ATMP(氨基三甲叉膦酸)及其顺磁性Co(Ⅱ)配合物的核磁共振研究

本文用¹H、³¹P和¹³C核磁共振谱研究了ATMP(氨基三甲叉膦酸,以简式H₆L表示)及其顺磁性Co(Ⅱ)配合物。测定了不同C_co/C_ATMP摩尔比在不同pH值下的各向同性位移。定性地讨论顺磁性Co(Ⅱ)配合物在不同pH条件下的组成、电荷和空间构型变化对化学位移的影响。运用快速交换反应中化学位移与配合物浓度的关系,确定不同pH下的条件稳定常数。     

Structural features of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution

The structure of the copper(II) chloride-triphenylphosphine-N-(2-pyrimidyl)imine complex in crystal and solution was investigated by x-ray analysis and EPR. It was found that despite the difference in the structures of the dissolved and crystalline complexes, the exocyclic nitrogen atom is contained in the coordination sphere of the metal together with the nitrogen atom of the heterocycle in both cases due to the electronic effect of the phosphorus atom. In the crystal, the copper atom is coordinated with two chlorine atoms and two molecules of the ligand, and the distance from the copper cation to the nitrogen atoms of the pyrimidine rings is significantly less than the distance to the nitrogen atoms of the phosphinimine groups (2.0 and 2.8 Å, respectively). The coordination polyhedron formed as a result is a strongly distorted axially asymmetric octahedron. In dissolution, the chlorine anions are substituted by molecules of the solvent, the complex acquires axial symmetry, and four nitrogen atoms from two ligands form a planar square with a copper(II) cation in the center.A. N. Nesmeyanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 118–125, January, 1992.     

End-to-End Thiocyanato-Bridged Helical Chain Polymer and Dichlorido-Bridged Copper(II) Complexes with a Hydrazone Ligand: Synthesis,Characterisation by Electron Paramagnetic Resonance and Variable-Temperature Magnetic Studies,and Inhibitory Effects on Human Colorectal Carcinoma Cells

The reactions of the tridentate hydrazone ligand, N′-[1-(pyridin-2-yl)ethylidene]acetohydrazide (HL), obtained by condensation of 2-acetylpyridine with acetic hyadrazide, with copper nitrate trihydrate in the presence of thiocyanate, or with CuCl₂ produce two distinct coordination compounds, namely a one-dimensional helical coordination chain of [CuL(NCS)]_n (1) units, and a doubly chlorido-bridged dinuclear complex [Cu₂L₂Cl₂] (2) (where L=CH₃C(O)=N–N=CCH₃C₅H₄N). Single-crystal X-ray structural determination studies reveal that in complex 1, a deprotonated hydrazone ligand L⁻ coordinates a copper(II) ion that is bridged to two neighbouring metal centres by SCN⁻ anions, generating a one-dimensional helical coordination chain. In complex 2, two symmetry-related, adjacent copper(II) coordination entities are doubly chlorido-bridged, producing a dicopper entity with a Cu⋅⋅⋅Cu distance of 3.402 (1) Å. The two coordination compounds have been fully characterised by elemental analysis, spectroscopic techniques including IR, UV–vis and electron paramagnetic resonance, and variable-temperature magnetic studies. The biological effects of 1 and 2 on the viability of human colorectal carcinoma cells (COLO-205 and HT-29) were evaluated using an MTT assay, and the results indicate that these complexes induce a decrease in cell-population growth of human colorectal carcinoma cells with apoptosis.     

Synthesis of a novel copper(II) complex and its crystal structure

One novel chiral copper(II) complex was successfully synthesized from the reaction of chiral 1,3-thiazolidine-2-thione ligand with CuCl₂ in dichloromethane in the presence of Et₃N and DMAP at room temperature. Its unique crystal structure was unambiguously disclosed by X-ray analysis. The crystal is tetragonal, space group I4(1), space group a=15.0875(11), b=15.0875(11), c=19.362(3) Å, =90, β=90, γ=90°, V=4407.4(8) ų, Z=8, ρ_calc=1.639 mg cm⁻³.     

