The Color Reaction of Mercury(II) with the New Reagent 2-Methylthiophenyldiazoaminoazobenzene and Its Application

A new and very sensitive and selective chromogenic reagent, 2-methylthiophenyldiazoaminoa-zobenzene (MTDAA), was synthesized and studied in detail for the determination of trace mercury(II) in water samples. The method is based on the color reaction between MTDAA and mercury(II). It was found that mercury(II) reacts with MTDAA in Na₂B₄O₇-NaOH buffer solution (pH = 10.0) to form 1 : 2 red complexes; these show maximum absorption at 520 nm. Beer’s law is obeyed in 0–15 µg of mercury(II) in 25 mL of solution. The apparent molar absorptivity of the complex is 1.33 × 10⁵ L/(mol cm); its limit of quantification, limit of detection, and relative standard deviation are 0.75 ng/mL, 0.27 ng/mL, and 1.0%, respectively, giving better sensitivity. The influence of the reaction variables and the effect of interfering ions are reported; most of the metal ions in water samples can be tolerated in considerable amounts. Only a few ions can interfere with the determination of trace mercury(II), but these can be eliminated by prior extraction. The proposed method is sensitive, simple, and rapid. It has been applied to the determination of trace mercury(II) in water samples with satisfactory results.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 7, 2005, pp. 703–706.Original English Text Copyright © 2005 by Guo, Din, Tian, Liu, Chang, Meng.The text was submitted by the authors in English.     

不同光滑度立方体氧化铁对液晶电光性能的改善

向列相液晶被广泛应用于液晶显示中,但是由于杂质的存在,会导致液晶的驱动电压变大,增加能耗。 为了降低阈值电压和饱和电压,通常向液晶中添加纳米颗粒来提高电光性能。 本文利用水热法制备了表面粗糙和光滑的两种立方体Fe₂O₃纳米颗粒,其形貌均匀,尺寸约550 nm。 将二者分别掺杂到向列相液晶E7中,结果表明,粗糙立方体Fe₂O₃/E7复合体系具有比光滑立方体Fe₂O₃/E7复合体系和向列相液晶E7更优的电光性能,且在掺杂质量分数为0.4%时,其电光性能达到最优,阈值电压和饱和电压分别降低9.9%和11.6%,对比度增大80%,响应时间降低至6.0 ms。 这归因于粗糙立方体Fe₂O₃具有足够的表面积和表面所带电荷更多,所以会更易吸附体系中的杂质离子和减弱杂质离子的屏蔽作用,从而提高了电光性能。     

SYNTHESIS AND PROPERTIES OF SULFONATED POLY（ARYLENE ETHER） CONTAINING TRIPHENYL METHANE MOIETIES FROM ISOCYNATE MASKED BISPHENOL

A novel sulfonated poly（arylene ether） containing triphenylmethane moieties was synthesized by the sulfonation of a designed parent polymer using chlorosulfonic acid as sulfonation agent. The sulfonation took place at the para position of the pendant phenyl rings because of the specially designed parent polymer. The position and degree of sulfonation were characterized by ^1H-NMR and elemental analysis. The sulfonated polymers are highly soluble in common organic solvents, such as dimethylsulfoxide, N,N＇-dimethylacetamide, dimethylformamide, ethylene glycol monomethyl ether, and can be readily cast into tough and smooth films from solutions. The films showed good thermal and hydrolysis stabilities. Moreover, Fenton＇s reagent test revealed that the films exhibited superior stability to oxidation. The proton conductivities of the films were comparable with Nation 117 under same conditions. The membrane electrode assembly （MEA） prepared with the asmade film （706 EW, 100 μm dry thickness） shows better cell performance than Nation 115-MEA in the whole current density range.     

硬木热解过程中颗粒内部二次反应的数值研究Ⅱ.数值模拟结果

为了研究生物质（硬木）热解过程中颗粒内部的二次反应，对流化床环境下单颗粒生物质热解模型进行了求解。计算针对典型大颗粒和典型小颗粒在流化床反应器反应条件下的热解过程，对不同大小颗粒内部各种产物的生成、消耗、积累以及逃逸行为进行了定量描述。计算结果表明：对于直径为2mm的小颗粒，颗粒内二次裂解的份额可以忽略，但是对于直径10mm的大颗粒，热争过程中有超过20%的一次焦油参加了颗粒内部二次反应，颗粒内二次裂解显著地改变了热解产物分布，改变了热解产物的品质。     

Synthesis, crystal structure and magnetic property of a new 1D molecular material [1-(4′-chlorobenzyl)-4-aminopyridinium](+) bis(maleonitriledithiolato)nickel(-)

A new ion-pair complex, [1-(4′-chlorobenzyl)-4-aminopyridinium](+)bis(maleonitrile-dithiolato)nickel(−),[ClbzPyNH₂][Ni(mnt)₂] (1), has been prepared and characterized. X-ray single crystal structure conforms that the Ni(mnt)₂⁻ anions and [ClbzPyNH₂]⁺ cations of 1 form completely segregated uniform stacking columns with the Ni?Ni distance 3.944 Å in the Ni(mnt)₂⁻ stacking column. The temperature dependence of the magnetic susceptibility reveals that 1 undergoes a magnetic transition, and exhibits ferromagnetic interaction in the high-temperature phase and spin gap system in the low-temperature phase.     

