Structural Information from the Infrared Spectra of Metal(II) Complexes of Tropolone and 2-Thiotropone

Evidence for polynuclear octahedral coordination in the complexes [MT²]_n (M = Ni, Zn; T = tropolonate anion; n > 1) is adduced by observing the effect of base adduct formation on their infrared spectra. The spectra of the complexes [M(ST)₂] (M = Co, Ni, Cu, Zn; ST = 2-thiotroponate anion) are discussed in relation to their known or probable structures.     

Calix Receptor Edifice; Scrupulous Turn Off Fluorescent Sensor for Fe(III), Co(II) and Cu(II)

Novel Supramolecular fluorescence receptor derived from calix-system i.e. calix[4]resorcinarene bearing dansylchloride as fluorophore was designed and synthesized. The compound was purified by column chromatography and characterized by elemental analysis, NMR and Mass spectroscopy. Tetradansylated calix[4] resorcinarene (TDCR) shows a boat conformation with C₂v symmetry. The complexation behaviour of metal cations [Ag(I), Cd(II), Co(II), Fe(III), Hg(II), Cu(II), Pb(II), Zn(II), U(VI) (1?×?10^-4?M)] with tetra dansylated calix[4]resorcinarene (1?×?10^-6?M) was studied by spectophotometry and spectrofluorometry. Red shift in the absorption spectra led us to conclude that there is strong complexation Fe(III), Co(II) and Cu(II) with TDCR. These metal cations also produce quenching with red shifts in the emission spectra. The maximum quenching in emission intensity was observed in the case of Fe(III) and its binding constant was also found to be significantly higher than that of Co(II) and Cu(II). Quantum yield of metal complexes of Fe(III) was found to be lower in comparison with Co(II) and Cu(II) complexes. Stern Volmer analysis indicates that the mechanism of fluorescence quenching is either purely dynamic, or purely static.     

The magnetic hyperfine field at Cu in Fe,Co and Ni and the magnetic moment of the 41 keV, 2+ state of62Cu

The magnetic hyperfine interaction of Cu in Fe, Co and Ni was studied by means of the γ-γ perturbed angular correlation method using⁶²Zn(⁶²Cu) as a probe. With the publishedg-factor (g=+0.661(12)) of the 41 keV, 2⁺ state hyperfine fields ofB _HF=16.95(51) T,B _HF=13.15(41) T andB _HF=4.05(30) T atT=0 K for Cu in Fe, Co and Ni are derived, respectively. The systematic discrepancy of these values with several independent measurements of these hyperfine fields is removed by deriving a new value ofg=0.55(5) for the 41 keV, 2⁺ state of⁶²Cu.     

Structural and magnetic properties of Ti12M clusters (M=Sc to Zn)

The geometries, electronic, and magnetic properties of the 3d atom doped icosahedron (ICO) Ti₁₂M (M=Sc to Zn), where a dopant atom replaces either the centra l(Ti₁₂M^c) or surface (Ti₁₂M^s) Ti atom in ICO Ti₁₃ cluster, have been systematically investigated by using the density functional theory. The structures of all the optimized Ti₁₂M^c and Ti₁₂M^s clusters are distorted ICO. Sc, Ni, Cu, and Zn atoms prefer to displace surface Ti atom, V, Cr, Mn, and Fe atoms prefer to displace central Ti atom. The position of impurity atom depends on the strength of the interaction between the central atom and the surface atoms. As compared to the pure Ti₁₃ cluster, Ti₁₂M^c and Ti₁₂M^s (M=V, Fe, Co, and Ni) clusters are more stable, Ti₁₂M^c and Ti₁₂M^s (M=Sc, Cr, Mn, Cu, and Zn) are less stable. Both Ti₁₂Ni^s and Ti₁₂Ni^c are magic clusters, which originate from their electronic as well as geometric closed shells. Because the exchange interaction prevails over the crystal field in Ti₁₂M clusters, the valence electrons fill molecular orbitals in terms of Hund’s rule of maximum spin.     

