Crystal structure of poly(pentamethylene 2,6-naphthalate)

The crystal structure of poly(pentamethylene 2,6-naphthalate) (PPN) was determined by using X-ray diffraction and molecular modeling. The unit cell of PPN was found to be triclinic ( space group) with dimensions of a=0.457 nm, b=0.635 nm, c=2.916 nm, =121.6°, β=90.4°, γ=87.6°, and the calculated crystal density was 1.311 g cm⁻³. The unit cell contains one polymer chain with two repeating units. In the unit cell, the PPN backbone takes gauche/gauche conformation in the middle part of each pentamethylene unit, and two naphthalene rings are in face-to-face arrangement.     

Crystal structures of palladium(II) and copper(II) complexes of meso-phenyl tripyrrinone

Meso-phenyl tripyrrinone (2), which is derived directly from N-confused porphyrin by Cu(II)-assisted oxygenolysis, can serve as a metal coordination ligand using three nitrogens and one oxygen in the core. The crystal structures of Pd(II) and Cu(II) complexes show the similar square-planar N₃O-coordination but the mode of oligomeric chains formed in the crystals by π–π stacking interaction is different: zig–zag for Cu(II) and straight for Pd(II) complex.     

Caffeine in copper(II) complexes: crystal and molecular structure of di(caffeine)tetrakis(naproxenato)dicopper(II)

The crystal and molecular structure of di(caffeine)tetrakis(naproxenato)- dicopper(II) was determined by direct method and Fourier techniques. The structure was refined by full-matrix least-squares methods to a weighted R factor of 0.0705. The compound is binuclear with square pyramidal geometry at each copper(II) centre. The two copper(II) atoms are bridged by four carboxylate groups, while the apical ligands are caffeine molecules. The Cu–Cu distance is 2.649(2) Å. The Cu atoms are displaced by 0.217 Å from the plane containing four oxygen atoms bonded to Cu towards the apical caffeine molecules. The structural data are compared with those found in similar [Cu₂(RCOO)₄(caf)₂] (caf = caffeine) complexes.     

Synthesis, structure and catalytic activities for the hydrogen transfer reactions of the ruthenium(II) carbonyl chloride complexes with pyridine-2,6-diimine

Two Ru(II) carbonyl chloride complexes with pyridine-2,6-diimine, (L)Ru(CO)Cl₂ (L = 2,6-diacetylpyridinebis(2,4,6-trimethylanil), 1; L = 2,6-diacetylpyridinebis(2,6-diisopropylanil), 2) have been synthesized and characterized. The structure of compound 1 has been determined by X-ray crystallography, which show the distorted octahedral geometry around Ru(II). Complexes 1 and 2 have been proved to be active in the transfer hydrogenation of acetophenone by propan-2-ol.     

A dinuclear copper(II) compound of a bis(imidazole)-containing tripodal ligand: Crystal structure and EPR spectroscopic studies

The dinuclear compound, 1, with the molecular formula of [Cu₂(H₃L)₂(ClO₄)₂][Cu₂(H₃L)₂(MeCN)₂](ClO₄)₆ was prepared by the reaction of [bis-(1H-imidazol-2-yl)-methyl]-pyridin-2-yl-methylamine (H₃L) with copper(II) perchlorate. The asymmetric unit of the crystal structure of 1 contains two dinuclear units, [Cu₂(H₃L)₂(ClO₄)₂]²⁺ and [Cu₂(H₃L)₂(MeCN)₂]⁴⁺ (abbreviated as 1^ClO4 and 1^MeCN), respectively, and they are linked through hydrogen bonding between the oxygen atom from the axial coordinated perchlorate anions and one of the neighboring imidazole rings from 1^MeCN. EPR spectroscopic studies of 1 in MeOH by addition of bridging ligands including NaN₃ and NaOH were carried out and the reaction process was discussed.     

