EPR powder spectra of Co(II) and Cr(III) in MgIn2S4 spinel

The EPR powder spectra of high spin Co(II) and Cr(III) diluted in partially inverse spinel matrix MgIn₂S₄ are reported. While the spectrum of Co(II) in octahedral sites is orthorhombic the Cr(III) one is axial. Evidence is given that the EPR spectra cannot be directly associated with the cation distribution of the matrix.     

EPR powder spectra of Co(II) in ZnRh2O4 spinel matrix

The EPR powder spectra of spinel solid solutions Co_xZn_1-xRh₂O₄ (x ? 0.10) have been studied in the temperature range 6–77 K. The spectra show that Co²⁺ ions occupy distorted tetrahedral sites. As the cobalt concentration increases, the spectrum of the isolated ions is gradually replaced by a strong absorption produced by antiferromagnetic exchange coupled clusters of Co²⁺ ions.     

Pressure Studies of the Unconventional Superconductors CeTIn 5 (T: Co,Ir)

In the quest for new superconductor compounds which adopt the superconducting state at increasingly higher transition temperatures T c , a non-phonon mediated coupling between the charge carriers seems to play a key role. In order to enhance our understanding of such unconventional coupling mechanisms, we studied a new family of heavy fermion (HF) superconductors CeTIn 5 (T: transition metal) whose properties point toward the realization of unconventional superconductivity (SC): the specific heat, thermal conductivity and nuclear spin-lattice relaxation rate of CeIrIn 5 and CeCoIn 5 decrease as a power law of temperature instead of exponentially for T < T c . We report on measurements of the heat capacity of CeIrIn 5 and CeCoIn 5 at hydrostatic pressures p h 1.6 GPa. In both compounds, T c increases with increasing pressure, while the mass of the quasi-particles m eff decreases, as indicated by the ratio C / T | T c . As a working hypothesis based on theories of a nearly antiferromagnetic Fermi-liquid (NAFFL), this may be interpreted as the stabilization of the superconducting state by an increase of the characteristic spin fluctuation temperature T_{\rm SF}\ (T_{\rm SF}\propto k_{\rm F}^{2}/m_{\rm eff}).     

EPR Studies on the intermolecular interactions of bis(di-ethanol-dithiocarbamato) copper(II)

The interaction of the title complex, [Cu(EtOH-dtc)₂], with I₂, Br₂ and different metal salts known as electron acceptors is studied in water-ethanol solution. Mixed-ligand complexes Cu(EtOH-dtc)⁺…X^? (X = Cl, Br, I, NO₃) are formed with X^? in the second coordination sphere of the metal ion. Cu(EtOH-dtc)₂ interacts with chloral-hydrate only in the presence of weak Lewis bases and Cu(EtOH-dtc)⁺…Cl^? mixed-ligand complex is formed. The interactions with metal chelates cause the formation of mixed-ligand chelate complexes. Cu(EtOH-dtc)₂ interacts with H₂O₂ and the appearance of mixed-ligand complexes as intermediate products is detected. The final product obtained is CuSO₄. In the presence of O₂ Cu(EtOH-dtc)₂ yielded spectra similar to the above intermediate products. The proposed mechanisms of all studied reactions are discussed on the ground of the recorded spectra.     

2-对二甲氨基苯基-5-氟-6-吗啉苯并咪唑的合成及其光谱学性质研究

合成了一种新的取代苯并咪唑化合物 ,2 对二甲氨基苯基 5 氟 6 吗啉苯并咪唑 ,采用紫外 可见光谱、荧光光谱及荧光寿命等方法探讨了溶液pH值对该化合物吸收光谱的影响及其与 β 环糊精的作用。结果表明 ,pH >7 0时 ,该化合物在溶液中主要以中性分子状态存在 ,当 3 8相似文献   

Structural elucidation of Cu(II) ion doped in hexaaquozincdiaquobis(malonato)zincate host by EPR spectroscopy

