An antiferromagnetically coupled hexanuclear copper(II) Schiff base complex containing phenoxo and dicyanamido bridges: Structural aspects and magnetic properties

A novel hexanuclear complex [{(CuL)₂Cu}₂(μ-dca)₂](ClO₄)₂·2L′(1) (where H₂L = (OH)C₆H₄C(CH₃)N(CH₂)₃NC(CH₃)C₆H₄(OH) or N,N′-bis(2-hydroxyacetophenone) propylenediimine and dca = N(CN)₂⁻ and L′ = 2-hydroxyacetophenone) has been synthesized and characterized by elemental analysis, UV-Vis, FT-IR spectroscopic and electrochemical methods. Single crystal X-ray structural characterization reveals a centrosymmetric nature of the complex unit, where the metal centers adopt distorted square-planar and distorted octahedral geometries. Structural analysis also reveals μ₂-phenoxo bridges between terminal and the central copper(II) centers of the asymmetric [(CuL)₂Cu(dca)] unit, the latter being interconnected to its symmetry related counterpart by double μ_1,5-dca bridges, leading to the hexanuclear complex ion [{(CuL)₂Cu}₂(μ-dca)₂]²⁺. Low temperature susceptibility measurements of 1 revealed the presence of strong antiferromagnetic coupling (2J = −407 cm⁻¹) between the copper(II) centers.     

Synthesis,crystal structure,and DNA binding of a new oxalato-bridged binuclear zinc(II) complex

A new binuclear zinc(II) complex bridged by μ-oxalate, and end-capped with 2,2′-bipyridine (bpy), [Zn₂(ox)(bpy)₄](ClO₄)₂ · H₂O, has been synthesized and characterized by elemental analyses, molar conductance, IR, and electronic spectra and single-crystal X-ray diffraction. The single-crystal X-ray analysis reveals that the [Zn₂(ox)(bpy)₄]²⁺ cation has two zinc(II) centers bridged by a planar bis(bidentate) oxalate group with Zn···Zn distance of 5.482(3) Å; each zinc(II) is in a distorted octahedral environment. The crystal structure is stabilized by non-classical C–H···O hydrogen bonds and π–π stacking interactions to form a 3-D supramolecular structure. The interaction of the complex with calf-thymus DNA (CT-DNA) was explored by using electronic and fluorescence spectra and viscosity measurements. The results reveal that the complex intercalates with CT-DNA with intrinsic binding constant of 4.1 × 10⁴ M^?1.     

Synthesis,crystal structure and antibacterial activity of a new binuclear copper(II) complex with N,N ′- bis ( N -hydroxyethylaminopropyl)oxamido as a bridging ligand

A new μ-oxamido-bridged dicopper(II) complex, [Cu₂(heap)](ClO₄)₂?·?2H₂O [H₂heap?=?N,N′-bis(N- hydroxyethylaminopropyl)oxamido], has been synthesized and structurally characterized by elemental analyses, molar conductance, IR and single-crystal X-ray diffraction. The single crystal X-ray analysis reveals that the asymmetric unit of the complex is composed of half a binuclear cation [Cu₂(heap)]²⁺, one perchlorate anion, and one lattice water molecule. Each copper(II) atom is tetracoordinate in a distorted square-planar geometry and the bridging ligand (H₂heap) adopts the trans conformation with an inversion centre at the middle of the C2–C2ⁱ bond. The structure cohesion is ensured by hydrogen bonding interactions, which form a two-dimensional supramolecular framework. The antibacterial assay indicates that the complex showed better activity than the ligand.     

A Computer Program for Identifying Anomalous Peaks in Automated Amino Acid Analyses

Abstract

In automated ion-exchange chromatography of amino acids utilizing spectrophotometric measurement., the ratio of the areas under the 40 mμ; and 570 mμ; absorption peak tracings has been shown to be specific for each amino acid. Symmetrical, but impure peaks have ratios deviating from these norms. A simple computer program for the rapid identification of these anomalous peaks has been designed. It is proposed as an addendum to any computer program now in use with amino-acid analyzers.     

Dependence of fluorescence properties on substitution of BaF2 for BaO in barium gallo-germanate glass

3.5 mol%, 6.5 mol%, 9.5 mol%, and 12.5 mol% BaF₂ were gradually substituted for BaO in 0.3 mol% Tm₂O₃ doped 12.5 BaO-12.5 Ga₂O₃-75 GeO₂ (BGG) glasses to study the effect of the substitution on the OH⁻ elimination and emission properties. The FTIR spectral demonstrated that the substitution effectively eliminated OH⁻ groups and 9.5 mol% BaF₂ was enough for the OH⁻ elimination. The J-O parameters of all the samples were calculated according to J-O theory. The calculation showed that the Ω₂ parameter decreased monotonically with BaF₂ content increasing, while Ω₄ and Ω₆ did not change much. The radiative lifetime increased while BaF₂ content increased as well. The emission cross section of ³F₄ → ³H₆ transition was calculated by the F-L formula. However, it decreased with the gradual BaF₂ addition.

