Synthesis and Reactivity of Mg(II)–Fe(II)–Fe(III) Hydroxycarbonates

Green rust-like compounds (GRs) were discovered as natural minerals in various hydromorphic soils, where anoxic conditions allow their stability. They may control some redox processes in aquifers and participate to the transformation of various pollutants. Since Mg(II) cations are present in the fields where GRs were discovered, a partial substitution of Mg(II) to Fe(II) leading to intermediate compounds between GRs and usual Mg(II)–Fe(III) hydroxysalts is suspected. Mg(II)–Fe(II)–Fe(II) hydroxycarbonates can be obtained as intermediate oxidation products of (Mg, Fe)(OH)₂ in carbonate-containing aqueous media obeying to [Fe^II _4(1–x)Mg^II _4x Fe^III ₂(OH)₁₂]²⁺ [CO₃ ^2– nH₂O]^–2. TMS spectra at 12 K are similar to those of GRs, i.e., two quadrupole doublets, one due to Fe(II) with a large isomer shift =1.29 mms^–1 (with respect to -iron at room temperature) and quadrupole splitting E _Q=2.76 mms^–1, the other one due to Fe(III) with smaller hyperfine parameters =0.49 mms^–1 and E _Q=0.44 mms^–1. Fe(II) ions oxidise rapidly into Fe(III) with dissolved O₂. The reactivity is similar to that of Fe(II)–Fe(III) hydroxysalts GR, and thus the potential of Mg(II)–Fe(II)–Fe(III) compounds for reducing pollutants.     

On the electronic structure of N,N′-ethylenebis(acetylacetonatiminato)Co(II), Co(II)acacen

Single crystal E.P.R. and cobalt ENDOR measurements on N,N′-ethylenebis(acetylacetonatiminato)Co(II), Coacacen, diluted in Niacacen·1/2 H₂O are reported. Forbidden Δm _Co = 1,2 transitions in the E.P.R. spectra have been observed. The g-tensor (E.P.R.) and the cobalt hyperfine and quadrupole tensors (ENDOR) have been determined. The g- and cobalt hyperfine tensors are discussed. They support the |² A ₂,yz? groundstate proposed for four coordinated low-spin Schiff base complexes of cobalt(II). The measured quadrupole coupling is also compatible with a |² A ₂,yz? groundstate, if anisotropic contraction of the cobalt 3d orbitals is taken into consideration.     

Synthesis and Spectral Studies of Novel Co(II), Ni(II), Cu(II), Cd(II), and Fe(II) Metal Complexes with N-[5′-Amino-2,2′-bis(1,3,4-thiadiazole)-5-yl]-2-hydroxybenzaldehyde Imine (HL)

Co(II), Ni(II), Cu(II), Cd(II), and Fe(II) complexes with Schiff base derived from 2-amino-5-(2-amino-1,3,4-thiadiazolyl)-1,3,4-thiadiazole (1) and salicylaldehyde have been prepared. The ligand and its complexes have been characterized by IR, ¹H NMR spectra, elemental analyses, magnetic susceptibility, UV-Vis. and thermogravimetry–differential thermal analysis (TGA-DTA). The analytical data show 1:2 metal-to-ligand ratio for Co(II), Ni(II), Cd(II), and Fe(II) and 2:2 metal-to-ligand ratio for Cu(II) complexes. The suggested structures for the N-[5′-Amino-2,2′-bis(1,3,4-thiadiazole)-5-yl]-2-hydroxybenzaldehyde Imine (HL) complexes of Fe(II), Co(II), and Cd(II) are octahedral, for the Ni(II) complex is tetrahedral, and for the Cu(II) complex is square-planar     

自由表面磁流体射流不稳定性分析(II)

用微分解析方法分析了自由表面磁流体射流在两个非均匀、相互垂直的横向磁场中的稳定性行为。获得了在给定射流初始速度分布和磁场分布条件下射流的速度空间分布表达式;分析了射流扭转及向外溅射的位置。     

Electronic and Resonance Raman Spectra of the μ-tris(Bipyrazine)ruthenium(II)-Hexaquis{ruthenium(II)EDTA} Supramolecular Complex

