水杨醛甘氨酸席夫碱-含氮杂环稀土配合物的合成及其与DNA作用的光谱研究

合成了以水杨醛甘氨酸席夫碱（Sal-GlyK）、邻菲罗啉（Phen）和2,2’-联吡啶（Bipy）为配体、Eu³⁺、La³⁺为中心的配合物。对其进行了元素分析和摩尔电导、红外光谱及紫外吸收光谱测定,推测配合物的组成分别为RE（Sal-Gly）（NO₃）·2H₂O和RE（Sal-Gly）（Phen）（NO₃）·H₂O、RE（Sal-Gly）（Bipy）（NO₃）·H₂O（RE³⁺=Eu³⁺,La³⁺）。通过紫外吸收光谱及荧光光谱研究了稀土配合物与小牛胸腺DNA的作用方式及其结合常数。结果表明,本文合成的配合物与DNA的结合能力的顺序为RE（Sal-Gly）（Phen）（NO₃）·H₂O>RE（Sal-Gly）（Bipy）（NO₃）·H₂O >RE（Sal-Gly）（NO₃）·2H₂O,表明配合物是以插入方式与DNA结合,含有良好平面性和较大表面积配体的配合物可以更好地插入到DNA的碱基对中。     

The adsorption of H2O on TiO2 and SnO2(110) studied by first-principles calculations

First-principles calculations based on density functional theory and the pseudopotential method have been used to investigate the energetics of H₂O adsorption on the (110) surface of TiO₂ and SnO₂. Full relaxation of all atomic positions is performed on slab systems with periodic boundary conditions, and cases of full and half coverage are studied. Both molecular and dissociative (H₂O→OH⁻+H⁻) adsorption are treated, and allowance is made for relaxation of the adsorbed species to unsymmetrica configurations. It is found that for both TiO₂ and SnO₂ an unsymmetrical dissociated configuration is the most stable. The symmetrical molecularly adsorbed configuration is unstable with respect to lowering of symmetry, and is separated from the fully dissociated configuration by at most a very small energy barrier. The calculated dissociative adsorption energies for TiO₂ and SnO₂ are in reasonable agreement with the results of thermal desorption experiments. Calculated total and local electronic densities of states for dissociatively and molecularly adsorbed configurations are presented, and their relation with experimental UPS spectra is discussed.     

Evidence for bicarbonate formation on vacuum annealed TiO2(110) resulting from a precursor-mediated interaction between CO2 and H2O

The reaction of CO₂ and H₂O to form bicarbonate (HCO⁻₃) was examined on the nearly perfect and vacuum annealed surfaces of TiO₂(110) with temperature programmed desorption (TPD), static secondary ion mass spectrometry (SSIMS) and high resolution electron energy loss spectrometry (HREELS). The vacuum annealed TiO₂(110) surface possesses oxygen vacancy sites that are manifested in electronic EELS by a loss feature at 0.75 V. These oxygen vacancy sites bind CO₂ only slightly more strongly (TPD peak at 166 K) than do the five-coordinated Ti⁴⁺ sites (TPD peak at 137 K) typical of the nearly perfect TiO₂(110) surface. Vibrational HREELS indicates that CO₂ is linearly bound at the latter sites with a ν_a(OCO) frequency similar to the gas phase value. In contrast, oxygen vacancies dissociate H₂O to bridging OH groups which recombine to liberate H₂O in TPD at 490 K. No evidence for a reaction between CO₂ and H₂O is detected on the nearly perfect surface. In sequentially dosed experiments on the vacuum annealed surface at 110 K, CO₂ adsorption is blocked by the presence of preadsorbed H₂O, adsorbed CO₂ is displaced by postdosed H₂O, and there is little or no evidence for bicarbonate formation in either case. However, when CO₂ and H₂O are simultaneously dosed, a new CO₂ TPD state is observed at 213 K, and the 166 K state associated with CO₂ at the vacancies is absent. SSIMS was used to tentatively assign the 213 K CO₂ TPD state to a bicarbonate species. The 213 K CO₂ TPD state is not formed if the vacancy sites are filled with OH groups prior to simultaneous CO₂+H₂O exposure. Sticking coefficient measurements suggest that CO₂ adsorption at 110 K is precursor-mediated, as is known to be the case for H₂O adsorption on TiO₂(110). A model explaining the circumstances under which the proposed bicarbonate species is formed involves the surface catalyzed conversion of a precursor-bound H₂O–CO₂ van der Waals complex to carbonic acid, which then reacts at unoccupied oxygen vacancies to generate bicarbonate, but falls apart to CO₂ and H₂O in the absence of these sites. This model is consistent with the conditions under which bicarbonate is formed on powdered TiO₂, and is similar to the mechanism by which water catalyzes carbonic acid formation in aqueous solution.     