Synthesis,characterization, crystal structure and non-isothermal dehydration kinetics of a copper(II) complex

A three-dimensional complex, [CuL₂(H₂O)]₂ (HL?=?3-hydroxy-1-adamantanecarboxylic acid), C₄₄H₆₄Cu₂O₁₄, was synthesized under hydrothermal conditions from CuCO₃?·?Cu(OH)₂ and HL. The crystal structure of the complex was determined by X-ray crystallography and its thermal behavior and IR spectra examined. The non-isothermal dehydration kinetics of the complex were investigated using the Achar differential method.     

Synthesis,crystal structure,and magnetic properties of 1D Azido-bridged copper(II) complex

A novel copper(II)-azide complex of [Cu₂(DMAP)₂(μ-1,1-N₃)₂(μ-1,3-N₃)₂]_n (DMAP = 4-(dimethylamino)pyridine) has been synthesized and characterized by IR spectra, X-ray diffraction, elemental analysis, and magnetism measurement. The complex reveals a 1D ladder-like chain structure, in which two μ-1,1-N₃ and two μ-1,3-N₃ bridges form a dimeric unit of [Cu₂(DMAP)₂(μ-1,1-N₃)₂(μ-1,3-N₃)₂] and are then connected to each other from the tail nitrogens of two asymmetric μ-1,3-N₃ bridges to generate a chain structure that stacks in the cell to construct the 3D crystal. The Cu atom is five-coordinated by azide anions to form a distorted square-pyramid of CuN₅ (τ = 0.2667). Magnetic susceptibility of complex exhibits a ferromagnetic interaction between the copper(II) ions through two kinds of azido-bridges. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis, crystal structure and imine bond activation of a copper(II) Schiff base complex

A new copper(II) complex [Cu(HL)(ClO₄)](ClO₄) (1), where HL is a multidentate Schiff base N,N′-(2-hydroxypropane-1,3-diyl)bis(pyridine-2-aldimine), is prepared, structurally characterized by X-ray crystallography and its spectral and electrochemical properties studied. The complex forms a one-dimensional chain in the solid state structure in which the monomeric Cu(HL) units are linked by the perchlorate ligand. The complex has an axially elongated six coordinate geometry (4+2) with a CuN₄O₂ core in which the Schiff base ligand displays a tetradentate mode of bonding in the basal plane. The axial ligand is perchlorate with a significantly long Cu–O bond of ca. 2.6 Å. The one-electron paramagnetic complex displays a cyclic voltammetric response for the Cu(II)/Cu(I) couple at 0.01 V versus SCE in MeCN–0.1 M TBAP. The azomethine bond of the Schiff base in 1 on treatment with H₂O₂ undergoes oxidative conversion to form a bis(picolinato)copper(II) · dihydrate species through the formation of an amido intermediate as evidenced from the solution infrared spectral studies.     

Synthesis,characterization, and crystal structure of a copper(II) complex of 1,10-phenanthroline and succinate

A mixed ligand complex of Cu(II) with 1,10-phenanthroline and succinate has been synthesized from the reaction of hydrated copper nitrate, succinate, and 1,10-phenanthroline. The nature of bonding and the structure of the complex were characterized by elemental analyses, infrared spectrum, TGA/DTA, and X-ray diffraction. The crystal crystallizes in triclinic space group P 1. The complex is polymeric and the geometry around each copper varies from square planar to distorted square pyramidal or octahedral. Each copper coordinates two oxygens of succinate and two nitrogens of 1,10-phenanthroline. The thermal decomposition of the complex has also been studied by TGA and DTA under inert atmosphere.     

