives by the Langmuir–Blodgett Technique

We report a novel method to prepare patterns of nanoparticles over large areas of the substrate. This method is based on the adsorption of the negatively charged nanoparticles dispersed in an aqueous subphase onto a monolayer of the phospholipid dipalmitoyl-l-α-phosphatidylcholine (DPPC) at the air–water interface. It has been used to prepare patterns of nanoparticles of Prussian blue analogues (PBA) of different size (K_0.25Ni­[Fe­(CN)₆]_0.75 (NiFe), K_0.25Ni­[Cr­(CN)₆]_0.75 (NiCr), K_0.25Ni­[Co­(CN)₆]_0.75 (NiCo), Cs_0.4Co­[Cr­(CN)₆]_0.8 (CsCoCr), and Cs_0.4Co­[Fe­(CN)₆]_0.9 (CsCoFe)). The behavior of DPPC monolayer at the air–water interface in the presence of the subphase of PBA nanoparticles has been studied by the compression isotherms and Brewster angle microscopy (BAM) images. Atomic force microscopy (AFM) of the transferred films on mica substrates shows that patterns of the nanoparticles are observed for a 10^–4 M concentration of the subphase, based on the nanoparticle precursors, at surface pressures between 1 and 6 mN/m and transfer velocities from 10 to 80 mm/min. Vertical, horizontal, or tilted fringes of the nanoparticles with respect to the transfer direction can be obtained depending on the transfer velocity and surface pressure

Nonanuclear Spin-Crossover Complex Containing Iron(II) and Iron(III) Based on a 2,6-Bis(pyrazol-1-yl)pyridine Ligand Functionalized with a Carboxylate Group

The synthesis and magnetostructural characterization of [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]­(ClO₄)₁₃·(CH₃)₂CO)₆·(solvate) (<b>2</b>) are reported. This compound is obtained as a secondary product during synthesis of the mononuclear complex [Fe^II(bppCOOH)₂]­(ClO₄)₂ (<b>1</b>). The single-crystal X-ray diffraction structure of <b>2</b> shows that it contains the nonanuclear cluster of the formula [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]¹³⁺, which is formed by a central Fe^III₃O core coordinated to six partially deprotonated [Fe^II(bppCOOH)­(bppCOO)]⁺ complexes. Raman spectroscopy studies on single crystals of <b>1</b> and <b>2</b> have been performed to elucidate the spin and oxidation states of iron in <b>2</b>. These studies and magnetic characterization indicate that most of the iron­(II) complexes of <b>2</b> remain in the low-spin (LS) state and present a gradual and incomplete spin crossover above 300 K. On the other hand, the Fe^III trimer shows the expected antiferromagnetic behavior. From the structural point of view, <b>2</b> represents the first example in which bppCOO^– acts as a bridging ligand, thus forming a polynuclear magnetic complex

Nonanuclear Spin-Crossover Complex Containing Iron(II) and Iron(III) Based on a 2,6-Bis(pyrazol-1-yl)pyridine Ligand Functionalized with a Carboxylate Group

The synthesis and magnetostructural characterization of [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]­(ClO₄)₁₃·(CH₃)₂CO)₆·(solvate) (<b>2</b>) are reported. This compound is obtained as a secondary product during synthesis of the mononuclear complex [Fe^II(bppCOOH)₂]­(ClO₄)₂ (<b>1</b>). The single-crystal X-ray diffraction structure of <b>2</b> shows that it contains the nonanuclear cluster of the formula [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]¹³⁺, which is formed by a central Fe^III₃O core coordinated to six partially deprotonated [Fe^II(bppCOOH)­(bppCOO)]⁺ complexes. Raman spectroscopy studies on single crystals of <b>1</b> and <b>2</b> have been performed to elucidate the spin and oxidation states of iron in <b>2</b>. These studies and magnetic characterization indicate that most of the iron­(II) complexes of <b>2</b> remain in the low-spin (LS) state and present a gradual and incomplete spin crossover above 300 K. On the other hand, the Fe^III trimer shows the expected antiferromagnetic behavior. From the structural point of view, <b>2</b> represents the first example in which bppCOO^– acts as a bridging ligand, thus forming a polynuclear magnetic complex

Nonanuclear Spin-Crossover Complex Containing Iron(II) and Iron(III) Based on a 2,6-Bis(pyrazol-1-yl)pyridine Ligand Functionalized with a Carboxylate Group

