Search results for "spin [structure function]"
showing 10 items of 1132 documents
Spin canting in Re(IV) complexes: magnetic properties of [ReX4(bpym)] ( X = Cl and Br; bpym = 2,2′-bipyrimidine)
2008
The mononuclear complexes [ReCl4(bpym)] (1) and [ReBr4(bpym)] (2) (bpym = 2,2′-bipyrimidine) are weak ferromagnets. Magnetic ordering occurs below 7.0 (1) and 20.0 K (2) and good hysteresis loops are observed for the two compounds at 2.0 K. A spin-canting phenomenon, i.e., a non-strict linearity of the individual spins aligned in an anti-parallel way by intermolecular antiferromagnetic coupling occurring in many Re(IV) complexes, accounts for these magnetic features which are unusual in molecular solids such as 1 and 2.
Pressure effect on temperature induced high-spin–low-spin phase transitions
2002
The effect of hydrostatic pressure on the transition temperature and the hysteresis widths of first-order spin crossover phase transitions is considered in the frame of the mean field theory and on the basis of the scope of recent pressure experiments. Relevant parameters for a qualitative description of the behaviour of spin transition compounds under pressure are derived and analysed.
Towards Large-Scale Steady-State Enhanced Nuclear Magnetization with In Situ Detection
2021
Signal Amplification By Reversible Exchange (SABRE) boosts NMR signals of various nuclei enabling new applications spanning from magnetic resonance imaging to analytical chemistry and fundamental physics. SABRE is especially well positioned for continuous generation of enhanced magnetization on a large scale, however, several challenges need to be addressed for accomplishing this goal. Specifically, SABRE requires (i) a specialized catalyst capable of reversible H2 activation and (ii) physical transfer of the sample from the point of magnetization generation to the point of detection (e.g., a high-field or a benchtop NMR spectrometer). Moreover, (iii) continuous parahydrogen bubbling accele…
Polymer/metal hybrid multilayers modified Schottky devices
2013
Insulating, polymethylmethacrylate (PMMA), and semiconducting, poly(3-hexylthiophene) (P3HT), nanometer thick polymers/Au nanoparticles based hybrid multilayers (HyMLs) were fabricated on p-Si single-crystal substrate. An iterative method, which involves, respectively, spin-coating (PMMA and P3HT deposition) and sputtering (Au nanoparticles deposition) techniques to prepare Au/HyMLs/p-Si Schottky device, was used. The barrier height and the ideality factor of the Au/HyMLs/p-Si Schottky devices were investigated by current-voltage measurements in the thickness range of 1-5 bilayers. It was observed that the barrier height of such hybrid layered systems can be tuned as a function of bilayers …
Innovazione e Imprenditorialità. Il ruolo degli spin-off universitari.
2013
Oggi il ruolo delle Università non si limita più soltanto alle tradizionali attività di formazione e di ricerca. La cosiddetta Seconda Rivoluzione Accademica ha attribuito alle Università una "terza missione", che consiste nella valorizzazione e commercializzazione della conoscenza accedemica sul mercato. L'Università diviene così "entrepreneurial university" creando valore non solo in termini di conoscenza ma anche di innovazione e sviluppo economico. Il libro intende approfondire il ruolo che le Università rivestono nel processo di trasferimento di conoscenza innovativa al mercato tramite la costituzione di imprese spin-off. Viene evidenziato come, attraverso il supporto di apposite strut…
Synthesis, crystal structure and magnetic properties of the spin crossover system [Fe(pq)3]2+
2008
Abstract Three new compounds formulated (ClO4)2[Fe(pq)3] (1), (BF4)2[Fe(pq)3] · EtOH (2) and {(ClO4)[MnCr(C2O4)3][Fe(pq)2(H2O)2]} (3), where pq is 2,2′-pyridylquinoline, have been synthesised and characterised. Despite the different crystal packing exhibited by 1 and 2, the cationic species [Fe(pq)3]2+ are structurally quite similar. At 293 K, the Fe–N bond lengths are characteristic of the iron(II) in the high-spin state. In contrast to 1, 2 undergoes a continuous spin transition. Indeed, at 95 K its structure experiences a noticeable change in the Fe–N bonds and angles, i.e. the Fe–N bonds shorten by 0.194 A on the average. The magnetic behaviour confirms that 1 is fully high-spin in the …
Spin crossover in iron(II) complexes: Recent advances
2009
In this review article, several representative multifunctional SCO materials exhibiting interplay/synergy between the spin transition and magnetic coupling or liquid crystalline properties together with the present pioneering works on nano-structuration of SCO materials are illustrated. As the Mossbauer spectroscopy has been decisive in the study of the physical properties of these multifunctional materials, special attention is given to their corresponding Mossbauer investigations.
Tuning the spin crossover above room temperature: iron(II) complexes of substituted and deprotonated 2,6-bis(benzimidazol-2-yl)pyridine
2005
Abstract The complex [Fe(tzimpy)2](ClO4)2 · 2H2O (tzimpy = 2,4,6-tris-(benzimidazol-2-yl)pyridine) shows an abrupt spin crossover (S = 0–2 transition) above room temperature centered at Tc = 323 K with a hysteresis width of ΔT = 35 K. The neutral iron(II) complex with deprotonated bzimpy ligands (bzimpy = 2,6-bis(benzimidazol-2-yl)pyridine) exhibits a gradual spin transition on the first heating with Tc = 424 K. There are irreversible changes between T = 503 and 523 K: the liberation of the crystal water, the color change (blue–green) followed by a structure change. Next thermal cycles are reproducible though, heating/cooling paths are different from the first heating.
Pressure Effect Investigations on the Spin Crossover Systems{Fe[H 2 B(pz) 2 ] 2 (bipy)} and {Fe[H 2 B(pz) 2 ] 2 (phen)}
2006
Pressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa–1.02 GPa at variable temperatures (100–310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Spin‐Crossover 2D Metal–Organic Frameworks with a Redox‐Active Ligand: [Fe(ttf‐adpy) 2 M(CN) 4 ]· n H 2 O (ttf‐adpy = 4‐Tetrathiafulvalenylcarboxamid…
2008
A new ttf (tetrathiofulvalene) ligand containing an amidopyridine moiety was synthesized and characterized. The electrochemical study of the 4-tetrathiofulvalenylcarboxamidopyridine (ttf–adpy) ligand showed two reversible oxidation processes at EI′1/2 = 0.08 V/Fc+–Fc and EII′1/2 = 0.26 V/Fc+–Fc. The crystal structure of [(ttf–adpyH)2Pt(CN)4] (1) was solved at 293 K, where 1 displays the triclinic space group P. The ttf–adpyH+ molecule is planar, and the bond lengths within the ttf core are in the usual range for neutral ttf moieties. The ttf–adpyH+ molecules and the [Pt(CN)4]2– anions organize in a three-dimensional network by means of hydrogen bonds and short S···S contacts. In the network…