Search results for "Crossover"

showing 10 items of 658 documents

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]2·3CH​3OH·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…

chemistry.chemical_classificationZeeman effect010405 organic chemistryChemistryInorganic chemistrychemistry.chemical_elementCrystal structure010402 general chemistry01 natural sciences0104 chemical scienceslaw.inventionInorganic Chemistrysymbols.namesakelawSpin crossoverMaterials ChemistrysymbolsPhysical chemistryElectron configurationPhysical and Theoretical ChemistryCounterionElectron paramagnetic resonanceCobaltNatural bond orbitalPolyhedron
researchProduct

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…

chemistry.chemical_classificationeducation.field_of_studymedicine.medical_specialtyNutrition and DieteticsMediterranean dietbusiness.industryEndocrinology Diabetes and Metabolismmedicine.medical_treatmentPopulationCrossover studyEndocrinologyAnimal scienceEndocrinologychemistryInternal medicineFibrinolysisSaturated fatty acidmedicineeducationbusinessPlasminogen activatorCompletely randomized designPolyunsaturated fatty acidNutrition Research
researchProduct

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.

chemistry.chemical_compoundCrystallographyHysteresisNuclear magnetic resonanceSpin statesChemistryHydrogen bondSpin crossoverPyridineSpin transitionInfrared spectroscopyCondensed Matter PhysicsSpin (physics)Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
researchProduct

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.

chemistry.chemical_compoundCrystallographySchiff baseMagnetic momentchemistrySpin crossoverStereochemistrySpin transitionHexacoordinateGeneral Physics and AstronomyPhysical and Theoretical ChemistryChemical Physics Letters
researchProduct

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>

chemistry.chemical_compoundThermal hysteresisMaterials scienceCondensed matter physicschemistrySpin crossoverSize dependentSpin transitionTriazoleShell (structure)NanoparticleSpin-½
researchProduct

Bidirectional Chemo-Switching of Spin State in a Microporous Framework

2009

The ins and outs of spin: Using the microporous coordination polymer {Fe(pz)[Pt(CN)(4)]} (1, pz=pyrazine), incorporating spin-crossover subunits, two-directional magnetic chemo-switching is achieved at room temperature. In situ magnetic measurements following guest vapor injection show that most guest molecules transform 1 from the low-spin (LS) state to the high-spin (HS) state, whereas CS(2) uniquely causes the reverse HS-to-LS transition.

chemo-switchingSpin statesPyrazinemicroporous materialsCoordination polymerGeneral ChemistryMicroporous materialCatalysiscoordination polymerschemistry.chemical_compoundCrystallographyspin crossoverchemistrySpin crossoverMoleculeMetal-organic frameworkSpin (physics)metal-organic frameworksAngewandte Chemie International Edition
researchProduct

Magnetic materials based on coordination chemistry: from switching molecules to multifunctional magnets

2021

Esta tesis tiene como objetivo principal la preparación de materiales moleculares multifuncionales magnéticos. Para ello se han usado dos estrategias diferentes: una aproximación iónica, en la que se han preparado sales de cationes funcionales y se han combinado con redes aniónicas extendidas (capítulos 2 y 3); y la segunda estrategia, donde, a través de enlaces covalentes entre ligandos funcionales y fulerenos (capitulo 4), o polioxometalatos (capítulo 5) se han obtenido sistemas que presentan la propiedad de transición de espín con efectos sinérgicos. En el capítulo 2 se presenta la síntesis y caracterización de varios polímeros de coordinación basados en el ligando anilato con cationes i…

coordination polymersspin crossovermagnetismUNESCO::QUÍMICA:QUÍMICA [UNESCO]
researchProduct

Hybrid magnetic materials based on coordination chemistry: from switching magnetic molecules to 2D coordination polymers

2015

El trabajo descrito en esta tesis se encuadra en el ámbito de los materiales moleculares. Presenta varias estrategias para preparar nuevos materiales híbridos multifuncionales. Los complejos de transición de espín (SCO) constituyen uno de los ejemplos más espectaculares de biestabilidad molecular. En estos sistemas, las transiciones entre los estados de bajo espín (LS) y alto espín (HS) pueden estar inducidos por una variedad de estímulos externos (temperatura, presión o radiación electromagnética). Además de los interesantes aspectos fundamentales, este fenómeno es de interés creciente en el área de los materiales funcionales debido a las posibles aplicaciones en sensores, memorias o dispo…

coordination polymersspin-crossoverUNESCO::QUÍMICAcoordination chemistrymultifunctional materials:QUÍMICA [UNESCO]
researchProduct

Crystal structure and magnetic properties of (tris­{4-[1-(2-meth­oxy­eth­yl)imidazol-2-yl]-3-aza­but-3-enyl}amine)­iron(II) bis­(hexa­fluorido­phosph…

2019

The title compound, [Fe(C27H41N10O3)](PF6)2, is an example of an iron(II) spin-crossover compound. In this compound, C⋯F and CH⋯F/O contacts, present between the cations and anions, extend the structure into a three-dimensional supra­molecular network.

crystal structureCrystal structure010402 general chemistry01 natural sciencesMedicinal chemistryIonResearch Communicationslcsh:Chemistrychemistry.chemical_compoundspin crossoverSpin crossoverImidazoleGeneral Materials Scienceta116010405 organic chemistryChemistryspin transitionGeneral ChemistrykompleksiyhdisteetCondensed Matter PhysicsHEXAkidetiedeMagnetic susceptibility3. Good health0104 chemical sciencesBond lengthlcsh:QD1-999Amine gas treatingActa Crystallographica Section E: Crystallographic Communications
researchProduct

Structural, thermal and photomagnetic properties of spin crossover [Fe(bpp)2]2+ salts bearing [Cr(L)(ox)2]- anions

2009

International audience; This paper is divided into two parts: in the first part, the influence of solvate molecules on the magnetic properties of spin crossover salts of [Fe(bpp)(2)][Cr(L)(ox)(2)]ClO(4) x nS (bpp = 2,6-bis(pyrazol-3yl)pyridine; L = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen); ox = oxalate dianion; S = solvent) is analyzed. The second part is devoted to the photomagnetic properties of the previously reported [Fe(bpp)(2)][Cr(L)(ox)(2)](2) family of compounds. The study describes the crystal structure, differential scanning calorimetry (DSC) and magnetic properties of [Fe(bpp)(2)][Cr(bpy)(ox)(2)]ClO(4) x EtOH x 4 H(2)O (1) and [Fe(bpp)(2)][Cr(phen)(ox)(2)]ClO(4) x 1.5 …

education.field_of_study010405 organic chemistryChemistryPopulationCrystal structure[CHIM.MATE]Chemical Sciences/Material chemistry010402 general chemistry01 natural sciencesLIESSTOxalate0104 chemical sciencesInorganic ChemistryCrystallographychemistry.chemical_compoundNuclear magnetic resonanceDifferential scanning calorimetrySpin crossoverPyridineMoleculeeducation
researchProduct