The synthesis and magnetostructural characterization of [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]­(ClO₄)₁₃·(CH₃)₂CO)₆·(solvate) (<b>2</b>) are reported. This compound is obtained as a secondary product during synthesis of the mononuclear complex [Fe^II(bppCOOH)₂]­(ClO₄)₂ (<b>1</b>). The single-crystal X-ray diffraction structure of <b>2</b> shows that it contains the nonanuclear cluster of the formula [Fe^III₃(μ₃-O)­(H₂O)₃[Fe^II(bppCOOH)­(bppCOO)]₆]¹³⁺, which is formed by a central Fe^III₃O core coordinated to six partially deprotonated [Fe^II(bppCOOH)­(bppCOO)]⁺ complexes. Raman spectroscopy studies on single crystals of <b>1</b> and <b>2</b> have been performed to elucidate the spin and oxidation states of iron in <b>2</b>. These studies and magnetic characterization indicate that most of the iron­(II) complexes of <b>2</b> remain in the low-spin (LS) state and present a gradual and incomplete spin crossover above 300 K. On the other hand, the Fe^III trimer shows the expected antiferromagnetic behavior. From the structural point of view, <b>2</b> represents the first example in which bppCOO^– acts as a bridging ligand, thus forming a polynuclear magnetic complex

Comparison of the performance of Skin Prick, ImmunoCAP, and ISAC tests in the diagnosis of patients with allergy

Background: Allergy is diagnosed from typical symptoms, and tests are performed to incriminate the suspected precipitant. Skin prick tests (SPTs) are commonly performed, inexpensive, and give immediate results. Laboratory tests (ImmunoCAP) for serum allergen-specific IgE antibodies are usually performed more selectively. The immuno-solid phase allergen chip (ISAC) enables testing for specific IgE against multiple allergen components in a multiplex assay. Methods: We retrospectively analysed clinic letters, case notes, and laboratory results of 118 patients attending the National Adult Allergy Service at the University Hospital of Wales who presented diagnostic difficulty, to evaluate which testing strategy (SPT, ImmunoCAP, or ISAC) was the most appropriate to use to confirm the diagnosis in these complex patients, evaluated in a “real-life” clinical service setting. Results: In patients with nut allergy, the detection rates of SPTs (56%) and ISAC (65%) were lower than those of ImmunoCAP (71%). ISAC had a higher detection rate (88%) than ImmunoCAP (69%) or SPT (33%) in the diagnosis of oral allergy syndrome. ImmunoCAP test results identified all 9 patients with anaphylaxis due to wheat allergy (100%), whereas ISAC was positive in only 6 of these 9 (67%). Conclusions: In this difficult diagnostic group, the ImmunoCAP test should be the preferred single test for possible allergy to nuts, wheat, other specific foods, and anaphylaxis of any cause. In these conditions, SPT and ISAC tests give comparable results. The most useful single test for oral allergy syndrome is ISAC, and SPT should be the preferred test for latex allergy

Stimuli Responsive Hybrid Magnets: Tuning the Photoinduced Spin-Crossover in Fe(III) Complexes Inserted into Layered Magnets

The insertion of a [Fe­(sal₂-trien)]⁺ complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHCl₃ (<b>1·CHCl</b>_<b>3</b>), [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHBr₃ (<b>1·CHBr</b>_<b>3</b>), and [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CH₂Br₂ (<b>1·CH</b>_<b>2</b><b>Br</b>_<b>2</b>). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn^II and Cr^III ions linked through oxalate ligands and a layer of [Fe­(sal₂-trien)]⁺ complexes and solvent molecules (CHCl₃, CHBr₃, or CH₂Br₂) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe­(sal₂-trien)]⁺ complexes at different temperatures <i>T</i>_1/2. The three compounds present a LIESST effect with a relaxation temperature <i>T</i>_LIESST inversely proportional to <i>T</i>_1/2. The isostructural paramagnetic compound, [Fe^III(sal₂-trien)]­[Zn^IICr^III(ox)₃]·CH₂Cl₂ (<b>2·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) was also prepared. This compound presents a partial spin crossover of the inserted Fe^III complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe^III doped compound [Ga_0.99Fe_0.01(sal₂trien)]­[Mn^IICr^III(ox)₃]·CH₂Cl₂ (<b>3·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe^III complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe^III compound

Stimuli Responsive Hybrid Magnets: Tuning the Photoinduced Spin-Crossover in Fe(III) Complexes Inserted into Layered Magnets