In order to understand the structural behaviour of Cu(II) in a variety of ligand environments, single crystal electron paramagnetic resonance studies of Cu(II) doped in hexaaquazincdiaquabis(malonato)zincate [Zn(H₂O)₆][Zn(mal)₂(H₂O)₂] are carried out at 300 K. Angular variation of copper hyperfine lines in three orthogonal planes shows the presence of single site, with spin Hamiltonian parameters as g_xx=2.034, g_yy=2.159, g_zz=2.388, A_xx=3.39 mT, A_yy=4.89 mT and A_zz=13.72 mT. The g/A tensor direction cosines are compared with various Zn-O directions in the host lattice, which confirm that Cu(II) enters substitutionally in the lattice. The low value of A_zz has been explained by considering admixture of d_²x−²y ground state with d_²z excited state. EPR powder spectra at 300 and 77 K give identical spin Hamiltonian parameters (g_∥=2.367, g_⊥=2.088, A_∥=11.47 mT, A_⊥=2.63 mT). IR, UV-vis and powder XRD data confirm the structure and symmetry of the Cu(II) ion in the host lattice.     

Spectroscopic Studies of Intramolecular Proton Transfer in 2-(4-Fluorophenylamino)-5-(2,4-Dihydroxybenzeno)-1,3,4-Thiadiazole

Spectroscopic studies of the biologically active compound 2-(4-fluorophenylamino)-5-(2,4-dihydroxybenzeno)-1,3,4-thiadiazole (FABT), have been performed. Absorption studies in the UV-Vis region for FABT in polar solvents, like water or ethanol, exhibit the domination of the enol form over its keto counterpart, with a broad absorption band centered around 340 nm. In non-polar solvents such as n-heptane or heavier alkanes the 340 nm absorption band disappears and an increase of the band related to the keto form (approximately 270 nm) is observed. Fluorescence spectra (with 270 nm and 340 nm excitation energies used) show a similar dependence: for FABT in 2-propanol a peak at about 400 nm dominates over that at 330 nm while in n-heptane this relation is reversed. The solvent dependent equilibrium between the keto and enol forms is further confirmed by FTIR and Raman spectroscopies. As can be expected, this equilibrium also shows some temperature dependences. We note that the changes between the two tautomeric forms of FABT are not related to the permanent dipole moment of the solvent but rather to its dipole polarizability.     

EPR and Optical Absorption Studies of Cu2+-Doped Bis(l-Asparaginato)Mg(II)

The electron paramagnetic resonance study of Cu²⁺-doped bis(l-asparaginato)Mg(II) is performed at room temperature. Two magnetically non-equivalent sites for Cu²⁺ are observed. The spin-Hamiltonian parameters evaluated by fitting spectra to the crystalline field of rhombic symmetry are as follows: g _x  = 2.0420 ± 0.0002, g _y  = 2.0808 ± 0.0002, g _z  = 2.3600 ± 0.0002, A _x  = (99 ± 2) × 10⁻⁴ cm⁻¹, A _y  = (108 ± 2) × 10⁻⁴ cm⁻¹, A _z  = (140 ± 2) × 10⁻⁴ cm⁻¹. The ground state wave function of Cu²⁺ is also determined. The g-anisotropy is estimated and compared with the experimental value. Further, with the help of optical study the nature of bonding of a metal ion with different ligands in the complex is discussed.     

Synthesis,Spectral Characterization,DNA Binding Studies and Antimicrobial Activity of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) Complexes with 4-Aminoantipyrine Schiff Base of Ortho-Vanillin