Characterization of nonstoichiometric nickel manganite spinels NixMn3−x□3δ/4O4+δ by temperature programmed reduction

Cation deficient spinels Ni_xMn_3−x□_3δ/4O_4+δ (0≤x≤1) have been prepared by thermal decomposition of mixed oxalates Ni_x/3Mn_(3−x)/3(C₂O₄)·nH₂O in air at 623 K. They have been characterised by temperature programmed reduction (TPR) under H₂, the reaction being followed by gravimetric and powder X-ray diffraction measurements. It has been shown that TPR proceeds in several steps. The first steps correspond to the loss of nonstoichiometric oxygen leading to the formation of a stoichiometric oxide. During the following stages the manganese cations are reduced, causing the spinel structure to be destroyed, and the formation of solid solution of NiO in a cubic MnO. Subsequently, Ni²⁺ cations undergo a reduction to metallic nickel, and, finally, a mixture of nonstoichiometric MnO_1−δ and metallic nickel is formed. These oxides contain a high level of vacancies which vary with the nickel content with a maximum of δ≈1 near x=0.6. This nonstoichiometry is ascribed both to the presence of Ni³⁺ and excess of Mn⁴⁺.     

Positive electrode materials for lithium batteries based on VOPO4

A detailed electrochemical study of Li insertion in the -form of VOPO₄ and the optimization of the cycling performance are presented. The redox process occurs in one step close to 3.76 V, along with a phase transition. In order to improve the intercalation kinetics, the electronic conductivity was optimized by introducing a mixed valency, and the ionic conductivity was favored by introducing ‘pillaring’ molecules or ions in the interlayer space. In this way, the electrochemical behaviors of -VOPO₄·2H₂O, -Na_xVOPO₄, -K_xVOPO₄ and -Mg_xVOPO₄ (0≤x≤1) have been studied: the hydrate compound shows a good specific capacity (100 mA h/g at a C/5 regime), but a poor cyclability was mainly because of water oxidation. The inserted large alkaline ions improved the cyclability up to 80 cycles (Na⁺) or over 100 cycles (K⁺). Enhancements of the VOPO₄ specific capacity have been obtained as well by mechanical ball-millings.     

H, V and N nuclear magnetic resonance studies of structure and properties of vanadia supported on TiOx/SiO2

¹H magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of TiO_x/SiO₂ catalysts suggest the interaction of surface TiO_x. species with Si-OH groups of the silica. Simultaneously, Ti-OH groups from surface titania species appear. The distribution of TiO_x species over SiO₂ is non-uniform, since a considerable part of surface OH groups remains unreacted with supported titania. Supported vanadia species interact both with Si-OH and Ti-OH groups. ⁵¹V NMR spectra suggest the interaction of vanadia with supported titania species and show the non-uniform distribution of titania over the SiO₂ surface. Deposition of titania as well as vanadia produces strong electron-accepting (Lewis) sites which interact with the terminal N atom of adsorbed N₂O molecules, resulting in a downfield shift of the resonance in ¹⁵N NMR spectra. The acid strength of electron-accepting sites is similar in both cases. Only about 10% of the total amount of supported titania and vanadia create Lewis sites.     

