{2,2′‐[1,1′‐(4‐Aza­heptane‐1,7‐diyl­dinitrilo)diethyl­idyne]­diphenolato}­copper(II)

The quinquedentate ligand 2,2′‐[1,1′‐(4‐aza­heptane‐1,7‐diyl­dinitrilo)diethyl­idyne]diphenol in the title compound, [Cu(C₂₂H₂₇N₃O₂)], furnishes an N₃O₂ donor set, which results in a distorted square‐pyramidal coordination; the two O and two imine N atoms lie in the basal plane, while the secondary amine N atom of the ligand occupies the axial position. The axial Cu—N bond is 0.33 Å longer than the average of the equatorial bonds, and the O atoms are trans. The symmetry of the mol­ecule is lowered by the twist–boat and chair conformations adopted by the two CuNN chelate rings. The complex contains two intra­molecular C—H⋯O inter­actions, and two mol­ecules of the complex are linked into a dimer by means of moderate N—H⋯O hydrogen bonds. Spectroscopic evidence supports the presence of hydrogen bonds.     

Promising new catalytic properties of a Co (II)-carboxamide complex and its derived Co3O4 nanoparticles for the Mizoroki-Heck and the Epoxidation reactions

The new Co(II) - carboxamide complex ( 1 ) and Co₃O₄ nanoparticles ( 2 ), by way of thermal decomposition of ( 1 ) have been efficiently synthesised in the environment-friendly. X-ray diffraction reveals a slightly distorted octahedral coordination of cobalt (four nitrogens and two oxygens) in ( 1 ) and regular octahedral or tetrahedral ones (oxygens only) in ( 2 ). The investigation of ( 1 ) and ( 2 ) in the Mizoroki-Heck and epoxidation of alkens reactions showed them both to be powerful, green and inexpensive catalysts.     

Straightforward Method for the Preparation of Lysine-Based Double-Chained Anionic Surfactants

Double-chained surfactants with potential biocompatibility have been prepared in high yields by lysine acylation with four natural saturated fatty acids (C₆ to C₁₂) and with cis-undec-5-enoic acid. The surfactants were found to assemble into nanotubules in aqueous medium and, when mixed with a commercial cationic surfactant, to spontaneously form liposomes.     

Preparation and evaluation of an ion imprinted sol–gel material for selective solid-phase extraction of Ni(II)

An ion imprinted silica sorbent was prepared using a sol–gel process for selective extraction of Ni(II) ions from water samples. Bis(dibenzoylmethanto)nickel(II) complex was used as template; phenyltrimethoxysilane and 3-aminopropyltriethoxysilane as functional monomers and tetraethylorthosilicate as reticulating agent. The material was packed in solid-phase extraction (SPE) column. The effect of sampling volume, elution conditions, sample pH and sample flow rate on the extraction of Ni ions from water samples were studied. The relative selectivity coefficients of imprinted sorbent for Ni(II)/Co(II), Ni(II)/Cu(II) and Ni(II)/Cd(II) were 23.7, 30.3 and 24.4, times greater than non-imprinted sorbent, respectively. The relative standard deviation of the eight replicate determinations of Ni(II) was 4.2%. The detection limit was 0.9 µg L^?1 using flame atomic absorption spectrometry. The developed method was successfully applied to the determination of trace nickel in water samples.     

Synthesis,crystal structure,and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H₂salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H₂Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.     

Benign synthesis of carboxamide ligands,H2Me2bqb and H2Me2bpb. Preparation,characterization and electrochemistry of Ni(II) complexes: The crystal structure of [Ni(Me2bqb)]

A novel and highly efficient approach for the synthesis of H₂Me₂bqb and H₂Me₂bpb using ionic liquid as an environmentally benign reaction medium has been developed, eliminating the need for the pyridine as a toxic solvent. The Ni(II) complex of the dianionic ligand Me₂bqb²⁻, [Me₂bqb²⁻ = 1,2-bis(quinoline-2-carboxamide)-4,5-dimethyl-benzene dianion], has been synthesized and characterized by elemental analyses and spectroscopic methods, and the crystal and molecular structure of [Ni(Me₂bqb)] (1), has been determined by X-ray crystallography. The complex exhibits distorted square-planar NiN₄ coordination geometry with two short and two long Ni–N bonds (Ni–N ∼1.85 and ∼1.96 Å, respectively). The electrochemical behavior of [Ni(Me₂bqb)] (1), has been studied by cyclic voltammetry and compared with the analogous complex, [Ni(Me₂bpb)] (2).     

Influence of the thermal treatment in the crystallization of NiWO4 and ZnWO4

NiWO₄ and ZnWO₄ were synthesized by the polymeric precursor method at low temperatures with zinc or nickel carbonate as secondary phase. The materials were characterized by thermal analysis (TG/DTA), infrared spectroscopy, UV–Vis spectroscopy and X-ray diffraction. NiWO₄ was crystalline after calcination at 350 °C/12 h while ZnWO₄ only crystallized after calcination at 400 °C for 2 h. Thermal decomposition of the powder precursor of NiWO₄ heat treated for 12 h had one exothermic transition, while the precursor heat treated for 24 h had one more step between 600 and 800 °C with a small mass gain. Powder precursor of ZnWO₄ presented three exothermic transitions, with peak temperatures and mass losses higher than NiWO₄ has indicating that nickel made carbon elimination easier.     

Influence of the precursor salts in the synthesis of CaSnO<Subscript>3</Subscript> by the polymeric precursor method

CaSnO₃ was synthesized by the polymeric precursor method, using different precursor salts as (CH₃COO)₂Ca·H₂O, Ca(NO₃)₂·4H₂O, CaCl₂·2H₂O and CaCO₃, leading to different results. Powder precursor was characterized using thermal analysis. Depending on the precursor different thermal behaviors were obtained. Results also indicate the formation of carbonates, confirmed by IR spectra. After calcination and characterization by XRD, the formation of perovskite as single phase was only identified when calcium acetate was used as precursor. For other precursors, tin oxide was observed as secondary phase.     

Synthesis,Characterization, and Crystal Structures of [Cu(ca2en)2]ClO4, and [Cu(ca2en)(PPh3)2]ClO4 Complexes

Synthesis, spectroscopy, and crystal structures of [Cu(ca₂en)₂]ClO₄ ( 1 ) and [Cu(ca₂en)(PPh₃)₂]ClO₄ ( 2 ) (ca₂en=N,N′‐bis(trans‐cinnamaldehyde)ethylenediimine) are reported. Compound 1 crystallizes in the orthorhombic space group Pbca, with a=12.5647(7), b=21.8203(11), c=27.992(2) Å, V=7674.3(7) ų, Z=8. Compound 2 crystallizes in the triclinic space group P , with a=13.0540(11), b=14.2935(13), c=14.9863(13) Å, α=84.130(2), β=69.761(2), γ=87.749(2)°, V=2609.8(4) ų, Z=2. The coordination polyhedron about the Cu^I center in the two complexes is best described as a distorted tetrahedron. The ¹H‐NMR and electronic spectra of these complexes are also reported and discussed. The cyclic voltammetry of the complexes indicate a quasireversible redox behavior for complex 1 (E_1/2=0.51 V). However, complex 2 displays an irreversible oxidation wave at 0.91 V. A weak emission is observed for complex 2 in CHCl₃ at room temperature.