A spin-crossover catecholato–iron(III) system: Synthesis,crystal structure and magnetic properties

A new mononuclear Fe(III)–catecholate complex, which exhibits an incomplete spin transition without hysteresis, had been synthesized and structurally characterized. Analyzed from the structural characteristics, the tripodal ligand must play the important role in affecting the spin crossover (SCO) behavior. The larger steric strain effect and weak cooperativity existed in the crystal lattice are inclined to favor the incomplete transition.     

Hydrothermal synthesis,crystal structure and magnetic properties of a novel nickel carboxylate–phosphonate with a layered structure

Hydrothermal reactions of N-(phosphonomethyl)proline (H₃L) with nickel sulfate hexahydrate resulted in a novel nickel carboxylate–phosphonate: |H₂O|[Ni₃(O₃PCH₂–NC₄H₇–CO₂)₂(H₂O)₄] (complex 1). Single-crystal X-ray diffraction analysis revealed that complex 1 crystallizes in the triclinic space group P-1 (No. 2), with lattice parameters of a = 10.0167(5) Å, b = 10.3882(5) Å, c = 11.9528(5) Å, α = 90.132(3)°, β = 107.246(3)°, γ = 111.158(3)°, V = 1099.39(9) Å³, and Z = 2. Complex 1 features a 2D layered structure. The structure contains alternating Ni-centered octahedra (Ni(1)O₆, Ni(2)O₅N and Ni(3)O₅N) and O₃PC tetrahedra linked to construct a layer with rhombohedral 12-MRs holes. The cyclopentylamine moieties of H₃L were grafted onto the layer through coordination of CPO₃, CO₂ and (CH₂)₂NCH₂ with central nickel atoms. These layers are stacked in an AA sequence, which results in a one-dimensional channel in the [001] direction. Water molecules are located in these channels. Magnetic studies showed that complex 1 exhibits predominantly paramagnetic behavior.     

Synthesis,crystal structure and magnetic properties of a new 2D cyanide-bridged heterobimetallic Cr(I)–Mn(III) complex

A new two-dimensional cyanide-bridged Cr(I)–Mn(III) coordination polymer {K[Mn(L)]₂[Cr(CN)₅NO]}·CH₃CN (1) (L = N,N-ethylene-bis(3-methoxysalicylideneiminate)) has been successfully synthesized by the reaction of K₃[Cr(CN)₅NO] with [Mn(L)(H₂O)₂]ClO₄ and characterized by elemental analysis, FT-IR and X-ray structure determination. Investigation systematic over magnetic susceptibility of the complex reveals the overall antiferromagnetic interaction between the cyanide-bridged Cr(I) ion and Mn(III) ion and its 3D antiferromagnetic ordering behavior with typical metamagnetic character below 12.5 K.     

Hydrothermal synthesis, crystal structure and properties of complex [Co (odpa) (phen) 2 ( H2O )] · H2O

以4,4’-氧化二苯四羧酸二酐和1,10-邻菲啰啉为配体在水热条件下合成了标题配合物,并用元素分析、红外光谱、X-射线单晶衍射以及热重分析对配合物进行了表征.晶体结构分析表明配合物为三斜晶系,P-1空间群a=11.190(2)(A),b=12.587(2) (A),c=13.097(3)(A),α=102.688(3)°,β=105.751(2)°,γ =92.615(2)°,V =1721.1(6)A3,Z=2.配合物为单核结构,相邻的单核分子通过氢键的识别作用形成一维超分子双链.π…π堆积作用和C-H…π之间弱相互作用将邻近超分子双链的进一步扩展为三维超分子结构.     

A tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline: Synthesis,structural, and magnetic properties

A new tetranuclear pyrophosphate-bridged Cu(II) complex with 4,4′-bipyridine and 1,10-phenanthroline [Cu₄(phen)₄(bpy)₂(P₂O₇)₂]·10H₂O (1) has been hydrothermal synthesized and characterized by single-crystal X-ray analysis, element analysis, IR spectroscopy, TG analysis, and UV–vis spectra. Variable-temperature magnetic susceptibility measurements show the occurrence of antiferromagnetic interactions between the neighbor Cu(II) centers in 1. The analysis of the magnetic data in the whole temperature range allows the determination of the value of the intramolecular magnetic coupling (J = − 13.16 cm^− 1).     