A series of transition metal complexes of Co(II), Ni(II), Zn(II), Fe(III) and VO(IV) have been synthesized involving the Schiff base, 2,3-dimethyl-1-phenyl-4-(2-hydroxy-3-methoxy benzylideneamino)-pyrazol-5-one(L), obtained by condensation of 4-aminoantipyrine with 3-methoxy salicylaldehyde. Structural features were obtained from their FT-IR, UV–vis, NMR, ESI Mass, elemental analysis, magnetic moments, molar conductivity and thermal analysis studies. The Schiff base acts as a monovalent bidentate ligand, coordinating through the azomethine nitrogen and phenolic oxygen atom. Based on elemental and spectral studies six coordinated geometry is assigned to Co(II), Ni(II), Fe(III) and VO(IV) complexes and four coordinated geometry is assigned to Zn(II) complex. The interaction of metal complexes with Calf thymus DNA were carried out by UV–VIS titrations, fluorescence spectroscopy and viscosity measurements. The binding constants (K_b) of the complexes were determined as 5?×?10⁵ M^?1 for Co(II) complex, 1.33?×?10⁴ M^?1 for Ni(II) complex, 3.33?×?10⁵ M^?1 for Zn(II) complex, 1.25?×?10⁵ M^?1 for Fe(III) complex and 8?×?10⁵ M^?1 for VO(IV) complex. Quenching studies of the complexes indicate that these complexes strongly bind to DNA. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through groove. The ligand and it’s metal complexes were screened for their antimicrobial activity against bacteria. The results showed the metal complexes to be biologically active, while the ligand to be inactive.     

Co（Ⅱ）,Ni（Ⅱ）非有机溶剂液—液萃取行为的研究

In PEG-Eriochrome cyanine R-(NH4)2SO4 system the liquid-liquid extraction behaviour of Co(II) and Ni(II) without organic solvents was investigated. We found that Ni(II) was almost extracted by PEG phase while Co(II) was not extracted in the water solutions of NaAc-HAc (pH=5) and (NH4)2SO4. Thus Co(II) was quantitatively separated from mixed solutions of Ni(II) and Co(II) ions.     

Studies on Cu(II), Zn(II), Ni(II) and Co(II) complexes derived from two dipeptide Schiff Bases

Some new metal complexes of two dipeptide Schiff bases derived from salicylaldehyde and dipeptides such as glycyl-DL-alanine and glycyl-DL-phenylalanine have been synthesized and characterized by elemental analysis, molar conductance, IR, UV spectra, TG and DTA studies. The COO stretching bands in IR spectra suggest that the carboxylate acts as a monodentate group when binding with metal. The ligands are coordinated to the central metal as tetradentate ligands. The bonding sites are the carboxylate oxygen, imino nitrogen, amide nitrogen and phenolic oxygen.     

One- and two-dimensional S=12 Heisenberg antiferromagnetism in Cu(C5H5NO)6 (ClO4)2 and Cu(C5H5NO)6 (BF4)2, respectively

Specific-heat data on CuL₆(ClO₄)₂ and CuL₆(BF₄)₂ in the temperature range 0.05 < T < 20 K are presented (L ≡ C₅H₅NO). The magnetic contributions are found to have the form of broad maxima, occurring near 1 K. Small χ-type anomalies are observed at T_c = 0.62 ± 0.01 K and 0.142 ± 0.002 K for CuL₆(BF₄)₂ and CuL₆(ClO₄)₂, respectively. The analyses show the magnetic structure to be an assembly of weakly coupled antiferromagnetic chains or layers for CuL₆(ClO₄)₂ and CuL₆(BF₄)₂, respectively. For CuL₆(ClO₄)₂ the intrachain exchange constant is J/K = -1.02 ± 0.02 K, for CuL₆(BF₄)₂ the intralayer exchange constant is J/K = -1.10 ± 0.02 K. Additional evidence for the lower-dimensional magnetic structures is obtained from the temperature dependences of the antiferromagnetic susceptibilities. The data on CuL₆(BF₄)₂ clearly indicate the absence of a divergence in the specific heat for the quadratic-layer Heisenberg antiferromagnet, and provide an estimate for the specific heat for this model. A comparison is made with the corresponding result for the ferromagnetic Heisenberg layer.     