Research Highlights

? OH⁻ groups were eliminated by the substitution of BaF₂ for BaO in (BGG) glass. ? The optimal substitution level of BaF₂ was 9.5 mol% for OH⁻ elimination. ? The Ω₂ parameter decreased monotonically by the elimination. ? The emission cross section of ³F₄ → ³H₆ transition was decreased by the substitution.     

联系数在梯形模糊数多属性决策中的应用

属性权重和属性值都是梯形模糊数的多属性决策问题是一种带有不确定性的决策,需要作不确定性分析后才能得出结论.为此把梯形模糊数表示的属性值和属性权重先用其特征函数"均值+偏差"联系数(特征联系数)表示,再利用联系数运算法则作"加权求和"运算,不仅获得与其它决策方法相同的结果,而且借助联系数中i的不同取值考察决策对象的排序变化,方法简便易行,且具有较强适用性.     

单位球上F(p,q,s)空间到β_μ空间的加权复合算子

研究了单位球上F(p,q,s)空间到β_μ空间的加权复合算子的有界性和紧性问题.利用泛函分析多复变的方法,获得了单位球上F(p,q,s)空间到β_μ空间的加权复合算子为有界算子和紧算子的充要条件.     

影响阻尼牛顿法收敛性的两个重要参数

对阻尼牛顿算法作了适当的改进,证明了新算法的收敛性.基于新算法,运用计算机代数系统Matlab,研究了迭代次数k,参数对(μ,λ)与初值x0三者间的依赖关系,研究了病态问题在新算法下趋于稳定的渐变(瞬变)过程.数值结果表明:(1)阻尼牛顿迭代中,参数对(μ,λ)与迭代次数k间存在特有的非线性关系;(2)适当的参数对(μ,λ)与阻尼因子α的共同作用能够在迭代中大幅度地降低病态问题的Jacobi阵的条件数,使病态问题逐渐趋于稳定,从而改变原问题的收敛性与收敛速度.     

New Analysis of the ν3 fundamental band of HDCO: Positions and intensities

Using high-resolution Fourier transform spectra of mono deuterated formaldehyde (HDCO) recorded in the 5.8-μm spectral range at Giessen (Germany), we carried out an extensive analysis of the strong ν₃ fundamental band (carbonyl stretching mode) at 1724.2676 cm⁻¹, starting from results of a previous analysis [J.W.C. Johns, A.R.W. McKellar, J. Mol. Spectrosc. 64 (1977) 327-339]. For this hybrid band (with both A- and B-type transitions) the analysis was pursued up to high rotational quantum numbers. In this way, it was possible to evidence a resonance which perturbs the ν₃ lines for high K_a values which is due to the existence of the 2ν₅ and ν₅ + ν₆ dark bands in the same spectral region. In addition a local resonance is perturbing the 3¹ levels in  = 8 which is due to a crossing with the 4¹ energy levels in K_a = 11. The model used to calculate the energy levels accounts for the observed A- type, B- type C-type Coriolis (and/or) Fermi resonances which couple the 3¹ and the 5¹6¹, 5², and 4¹ energy levels. However the 4¹ state is also involved in strong vibration-rotation interactions coupling the {5¹,6¹,4¹} system of resonation states of HDCO [A. Perrin, J.M. Flaud, L. Margulès, J. Demaison, H. Mäder, S. Wörmke, J. Mol. Spectrosc. 216 (2002) 214-224]. Therefore the final energy levels calculation was performed for the {5¹,6¹,4¹,3¹,5²,5¹6¹} resonating states and in this way it was possible to reproduce the observed line positions, within their experimental uncertainties. The present work also led to the determination of the intensity ratio of the B- to A-type components of the ν₃ band I_A/I_B ∼24 band from spectral fittings performed in several parts of the observed spectrum. Finally, using the 5.8 μm band intensity available in the literature we generated, for the first time, a list of line parameters (positions and intensities) for the 5.8 μm region of HDCO.     

高功率腔内双共振2μm光参量振荡器特性研究

报道了一种稳定的高功率双共振2?μm 光参量振荡器（OPO）. 该OPO使用调Q的线偏振全固态Nd∶YAG激光器作为抽运源,利用双棒串接补偿热致双折射和双Q开关正交放置技术提高了抽运源的输出功率和光束质量,通过腔内抽运单块KTP晶体实现了稳定的高功率2?μm 激光输出. 在调Q频率为5?kHz时,得到了295 W的2?μm 激光输出. 研究了OPO输出功率同KTP晶体温度和声光Q调制频率的关系,并测量了在29W时2?μm激光的功率稳定性. 在1 h内该OPO的功率起伏小于1.4%. 关键词： 光参量振荡器 2?μm激光器 KTP晶体 双共振