The first macrocyclic “layer-to-layer” type tetranuclear copper(II) complex: structure,stability and unprecedented catalase-like activity

The macrocyclic tetranuclear copper(II) complex [L₂Cu₄(μ-CO₃)₂](ClO₄)₄·4H₂O is synthesized by [2 + 2] condensation of the organic ligand L and a rational [2 + 2] assembly of the polynuclear complex; the structure, stability and catalase-like activity are investigated.     

Hydrothermal synthesis,crystal structure,spectroscopy, electrochemistry and antimycobacterial evaluation of the copper (II) ciprofloxacin complex: [Cu(cf)2(BF4)2]·6H2O

The hydrothermal reaction of ciprofloxacin (1) with Cu(BF₄)₂·6H₂O yields a copper complex having a molecular formula, [Cu(cf)₂(BF₄)₂]·6H₂O (cf = ciprofloxacin), which is characterized by spectroscopic and electrochemical measurements as well as single crystal X-ray studies [a=9.1079(13), b=9.6112(16), c=11.4542(18) Å, α=90.518 (19)°, β=99.160 (18)°, γ=93.315 (19)°, P1bar, Z=1]. The F₂O₄ donor atom set forms a (4+2) distorted octahedral geometry around the central copper atom; which has a highly facile copper redox couple (+0.23 V). The copper conjugate exhibits a significant enhancement in the antitubercular activity probably arising out of its rapid intracellular reduction leading to oxygen activation, which is detrimental to the mycobacteria.     

Three lanthanide–nitronyl nitroxide complexes: Syntheses,crystal structures and magnetic properties

Three rare earth–nitronyl nitroxide radical complexes [Ln(hfac)₃(NIT-1′-MeBzIm)] (Ln(III) = Gd 1, Tb 2, Dy 3; hfac = hexafluoroacetylacetonate; NIT-1′-MeBzIm = 2-{2′-[(l′-methyl)-benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been successfully prepared and structurally characterized. X-ray crystallographic analysis reveals that all the three complexes are isomorphous. The center lanthanide(III) ions are eight-coordinated to one NIT-1′-MeBzIm and three hexafluoroacetylacetonate ligands. The NIT-1′-MeBzIm acts as a bidentate ligand via its nitrogen atom of the imidazole ring and the oxygen atom of the N–O group. The magnetic properties of complexes 1, 2 and 3 were studied. All of them exhibit ferromagnetic interaction. AC magnetic susceptibility studies show that Tb complex displays frequency-dependent signals at low temperature suggesting that it behaves as SMM.     

A new μ1,5-dicyanamide bridged cyclic tetranuclear copper (II) complex with 1,5,9-triazacycledodecane ligands: structure,ESR spectroscopic and magnetic properties

The tetranuclear complex [Cu₂L₂(dca)₂(ClO₄)₂]₂ (1) (L = 1,5,9-triazacyclododecane, dca = dicyanamide [N(CN)₂]⁻) has been synthesized and its crystal structure, ESR spectra and magnetic properties determined. The complex contains a tetranuclear copper (II) moiety in which two dimeric units are bridged by two dca ligands. In each dimeric moiety the two copper (II) ions are bridged by one μ_1,5-dicyanamide ligand. Magnetic susceptibilities for the complex in the solid state are measured over the temperature range 4–300 K. The complex shows a weak antiferromagnetic coupling with a best fit J value −0.436 cm⁻¹. The μ_1,5-dicyanamide bridges are the principal pathway for the super-exchange interaction and the weak antiferromagnetic coupling of the complex is interpreted in term of the μ_1,5-dicyanamide ligand behavior as a poor magnetic mediator.     

Palladium(II) thiosemicarbazone complex: Synthesis,structure and application to carbon–oxygen cross-coupling reaction

A simple route for the synthesis of square-planar palladium(II) 3-methyl-thiophene-2-aldehyde thiosemicarbazone complex is described. The composition of the complex has been established by elemental analysis and spectral methods. The molecular structure was confirmed by single crystal X-ray diffraction study. Further, the complex was used as a potential catalyst for the carbon–oxygen cross-coupling reaction of activating, non-activating and deactivating aryl iodides or aryl bromides with p-cresol.     