Studies of EPR and ENDOR spectra of14N and15N label bis(2-hydroxyacetophenyl ketoxime)-63Cu(II) and-65Cu(II) complexes in disordered system

The EPR spectra of isotopic label bis(2-hydroxyacetophenyl ketoxime)-Cu(II) [N?Cu-HAP] complexes, such as¹⁴N?⁶³Cu-HAP,¹⁵N?⁶³Cu-HAP and¹⁴N?⁶⁵Cu-HAP in frozen THF solution below 77 K, and their ENDOR spectra in frozen DMSO/EtOH (5∶1) solution below 20 K were studied. The exact values of the components ofg-tensor, of hyperfine tensors of copper isotopes, and of superhyperfine interaction tensors of copper with nuclei of nitrogen isotopes and¹H nuclei, and of the¹⁴N nuclear quadrupolar moment coupling tensor were obtained. The bond parameters α, β, δ, γ and the corresponding energy levels of N?Cu-HAP complexes were calculated by using EPR and ENDOR data. It was shown that the unpaired, electron is delocalized not only to the nearest N atom but also to the H atom, of ligands, which is more far from the Cu ion.     

光谱法研究2-(4-二甲氨基苯基)-5-氟-6-吗啉-1-氢-苯并咪唑与小牛胸腺DNA的相互作用

研究了2-(4-二甲氨基苯基)-5-氟-6-吗啉-1-氢-苯并咪唑(1)在不同pH条件下的紫外-可见吸收光谱,采用非线性最小二乘法得出分子1的三级加质子常数lgβ₁, lgβ₂, lgβ₃分别为4.96±0.03, 5.72±0.07和7.95±0.10。当pH 3.40时,分子1主要以一价离子状态存在,紫外-可见吸收光谱及荧光光谱表明该条件下分子与小牛胸腺DNA存在明显的相互作用,并得出分子1与DNA的结合常数K_b为(2.30±0.10)×104 mol-1·L。当分子浓度为10-8～1.2×10-6 mol·L-1时,荧光强度随DNA含量的增加而线性增强,分子1是一种潜在的测定DNA的定量试剂。     

[Co(H2O)4(NCS)2](18-C-6)配合物的NMR研究

该文测定了最近合成的[Co(H₂O)₄(NCS)₂](18-C-6)的¹H、¹³C、¹⁴N核磁共振谱,验证了其配合物的结构,并用红外光谱(IR)作了进一步的确定.     

EPR of Mn2+ in single crystals of [Zn(H2O)6]SnF6 and [Co(H2O)6]SnF6; Co2+ spin-lattice relaxation time

EPR studies have been carried out in Mn²⁺-doped single crystals of [M(H₂O)₆]SnF₆ (M  Zn, Co) at different temperatures using X-band microwave frequency. Mn²⁺ has been found to substitute for Zn²⁺ or Co²⁺ exhibiting a unique magnetic complex with z-axis directed long the c-axis of the crystals. Observation of resolved Mn²⁺ spectrum in [Co(H₂O)₆]SnF₆ and broadening of the resonance lines on cooling the crystals have been explained on the basis of host spin-lattice relaxation narrowing. The T₁ of Co²⁺ has been estimated to be ≈ 1.8 × 10⁻¹² s at 293 K.     

EPR of Co+2 in Mg(CH3COO)2·4H2O

EPR spectra of the ⁵⁹Co⁺² ion in oriented crystals of Mg(CH₃COO)₂·4H₂O have been measured at 9.4 GHz and a temperature of 4.2 K. The data for each of the two metal ion sites per unit cell are well-described by a spin Hamiltonian for $\text{S =}\text{1}\text{2}\text{, I =}\text{7}\text{2}$ with g_x = 6.13, g_y = 389, g_z = 2.49 and A_x = 0.0193, A_y' = 0.075, A_z' = 0.0032 cm^?1. Only the x-axes of the g- and A-tensors coincide. Orientation of the principal directions relative to the crystal axes has been established for the g- and A-tensors at both sites. They are consistent with the weakly ferromagnetic canted antiferromagnetism found in Co(CH₃COO)₂·4H₂O below T_N ?85mK.