二甲苯异构体双电荷离子和单电荷离子的动能谱研究

利用质量分析离子动能谱和碰撞诱导解离技采研究了邻、间、对二甲苯分子在电子轰击质谱中产生的双电荷离子[C8H10]2+、[C8H9]2+和单电荷离子[C8H10]+。根据测定的电荷分离反应的释放动能T和由此估算的双电荷离子电荷分离反应过渡态两电荷间距R,推测出过渡态的结构,利用单电荷离子[C8H10]+的MIKES/CID谱可区分邻二甲苯与间、对二甲苯异构体.     

Complexing equilibria and redox potentials in the system Ag(II)/Ag(I)-1,10-phenanthroline in propylene carbonate

Predominance areas of various equilibria were identified and complex formation constants of Ag(I) with 1,10-phenanthroline were determined as well as the solubility product of the complex salt for Ag(phen)₂ClO₄ in propylene carbonate. The solubility product of AgNO₃ in propylene carbonate was estimated. The value of the formal potential of the system Ag(phen) ₂ ²⁺ /Ag(phen) ₂ ⁺ inPC was determined by chronovoltammetry. Differences in the stability of analogous complexes in water andPC are discussed.

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Die Gleichgewichtskonstante der Komplexierung und die Redoxpotentiale im System Ag(II)/Ag(I)-1,10-Phenantrolin in Propylencarbonat

Zusammenfassung Die Gebiete der Dominanz der einzelnen Gleichgewichte, die Bildungskonstanten ₁ und ₂ der Komplexe Ag(I) mit 1,10-Phenantrolin und der Wert des Löslichkeitsproduktes Ag(phen)₂ClO₄ in Propylencarbonat wurden bestimmt. Das Löslichkeitsprodukt von AgNO₃ in Propylencarbonat wurde abgeschätzt. Die Werte des formalen Potentials des Systems Ag(phen) ₂ ²⁺ /Ag(phen) ₂ ⁺ inPC wurden mit Hilfe cyclischer Voltametrie ermittelt. Es wurden weiterhin die Unterschiede in der Stabilität analoger Komplexe in Wasser und in Propylencarbonat diskutiert.

     

硼离子对铕掺杂SiO2干凝胶发光性能的影响

采用溶胶-凝胶法制备了Al单掺和B，Al共掺的Eu掺杂SiO2干凝胶。利用荧光光谱、IR，XRD，DSC，TG／DTG等技术研究了硼离子、退火温度对样品发光性质的影响。经500℃以上退火处理用248nm激发的样品，产生Eu^3＋离子^5D0→^7FJ的特征发射，^5D0→^7F1的跃迁分裂为两个峰。比较615nm处的发光强度，掺硼酸样品的发光强度是不加硼酸发光强度的3．3倍。这是因为B离子的加入，在材料中形成了Si—O—B键，破坏了网络的对称性，加强了Eu^3＋的红光发射。当退火温度上升到850℃用350nm激发时，样品有很强的Eu^2＋蓝光发射。Al单掺的发射中心在437nm处，发射半峰宽约为70nm，而B，Al共掺样品的发光中心蓝移到425nm处，单掺样品的蓝光强度几乎是共掺样品强度的2倍。这是由于硼酸的加入改变了基质的网络结构，从而导致单掺和共掺样品发射峰位和强度的改变。     

3,3,3-Trifluoro-<Emphasis Type="Italic">N</Emphasis>′-(3-trifluoromethylphenyl)-1,2-propanediamine and its <Emphasis Type="Italic">N</Emphasis>-mono-and <Emphasis Type="Italic">N,N</Emphasis>-dicarboxyethyl derivatives: synthesis,protolytic and complexation properties

3,3,3-Trifluoro-N′-(3-trifluoromethylphenyl)-1,2-propanediamine (5) was synthesized by the reaction of 2-diazo-1,1,1-trifluoro-3-nitropropane or 3,3,3-trifluoro-1-nitropropene with 3-aminobenzotrifluoride followed by the reduction of the nitro group. The Michael 1,4-addition of diamine 5 to acrylic acid occurs only at the N(1) atom and affords N-mono-or N,N-dicarboxyethyl derivatives 6 and 7, depending on the reactant ratio. Protolytic equilibria 5–7 in aqueous solutions were studied by pH-potentiometry and UV spectroscopy. Only the aliphatic amino group can be protonated in an aqueous solution, while the aromatic amino group remains unprotonated even in 12 M HCl. The stability constants of transition metal (Cu²⁺, Ni²⁺, Zn²⁺) complexes with ligands 5–7 were determined by pH-potentiometric titration. The stability of the complexes and selectivity of the ligands toward Cu²⁺ ions increase with an increase in the number of N-carboxyethyl groups. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2465–2469, November, 2005.     