Structural, vibrational, thermal and magnetic investigation of novel Co(II), Cu(II), Zn(II) and Hg(II) crystalline metal complexes with 2-amino-5-benzylmercapto-1,3,4-thiadiazole: a low weight model of protonated copolymer resin

The 2-amino-5-benzylmercapto-1,3,4-thiadiazole (C₉H₉N₃S₂) is a low weight model of a protonated copolymer resin used as a metal uptake agent. New monomeric crystalline metal complexes of C₉H₉N₃S₂ with Co(II), Cu(II), Zn(II) and Hg(II) were synthesized and investigated in order to facilitate the interpretation of the metal/resin binding mode. These materials have been studied by single crystal X-ray Diffraction and FTIR Spectroscopy at room temperature. Crystal data for these triclinic phases are reported. All frameworks consist of discrete monomeric units that provide crystalline stability through a network of hydrogen bond interactions. The Co(II), Zn(II) and Hg(II) ions are surrounded by a tetrahedral arrangement of two thioether monodentate ligands (each one coordinating by a N(1)_thiadiazole atom) and two chlorine atoms. The Cu(II) ion is coordinated by four thioether monodentate ligands (each one coordinating by a N(1)_thiadiazole atom) and one chlorine atom as nearest neighbor in a distorted square pyramidal polyhedron. The spectroscopic data are consistent with the structural model. FTIR spectra evidence changes in the H-bonds in the crystal packing when coordination with these divalent ions is present. Magnetic susceptibility at room temperature for Cu(II) and Co(II) complexes, EPR spectrum at room temperature for Cu(II) complex and thermal properties for all complexes were measured. These results could be useful for the interpretation of the binding mode of M(II)/1,3,4-thiadiazole-2-amino-5-thiol in protonated copolymer resin which are used as uptake agents of toxic metallic ions.     

YBa2(Cu0.95M0.05)3O7-δ的代换效应及其中子衍射研究

X射线衍射实验表明YBa₂(Cu_0.95M_0.05)₃O_7-δ(M=Ti,V,Cr,Mn,Fe,Co,Ni,Cu和Zn)均为单相结构。Fe,Co,Ni和Zn对Cu的替代使超导临界温度T_c显著下降,而同样含量的Ti,V,Cr,Mn对Cu的替代并未对超导性能产生显著影响。并利用中子衍射分析了Ti,Mn,Fe和Co对Cu原子的取代,发现代换原子对Cu的两个晶位各自存在不同的择优占据 关键词：     

The Infrared Spectra of the First Transition Series Metal(II) Bis(Aquo) Complexes Of 8-Hydroxyquinoline

Abstract

The infrared spectra (700–100 cm^?1) of the complexes [M(ox)₂(H₂O)₂] (ox = 8-hydroxyquinolinate anion, M = Mn, Fe, Co, Ni, Cu, Zn) are discussed. For the purposes of assignment of the metal ligand modes, deuterated 8-hydroxyquinoline-d ₇ was prepared by the Skraup synthesis and the spectra of the deuterated complexes were compared with those of the unlabelled species. Furthermore, [⁶⁴Zn(ox)₂(H₂O)₂] and [⁶⁸Zn(ox)₂(H₂O)₂] were prepared by reaction of ⁶⁴ZnSO₄ and ⁶⁸ZnSO₄ with 8-hydroxyquinoline and the effects of metal isotope labelling on the spectra were examined and compared with earlier isotopic data on the nickel and zinc complexes.     

A study of KαL1 X‐ray satellite spectrum of the elements 27 ≤ Z ≤ 31 by photon excitation

K _α X‐ray satellite spectra of Co, Ni, Cu, Zn, and Ga generated by photon excitation are analyzed using a wavelength dispersion spectrometer. Spectra of Ni, Cu, Zn, and Ga are studied for the first time using a LiF420 crystal. Spectrum of Co was studied with LiF200 crystal in second order. K_αL¹ X‐ray satellite energies and relative intensities are measured. The energy shifts relative to diagram line are computed and are compared with theoretical and semi‐empirical values. Dependence of energy shifts and relative intensities on Z and mode of excitation is analyzed.     