One-dimensional copper(II) complex containing alternate single and double end-on azide ligands: Crystal structure and magnetic characterization

A novel one-dimensional azido-bridged coordination polymer of formula [Cu₂(L)₂(H₂O)(N₃)₄]_n (1) has been synthesized and characterized crystallographically and magnetically, where L is 5-methylpyrimidin-2-amine. Complex 1 consists of 1D chain in which the Cu(II) ions with a square pyramidal geometry are alternately bridged by asymmetric single and symmetric double end-on (EO) azido ligands. Magnetic analysis reveals that the dominating ferromagnetic interaction is mediated by the symmetric double azido bridge with the exchange parameter J = 55.17 cm⁻¹.     

Capturing copper(II) ions using {Cu(tpy)(bpy)} domains

The reaction of 6,6"'-dimethyl-2,2':6',2":6",2'"-quaterpyridine (2) with 2,2':6',2"-terpyridine (tpy) and Cu(NO₃)^·3H₂O leads to the formation of [Cu(tpy)(2)]²⁺ and [Cu₂(tpy)₂(2)]⁴⁺, isolated as the hexafluoridophosphate salts. Single crystal structures of [Cu₂(tpy)₂(2)][PF₆]₄·2H₂O and [Cu(tpy)(2)][PF₆]₂·MeCN are presented and illustrate the special stability of the 5-coordinate {Cu(tpy)(bpy)}²⁺ motif in mono- and dinuclear environments.     

Crystal structure and modeling calculation of the columnar helix 2,6-Bis(imino)phenoxy iron(III) chloride

Crystal structure of novel bis(imino)phenoxychloro-iron(III) chloride demonstrated a columnar helix through hydrogen bonding of anion–cation molecules and intermolecular π–π interactions, along with the syntheses and characterization of the new compounds. A quantum-chemical single point calculations of the interaction energies were performed on the basis of the X-ray structural data.     

A novel water soluble octaazamacrocyclic dinuclear copper(II) complex with tetra-pendant arms: Crystal structure and SOD activity

A novel water-soluble octaazamacrocyclic dinuclear copper(II) complex with tetra-pendant arms, [Cu₂L] Cl₂? 5H₂O, was synthesized by [2+2] condensation between 2, 6-diformyl-4-chlorophenol and N, N, N', N'-tetrakis(2'-aminoethyl)-1, 2-diaminopropane in the presence of Cu(OAc)₂·H₂O. Single-crystal X-ray structural analysis reveals that every copper(II) adopts a trigonal bipyramid coordination configuration. Macrocyclic units are joined together by strong π–π stacking interaction with centroid–centroid distance of 3.658 Å. Water pentamers with O–O distances of 2.099–2.841 Å are observed in the complex. The activity of superoxide dismutase of the complex has been investigated by the nitro blue tetrazolium method.     

Crystal structure of the low temperature phase (II) of polytetrafluoroethylene

An electron diffraction pattern from polytetrafluoroethylene in Phase II was analysed to determine a chain conformation of 2.1598 CF₂ units per turn of the helix. A structure was established from a combination of electron and X-ray diffraction data. The structure contains an ordered repeating pattern of a left- right-handed pair of chain stems. Although the structure is ordered in three dimensions, it cannot be described meaningfully in terms of classical space group nomenclature because very small changes in the structure result in very large changes in the cell parameters. The structure has a volume of 0.03542 nm³ per CF₂ group, corresponding to a density of 2344 kg m^?3.     

Bis(pyridine-2-carboxaldehyde oxime)copper(II) sulphate as catalyst precursor in the oxidation of veratryl alcohol by dioxygen

In situ generated [Cu^II(pyridine-2-carboxaldehyde oxime)₂] complex catalyses selective oxidation of veratryl alcohol (3,4-dimethoxybenzyl alcohol) to aldehyde by molecular oxygen in aqueous solution. Under alkaline conditions, the catalyst has both oxime groups deprotonated and the solid state structure of the complex reveals a square pyramidal geometry established by two pyridine-2-carboxaldehyde oxime ligands and sulphate as a counter anion.     