A study of the thermal decarboxylation of three perfluoropolyether salts

The thermal decarboxylation of three dicarboxylic perfluoropolyether potassium salts of relatively short chain length has been investigated and the products and kinetics of the main reactions have been defined. From the rate constants and Arrhenius parameters data, the second decarboxylation appears to be quantitatively rather close to the first.     

A practical approach to the fused β-carboline system. Asymmetric synthesis of indolo[2,3-a]indolizidinones via a diastereoselective intramolecular α-amidoalkylation reaction

Fused β-carboline systems, as indolo[2,3-a]indolizidinones, indolo[2,3-a]quinolizidinones, their 2-oxa analogues, and benzo[a]indolo[2,3-a]indolizidinones are prepared efficiently via an RLi addition-N-acyliminium ion cyclisation sequence on readily available imides. In an enantioselective variant of these α-amidoalkylation reactions, the addition of MeLi to a chiral non-racemic imide derived from tryptophan yielded an oxo amide, which was cyclised diastereoselectively upon treatment with BF₃·OEt₂, to afford 5,11b-trans-indoloindolizidinone in moderate yield and high ee (99%).     

Spectral studies on VO ions in potassium thiourea bromide single crystals using EPR and optical absorption spectroscopy

Electron paramagnetic resonance (EPR) studies have been carried out on VO²⁺ ions doped in single crystals of ferroelectric material, potassium thiourea bromide (PTB) at room temperature and in the temperature range 103–343 K on X-band MW frequency. An isotropic octet spectrum characteristic of VO²⁺ ion was obtained due to the fast re-orientation of the VO²⁺ in PTB lattice, which exhibits glassy nature at certain range around room temperature. The temperature dependant EPR spectra of VO²⁺ ions in this host lattice has been attributed to the occurrence of multiple phase transitions due to the combined environment effects of KBr and thiourea materials in the single crystal. From the optical absorption spectrum, the crystal field splitting parameter Dq, tetragonal parameters Ds and Dt have been evaluated and discussed.     

Effects of substituted ligands on the mobility of complexed anions

From conductance and viscosities measurements on Pr₄NCl, Et₄NBr, and AgNO₃ in acetonitrile and Et₃NBr in nitrobenzene, the Walden products of the anion at infinite dilution were determined in presence of various concentrations of substituted benzoic acids. From these data it was possible to compute the values of the Walden products of the once complexed anions and to estimate the order of magnitude of the Walden products of twice complexed anions. Stokes' law is not obeyed, and the Walden products are not proportional to the third root of the molar volume of the complexed ions, as a consequence of their lack of sphericity. The assumption that the drag force which acts on the ions is proportional to the volume of the substituents results in a linear expression between the reciprocals of the Walden products and the molar volume of the ligands. The experimental results fit this expression within the limits of the experimental errors, and the slopes of the lines are nearly the same for all the anions and for the two solvents studied here, namely, 2.5×10^–4 ohm-cm^–5 mole-cP^–1.     

Developments in suppressor technology for inorganic ion analysis by ion chromatography using conductivity detection

A review is presented detailing the development and use of suppression devices for the conductimetric detection of inorganic ions by ion chromatography (IC). An overview of the general response equation for conductivity detection is also given. Topics of discussion include the role and function of suppressors, the development of early suppressors including packed column and membrane devices from 1975 to 1990 and the subsequent progression towards present day commercially available suppressors and recent innovations. Post-suppression devices for signal enhancement are also discussed.     

CS2+离子 C2Σg+←B2Σu+跃迁的Franck-Condon因子计算以及与光解离谱的比较

将线性三原子分子离子CS2+的对称伸缩振动简化为SC和S之间的简谐振动, 用谐振子的势能曲线和波函数对CS2+分子离子 C2Σg+和 B2Σu+电子态(对称伸缩)振动能级间跃迁的Franck-Condon因子进行了计算, 得到的结果与 C2Σg+←B2Σu+跃迁的光解离谱实验强度进行了比较, 对前人给出的分子数据(转动常数、分子平衡核间距)进行了验证和分析, 讨论了经由 C2Σg+←B2Σu+电子态振动能级间跃迁的光解离机理.