Interaction of copper and NO2: Effect of joint presence of SO2, relative humidity and temperature

This paper reports laboratory tests involving the dry deposition on copper surfaces of NO₂, alone and in combination with SO₂, at different concentrations (200 and 800 μg m⁻³), temperatures (15, 25 and 35 °C) and relative humidities (50%, 70% and 90%). Gravimetric results and characterisation of the corrosion products by optical microscopy, scanning electron microscopy (SEM/EDX), grazing incidence X-ray diffraction (GIXD) and X-ray photoelectron spectroscopy (XPS) show that the corrosive effect of NO₂ acting alone depends greatly on the RH. At 90% RH copper behaves in the same way as in unpolluted atmospheres, while at lower RH localised attack is detected. Analysis reveals the presence of basic copper nitrate (gerhardtite, Cu₂(OH)₃NO₃). However, in SO₂-polluted atmospheres no differential behaviour with RH or temperature is observed. In these atmospheres copper corrosion is similar to that obtained in unpolluted or in NO₂-polluted atmospheres at high RH, although GIXD detects basic copper sulphate (posnjakite, Cu₄(OH)₆SO₄·2H₂O). In the case of mixed atmospheres (SO₂+NO₂) a significant accelerating effect is observed when [NO₂]>[SO₂]. Otherwise an inhibitive effect is detected. At high RH in the presence of SO₂, NO₂ favours SO₂ oxidation and finally sulphuric acid formation, which attacks the cuprite layer. S-containing compounds, especially basic copper sulphate, are easily detected by GIXD and XPS in the outermost corrosion product layer. However, at low RH, NO₂ reacts preferentially with adsorbed water to produce nitrous and nitric acids that attack the cuprite layer. In this case, an outer corrosion product layer containing copper nitrite (soluble) and basic copper nitrate is formed over an intermediate layer that contains significant amounts of basic copper sulphate from the previous interaction of sulphuric acid and cuprite.     

Shaped crystal growth and scintillating properties of Yb:(Gd,Lu)3Ga5O12 solid solutions

Shaped single crystals of (Lu_xGd_1−x)₃Ga₅O₁₂ (0.0x1.0) and (Yb_0.05Lu_xGd_0.95−x)₃Ga₅O₁₂ (0.0x0.9) were grown by the modified micro-pulling-down method. Continuous solid solutions with garnet structure and a linear compositional dependency of crystal lattice parameter in the system Yb:(Gd,Lu)₃Ga₅O₁₂ are formed. Measured optical absorption spectra of the samples show 4f–4f transitions related to Gd³⁺ ion at 275 and 310 nm, and also an onset of charge transfer transitions from oxygen ligands to Gd³⁺ or Yb³⁺ cations below 240 nm. A complete absence of Yb³⁺ charge transfer luminescence under X-ray excitation in any of the investigated samples was explained by the overlapping of charge transfer absorption of Yb³⁺ by that of Gd³⁺ ions. For specific composition of Lu_1.5Gd_1.5Ga₅O₁₂ an intense defect-host lattice-related emission, which achieve of about 40% integrated intensity compared with Bi₄Ge₃O₁₂, was found.     

The crystal structure of (Pb0.5Cd0.5)Sr2 (Y1−xCax)Cu2O7

The crystal structures of (Pb_0.5Cd_0.5)Sr₂YCu₂O₇, (Pb_0.5Cd_0.5)Sr₂(Y_0.6Ca_0.4)Cu₂O₇ and (Pb_0.5Cd _0.5)Sr₂(Y_0.5Ca_0.5)Cu₂O₇ have been refined by the Rietveld method for the X-ray diffraction data. The refinement results indicate that both Pb and Cd atoms in the (Pb, Cd)O layers and O(3) atoms are displaced from their ideal sites, and that there is a complicated occupation in the (Pb, Cd)O layers, i.e., other cations, such as Sr²⁺, Cu²⁺ and Ca²⁺, can occupy the (Pb, Cd) site for these samples. This may be the reason why the lattice constants do not vary monotanically with the calcium content, and why there exist broad superconducting transitions in the system (Pb_0.5Cd_0.5)Sr₂(Y_1−xCa_x)Cu₂O₇. The refinement results also indicate that, as the calcium content increases, the O(2) atoms move close to the CuO₂ planes and far from the (Pb, Cd)O layers. Thus, the increase of calcium content results in charge transfer from the charge reservoir layer (Pb, Cd)O to the CuO₂ planes. This result is consistent with the bond valence sums of the Cu ions in the CuO₂ planes.     