Oxidative dehydrogenation of 5-(pyridine-2-yl-methyl)-2-thioxo-4-imidazolidinones in complexation reaction with copper(II) chloride

The treatment of 5-(pyridine-2-yl-methyl)-2-thioxo-4-imidazolidinones with copper(II) chloride dihydrate led to the formation of a dinuclear copper complex L₂Cu₂Cl where L is a dehydrogenated initial organic ligand. X-ray diffraction analysis indicated that the starting 3,5-dihydro-4H-imidazole-4-ones undergo oxidation in the course of the reaction with the formation of an exocyclic double bond at C5 position.     

DCC法合成烟酸对乙酰氨基苯酯及其晶体结构表征

烟酸与对乙酰氨基苯酚在无水丙酮溶液中,在DCC作脱水剂、DAMP作催化剂作用下,常温反应3 h,收率82.1%,操作简单,条件温和,收率高。同时对其进行红外、核磁和X-射线衍射测定,结果表明,其分子式为C14H12N2O3,分子量为256.26,a=0.554 7(11)nm,b=2.733 6(5)nm,c=0.830 30(17)nm,α=90°,β=94.14(3)°,γ=90°,属于单斜晶系C/c空间群。     

Adsorption of copper(II) and EDTA‐chelated copper(II) onto granular activated carbons

Waste streams generated by electroless copper plating in the printed circuit boards manufacturing industry often contain copper complexed by strong chelating agents such as EDTA. The consequence of metal complexation by chelating agents is that alternative treatment to chemical precipitation is often necessary to achieve the low metal concentrations required by increasingly stringent environmental regulations. This paper examines the feasibility of using activated carbon to remove EDTA‐chelated copper(II) species as well as free copper(II) ions from aqueous solution. The adsorption characteristics of copper(II) and EDTA‐chelated copper(II) on two granular activated carbons prepared from coal and coconut shell were evaluated. Adsorption equilibrium data of copper(II) on the two carbons corresponded well to the Langmuir model. The coconut shell‐based carbon exhibited a greater adsorption capacity for copper(II) than the coal‐based carbon under similar experimental conditions. Solution pH had a considerable influence on copper(II) adsorption by the two carbons. Low adsorption levels of copper(II) at pH 3 and high adsorption levels in the pH range of 4–6 were observed. However, a reverse adsorption trend was observed when the chelating agent EDTA was added to the copper(II) solution. Adsorption of EDTA‐chelated copper(II) by the two carbons was higher at pH 3 than at pH 6. The contrasting adsorption behaviour of copper(II) ions and EDTA‐chelated copper(II) species can be readily explained in terms of electrostatic interaction in that solution pH influences the surface charge of the carbons as well as the charge property of copper(II) ions and EDTA‐chelated copper(II) species. © 2000 Society of Chemical Industry     

Oxidative coupling of 2,6‐dimethylphenol catalyzed by copper(II) complexes in aqueous solution

The oxidative coupling reaction of 2,6‐dimethylphenol (DMP) with H₂O₂ catalyzed by four copper(II) complexes was investigated in Tris‐HNO₃ buffer solution at 25°C. The kinetics of formation of diphenoquinone (DPQ, 4‐(3,5‐dimethyl‐4‐oxo‐2,5‐cyclohexadienylidene)‐2,6‐dimethyl‐2,5‐cyclohexadienone) from DMP was studied in detail. The kinetic parameters k₂ and K_m were obtained in the pH range of 6.0–9.0. The copper(II) complexes exhibited the optimal catalytic activity at around pH 7.0. The pH effect was reasonably explicated by the catalytic kinetic model suggested in this work. The catalytic mechanism was discussed. The deprotonized associated radical LCu^I(OH^?)‐^?OOH was suggested as the possible predominant species to oxidize DMP. The C? C and C? O coupling products were analyzed and the ratio of poly (2,6‐dimethyl‐1,4‐phenylene ether) (PPE) to DPQ was also evaluated. Both in weak acidic (pH < 6.5) and in alkaline aqueous solution (pH > 8) were suitable to the C? O coupling reaction in our catalytic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,crystal structure and nonlinear optical property of cadmium(II) and copper(II) complexes with novel chiral ligand

