Cobalt(II), nickel(II) and copper(II) complexes of a Schiff base ligand: synthesis,structural characterization and luminescence properties

A Schiff base ligand (HL), 2,4-dimethoxy-N-(5-chloro-2-hydroxybenzylidene)-benzenamine, derived from 5-chloro-2-hydroxybenzaldehyde and 2,4-dimethoxyaniline, and its metal complexes [Co(L)₂]·CH₃OH (1), [Ni(L)₂] (2), [Cu(L)₂] (3) have been synthesized. The compounds were characterized by analytical and spectroscopic methods. In addition, the structures of the Schiff base HL and its Co(II) complex were determined by single-crystal X-ray analysis. The Co(II) center is six-coordinate, being coordinated to two imine nitrogen, two phenolate oxygen and two methoxy oxygen atoms of two crystallographically independent Schiff base ligands. Luminescence properties of HL and its complexes were investigated both in solution and in the solid state.     

Surfactant-assisted polyol preparation of nickel powders with different morphologies

Sub-micrometer nickel powders of controlled size and morphology were produced by a surfactant-assisted polyol method, using ethylene glycol (EG) as solvent and reductant in the presence of sodium dodecyl sulfate (SDS) surfactant and NaOH. The resultant Ni powders were characterized by XRD, SEM, EDS, and FTIR. Spherical, hexagonal, and triangular fcc Ni powders from 0.30 to 0.60 μm were obtained in the presence of SDS; irregular spherical fcc Ni powders were obtained in its absence. The concentrations of SDS, NaOH and Ni(CH₃COO)₂·4H₂O greatly influence the product morphology and size.      

Syntheses, characterization, antimicrobial and genotoxic activities of new Schiff bases and their complexes

Two new Schiff base ligands (L¹, L²) have been prepared from the reaction of 2,6-diacetylpyridine and 2-pyridinecarboxyaldehyde with 4-amino-2,3-dimethyl-1-phenyl-3-pyrozolin-5-on, and their Co(II), Cu(II), Ni(II), Mn(II), and Cr(III) metal complexes have also been prepared. The complexes are formed by coordination of N and O atoms of the ligands. Their structures were characterized by physico-chemical and spectroscopic methods. The analytical data shows that the metal to ligand ratio in the Schiff base complexes is 1:2. The Schiff base ligands and all complexes were evaluated for their in vitro antibacterial and antifungal activities by the disc diffusion method. In addition, the genotoxic properties of the ligands were studied.     

Calculations of Isoelectronic Series of He Using Noninteger n‐Slater Type Orbitals in Single and Double Zeta Approximations

Using integer and noninteger n-Slater type orbitals in single- and double-zeta approximations, the Hartree-Fock-Roothaan calculations were performed for the ground states of first ten cationic members of the isoelectronic series of He atom. All the noninteger parameters and orbital exponents were fully optimized. In the case of noninteger n-Slater type orbitals in double zeta basis sets, the results of calculations obtained are more close to the numerical Hatree-Fock values and the average deviations of our ground state energies do not exceed 2×10^－6 hartrees of their numerical results.     

Degree of Approximation for Bivariate Chlodowsky–Szasz–Charlier Type Operators

We consider a combination of Chlodowsky polynomials with generalized Szasz operators involving Charlier polynomials. We give the degree of approximation for these bivariate operators by means of the complete and partial modulus of continuity, and also by using weighted modulus of continuity. Furthermore, we construct a GBS (Generalized Boolean Sum) operator of bivariate Chlodowsky–Szasz–Charlier type and estimate the order of approximation in terms of mixed modulus of continuity.     

《Organic Stereochemistry---Experimental and Computational Methods》(有机立体化学---实验与计算方法)书评

正河北大学药学院朱华结教授编著的《Organic Stereochemistry—Experimental and Computational Methods》(有机立体化学—实验与计算方法)[1],由世界著名出版社Wiley-VCH正式面向全球出版发行。应作者邀请我很高兴向大家推荐这本著作。手性是自然界普遍而重要的特征。自然界中很多分子虽然原子组成相同,但其空间结构完全不同,呈实物与镜像不重合的关系,因而被形象地     

On {\left(1,3 \right) }-Cartan null Bertrand curves in semi-Euclidean 4-space with index 2

In this paper, we study generalized Cartan null Bertrand curves in semi-Euclidean 4-space \({\mathbb{E}_{2}^{4}}\) with index 2.     

Phase equilibria of (water + levulinic acid + dibasic esters) ternary systems

Liquid–liquid equilibrium (LLE) data of the solubility (binodal) curves and tie-line end compositions were examined for mixtures of {(water (1) + levulinic acid (2) + dimethyl succinate or dimethyl glutarate or dimethyl adipate (3)} at 298.15 K and 101.3 ± 0.7 kPa. The reliability of the experimental tie-line data was confirmed by using the Othmer–Tobias correlation. The LLE data of the ternary systems were predicted by UNIFAC method. The LLE data were correlated fairly well with UNIQUAC and NRTL models, indicating the reliability of the UNIQUAC and NRTL equations for these ternary systems. The best results were achieved with the NRTL equation, using non-randomness parameter (α = 0.3) for the correlation. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the solvents.     

Structural and aromatic aspects for tautomerism of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa-2,4-dienone

The molecular and crystal structure of (Z)-6-((4-bromophenylamino)methylene)-2,3-dihydroxycyclohexa-2,4-dienone were determined by single crystal X-ray diffraction and spectroscopic methods. Molecules of the compound can be regarded as a resonance hybrid of cis-keto tautomer and zwitterionic form. Pairs of molecules of the compound generate pseudocyclic centrosymmetric R₂² (10) R_{2}^{2} (10) supramolecular synthons with the aid of O–H···O type intermolecular H-bonds. Stacking of R₂² (10) R_{2}^{2} (10) synthons along b-axis is stabilized by π···π interactions. Changes in both covalent topology and molecular geometry of the compound accompanying proton transfer were monitored by a relaxed PES scan with respect to hydroxyl bond length used as redundant internal coordinate. Quantum chemical studies at 6-311 + G(d,p) level reveal that bond lengths which are indicative to tautomerization process cannot reach their expected values even if proton transfer occurs in gas phase and pseudo-aromatic chelate ring formation has primary effect on the stabilization of NH tautomer. Resonance-assisted intramolecular H-bond affects the electronic state of its neighboring aromatic fragments.