Search results for "osso"
showing 10 items of 801 documents
Anisotropic Effect after Stretching of the Spin-Crossover Compound [Fe(II)(2,6-bis-(benzimidazol-2′-yl)pyridine)2] (C1O4)2 in Polyvinylalcohol Polyme…
1999
Abstract [Fe(II)(2,6-bis-(benzimidazol-2′-yl)-pyridine)2](C1O4)2 diffused into a poly(vinyl)alcohol polymer matrix, exhibits an thermally induced spin-crossover. After stretching the matrix, the compound orients itself in the matrix. Polarised UV/VIS spectra measured parallel and perpendicular to the stretching direction allowed to calculate the distortion of the molecule in the matrix by means of semi-empirical PPP SCF-CI calculations.
Bistable Hofmann-Type FeII Spin-Crossover Two-Dimensional Polymers of 4-Alkyldisulfanylpyridine for Prospective Grafting of Monolayers on Metallic Su…
2021
Aiming at investigating the suitability of Hofmann-type two-dimensional (2D) coordination polymers {FeII(Lax)2[MII(CN)4]} to be processed as single monolayers and probed as spin crossover (SCO) junctions in spintronic devices, the synthesis and characterization of the MII derivatives (MII = Pd and Pt) with sulfur-rich axial ligands (Lax = 4-methyl- and 4-ethyl-disulfanylpyridine) have been conducted. The thermal dependence of the magnetic and calorimetric properties confirmed the occurrence of strong cooperative SCO behavior in the temperature interval of 100-225 K, featuring hysteresis loops 44 and 32.5 K/21 K wide for PtII-methyl and PtII/PdII-ethyl derivatives, while the PdII-methyl deri…
Pressure effect studies in molecular magnetism
2004
We report on temperature dependent magnetic susceptibility and Mossbauer effect studies of the influence of hydrostatic pressure (up to 1.2 GPa) on dynamic electronic structure phenomena in 3d transition metal coordination compounds. The systems under investigation are mononuclear spin crossover compounds of iron (II) and chromium (II), dinuclear complexes of iron (II) exhibiting coexistence of intramolecular antiferromagnetic coupling and thermal spin crossover, 1D, 2D and 3D polynuclear spin crossover complexes of iron (II), a valence tautomeric system of cobalt (II) showing a thermal transition from a high spin [CoII (semiquinone)] to a low spin [CoII (catecholate)] species on lowering t…
Molecular magnetism, quo vadis? A historical perspective from a coordination chemist viewpoint☆
2017
Abstract Molecular magnetism has travelled a long way from the pioneering studies on electron exchange and double exchange or spin crossover and valence tautomerism in small oligonuclear complexes, from mono- to di- and tetranuclear species, to the current investigations about magnetic anisotropy and spin dynamics or quantum coherence of simple mono- or large polynuclear complexes, behaving as switchable bistable molecular nanomagnets for potential applications in information data storage and processing. In this review, we focus on the origin and development of the research in the field of molecular magnetism from a coordination chemistry viewpoint, which dates back to the establishment of …
Oxotris(oxalato)niobate(V) as counterion in cobalt(II) spin-crossover systems
2016
Abstract This work is devoted to the investigation of the thermally induced spin-crossover behavior from a high-spin state (HS, S = 3/2) at higher temperatures to a low-spin phase (LS, S = 1/2) at lower temperatures of the six-coordinate cobalt(II) complex in the compound [Co(terpy)2]3[NbO(C2O4)3]2·3CH3OH·4H2O (2). The crystal structure of 2 together with that of its counterion as tetraphenylarsonium(V) salt (AsPh4)3[NbO(C2O4)3]·9H2O (1) are also included. The spin-crossover process was followed by the thermal variation of the χMT product between 2.0 and 400 K under the warming mode, with the LS configuration being achieved at T ⩽ 200 K and the LS → HS interconversion being incomplete at 4…
Acetogenins from Annona glabra seeds
1998
Abstract From the cytotoxic ethanol extract of Annona glabra seeds, a new mono-tetrahydrofuranic (mono-THF) acetogenin, glabranin, as well as pair of 22-epimer bis-THF acetogenins, were isolated by semipreparative HPLC. Four known mono-THF acetogenins with an identical threo/trans/threo relative configuration, annonacin, annonacinone, corossolin and corossolone, were found to be potent inhibitors of complex I of the mitochondrial respiratory chain.
Cross-over study on effects of Mediterranean diet in two randomly selected population samples
2003
Abstract Two randomly selected population samples in Western Sicily, one rural (n = 40) and one urban (n = 40), were studied to evaluate the impact of dietary intervention on lipid, coagulative and fibrinolytic parameters. The two groups received the diets in a cross-over design with the following sequences: (a) baseline period; (b) 8-week dietary intervention period; (c) 8-week return to the original diet. During (a) and (c) all subjects consumed their usual diet. During the dietary intervention period (b), the rural sample consumed the urban sample's diet, while the urban sample consumed the rural sample's diet (the so-called “Mediterranean diet”). At baseline, after 8 weeks' dietary inte…
Spin-Transition in [Fe(II)(2,6-Bis-(Benzimidazol-2′-yl)pyridine)2] (CIO4)2: Hysteresis Effect Dependent on the Matrix
1999
Abstract Far-Infrared spectroscopical investigation of the spin-crossover in [Fe(II)(2,6-bis-(benzimidazol-2′-yl)-pyridine)2] (CIO4)2 exhibits a hysteresis in both CsI and polyethylene matrices within temperature cycles between 100K and 520K. The hysteresis broadening is dependent on the matrix and bigger in CsI. This can be explained due to polarity and hydrogen bonding. Two low spin vibrations, LS1 at 437 cm−1 and LS2 at 424cm−1, are observed. On heating from 100K to 520K: during LS1 decreases, the LS2 raises temporarily, until both LS1 and LS2 disappear; for the HS only one raising species was observed. This gives raise to assume two different sub-lattices.
Spin crossover in mononuclear and binuclear iron(III) complexes with pentadentate Schiff-base ligands
2000
Abstract A series of mononuclear hexacoordinate iron(III) complexes, [Fe( 5 L )(py)]BPh 4 , and binuclear hexacoordinate iron(III) complexes, [( 5 L )Fe(μ 2 -bpy)Fe( 5 L )](BPh 4 ) 2 , has been prepared and their magnetic properties were investigated; the pentadentate ligands were derivatives of 5 L =saldptn=N,N′-bis(2-hydroxybenzyliden)-1,7-diamino-4-azaheptane. Temperature variation of the effective magnetic moment for them shows that a spin transition from the low-spin to the high-spin state occurs. The magnetic data were fitted to an Ising-like model appropriate for the mono- and binuclear systems.
Size-Dependent Spin Switching in Robust Fe-triazole@SiO2 Spin-Crossover Nanoparticles with Ultrathin Shell
2019
<p>A familly of chemically robust hybrid [Fe(Htrz)2(trz)](BF4)@SiO2nanoparticles (NPs) presenting different sizes (from ca. 90 to 28 nm) and an ultrathin silica shell (< 3 nm) have been prepared. All NPs present a characteristic abrupt spin transition with a subsequent decrease in the width of the thermal hysteresis upon reducing the NP size.<br></p>