Rietveld refined crystal structure,magnetic, dielectric,and electric properties of Li- substituted Ni–Cu–Zn ferrite and Sm,Dy co-doped BaTiO3 multiferroic composites

The conventional solid-state reaction technique is used to fabricate the multiferroic xLi_0.1Ni_0.3Cu_0.1Zn_0.4Fe_2.1O₄(LNCZFO)+(1-x)Ba_0.95Sm_0.05Ti_0.95Dy_0.05O₃(BSTDO) composites. To determine the ferrite and ferroelectric phases, the Rietveld refinement analysis is used. The excellent fit of experimental diffraction data is confirmed by the low values of reliability factors and the goodness of fit index, and so the crystal structure is perfect. Increasing the LNCZFO phase in the composites causes the formation of more ferrite grains and enhancement of magnetization values. The anisotropy field varies due to compressive stress created by a lattice mismatch between the BSTDO and LNCZFO phases. The dielectric peak shifts to higher temperatures as the ferrite phase increases, indicating that magnetoelectric interaction between the constituent phases exists in composites. At 100 kHz, the diffuseness exponent ranged from 1.01 to 1.79, indicating that a diffuse phase transition (DPT) occurred for some composites. As the ferrite content increases, the DPT effect decreases, resulting a narrower dielectric peak. The small polaron hopping mechanism is responsible for electrical conduction, which followed Jonscher's power law. The magnitude of the angular frequency exponent factor increases with frequency, indicating an increase in charge carrier mobility from long to short range.     

New dinuclear cobalt (ΙΙ, ΙΙΙ) and tetranuclear manganese (ΙΙΙ) complexes assembled by a polydentate Schiff-base ligand: synthesis,structure and magnetic properties

The reactions of 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol (H₄L) and Mn(ClO₄)₂·6H₂O or Co(SCN)₂·3H₂O in the presence of triethylamine in methanol led to the formation of two new complexes [Mn^ΙΙΙ₄(HL)₂(H₂L)₂(CH₃OH)₄]·4CH₃OH·(ClO₄)₂ (1) and [Co^ΙΙCo^ΙΙΙ(H₂L)₂(CH₃OH)(SCN)]·1.5CH₃OH·1.5H₂O (2), respectively. According to structural data and magnetic properties tetranuclear complex 1 contains four homo-valence manganese (ΙΙΙ) atoms, while in the binuclear complex 2 composed of hetero-valence bi- and trivalent cobalt (ΙΙ, ΙΙΙ) atoms. Weak antiferromagnetic exchange interactions between neighboring manganese ions in 1 have place. χ_MT for 2 was fitted using a model of isolated cobalt (ΙΙ) ion with zero-field splitting parameters and the study confirms its mixed valence Co^ΙΙ/Co^ΙΙΙ nature. No slow magnetic relaxation effects were observed for both complexes in the absence of an applied dc magnetic field.     

A unique 3D Co(II)-MOF based on [Co6(μ3-OH)4]8 +n chains: Synthesis,crystal structure,and magnetic property

A novel metal-organic framework, [Co₆(μ₃-OH)₄(ndc)₄(bip)₂(H₂O)₂]_n (1)[H₂ ndc = 1,4-naphthalenedicarboxylic acid, bip = 1,5-bis(imidazole-1-yl)pentane], constructed from unique [Co₆(μ₃-OH)₄]^8 +_n chains containing alternate [Co₄(OH)₂]^6 + and [Co₂(OH)₂]^2 + subunits, was reported, which has a new (3,3,8,12)-connected or 12-connented fcu/cubic network and shows weak antiferromagnetic interaction between the adjacent Co(II) ions mediated through the carboxylate and hydroxyl groups.     

A series of unusual three-dimensional 3d–4f (Ln/Cu/Cl/Br) cyanide heterometallic coordination polymers: Synthesis,crystal structure and magnetic properties

A series of unusual three-dimensional (3D) 3d–4f cyanide heterometallic coordination polymers (HCPs), namely [Ln_1.5Cu₃(ina)₃(ga)(CN)_1.5(X)(H₂O)] [Ln = Dy, X = Cl (1), Ln = Tb, X = Br (2), Ln = Dy, X = Br (3); ina = isonicotinic acid; ga = glycolic acid] have been synthesized via hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analyses, FT–IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). X-ray structural analysis reveals that HCPs 1 to 3 are constructed from the linkage between Ln–organic layer motifs and double-stranded cyano-containing Cu-inorganic ribbon motifs. In these complexes, the carboxyl group and hydroxyl group of H₂ga are all deprotonated and the coordinated ga ligands adopt a very interesting μ₃-kO:kO,O′:kO′,O″ coordination mode. Moreover, magnetic properties of HCP 1 were investigated.     

