Search results for "C.M.M."
showing 10 items of 1066 documents
Single-ion magnet behaviour in mononuclear and two-dimensional dicyanamide-containing cobalt(ii) complexes.
2016
Three cobalt(II) complexes of formulae [Co(dca)2(bim)4] (1), [Co(dca)2(bim)2]n (2) and [Co(dca)2(bmim)2]n (3) [dca = dicyanamide, bim = 1-benzylimidazole and bmim = 1-benzyl-2-methylimidazole] were prepared and structurally analyzed by single-crystal X-ray crystallography. Compound 1 is a mononuclear species where the cobalt(II) ion is six-coordinate with four bim molecules in the equatorial positions [Co–Nbim = 2.1546(15) and 2.1489(15) A] and two trans-positioned dca ligands [Co–Ndca = 2.1575(18) A] in the axial sites of a somewhat distorted octahedral surrounding. The structures of 2 and 3 consist of two-dimensional grids of cobalt(II) ions where each metal atom is linked to the other fo…
EPR and Magnetic Susceptibility Studies of Cobalt(II)- and Nickel(II)-Substituted Azurins from Pseudomonas aeruginosa. Electronic Structure of the Ac…
1996
The electronic properties of cobalt(II)- and nickel(II)-substituted azurins from Pseudomonas aeruginosa have been investigated. EPR data for the cobalt derivative and paramagnetic susceptibility data for the nickel derivative are reported. The EPR spectrum of Co(II)−azurin shows the typical pattern of a Kramers' doublet (±1/2) associated with an S = 3/2 ground state in a distorted axial symmetry environment. The temperature dependence of the EPR intensities shows that this Kramers' doublet is the excited doublet and, therefore, that the corresponding zero-field splitting parameter D is negative (∼−3.5 cm-1). The mean g value is equal to 2.3. Nickel(II) azurin exhibits an effective magnetic …
Dysprosium-Based Ionic Liquid Crystals: Thermal, Structural, Photo- and Magnetophysical Properties
2009
[C12mim]3[DyBr6] (C12mim = 1-dodecyl-3-methylimidazolium) represents a new material with interesting luminescent behavior as well as mesomorphic and magnetic properties. The compound was found to show thermotropic liquid crystalline behavior and forms smectic mesophases which were investigated by hot-stage polarizing optical microscopy and differential scanning calorimetry. The emission color of [C12mim]3[DyBr6] can be tuned from white to orange-yellow by the choice of the excitation wavelength. Sample excitation with λex = 366 nm leads to the blue-whitish luminescence from the imidazolium cation itself. With λex = 254 nm the common Dy(III) emission is observed which mainly arises from the …
Synthesis and magnetic characterization of trans-dichloroplatinum blues with creatinine
1992
Abstract By reaction of trans -[Pt II Cl 4 ] 2− with the amidate ligand creatinine two new paramagnetic blue platinum complexes have been obtained, namely violet and green varieties. These complexes have been characterized from thermal analysis, EPR and magnetic susceptibility. The violet complex has been formulated as trans -[Pt(creat)(H 2 O)Cl] 4 Cl. This compound has shown to be very stable, showing an extensive hyperfine structure in the powder EPR spectra. This result is a clear evidence of a tetranuclear oligomeric structure with one delocalized unpaired spin in the unit. EPR spectra in frozen solutions indicate that this mixed-valence complex maintains its oligomeric structure upon d…
S29i attribution of the 1.3 mT hyperfine structure of the E′γ centers in amorphous SiO2
2009
We report an experimental investigation by electron paramagnetic resonance of the doublet of lines split by ∼1.3 mT and centered on the E′γ; center resonance line in the spectrum of irradiated amorphous SiO2 . Commercial and sol-gel materials, some of which subjected to hydrogen-deuterium exchange, were investigated. Exposure to γ or Β rays at room temperature of the samples and subsequent thermal treatments were carried out to induce the defects and to study their thermal stability. In all the materials used the ratio between the signal of the E′γ centers and that of the 1.3 mT doublet is constant and independent of the OH and OD contents. Furthermore, the 1.3 mT doublet and the E′γ center…
