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A novel nitronyl nitroxide NIT-thien-3-Py (2-(3-(m-pyridyl)-2-thienyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) and its Mn(II) complex [Mn(hfac)2(NIT-thien-3-Py)]2 (hfac = hexafluoroacetylacetonate) have been obtained. X-ray analysis indicates that the Mn(II) complex possesses a cyclic dimer structure in which two radical ligands link two Mn(II) ions through their NO groups and pyridine rings. The study of the magnetic data indicates that the manganese(II) ion strongly and antiferromagnetically interacts with the directly bonding NO group and there is weak ferromagnetic coupling between two Mn–NO pairs through the thiophene and pyridine rings of the radical ligand in agreement with a spin polarization mechanism. [ABSTRACT FROM AUTHOR]

By assembling CoII ions and a combination of 5-(4-pyridyl)tetrazole (4-ptz) and formate ions, two distinct metal-organic frameworks, [Co3(4-ptz)5(HCOO)(H2O)2] and [Co3(4-ptz)4(dmf)2(HCOO)2 ] (dmf= N, N′-dimethylformamide), were synthesized. They were both characterized by single-crystal X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction. Structural analyses revealed that by slightly modulating the coordination environment of the trinuclear cobalt cluster, two complexes were formed featuring unusual six-connected nets reminiscent of a pyrazole-type linear trinuclear cobalt cluster as compared with the classic eight-connected bcu topology. In addition, [Co3(4-ptz)5(HCOO)(H2O)2] interacted strongly with CO2, with an adsorption enthalpy of 29.2 kJ mol−1, and in a selectivity study, the uptake ratios of CO2/N2 (from a 15:85 mixture) and CO2/CH4 (50:50 mixture) were 77.6 and 37.7, respectively. Magnetic studies on both complexes revealed weak antiferromagnetic coupling between the CoII ions. [ABSTRACT FROM AUTHOR]

Observations of lamellar like fringes in iron-carbon-filled vertically aligned carbon nanotubes (CNTs) produced by pyrolysis of ferrocene and rapid cooling methodologies (controlled quenching) have been investigated. The quantitative phase analysis of encapsulated Fe3C, γ-Fe, and α-Fe by X-ray diffraction reveals that controlling the phase-percentage leads to control of the crystal habit and of magnetic properties. Large coercivities and variable saturation magnetizations were observed. In addition, we reported a thorough study of the hysteresis behavior, the Barkhausen effect which has to be possibly associated with the formation of interfacial-defects in the crystal areas in contact with CNT layers. [ABSTRACT FROM AUTHOR]

In this work a flexible multi-dentate 1-(4-aminobenzyl)-1,2,4-triazole (abtz) ligand has been employed, two novel triazole-Cu(II) coordination polymers {[Cu(abtz) 2 (Br) 2 ]·(H 2 O) 2 } n ( 1 ) and {[Cu(abtz) 2 ]·(SiF 6 )·(H 2 O) 2 } n ( 2 ) have been isolated under solvo-thermal conditions. 1 is a 2D neutral Cu II coordination polymer while 2 is 2D cation micro-porous Cu II coordination polymer with the channel dimensionalities of 11.852(1) Å × 11.852(1) Å (metal-metal distances). Variable-temperature magnetic susceptibility data of 1 and 2 have been recorded in the 2–300 K temperature range indicating weak anti-ferromagnetic interactions. Further absorption properties of anion pollutants for 2 also have been investigated. 2 presents the novel example of cationic triazole-copper(II) coordination framework for effectively capturing anion pollutants Cr 2 O 7 2− in the water solutions and selectively capturing Congo Red in the methanol solutions. [ABSTRACT FROM AUTHOR]

X-ray diffraction (XRD) analysis showed that metal oxide peaks appear at 2θ = 47.7°, 54.5°, and 56.3°, corresponding to Yb2O3 (440), Co2O3 (422), and Co2O3 (511). It was found that oxide formation plays an important role in magnetic, electrical, and surface energy. For magnetic and electrical measurements, the highest alternating current magnetic susceptibility (χac) and the lowest resistivity (×10−2 Ω·cm) were 0.213 and 0.42, respectively, and at 50 nm, it annealed at 300 °C due to weak oxide formation. For mechanical measurement, the highest value of hardness was 15.93 GPa at 200 °C in a 50 nm thick film. When the thickness increased from 10 to 50 nm, the hardness and Young's modulus of the Co60Fe20Yb20 film also showed a saturation trend. After annealing at 300 °C, Co60Fe20Yb20 films of 40 nm thickness showed the highest surface energy. Higher surface energy indicated stronger adhesion, allowing for the formation of multilayer thin films. The optimal condition was found to be 50 nm with annealing at 300 °C due to high χac, strong adhesion, high nano-mechanical properties, and low resistivity. [ABSTRACT FROM AUTHOR]

Here we report the structure, electrical and magnetic properties of polycrystalline Ba(Mn 1 − x Cr x) 2 As 2 (x =0.0-0.1) and Ba 0.8 K 0.2 (Mn 1 − x Cr x) 2 As 2 (x =0.0-0.4). Upon the substitution of Cr for Mn in BaMn 2 As 2 semiconductor, it is found that the resistivity can be substantially decreased by five orders in magnitude without changing the structural symmetry. The XPS and Hall measurements demonstrate that the valence of doped Cr is +3 instead of expected Cr2＋, which can effectively introduce electron carriers. Meanwhile, a magnetic transition shows up at ∼ 40 K with small saturated moment of M sat =0.02 μ B /Mn(Cr) and a low coercive field of H c =135 Oe. The transition may originate from the change in spin re-orientation from ideal AFM to canted AFM state. For p -type AFM metal Ba 0.8 K 0.2 Mn 2 As 2 , doping Cr3＋ equivalently provides electrons to compensate the holes, leading to a metal–semiconductor transition and a similar canted AFM state. Our results demonstrate that majority carriers, resistivity and magnetism in BaMn 2 As 2 can be controlled through relatively low levels of Cr3＋ doping. • Cr of +3 valance serves as a strong electron donor. • Light doping of Cr3＋ changes the resistivity by five orders in magnitude. • Cr3＋ substitution induces a canted transition in magnetism at low temperature. [ABSTRACT FROM AUTHOR]

Based on the bis-triazole ligand 2, 6-bis(1, 2,4-triazole-4-yl)pyridine (L), the triazole-iron(II) complexes [Fe(L)2(dca)2(H2O)2] ·2H2O ( 1) (Nadca = sodium dicyanamide), {[Fe(μ2-L)2(H2O)2]Cl2} n ( 2), and {[Fe(μ2-L)2(H2O)2](ClO4)2 ·L ·H2O} n ( 3) were isolated by solvent diffusion methods. When iron(II) salts and Nadca were used, compound 1 was isolated, which contains mononuclear Fe(L)2(dca)2(H2O)2 units. When FeCl2 or FeClO4 were used, one-dimensional (1D) cation iron(II) chains ( 2) and two-dimensional (2D) cation iron(II) networks ( 3) were isolated indicating anion directing structural diversity. Moreover, variable-temperature magnetic susceptibility data of 1- 3 were recorded in the temperature range 2-300 K. The magnetic curve of complex 2 was fitted by using the classical spin Heisenberg chain model indicating anti-ferromagnetic interactions ( J = -5.31 cm-1). Obviously complexes 1- 3 show no detectable thermal spin crossover behaviors, the lack of spin-crossover behavior may be correlated with FeN4O2 coordination spheres in 1- 3. [ABSTRACT FROM AUTHOR]