The insertion of a [Fe­(sal₂-trien)]⁺ complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHCl₃ (<b>1·CHCl</b>_<b>3</b>), [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHBr₃ (<b>1·CHBr</b>_<b>3</b>), and [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CH₂Br₂ (<b>1·CH</b>_<b>2</b><b>Br</b>_<b>2</b>). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn^II and Cr^III ions linked through oxalate ligands and a layer of [Fe­(sal₂-trien)]⁺ complexes and solvent molecules (CHCl₃, CHBr₃, or CH₂Br₂) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe­(sal₂-trien)]⁺ complexes at different temperatures <i>T</i>_1/2. The three compounds present a LIESST effect with a relaxation temperature <i>T</i>_LIESST inversely proportional to <i>T</i>_1/2. The isostructural paramagnetic compound, [Fe^III(sal₂-trien)]­[Zn^IICr^III(ox)₃]·CH₂Cl₂ (<b>2·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) was also prepared. This compound presents a partial spin crossover of the inserted Fe^III complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe^III doped compound [Ga_0.99Fe_0.01(sal₂trien)]­[Mn^IICr^III(ox)₃]·CH₂Cl₂ (<b>3·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe^III complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe^III compound

Stimuli Responsive Hybrid Magnets: Tuning the Photoinduced Spin-Crossover in Fe(III) Complexes Inserted into Layered Magnets

The insertion of a [Fe­(sal₂-trien)]⁺ complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHCl₃ (<b>1·CHCl</b>_<b>3</b>), [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHBr₃ (<b>1·CHBr</b>_<b>3</b>), and [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CH₂Br₂ (<b>1·CH</b>_<b>2</b><b>Br</b>_<b>2</b>). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn^II and Cr^III ions linked through oxalate ligands and a layer of [Fe­(sal₂-trien)]⁺ complexes and solvent molecules (CHCl₃, CHBr₃, or CH₂Br₂) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe­(sal₂-trien)]⁺ complexes at different temperatures <i>T</i>_1/2. The three compounds present a LIESST effect with a relaxation temperature <i>T</i>_LIESST inversely proportional to <i>T</i>_1/2. The isostructural paramagnetic compound, [Fe^III(sal₂-trien)]­[Zn^IICr^III(ox)₃]·CH₂Cl₂ (<b>2·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) was also prepared. This compound presents a partial spin crossover of the inserted Fe^III complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe^III doped compound [Ga_0.99Fe_0.01(sal₂trien)]­[Mn^IICr^III(ox)₃]·CH₂Cl₂ (<b>3·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe^III complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe^III compound

Stimuli Responsive Hybrid Magnets: Tuning the Photoinduced Spin-Crossover in Fe(III) Complexes Inserted into Layered Magnets

The insertion of a [Fe­(sal₂-trien)]⁺ complex cation into a 2D oxalate network in the presence of different solvents results in a family of hybrid magnets with coexistence of magnetic ordering and photoinduced spin-crossover (LIESST effect) in compounds [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHCl₃ (<b>1·CHCl</b>_<b>3</b>), [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CHBr₃ (<b>1·CHBr</b>_<b>3</b>), and [Fe^III(sal₂-trien)]­[Mn^IICr^III(ox)₃]·CH₂Br₂ (<b>1·CH</b>_<b>2</b><b>Br</b>_<b>2</b>). The three compounds crystallize in a 2D honeycomb anionic layer formed by Mn^II and Cr^III ions linked through oxalate ligands and a layer of [Fe­(sal₂-trien)]⁺ complexes and solvent molecules (CHCl₃, CHBr₃, or CH₂Br₂) intercalated between the 2D oxalate network. The magnetic properties and Mössbauer spectroscopy indicate that they undergo long-range ferromagnetic ordering at 5.6 K and a spin crossover of the intercalated [Fe­(sal₂-trien)]⁺ complexes at different temperatures <i>T</i>_1/2. The three compounds present a LIESST effect with a relaxation temperature <i>T</i>_LIESST inversely proportional to <i>T</i>_1/2. The isostructural paramagnetic compound, [Fe^III(sal₂-trien)]­[Zn^IICr^III(ox)₃]·CH₂Cl₂ (<b>2·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) was also prepared. This compound presents a partial spin crossover of the inserted Fe^III complex as well as a LIESST effect. Finally, spectroscopic characterization of the Fe^III doped compound [Ga_0.99Fe_0.01(sal₂trien)]­[Mn^IICr^III(ox)₃]·CH₂Cl₂ (<b>3·CH</b>_<b>2</b><b>Cl</b>_<b>2</b>) shows a gradual and complete thermal spin crossover and a LIESST effect on the isolated Fe^III complexes. This result confirms that cooperativity is not a necessary condition to observe the LIESST effect in an Fe^III compound