Synthesis,crystal structure and electronic properties of bis(N-2-bromophenyl-salicydenaminato)copper(II) complex

A new series of complexes of the type bis(N-substituted-salicydenaminato)copper(II) (1–9), have been synthesized and characterized by IR, UV–Vis and elemental analysis methods. The molecular structure of bis(N-2-bromophenyl-salicydenaminato)copper(II) (6), was determined using X-ray crystallography. There are two independent molecules in the structure. Each shows a neutral, mononuclear, four-coordinate, square-planar trans-Cu[N₂O₂] geometry and, in each, the Cu atom and the ligating atoms are coplanar. The chelating N–Cu–O angle is 91.39(11)° for molecule one and 91.20(11)° for molecule two, whereas the non-chelating N–Cu–O angles are 88.61(11) and 88.80(11)°, respectively. The trans-N–Cu–N and trans-O–Cu–O bond angles are 180°. The electronic absorption spectra of copper(II) complexes (1–9), indicate that the d–d band energy is dependent on the nature and position of substituent on phenyl ring of the salicyldenimine ligand. The UV–Vis spectra in various solvents were measured and a relationship between absorption spectra and dielectric constant of the solvents is reported.     

Synthetic, spectral and solution studies on imidazolate-bridged copper(II)-copper(II) and copper(II)-zinc(II) complexes

Synthesis, spectral and solution studies on 2-ethyl imidazolate-bridged (2-EtIm) homo-binuclear copper(II)-copper(II) and hetero-binuclear copper(II)-zinc(II) homologue are described. Magnetic moment values of homo-binuclear complexes indicate that the imidazolate group can mediate antiferromagnetic interactions. Optical spectra of hetero-binuclear complex at varying pH values suggest that the imidazolate-bridged complex is stable over the pH-range 7.15–10.0.     

Magnetic Resonance Access to Transiently Formed Protein Complexes

Protein–protein interactions are of utmost importance to an understanding of biological phenomena since non-covalent and therefore reversible couplings between basic proteins leads to the formation of complex regulatory and adaptive molecular systems. Such systems are capable of maintaining their integrity and respond to external stimuli, processes intimately related to living organisms. These interactions, however, span a wide range of dissociation constants, from sub-nanomolar affinities in tight complexes to high-micromolar or even millimolar affinities in weak, transiently formed protein complexes. Herein, we demonstrate how novel NMR and EPR techniques can be used for the characterization of weak protein–protein (ligand) complexes. Applications to intrinsically disordered proteins and transiently formed protein complexes illustrate the potential of these novel techniques to study hitherto unobserved (and unobservable) higher-order structures of proteins.     

Magnetic resonance tracking of copper ion fixation on the surface of carboxylated nanodiamonds from viewpoint of changes in carbon-inherited paramagnetism

Detonation nanodiamonds with a particle size of 5 nm and a carboxylated surface are easily modified by doubly charged copper ions to form copper chelate complexes. The concentration of copper complexes in a dry powder of such nanodiamonds is well monitored by the method of electron paramagnetic resonance, both by the signal width of intrinsic paramagnetic centers in nanodiamonds and by the signal shape for the surface Cu²⁺ ions themselves, including the set of hyperfine splitting lines for the parallel component and the line with an unresolved hyperfine structure for the perpendicular component.     

Tridentate (NNO) Schiff-base copper(II) complex: synthesis,crystal structure,and magnetic study

A new azido adduct of a tridentate Schiff-base copper(II) complex has been synthesized and characterized structurally and magnetically. X-ray single crystal structure analysis reveals that the asymmetric unit of [Cu₂(L)₂(µ_1,1-N₃)₂][Cu(L)(N₃)] (1) [HL = 1-(N-ortho-hydroxyacetophenimine)-2,2-diethyl-aminoethane] has two independent moieties. One of these forms a dimer, containing end-on azido bridges, with its center of inversion related equivalents. The complex crystallizes in monoclinic space group P₂1/c with a = 10.112(2), b = 31.938(4), c = 9.718(2) Å and β = 95.00(2)°. Variable temperature magnetic susceptibility data show antiferromagnetic interactions between copper(II) centers.     