Abstract

Resonance Raman and electronic spectra of the μ-tris(bipyrazine)ruthenium(II)-hexaquis{ruthenium(II)EDTA} supramolecular complex are reported in this paper. Excitation in the 457–676 nm range leads to the selective enhancement of the Ru-bipyrazine vibrational peaks according to distinct patterns, supporting the assignment of the absorption bands at 670 and 490 nm as charge-transfer (MLCT) transitions from the [Ru^IIEDTA] d_π orbitals to the π₁? and π₂? LUMO levels of the bipyrazine ligand. A vibronic coupling mechanism involving the two excited states is suggested for the excitation at 490 nm. The occurrence of MLCT transitions in the [Ru(bpz)₃]²⁺ central unity, around 440 nm, is supported by the Raman and fluorescence excitation profiles.     

Red-Emitting Ru(II) Metal–Ligand Complexes

A series of Ru(N–N)₂(dcbp or mcmabp) complexes were synthesized where N-N represents a diimine ligand, dcbp is 4,4-dicaboxylic 2,2-bipyridine, and mcmabp is 4,4-2,2-bipyridine monocarboxy amide. The N-N ligand was either 2,2-bipyridine (bpy), 4,4-dimethyl-2,2-bipyridine (dmbp), or 4,4,5,5-tetramethyl-2,2-bipyridine (tmbp). We observed a red shift in both the absorption and emission with the presence of dcbp in the mixed ligand complex when compared to Ru(bpy)₃. Conversion of one of the carboxylic groups in dcbp to amide resulted in further red shifts. A red shift in the absorption and the emission was also observed with increasing numbers of electrons donating methyl substitutions on bpy. The lifetimes of the complexes decreased as expected with the red shift emission. The tris heteroleptic Ru (tmphen)(tmbp)(dcbp or mcmabp) were the most red-shifted among the complexes. Because of the red shift in the absorption, the maxima in the fundamental anisotropies of the mixed ligand Ru complexes are now coincident with the maxima in the absorption. Overall we have been able to make an Ru complex which emits at about 700 nm in all aqueous environment and has a lifetime of about 220 ns.     

高温超导体磁通动力学和混合态相图(II)

文章简要介绍了高温超导体磁通动力学和混合态物理在过去十余年的发展.高温超导体由于其自身的一些特点,使得它与常规超导体相比较拥有极其丰富的相图,磁通动力学也表现出了非常丰富的研究内容,很多新的概念被提出,新的现象被观察到.比如说涡旋玻璃态,集体钉扎和蠕动,磁通格子的一级和二级熔化相变,布拉格玻璃,峰值效应,二维涡旋饼态,Josephson 磁通运动等等,均是在高温超导体发现之后提出来的新的概念或新发现的现象.有些研究结果目前尚无定论,如关于涡旋玻璃态存在与否的争论至今仍然在进行,但是这些研究内容无疑会大大促进超导物理的发展.高温超导体磁通动力学纷繁复杂的研究内容可以归结为三个相互关联的数字：Ginzburg数(Tc/H2cεζ3)2/2,量子电阻Qu=(e2/)(ρn/εζ),和临界电流的比值jc/j0,这里ζ是相干长度,Hc是热力学临界磁场,ε是有效质量的各向异性度,ρn是正常态电阻率,jc是零温临界电流,j0是拆对临界电流.对于高温超导体前两个数值（Ginzburg数和量子电阻）很大,而临界电流比值较小,因此导致有强的热涨落和量子涨落,以及很强的磁通运动行为（对应小的实测临界电流）.磁通动力学的研究从更深层次影响超导体的临界电流问题和强电应用的发展,最后简要地介绍了这方面的情况.     

高温超导体磁通动力学和混合态相图(II)

(上接2006年第1期第16页)5涡旋态相图的发展随着理论和实验工作的不断进展,高温超导体混合态相图变得丰富多彩.首先在涡旋玻璃态理论出现后,相图就较常规超导体有了很大的变化.在常规超导体中,相图上就只有两根标志相边界的线,即上临界场Hc2(T)和下临界场Hc1(T).在Hc2(T)和Hc1(T)之间就是混合态.由于涨落较弱,Hc2(T)和磁通运动的不可逆线Hirr(T)很靠近.而高温超导体中由于涨落较强,Hc2(T)以下较大的区域内形成了涡旋液态,而Hirr(T)以下才能形成涡旋固态(可以是涡旋玻璃或磁通格子有序态).在下临界场Hc1(T)附近,如果结构无序较少,则…     