(Sr_(1-1.5x)Y_x)TiO_3模拟固化~(90)Y的稳定性研究

为了研究钙钛矿结构的SrTiO_3固化Y~(3+)(~(90)Y的模拟物)的化学稳定性,以Sr(NO_3)_2,TiO_2及Y_2O_3粉体作为原料,按照化学计量比Sr_(1-1.5x)Y_xTiO_3(0≤x≤0.12)设计配方,采用高温固相法制备一系列固化体.利用X射线衍射、扫描电镜和Raman对制备固化体的物相、结构和微观形貌进行分析表征,并对其抗浸出性能进行了研究.结果表明:当x0.08时,固化体为单一物相,当x≥0.08时,固化体中出现部分烧绿石相;固化体中的Sr~(2+),Y~(3+)的浸出浓度随浸泡时间延长而增大,在浸泡42d时,Sr~(2+)的最大浸出浓度为0.004μg·mL~(-1),Y~(3+)的最大浸出浓度为0.02μg·mL~(-1).     

Oxygen diffusion and surface exchange in La1−xSrxFe0.8Cr0.2O3−δ (x=0.2, 0.4 and 0.6)

Oxygen tracer diffusion (D*) and surface exchange rate constant (k*) have been measured, using isotopic exchange and depth profiling by secondary ion mass spectrometry (SIMS), in La_1−xSr_xFe_0.8Cr_0.2O_3−δ (x=0.2, 0.4 and 0.6). Measurements were made as a function of temperature (700–1000 °C) and oxygen partial pressure (0.21–10⁻²¹ atm) in dry oxygen, water vapour and water vapour/hydrogen/nitrogen mixtures. At high oxygen activity, D* was found to increase with increasing temperature and Sr content. The activation energies for D* in air are 2.13 eV (x=0.2), 1.53 eV (x=0.4) and 1.21 eV (x=0.6). As the oxygen activity decreases, D* increases as expected qualitatively from the increase in oxygen vacancy concentration. Under strongly reducing conditions, the measured values of D* at 1000 °C range from 10⁻⁸ cm² s⁻¹ for x=0.2 to 10⁻⁷ cm² s⁻¹ for x=0.4 and 0.6. The activation energies determined at constant H₂O/H₂ ratio are 1.21 eV (x=0.2), 1.59 eV (x=0.4) and 0.82 eV (x=0.6).

The surface exchange rate constant of oxygen for the H₂O molecule is similar in magnitude to that for the O₂ molecule and both increase with increasing Sr concentration.     

Electrical conductivity and defect structure of Mg-doped Cr2O3

The electrical conductivity of Cr₂O₃ nominally doped with 2 mol% MgO has been studied by the four point a.c. technique as a function of the oxygen activity (O₂ + Ar, CO + CO₂ and H₂ + H₂O) in the temperature range 400–1200 °C. It is concluded that Cr₂O₃ doped with MgO is an extrinsic conductor and that the dissolved Mg-dopant is compensated by the formation of electron holes at near atmospheric oxygen pressures and by oxygen vacancies (or possibly interstitial chromium ions) at highly reduced oxygen activities (in CO + CO₂ and H₂ + H₂O gas mixtures). In H₂ + H₂O mixtures Mg-doped chromia also dissolves hydrogen as protons and significantly affects the defect structure and electrical conductivity. The defect structure of the oxide under various conditions is discussed.     

Paramagnetic relaxation in two double nitrates

Relaxation measurements have been performed on a single crystal of Ce₂Mg₃(NO₃)₁₂ · 24H₂O and of La₂Mn₃(NO₃)₁₂ · 24H₂O at liquid He temperatures.     