Synthesis, crystal structure and DFT analysis of a new trinuclear complex of copper

The new trinuclear complex [Cu₂(μ-L)₂CuCl₂] has been synthesized and characterized by elemental analysis, IR, UV-Vis and X-ray spectroscopy, where L is a dianionic tetradentate Schiff base ligand with N₂O₂ donor atoms. The molecular structure of [Cu₂(μ-L)₂CuCl₂] was determined by X-ray crystallography. In the complex, the most remarkable aspect of the trinuclear complex is that it adopts a bent structure for the three copper atoms, with a Cu1Cu3Cu2 intramolecular angle of approximately 90.62(2)°. All three copper atoms are five coordinate, with a slightly distorted square pyramidal geometry. In the two terminals moieties, the basal plane of the square pyramidal is formed by two oxygen atoms and two nitrogen atoms of the Schiff base ligand, and the apical position at the Cu atom is occupied by the bridging Cl1 anion. The Cu1Cl1Cu2 angle is 110.51(5)°. The central copper atom also has a five-coordinate, slightly distorted square pyramidal geometry, with four phenolato oxygens belonging to the Schiff base ligands from Cu(salpn) units describing the square planar base and the Cl anions being apical. The optimized structure of the complex has been studied using the B3LYP/6-31G(d)/LanL2TZf level of theory. The calculation shows that all the copper atoms are five coordinate with distorted square pyramidal structures, which is consistent with experimental data.     

Synthesis,spectroscopy, X-ray crystal structure,and DFT studies on a platinum(II) Schiff-base complex

[PtCl₂(SMe₂)₂] reacts with (N,N′-bis(salicylidene)-1,2-cyclohexanediamine) to give (N,N′-bis(salicylidene)cyclohexane-1,2-diamine)platinum(II). The complex has been characterized by elemental analysis, infrared (IR), UV-Vis, and single-crystal X-ray diffraction. Pt(II) is in a square-planar environment, coordinated by a chelating N₂O₂ donor. Density functional theory (DFT) calculations such as geometry optimization, vibrational frequency, electronic properties, and natural bond orbital (NBO) have been performed for the platinum compound using the OLYP method at TZP(6-311G*) basis set. The optimization calculation shows that the geometry parameters can be reproduced with the OLYP/TZP basis set. Experimental IR frequencies and calculated vibrational frequencies support each other. Time-dependent DFT has been used for absorption wavelengths and results were compared with experimental data. Moreover, NBO analysis has been performed.     

Large Easy‐Plane Magnetic Anisotropy in a Three‐Coordinate Cobalt(II) Complex [Li(THF)4][Co(NPh2)3]

Magnetic anisotropy is the key element in the construction of single‐ion magnets, a kind of nanomagnets for high‐density information storage. This works describes an unusual large easy‐plane magnetic anisotropy (with a zero‐field splitting parameter D of +40.2 cm^?1), mainly arising from the second‐order spin‐orbit coupling effect in a trigonal‐planar Co^II complex [Li(THF)₄][Co(NPh₂)₃], revealed by combined studies of magnetism, high frequency/field electron paramagnetic resonance spectroscopy, and ab initio calculations. Meanwhile, the field‐induced slow magnetic relaxation in this complex was mainly attributed to the Raman process.     

Synthesis, crystal structure, and magnetic properties of a cobalt(II) complex with (3,5-dichloropyridin-4-yl)(pyridin-4-yl)methanol

A novel bridging ligand, (3,5-dichloropyridin-4-yl)(pyridin-4-yl)methanol (I), and its cobalt(II) complex, [Co(I)₂(NCS)₂]_n (II), were prepared. The structures of ligand I and complex II were determined by single crystal X-ray analysis. Magnetic susceptibility measurements were performed for cobalt (II) complex II. Compound I crystallised in orthorhombic space group Pbca with a = 7.6585(14) Å, b = 12.209(2) Å, c = 23.207(4) Å, V= 2170.0(7) ų and Z=8. Complex II crystallised in monoclinic space group P2₁/n with a = 13.223(8) Å, b = 16.959(10) Å, c = 13.948(8) Å, β = 115.395(10)°, V= 2826(3) ų and Z = 4. Each cobalt(II) ion is surrounded by two NCS^? anions and four pyridyl moieties from two bridging ligands. Each bridging ligand connects two neighbouring Co(II) ions to form a 2-dimensional structure. Temperature dependence of the molar magnetic susceptibilities in the temperature range of 2–300 K revealed that magnetic interactions between the cobalt ions are weak.