Search results for "osso"
showing 10 items of 801 documents
Fe(II) spin crossover complexes of a derivative of 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) functionalized with a carboxylic acid in the 3-pyridyl posit…
2019
Abstract The preparation of a new bis(pyrazol-1-yl)pyridine (1-bpp) derivative functionalized with a carboxylic acid in the 3-pyridyl position, bpp3-COOH ligand is reported together with the structure and spin-crossover (SCO) properties of [FeII(bpp3-COOH)2](ClO4)2·0.5EtOH·0.5H2O (1). Magnetic properties of 1 indicate that LS is favored. Desolvation leads to a gradual and incomplete SCO. Solvated and desolvated compounds show LIESST effect.
Heteroleptic Iron(II) Spin-Crossover Complexes Based on a 2,6-Bis(pyrazol-1-yl)pyridine-type Ligand Functionalized with a Carboxylic Acid
2019
Two new heteroleptic complexes [Fe- (1bppCOOH)(3bpp-bph)](ClO4)2·solv (1·solv, solv = various solvents; 1bppCOOH = 2,6-bis(1H-pyrazol-1-yl)- isonicotinic acid; 3bpp-bph = 2,6-bis(5-([1,1′-biphenyl]-4- yl)-1H-pyrazol-3-yl)pyridine) and [Fe(1bppCOOH)- (1bppCOOEt)](ClO4)2 ·0.5Me2CO (2·0.5Me2CO, 1bppCOOEt = ethyl 2,6-bis(1H-pyrazol-1-yl)isonicotinate) were designed and prepared. The heteroleptic compound 1· solv was obtained by the combination of stoichiometric amounts of Fe(ClO4)2, 1bppCOOH, and 3bpp-bph, and it was designed to fine-tune the spin crossover (SCO) properties with respect to the previously reported homoleptic compound [Fe(1bppCOOH)2](ClO4)2. Indeed, the introduction of a new subs…
Spin-crossover compounds based on iron(II) complexes of 2,6-bis(pyrazol-1-yl)pyridine (bpp) functionalized with carboxylic acid and ethyl carboxylic …
2018
International audience; Four new salts of the iron(II) complex of the 2,6-bis(pyrazol-1-yl)pyridine ligand functionalized with a carboxylic acid group (bppCOOH) of formulas [Fe(bppCOOH)2](BF4)2 (1(BF4)2), [Fe(bppCOOH)2](CF3SO3)2·yMe2CO (1(CF3SO3)2·yMe2CO), [Fe(bppCOOH)2](AsF6)2·yMe2CO (1(AsF6)2·yMe2CO) and [Fe(bppCOOH)2](SbF6)2·yMe2CO (1(SbF6)2·yMe2CO) have been prepared and characterized together with a more complete structural and photomagnetic characterization of the previously reported [Fe(bppCOOH)2](ClO4)2 (1(ClO4)2). Furthermore, the iron(II) complex of the ethyl ester derivative of bppCOOH (bppCOOEt) has been prepared and characterized (compound [Fe(bppCOOEt)2](ClO4)2·yMe2CO, 2(ClO4)…
Iron(II) complex of 2-(1H-pyrazol-1-yl)pyridine-4-carboxylic acid (ppCOOH) suitable for surface deposition
2018
The synthesis, structural and magnetic characterization of the tris iron(II) complex of 2-(1H-pyrazol-1-yl)pyridine-4-carboxylic acid (ppCOOH) ligand are reported in [Fe(ppCOOH)3](ClO4)2·0.5H2O·2EtOH. Single crystal structure and magnetic characterization of the bulk compound show that the low-spin state is dominant from 2 to 400 K. ESI-MS and UV–Vis spectroscopy experiments indicate that acetonitrile solutions of this complex are stable with time. ESI-MS confirms the presence of the tris complex in solution. This complex can be deposited onto SiO2 surfaces due to the presence of carboxylic acid groups by immersing the substrates into acetonitrile solutions of the complex. XPS spectra of th…
The First 1,3,4‐Oxadiazole Based Dinuclear Iron(II) Complexes Showing Spin Crossover Behavior with Hysteresis
2015
Three new dinuclear complexes [FeII2(μ-L)2]X4 (L is the bis-tridentate ligand 2,5-bis{[(2-pyridylmethyl)amino]methyl}-1,3,4-oxadiazole and X = ClO4–, BF4– and CF3SO3–) have been synthesized and fully characterized by single-crystal X-ray diffraction, Mossbauer spectroscopy and magnetic susceptibility measurements. Upon cooling, a trapped [high-spin–low-spin] state of the iron(II) centres is detected. Depending on the counterion, a pronounced thermal hysteresis is found. In one case, it was possible to observe a space group change that accompanies the spin transition. This is the first system showing spin crossover based on an oxadiazole ligand.