The EPR Spectrum of Di-μ-(pyridine N-oxide) bis [bisnitrato(pyridine N-oxide)copper(II)] in the Corresponding Zinc(II) Crystal

It has been shown^1–3 that the exchange interactions in the dimeric⁴ complex di-μ-(pyridine N-oxide) bis [bisnitrato(pyridine N-oxide) copper(II)], [Cu(pyO)₂]₂ lead to a triplet ground state for the copper(II) pairs. The triplet state epr spectrum has been observed^1,3,5,6 for a powdered sample of the complex coprecipitated with the corresponding zinc(II) complex, and the computer simulation of this spectrum has been carried out by two different groups^3,5,6. As is often the case when dealing with spectra of powdered samples, there exist ambiguities with the spectrum of [Cu(pyO)₂-(NO₃)₂]₂ since all of the resonances were not observed, and consequently, the interpretation and values of the parameters remain in question. It was felt that examination of the epr spectra of single crystal samples should permit a rigorous analysis of this problem.     

Highly efficient simultaneous ultrasonic-assisted adsorption of Pb(II), Cd(II), Ni(II) and Cu (II) ions from aqueous solutions by graphene oxide modified with 2,2′-dipyridylamine: Central composite design optimization

In present work, a graphene oxide chemically modified with 2,2′-dipyridylamine (GO-DPA), was synthesized by simple, fast and low-cost process for the simultaneous adsorption of four toxic heavy metals, Pb(II), Cd(II), Ni(II) and Cu(II), from aqueous solutions. The synthesized adsorbent was characterized by FT-IR, XRD, XPS, SEM and AFM measurements. The effects of variables such as pH solution, initial ion concentrations, adsorbent dosage and sonicating time were investigated on adsorption efficiency by rotatable central composite design. The optimum conditions, specified as 8 mg of adsorbent, 20 mg L⁻¹ of each ion at pH 5 and short time of 4 min led to the achievement of a high adsorption capacities. Ultrasonic power had important role in shortening the adsorption time of ions by enhancing the dispersion of adsorbent in solution. The adsorption kinetic studies and equilibrium isotherms for evaluating the mechanism of adsorption process showed a good fit to the pseudo-second order and Langmuir model, respectively. The maximum adsorption capacities (Q_m) of this adsorbent were 369.749, 257.201, 180.893 and 358.824 mg g⁻¹ for lead, cadmium, nickel and copper ions, respectively. The removal performance of adsorbent on the real wastewater samples also showed the feasibility of adsorbent for applying in industrial purposes.     

Interaction of β-cyclodextrin with mercury(II) nitrate

The interaction of β-cyclodextrin with mercury(II) nitrate has been studied using UV, IR, and ¹H NMR spectroscopy, elemental analysis, and quantitative chemical analysis. The optimum conditions for complex formation were established. The stability constant of the 1:1 inclusion complex of β-cyclodextrin and nitrate was calculated. The formation of supermolecules of composition C₄₂H₇₀O₃₅·3Hg(NO₃)₂ in solution and on a silica surface chemically modified with β-cyclodextrin was shown. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 4, pp. 476–481, July–August, 2008.     

Semiempirical assignment of the electron transitions in manganese(II)-doped II–VI compounds

The electron transitions in manganese(II)-doped II–VI compounds have been assigned by the Angular Overlap Model (AOM). The extracted AOM and electron repulsion parameters are applied to assess the covalency of the respective manganese-ligand bonds. A comparison with Crystal Field Theory (CFT) is made in order to demonstrate the advantages offered by the AOM. The Dq values for Mn(II) in CdS and CdSe were found by interpolation from the Dq vs R⁻⁵_ml relation.     

Spin-glass state and ferromagnetic order in Cu(II)－Fe(III) cyanides

The static and dynamic magnetic properties of a Prussian blue analogue, molecular magnet Cu^Ⅱ_{3}[Fe^Ⅲ(CN)_6]_2·3NH_3·6H_2O were investigated in detail. The H dependence of the linear AC susceptibility, the irreversibility in the field-cooled (FC)/zero-field-cooled (ZFC) magnetization (M_{FC}/M_{ZFC}) and the relaxation of M_{ZFC} suggest that the magnetic system can be visualized as containing a ferromagnetic cluster of spin below T_C, mixed with small spin-glass clusters formed below temperature T_g less than T_C. The observed magnetic properties are explained with a ferromagnetic-spin-glass phase model. The magnetic ordering of the sample occurs below 19.8K.     