Two novel metal-organic frameworks (MOFs) [Cd(3-MPCA)₂ · H₂O] · 5.5H₂O (1) and [Cu(3-MPCA)₂ · H₂O] · 4H₂O (2) [3-MPCA⁻ = (1R, 3S)-1,2,2-trimethyl-3-(pyridin-3-ylmethylcarbamoyl)cyclopentanecarboxylate] were hydrothermally synthesized and characterized by X-ray crystallography. Complexes 1 and 2 are homochiral and have similar one-dimensional (1D) chain structure, which are further linked by strong hydrogen bonds to give 3D architectures. There are oxygen hexmers and heptamers from water molecules and carbonyl group in 1 with O⋯O distances and O–O–O angles comparable to the corresponding values in ice. Nonlinear optical measurements on powdered sample of 1 and 2 revealed that they display second-harmonic-generation (SHG) response of 0.8 and 0.3 times of that for urea, respectively.     

Synthesis,crystal structure and magnetic properties of a new cyanide-bridged mixed-valence copper(I)/copper(II) clathrate

A unique cyanide-bridge mixed-valence Cu^I/Cu^II clathrate of formula [Cu^I₂(CN)₃][{Cu^II(tren)}₂(μ-CN)](CF₃SO₃)₂ [tren = tris(2-aminoethyl)amine] containing cyanide-bridged [{Cu^II(tren)}₂(μ-CN)]^3 + binuclear cations stacked between anionic honeycomb layered copper(I) cyanide networks, was synthesized and structurally characterized by single crystal X-ray diffraction. Variable-temperature magnetic susceptibility studies showed that the cyanide bridge mediates a strong antiferromagnetic interaction between the copper(II) centers (J = − 160 cm^− 1, the spin Hamiltonian being defined as H = −J S_A⋅S_B).     

Towards a protocol for solution structure determination of copper(II) proteins: the case of Cu(II)Zn(II) superoxide dismutase

We have developed an optimized protocol to solve the solution structure of copper(II) proteins. After assignment, proton-proton NOEs are used for the shell where 1H spectra are conveniently observed. In a shell closer to the metal ion, 13C NMR spectra with band-selective homonuclear decoupling provide the assignment of all nuclei except for those of the metal ligands. A convenient method for the measurement of 13C longitudinal-relaxation rates (R1) of carbonyls and carboxylate moieties is proposed. 1H NOEs and 1H and 13C R1 data are sufficient to produce a good/reasonable solution structure, as demonstrated for a monomeric species of superoxide dismutase, a 153-residue protein.     

The crystal structure of poly(2,6-naphthalenebenzobisthiazole)

The crystal structure of poly(2,6-naphthalenebenzobisthiazole) (Naph-2,6-PBT) was studied using X-ray and molecular modeling methods. The X-ray pattern of the annealed Naph-2,6-PBT fiber showed several Bragg reflections as well as streaks along the layer lines indicating that the registry between adjacent chains exists in the crystal with a great deal of axial disorder. Disordered structure in the crystal was fitted into the triclinic unit cell with the unit cell parameters of a=6.78 Å, b=3.46 Å, c=14.61 Å, α=88.0°, β=114.7°, and γ=94.8° with space group. The calculated density, 1.68 g/cm³ was comparable with the observed density, 1.56 g/cm³. The Δc/c (staggering ratio) representing the registry between the adjacent chains in the ac plane was −0.19, which is in good agreement with the energy calculation although another local energy minimum was found at Δc/c=0.31. The disordered structure in Naph-2,6-PBT was probably due to the discrete axial shift between Δc/c=0.31 and −0.19 in the ac plane. The LALS refinement showed that the naphthalene group was rotated by 9 (±3)° from the ac plane on the projected structure along the chain axis with a torsion angle between the naphthalene and benzobisthiazole rings of 23°.