Hume-Rothery electron concentration rule across a whole solid solution range in a series of gamma-brasses in Cu–Zn,Cu–Cd,Cu–Al,Cu–Ga,Ni–Zn and Co–Zn alloy systems

The aim of the present work is to examine if the Hume-Rothery stabilisation mechanism holds across whole solid solution ranges in a series of gamma-brasses with especial attention to the role of vacancies introduced into the large unit cell. The concentration dependence of the number of atoms in the unit cell, N, for gamma-brasses in the Cu–Zn, Cu–Cd, Cu–Al, Cu–Ga, Ni–Zn and Co–Zn alloy systems was determined by measuring the density and lattice constants at room temperature. The number of itinerant electrons in the unit cell, e/uc, is evaluated by taking a product of N and the number of itinerant electrons per atom, e/a, for the transition metal element deduced earlier from the full-potential linearised augmented plane wave (FLAPW)-Fourier analysis. The results are discussed within the rigid-band model using as a host the density of states (DOS) derived earlier from the FLAPW band calculations for the stoichiometric gamma-brasses Cu₅Zn₈, Cu₉Al₄ and TM₂Zn₁₁ (TM = Co and Ni). A solid solution range of gamma-brasses in Cu–Zn, Cu–Cd, Cu–Al, Cu–Ga and Ni–Zn alloy systems is found to fall inside the existing pseudogap at the Fermi level. This is taken as confirmation of the validity of the Hume-Rothery stability mechanism for a whole solute concentration range of these gamma-brasses. An exception to this behaviour was found in the Co–Zn gamma-brasses, where orbital hybridisation effects are claimed to play a crucial role in stabilisation.     

Normal Coordinates Analysis for The M(NH3)2+ 4 Complex Ions in D4h and Td Symmetries. Simplified Molecular Models

A normal coordinates analysis for the M(NH₃)²⁺ ₄ complex ions in T_d symmetry (M = Zn, Cd, Co) and in D_4h symmetry (M = Cu, Pd, Pt) has been undertaken on the basis of a General Valence Force Field (GVFF), using simplified molecular models. Throughout the course of the present work, we have relaxed the point mass approximation for the NH₃-ligands in order to investigate, on a quantitative basis, some relevant ligand - framework coupling vibrations. The simplest molecular model able to accomplish this purpose is to treat the ammino group, in a linear ligator approximation. We show that these model calculations provide a satisfactory set of vibrational frequencies as well as consistent sets of force constants.     

All-electron relativistic calculation on Au5X (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) clusters

All-electron scalar relativistic calculations on Au₅X (X = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) clusters have been performed by using density functional theory with the generalized gradient approximation. Our calculation results indicate that all the lowest energy geometries of Au₅X clusters have planar structures; the doped X atoms prefer to occupy the fourfold coordination site. Except Au₅Fe, Au₅Co and Au₅Zn, for other clusters including pure Au₆ cluster, the HOMO are delocalized obviously with a contribution from all atoms in the cluster. On the contrary, the electron localization in Au₅Zn is very strong resulting in the least stability of this cluster. Au₅Cu cluster with six delocalized electrons being defined as magic number for two-dimensional system has the largest VIP and deepest HOMO energy level. With the substitution Au for X atoms, the metallicity of all Au₅X clusters is reinforced.     

Controlling spin off state by gas molecules adsorption on metal-phthalocyanine molecular junctions and its possibility of gas sensor

Employing Green's function (GF) technique in combination with spin-polarized density functional theory (DFT), we study the electronic structure and magnetic properties of metal phthalocyanine (MPc) (M?=?Mn, Fe, Co, Ni, Cu, Zn) with or without four different gas molecules (NO, CO, O₂ and NO₂) adsorbing on the M atom of MPc molecule. The corresponding stable adsorption structural configurations and transport properties of MPc molecular junctions are also investigated. Our results indicate that the magnetic moment of MPc for M?=?Mn, Fe and Co can be modified by the specific gas molecule adsorption, which is mainly ascribed to competitive relation of HOMO-LUMO Gap and Hund's rules. However, for M?=?Ni, Cu and Zn, it is difficult to detect gas molecule because the interaction of M atom and these gases is most of weak van der Waals interaction. Remarkably, the spin of MPc molecule can be switched to a magnetic off-state by specific gas absorption, giving rise to a potential application on controllable spintronic devices. In addition, CO, NO, O₂ and NO₂ gas molecules can be detected selectively by measuring spin filter efficiency of these MPc molecular junctions. On the basis of our results, MPc (M?=?Mn, Fe, Co) molecular junctions can be considered as a promising nanosensor device to detect individual gas molecules.     