Spectroscopic study of BixEu1−xVO4 and BiyGd1−yVO4 mixed oxides

The mixed oxides Bi_xEu_1−xVO₄ and Bi_yGd_1−yVO₄ crystallize in a zircon-type structure, for 0 <x < 0.6 and 0 < y < 0.64, and in a fergusonite-type structure, for 0.94 < x < 1 and 0.93 < y < 1. A process of competition between the dominant and the constrained effects of the lone-pair 6s² of Bi³⁺ is discussed. The diffuse reflectance spectroscopic studies of these mixed oxides are presented. The observed broad bands are attributed to charge transfer processes and the sharp peaks in the Bi_xEu_1−xVO₄ spectra are ascribed to intra-configurational 4f – 4ftransitions of the Eu³⁺ ion. The broad absorption shift in BiLnVO₄ (Ln : Eu and Gd) compounds to the longer wavelengths range, when Bi is introduced in the LnVO₄ lattice, is ascribed to charge transfer processes in a Bi-VO₄ center and are interpreted assuming a Jahn-Teller effect in the excited state of Bi³⁺. The concept of an internal pressure of Bi³⁺ ions is also used to explain the broad A-band shifts.     

Al2O3吸附[Cu(H2O)6]2+基团的自旋哈密顿参量和四角畸变

采用微扰方法和对角化完全能量矩阵法计算了Al₂O₃粉末吸附的四角对称[Cu(H₂O)₆]²⁺基团的自旋哈密顿参量（g因子g∥,g_⊥和超精细结构常数A_∥和A_⊥）. 计算结果表明用这两种理论方法计算的自旋哈密顿参量很接近,并且都与实验结果比较一致. 表明这2种方法都可用于晶体中3d9离子基团的自旋哈密顿参量的研究,通过计算,我们还获得了[Cu(H₂O)₆]²⁺基团四角畸变的大小,并对结果进行了讨论.     

Ca~(2+)掺杂对SmFeO_3的介电、铁磁特性及磁相变温度的影响

采用固相反应法制备Sm_(1-x)Ca_xFeO_3(x=0,0.1,0.2,0.3)样品,研究Ca~(2+)掺杂对SmFeO_3介电性能、铁磁性及磁相变温度的影响.X射线衍射图谱分析表明:所有样品的主衍射峰与SmFe03相符合且具有良好的晶体结构.随着x的增加,SmFeO_3样品的晶粒尺寸由原来的0.5μm逐渐增大到2μm.当f=1 kHz时,Sm_(1-x)Ca_xFeO_3(x=0.1,0.2,0.3)样品的ε_r分别是SmFe03的5倍、3倍和2.6倍,而tgσ增大一个数量级.在3T磁场作用下,SmFe03样品的M-H呈线性,随着x的增加,M-H逐渐趋向饱和,Sm_(1-x)Ca_xFeO_3(x=0.1,0.2,0.3)样品的M_r分别是SmFeO_3的20倍、31倍和68倍.X射线光电子能谱分析表明:Fe~(2+)和Fe3+共存于Sm_(1-x)Ca_xFeO_3样品中,Fe~(2+)/Fe~(3+)比例随着x的增加而增大,证明Ca~(2+)掺杂增加了Fe~(2+)的含量,形成Fe~(2+)—O~(2-)—Fe~(3+)超交换作用,增强SmFe03的铁磁特性.测量了Sm_(1-x)Ca_xFeO_3样品在外加磁场为1000 Oe(1 Oe=79.5775 A/m)的M-T变化关系,观测到其自旋重组温度(T_(SR))和尼尔温度(T_N)分别为438 K和687 K,发现SmFe03样品的T_(SR)和T_N均随着x的增加向低温方向移动,当x=0.3时,自旋重组现象消失.这主要是SmFeO_3样品磁结构的稳定性和Fe~(3+)—O~(2-)—Fe~(3+)及Sm~(3+)—O~(2-)—Fe~(3+)超交换三者共同作用的结果.     