Hybrid functional study of structural, electronic and magnetic properties of S-doped ZnO with and without neutral vacancy
2013
Abstract The structural and electronic properties of S-doped ZnO are investigated by density functional theory (DFT) and empirical pseudopotential method (EPM). Using the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional with an adjusted mixing coefficient α , we obtain a good agreement on lattice parameters and band gap energy with the available experimental data. We have also investigate the Zn-vacancy effects on the electronic and magnetic properties of S-doped ZnO. Our calculations demonstrate that S impurity prefers to be close to the cation vacancy in the apical position. The magnetic analysis with the HSE functional shows a triplet state character with a total magnetic moment of 1.81 μ…
Uncompensated magnetization in the layered molecular antiferromagnet {N(n-C5H11)4[MnIIFeIII(ox)3]}∞
2009
Abstract Studies on the magnetic properties of the molecular antiferromagnetic material {N( n -C 5 H 11 ) 4 [Mn II Fe III (ox) 3 ]} ∞ , carried out by various physical techniques (AC/DC magnetic susceptibility, magnetization, heat capacity measurements and Mossbauer spectroscopy) at low temperatures, have been presented. Different experimental observations complement each other and provide a clue for the observation of an uncompensated magnetization below the Neel temperature and short-range correlations persisting high above T N . It is understood that the honeycomb layered structure of the compound contains non-equivalent magnetic sub-lattices, (Mn II –ox–Fe III A –...) and (Mn II –ox–Fe …
Co2CrIn: A further magnetic Heusler compound
2006
Summary and Outlook In summary, this work presents the synthesis andcharacterisation of the Heusler compound Co 2 CrIn.The compound is L2 1 ordered and shows no major an-tisite disorder. Co 2 CrIn turns out to be a ferrimagnetwith a magnetic moment of 1.18 µ B at 5 K. In addi-tion, the hysterisis curve reveals a soft magnetic be-haviour. A measurement of the site specific magneticmomentsis highlydesirableas it might leadto a deeperunderstanding of the magnetic properties of Co 2 CrIn.Furthermore, the measured magnetic moment is not aninteger number, as expected for a half-metallic ferro-magnet. Thus, Co 2 CrIn can not be a half-metallic fer-romagnet, as most of the other Co 2 YZ Heusler com-…
The Properties of Co2Cr1-xFexAl Heusler Compounds
2006
The classical concept of band structure tuning as used for semiconductors by partly replacing one atom by a chemical neighbor without altering the structure is applied examplarily to the half-metallic ferromagnetic Heusler compound Co 2 Cr 1 - x Fe x Al. Band structure calculations are presented for ordered and disordered compounds. We present experimental and theoretical results. The connection between specific site disorder and the band structure is shown explicitly with particular emphasis on the half-metallic properties. Experimentally observed deviations from the ideal Heusler structure and from the simple Slater-Pauling rule for the magnetization are discussed in close relation to the…
First Cobalt(II) Spin Crossover Compound with N4S2-Donorset
2020
Herein we report the synthesis and characterization of a novel bis-tridentate 1,3,4-thiadiazole ligand (L = 2,5-bis[(2-pyridylmethyl)thio]methyl-1,3,4-thiadiazole). Two new mononuclear complexes of the type [MII(L)2](ClO4)2 (with M = FeII (C1) and CoII (C2)) have been synthesized, containing the new ligand (L). In both complexes the metal centers are coordinated by an N4S2-donorset and each of the two ligands is donating to the metal ion with just one of the tridentate pockets. The iron(II) complex (C1) is in the low spin [LS] state below room temperature and shows an increase in the magnetic moment only above 300 K. In contrast, the cobalt(II) complex (C2) shows a gradual spin crossover (S…