DNA Binding and Photocleavage Study of Cationic Metalloporphyrins by Spectral Methods

The DNA binding and photocleavage specificities of the Zn(II), Cu(II), Co(III), Mn(III) complexes of 5,10,15-tris(1-methylpyridinium-4-yl)-20-(4-propionoxyphenyl)porphyrin have been studied by using a combination of absorption, fluorescence titration, surface-enhanced Raman spectroscopy (SERS), induced circular dichroism (ICD) spectroscopy, thermal DNA denaturation as well as gel electrophoresis experiment. It is found that Cu(II) porphyrin has comparable binding ability with the free base porphyrin while the axial-coordinated Zn(II), Co(III), and Mn(III) porphyrins have lower K_b because of the molecular steric hindrance. However, those metalloporphyrins with lower K_b have similar DNA cleavage efficiencies with the free base porphyrin. This could be best understood by the enhancement of the ¹O₂ productivity which may also result from the steric hindrance of the axial-coordinated metalloporphyrins.     

Effect of 3d metal ion doping on the structure and superconductivity of (Tl0.5Pb0.5)Sr2CaCu2O7

(Tl_0.5Pb_0.5)Sr₂Ca(Cu_2−xM_x)O₇ (M=Co, Ni and Zn) have been synthesized and investigated by means of X-ray diffraction, scanning electron microscope, electrical resistivity and magnetic susceptibility measurements. X-ray diffraction patterns show that all studied samples contain the nearly single ‘1212’ phase. They crystallize in a tetragonal unit cell with a=3.8028-3.8040 Å and c=12.0748-12.1558 Å. In (Tl_0.5Pb_0.5)Sr₂Ca(Cu_2−xM_x)O₇ system (M=Co or Ni), the superconducting critical temperature T_c decreases linearly with both Co and Ni concentrations and the rate of T_c decrease is around −6.5 and −7.0 K/at%, respectively. For (Tl_0.5Pb_0.5)Sr₂Ca (Cu_2−xZn_x)O₇ system, the dependence of T_c on the Zn dopant concentration deviates from a linear behavior and the Zn substitution suppresses T_c much less (−2.5 K/at%) than the Co and Ni substitutions. The suppression in T_c in Co and Ni doped samples are attributed to the magnetic pair-breaking mechanism and the reduction in the carrier concentration. The suppression of T_c in Zn doped samples is not caused by the reduction in carrier concentration which should remain constant, but rather due to nonmagnetic pair-breaking mechanism induced by disorder as well as the filling of the local Cu d_x²−y² state due to the full d band of Zn ions.     

Sputtering of Cu and Zn atoms from elemental and alloy targets

The energy distributions of Cu and Zn atoms sputtered from elements and Cu_xZn_1-x alloys (x=0.80, 0.24) with a 6 keV Ar⁺ beam have been measured. It was found that the collision-cascade theory properly described the flux of sputtered atoms. From the spectra the binding energies of Cu and Zn atoms in the elemental and alloy surfaces were determined. The collision-cascade theory and the experimentally adjusted values of the binding energies allowed for calculation of the total and partial sputtering yields, and the equilibrium surface composition of the ion bombarded alloys. This work was carried out as a part of Research Project M.R. I/5.     

从对Cu的取代看YBa2Cu3O7-y中Cu-O平面和Cu—O链的作用

通过测量YBa₂Cu_3-xM_xO_7-y(M=Zn,Ni,x=0,0.025,0.05,0.075,0.1,0.15,0.2,0.3)系列样品的晶体结构、正常态电子输运性质、超导电性以及O含量,给出了Zn择优取代Cu(2)的更直接证据;同时,观察到掺Zn系统中的由正交相Ⅰ到正交相Ⅱ的结构相变以及Ni取代Cu带来的电子局域化效应。研究结果表明,具有正二价态的Zn对Cu(2)具有择优取代性,而具有正二价和正三价的Ni并不具有明显的择优取代。对Cu(2)的取代引起超导临界温度的显著变化,但对正常态电子输运性质的影响不明显;对Cu(1)的取代更显著地影响了晶体结构和正常态电子输运性质,同时对T_c产生抑制,我们认为,YBa₂Cu₃0₇中的高温超导电性以及正常态输运性质是由CU-O平面和Cu-0链共同承担,而Cu-O平面和Cu-0链之间的耦合强度决定着该系统的超导电性的强弱。 关键词：     

Preparation,Chemical Characterization and Electronic Spectra of 6-(2-Pyridylazo)-3-Acetamidophenol and Its Metal Complexes