TBAB‐CO2水合物形成过程的微观实验

四丁基溴化铵（TBAB）半笼型水合物在二氧化碳（CO₂）捕集和封存技术中具有巨大的发展与应用潜力。由于晶体结构的复杂性,TBAB半笼型水合物的动力学过程尚未得到充分的研究。为了解TBAB半笼型水合物在储气方面的动力学特性,实验采用原位激光拉曼技术和多晶粉末X射线衍射仪（PXRD）对nCO₂·TBAB·26H₂O和nCO₂·TBAB·38H₂O水合物的光谱特征进行了鉴别与分析,利用原位激光拉曼技术考察了CO₂分子分别进入2种晶体结构的动力学过程。研究结果表明,2种晶体结构的拉曼光谱具有较高的相似性,值得注意的是nCO₂·TBAB·26H₂O中位于1 309.5和1 326.9 cm-1的拉曼峰为TBA+阳离子中C-C键的变形振动峰,在nCO₂·TBAB·38H₂O水合物中峰基本不发生改变,但半峰宽降低,峰形也变得相对清晰;同时,nCO₂·TBAB·26H₂O中位于1 446.6和1 458 cm-1的拉曼峰为TBA+阳离子中C-H键的剪切振动峰,在nCO₂·TBAB·38H₂O水合物中分别向左、右两边发生了位移,峰形的重叠度也随之下降。依据上述2处拉曼光谱特征可以对2种晶体结构进行辨别。通过PXRD图谱可以发现2种晶体结构的衍射图谱存在着比较明显的差距。nCO₂·TBAB·26H₂O晶体属于四方晶系,空间群(P4/m),而nCO₂·TBAB·38H₂O属于正交晶系,空间群(Pmma)。图谱中2θ=8.406°和10.941°分别为nCO₂·TBAB·38H₂O的(200)和(220)晶面的特征峰,而2θ=5.976°和6.969°分别为nCO₂·TBAB·26H₂O的(012)和(003)晶面特征峰,可以用来判别样品中水合物的晶体结构。在原位拉曼测量过程中,nCO₂·TBAB·26H₂O和nCO₂·TBAB·38H₂O分别在已经合成好的TBAB·26H₂O和TBAB·38H₂O水合物表面形成。在276 K,2 MPa条件下,气相中的CO₂分子分别进入2种晶体结构中用于储气的512笼形结构,在1 275.4和1 379.3 cm-1处形成特征峰并逐渐增长。实验以2种TBAB水合物位于1 110.3 cm-1的拉曼峰作为参考,比较了CO₂在水合物中的增长速率。研究发现在反应初期的75 min内CO₂在2种水合物中的含量基本保持线性增长且上升速率的差别不大。由于测量点位于水合物表面,受气体在水合物中扩散的阻力较小同时2种TBAB水合物均采用512笼形结构储气导致了储气速率相近。以上的微观晶体结构研究结果对TBAB水合物法捕集和封存CO₂技术应用具有重要的意义。     

The chloroform / TBP / aqueous nitric acid interfacial system: a molecular dynamics investigation

We report MD studies on a chloroform / nitric acid water interface, either neat, or saturated by TBP molecules. Two extreme models are compared, where the acid is either neutral HNO₃ or dissociated to NO₃⁻ and H₃O⁺. The latter species are found to be “repelled” by the neat interface, while the neutral HNO₃ molecules are surface active. When the neat interface is saturated by TBP molecules, the latter form highly disordered arrangements instead of a regular monolayer, and water is dragged to the organic phase as 1:1, 1:2 and 2:2 hydrates of TBP. Simulations with the neutral HNO₃ model lead to extraction of acid to the organic phase, hydrogen bonded to the phosphoryl oxygen of TBP, forming HNO₃:TBP adducts of 1:1 and 2:1 types. Simulations with the ionic model lead to H₃O⁺:TBP adducts of 1:1, 1:2 and 1:3 types in the organic phase and significant mixing of the chloroform, TBP and water liquids in the interfacial region.     

Ln(Ⅲ)-Ni(Ⅱ)与双水杨醛缩乙二胺席夫碱异核配合物的合成与波谱

合成了双水杨醛缩乙二胺席夫碱(SALEN)与镍的配合物Ni₃(SALEN)₂(NO₃)₆·H₂O及镧系镍的异核配合物Ln₂Ni₃(SALEN)₆(NO₃)₁₂·H₂O(Ln=La,Nd,Sm,Gd,Yb,Y).以紫外、红外光谱、磁化率,特别是¹H NMR及EPR波谱等方法研究了它们在组成、结构和配位等方面的异同.Gd-Ni-SALEN配合物的EPR谱表明其在低温THF中呈"单峰效应".文中讨论了配合物在不同溶剂中峰宽的相对关系、配合物晶体场强度及Gd³⁺周围局部对称性问题.