One-pot synthesis of two new metal–organic networks: hydrogen bonded mononuclear Cu(II) complex and mixed-valence Cu(I,II) coordination polymer with encapsulated 14-membered unique water cluster

{[Cu₄(μ-bpe)₄Cu₂(μ-pydc)₂(μ₃-pydc)₂]·14H₂O}_n (1) and [Cu(pydcH)₂(bpe)₂] (2) have been solvothermally synthesized by 1,2-bis(4-pyridyl)ethylene (bpe) along with dianionic pyridine-2,3-dicarboxylate (pydc) ligands and characterized by elemental, FT-IR and thermal analyses techniques. In the solvothermal synthesis of complexes, 1 was isolated when the reactor was opened whereas 2 was crystallized after 3 weeks. The X-ray crystallographic studies show that complex 1 exhibits ladder-like structure involving mixed-valence Cu(I,II) which has generated a simultaneous in situ redox reaction and a unique 14-membered water cluster consisting of an eight-membered open-cube hexamer and two cyclic water trimers has been observed in hydrophilic cavities of 1. Supramolecular network of 2, which has proton transfer product of pydcH cations, is formed by O–H···N and aromatic interactions.     

Natural fuel assisted synthesis of Mg–Cu ferrite nanoparticles: Evaluation of structural,dielectric, magnetic and humidity sensing properties

The effects of lemon juice and annealing treatment on phase composition, vibrational modes, microstructural and dielectric behavior of Mg doped copper ferrite nanoparticles have been synthesized and analyzed in detail in this present work. The various characterization techniques are used to examine the phase, microstructural, vibrational and dielectric nature of the samples at different annealing temperatures (600 °C and 900 °C). The phase and microstructure of Mg substituted CuFe₂O₄ nanoparticles have been analyzed by XRD, SEM and TEM. The secondary phase peaks free XRD spectra revealed that the as burst and the annealed Mg–CuFe₂O₄ nanoparticles have single phase cubic spinel structure. The average crystallite size of the as burnt, annealed 600 °C and annealed 900 °C of as prepared nanoparticles are calculated as 8.9 nm, 12.8 nm and 31.6 nm respectively. Another verification of the spherical shaped particle's size was confirmed by TEM analysis and it found as average size of 28.7 nm, this result is well matched with XRD analysis. The effect of size with impact of annealing treatment on magnetic and dielectric properties also analyzed. The size-dependent Mg–CuFe₂O₄ nanostructures exhibit promising sensing properties which ensure them as a potential candidate for humidity sensor applications. The as-burnt and annealed samples both show a humidity response over the humid range of 10–95 %RH. The sample annealed at 900 °C has the highest average sensor response (6.02 MΩ/%RH) among the as-burnt sample (6.38 MΩ/%RH) and annealed sample at 600 °C (7.11 MΩ/%RH).     

Synthesis,characterization and crystal structure of one Mn(II) complex with 4,4′-bisimidazolylbiphenyl and 4,4′-sulfonyldibenzoic acid

One new title compound [Mn₃(BIBP)(sdb)(NO₂⁻)₂(H₂O)₂]_n·2DMF (1) (BIBP = 4,4′-bisimidazolylbiphenyl, sdb = 4,4′-sulfonyldibenzoic acid) has been synthesized under hydrothermal condition. The title compound was characterized by IR spectra, thermal analysis, single crystal and powder X-ray diffraction. Magnetic susceptibility measurements indicate that compound 1 exhibits antiferromagnetic coupling interaction.     

Thin‐Layer Chromatography of Cu(II), Co(II) and Ni(II)

Abstract

The chromatographic behavior of some heavy metals on thin layer of silica gel was studied. The effect of polarity of mixed developing agent systems on the R_f values of metal complexes was investigated. The linear dependence between the R_f values and the polarity of developing agents was deduced and a series of good separations of Cu(II),Co(II) and Ni(II) were obtained successfully. This method was applied to separate Cu(II) and Ni(II) in a real sample.