The stereochemistry of new iron (III), cobalt (II), nickel (II), copper (II), zinc (II) and cadmium (II) complexes of 6-(2-pyridylazo)-3-acetamidophenol (H2L) was studied on the basis of their analytical, spectroscopic, magnetic and conductance data. the dissociation constant of the ligand, as well as the stability constants of its metal complexes had been determined by spectrophotometric method. on the basis of infrared spectra, the coordination behaviour of the ligand to the metal ions was investigated. Magnetic susceptibility and solid reflectance spectra measurements were used to infer the structure. the isolated complexes were found to have the general formulae [M (HL). xH₂O] (A).yH₂O, M = Cu (II), Zn (II), Cd (II) and Fe (HI); HL = 6-(2-pyridylazo)-3-acetamido-phenol; a = acetate in the case of Cu (II) and Zn (II) or chloride in the case of Cd (II) and Fe (Ill), x = 1-3 and y=0-5. for [M (H₂L).xH₂O]Cl₂.yH₂O, M = Ni (II) and Co (II); HL = 6-(2-pyridyl-azo)-3-acetamidophenol, x=3 and y=5-6).     

Influence of Co, Ni and Zn substitution for Cu on the structural and superconducting properties of (Hg0.7Cr0.3)Sr2CuO4+δ

The effect of Co, Ni and Zn substitutions for Cu on the phase stability and superconducting properties of (Hg_0.7Cr_0.3)Sr₂CuO_4+δ was investigated. X-ray diffraction (XRD) revealed that both Co and Zn are soluble in the (Hg_0.7Cr_0.3)Sr₂CuO_4+δ material up to about 5% of the Cu content, whereas the solubility of Ni is extended up to 10%. Electrical resistivity and magnetic susceptibility measurements show that the value of the superconducting critical temperature T_c decreases linearly with the impurity content. The depression of T_c indicates that the suppression of the superconductivity in Co- and Ni-substituted samples is much stronger than that in Zn-substituted ones. The residual resistivity scales linearly with the doping level as expected from the impurity scattering due to disorder. Some possible explanations for the stronger suppression of T_c by the Co and Ni substitution than by Zn substitution are provided.     

Oxidation of divalent tin in aqueous solutions of SnF2 and 3D transition metals allowed to crystallize slowly in air

Chlorides, nitrates and sulfates of M (M=Mn, Fe, Co, Ni and Zn) were dissolved in aqueous solutions of SnF₂ at M/Sn molar ratios of 0.5 to 3. No HF was used. The solutions were allowed to evaporate in air. Very small amounts of hexagonally shaped crystals of unknown materials were obtained for M=Mn, Co, Ni and Zn. Fe did not yield this phase. X-ray powder diffraction gives identical patterns for the four materials, which are therefore most likely isostructural, and showed that the products are not MSn₂F₆·6H₂O or MSnF₆·6H₂O. Tin-119 Mössbauer spectroscopy gives a single line at negative isomer shift, characteristic of [Sn(IV)F₆]^2– ions.     

Infrared phonon spectra of 3d-metal doped YBa2(Cu1-x M x )3O7-δ

Infrared (IR) absorption spectra of doped YBa₂(Cu_1–x M _x )₃O_7–, with M representing Co, Fe, Ni, and Zn were observed as a function of concentrationx. TheB _1u IR mode at 580 cm^–1 was observed for all samples which were in the orthorhombic phase, which includes all the Ni and Zn doped samples and the lower concentrations (x<2.5%) for Fe and Co samples. The tetragonal phase of Co and Fe systems (x%>2.5%) shows three new IR modes at 655 cm^–1, 340 cm^–1, and 175 cm^–1. The frequency of the B_1u mode at 580 cm^–1 remains unchanged for all the Ni and Zn concentrations. In contrast, this mode shows a strong monotonic frequency softening with increase in Co substitution, while in the Fe-system it shows a comparable monotonic mode softening for 3%x%0%, and then remains unchanged for 12%x%3%. These observations indicate that Fe and Co substitute on the Cu(1) sites, whereas Ni and Zn most likely substitute on Cu(2) sites. We attribute the difference in the mode softening for Co and Fe to different Cu(1) local environments for these two elements. Indication for a chain-plane charge transfer based on our results is also discussed.