The Spectrochemical Properties of bis-(α-Methioninephosphonato)Copper(II) in Aqueous Solution

The combined results of spectrophotometric measurements and e.s.r. spectra, as well as those obtained from potentiometric titration studies, are used to determine the structure of the individual complex species formed between copper(II) ion and 1-amino-3-methylthiopropane-phosphonic acid (α-MetP) in aqueous solution. The e.s.r. parameters are typical for CuN₂O₂ coordination geometries. The d-d absorption spectrum of [Cu(α-MetP)₂]^2-chromofore in aqueous solution has been treated by the Angular Overlap Model in C_2h, symmetry. Low-symmetry splittings of the broad asymmetric absorption band in the measured spectrum were found by Gaussian analysis. The effect of the σ-and π-bonding of bidentate ligand upon the central ion d-orbital energies is destribed in a ligand-field framework.     

Synthesis and Spectroscopic Characterizations of New Mercury(Ⅱ), Cerium(Ⅲ), and Thorium(Ⅳ) Captopril Drug Complexes

In this article, three types of metal ions with different oxidation state as mercury(Ⅱ), cerium(Ⅲ) thorium(Ⅳ) have been reacted with captopril drug(CAP). The isolated solid complexes were explained using elemental analysis, conductance measurements, infrared and ~1H-NMR spectroscopy as well as the thermo gravimetric(TG/DTG) analysis. The micro analytical and spectroscopic results for all CAP complexes were agreement with the speculated structures. The stoichiometry for divalent Hg~(2+), trivalent Ce~(3+) and tetravalent Th~(4+) metal ions with CAP ligand was established with 1∶2(M~(n+):CAP) molar ratio. The qualitative analysis showed that in case of the mercury(Ⅱ) complex, the chloride ions didn't involved in the complexity, suggesting formula [Hg(CAP)_2] in neutral form. However, regarding both Ce(Ⅲ) and Th(Ⅳ) complexes as [Ce(CAP)_2(NO_3)]·3 H_2O and [Th(CAP)_2(NO_3)_2(H_2O)]·3 H_2O formulas, the nitrate group is existed inside the coordination sphere. The infrared analysis data proved that CAP drug act as a bidentate ligand with the metal ions of Ce(Ⅲ) and Th(Ⅳ) through oxygen carbonyl group ■ and oxygen of the deprotonated carboxylic COOH group, while for the Hg(Ⅱ) complex, the CAP acts as a bidentate ligand through oxygen of ■ group and sulfur atom of the deprotonated —SH group. Thorium(Ⅵ) complex has a nine-coordinate geometry, while Hg(Ⅱ) and Ce(Ⅲ) have a four and six-coordination behaviors respectively. The ~1H-NMR data of the CAP compound has a singlet sharp signal at 1.90 ppm due to the proton of —SH group, this peak absent in the spectrum of the Hg(Ⅱ) CAP complex upon the deprotonated of thiol group.     

关于物理学为经济建设服务的问题(II)

３．光学与以上讲的气体和凝聚态物质不同,光和红外线属于电磁场．十九世纪光学主要研究光的传播特性．到了二十世纪发展到光发射以及光和介质作用的微观机制的研究．它的频段并扩展到与微波相衔接．二次大战后逐步发展了光学遥感和红外探测等应用技术,使光学的应用有了发展．六十年代做成了激光器．激光器是利用光受激发射原理做成的光放大器．它产生的光单色性好,相干长度长,而且亮度高．激光的发展不仅使光学面貌发生了?...     

1993年新当选的中国科学院院士介绍(II)

新当选的院士王崇愚王崇愚６１岁,金属缺陷及电子结构与材料设计科学家。现任冶金部钢铁研究总院教授。王崇愚长期从事金属材料的研究,在金属缺陷及电子结构与宏观物性的对比方面,作出过重要贡献。６０年代至８０年代期间,创造性地研制成功一组特性分别超过或达到国际先进水平的合金材料,包括合金成分设计、工艺和物性实验以及缺陷理论的综合性系统研究,完成了国家重要工程?...