Strong Cooperative Spin Crossover in 2D and 3D FeII −MI,II HofmannLike Coordination Polymers Based on 2‑Fluoropyrazine
2016
Self-assembling iron(II), 2-fluoropyrazine (Fpz), and [MII(CN)4] 2− (MII = Ni, Pd, Pt) or [AuI (CN)2] − building blocks have afforded a new series of two- (2D) and threedimensional (3D) Hofmann-like spin crossover (SCO) coordination polymers with strong cooperative magnetic, calorimetric, and optical properties. The iron(II) ions, lying on inversion centers, define elongated octahedrons equatorially surrounded by four equivalent centrosymmetric μ4-[MII(CN)4]2− groups. The axial positions are occupied by two terminal Fpz ligands affording significantly corrugated 2D layers {Fe(Fpz)2([MII(CN)4]}. The Pt and Pd derivatives undergo thermal- and light-induced SCO characterized by T1/2 temperatur…
Switchable Spin-Crossover Hofmann-Type 3D Coordination Polymers Based on Tri- and Tetratopic Ligands
2018
[EN] Fe-II spin-crossover (SCO) coordination polymers of the Hofmann type have become an archetypal class of responsive materials. Almost invariably, the construction of their architectures has been based on the use of monotopic and linear ditopic pyridine like ligands. In the search for new Hofmann-type architectures with SCO properties, here we analyze the possibilities of bridging ligands with higher connectivity degree. More precisely, the synthesis and structure of {Fe-II(L-N3)[M-I(CN)(2)](2)}center dot(Guest) (Guest = nitro-benzene, benzonitrile, o-dichlorobenzene; M-I = Ag, Au) and {Fe-II(L-N4)[Ag-2(CN)(3)][Ag(CN)(2)]}center dot H2O are described, where L-N3 and L-N4 are the tritopic…
Spin Transition of 1D, 2D and 3D Iron(II) Complex Polymers The Tug-of-War between Elastic Interaction and a Shock-Absorber Effect
2003
The structures of linear chain Fe(II) spin-crossover compounds of α,β- and α,ω-bis (tetrazol-1-yl)alkane type ligands are described in relation to their magnetic properties. The first threefold interlocked 3-D catenane Fe(II) spin-transition system, [μ-tris(1,4-bis(tetrazol-1-yl)butane-N1,N1′) iron(II)] bis(perchlorate), will be discussed. An analysis is made among the structures and the cooperativity of the spin-crossover behaviour of polynuclear Fe(II) spin-transition materials.
Extrinsicvs.intrinsic luminescence and their interplay with spin crossover in 3D Hofmann-type coordination polymers
2020
The research of new multifunctional materials, as those undergoing spin crossover (SCO) and luminescent properties, is extremely important in the development of further optical and electronic switching devices. As a new step towards this ambitious aim, the coupling of SCO and fluorescence is presented here following two main strategies: whether the fluorescent agent is integrated as a part of the main structure of a 3D SCO coordination polymer {FeII(bpan)[MI(CN)2]2} (bpan = bis(4-pyridyl)anthracene, MI = Ag (FebpanAg), Au (FebpanAu)) or is a guest molecule inserted within the cavities of the 3D switchable framework {FeII(bpb)[MI(CN)2]2}·pyrene (bpb = bis(4-pyridyl)butadiyne, MI = Ag (FebpbA…
The mechanism of the antioxidant effect of smoked paprika from La Vera, Spain
2013
This study aimed at further investigating the antioxidant effect of smoked paprika (Pimenton La Vera, Spain) in healthy subjects. Crossover study included male students (age 20.6 ± 1.7 years) who consumed smoked or non-smoked paprika (2 g/day, 20 times, over 30 days). After ingestion of smoked paprika, plasma malondialdehyde (MDA) levels were significantly (p < 0.01) reduced versus basal and non-smoked paprika ingestion values. Reduced glutathione (GSH) levels were increased and oxidised glutathione (GSSG) levels reduced significantly (p < 0.05) in paired subjects after consumption of smoked paprika. Smoked paprika significantly increased mRNA levels of glutathione peroxidase and cytochrome…