Ionic pair complexes with well-separated columnar stack structure based on [Pt(mnt)2]- ions showing unusual magnetic transition: syntheses, crystal structures, and magnetic properties

Three ion pair complexes, [4-R-benzylpyridinium][bis(maleodinitriledithiolato)platinum(III)] (abbreviated as [RBzPy][Pt(mnt)(2)]; R = Cl (1), Br (2), or NO(2) (3)), have been synthesized. The cations and anions stack into well-separated columns in the solid state, and the Pt(III) ions form a 1-D zigzag chain within a [Pt(mnt)(2)](-) column through Pt...S, S...S, and Pt...S...Pt interactions. The chain is uniform in 1 and 2, while it alternates in 3. Unusual magnetic phase transitions from paramagnetism to diamagnetism were observed in these three complexes at approximately 275 K for 1, approximately 269 K for 2, and approximately 184 K for 3. These phase transitions were also found in DSC measurements for 1 and 2. The overall magnetic behaviors for 1-3 indicate the presence of antiferromagnetic exchange interactions in the high-temperature phase and spin-gapped systems in the low-temperature phase. Below 50 K, 2 exhibits weak ferromagnetism. The spontaneous moments are nearly repressed by a field of 1.0 T. The crystal structure of 2 at 173 K reveals that there are two crystallographically independent [Pt(mnt)(2)](-) entries in an asymmetric unit. These two crystallographically independent [Pt(mnt)(2)](-) entries satisfy the spin-canting condition, and the EPR spectra measured at room temperature exhibit anisotropic character. Therefore, the weak ferromagnetic behavior in the low-temperature region for 2 can be attributed to the spin-canting phenomenon.     

Synthesis,structure and the e.s.r. spectrum of the mixed-valence molybdovandate Na2(NH4)4[(VIVVV8Mo)O28] · 10H2O

The mixed-valence molybdovanadate compound Na₂(NH₄)₄[V^IVV^V ₈Mo)O₂₈] · 10H₂O [Vanadata(6-)tetradeca--oxotetra-₃-oxodi-₆-oxoheptaoxo(oxomolybdate) nonatetrammonium disodium, decahydrate] has been synthesized from sodium molybdate(VI) dihydrate and sodium metavanadate dihydrate in aqueous solution by adding NH₂OH · HCl. The molecular structure has been determined by X-ray diffraction and is based on the isopolydecavanadate structure. The molybdate atom is crystallographically disordered over 6MO₆ octahedral sites. The e.s.r. spectrum clearly indicates that one vanadium atom has the oxidation number +4.     

Synthesis of the anionic fluororeceptors based on thiourea and amide groups and recognition property for α,ω-dicarboxylate

Three new neutral receptors (1, 2 and 3) containing thiourea and amide groups were synthesized by simple steps in good yields. The binding properties for anions of 1, 2 and 3 were examined by UV-vis, fluorescence, and ¹H NMR spectroscopy. Receptors 1, 2 and 3 all had a better adipate anion selectivity by comparison with other dicarboxylate anions. The association constants of 1, 2 and 3 with adipate were higher as compared to other anions (malonate, succinate, glutarate). In particular, a distinct color change was observed from light yellow to orange-red upon addition of adipate to the solution of 1 in DMSO. The UV-vis and fluorescence data indicate that a 1:1 stoichiometry complex is formed between compound 1, 2 or 3 and dicarboxylate anions through hydrogen bonding interactions.     

Synthesis and Crystal Structure of the Binuclear Complex [Pr2(C10H8N2O4)2(C10H9N2O4)2(H2O)4]·3H2O·C6H6

The binuclear praseodymium(III) complex with N‐(1‐carboxyethylidene)‐salicylhydrazide (C₁₀H₁₀N₂O₄, H₂L) was prepared in H₂O‐C₂H₅OH mixed solution, and the crystal structure of [Pr₂L₂(HL)₂(H₂O)₄]·3H₂O·C₆H₆ was determined by X‐ray single crystal diffraction. The crystal complex crystallizes in the triclinic system with space group P‐1, and in the structure each Pr atom is 9‐coordinated by carboxyl O and acyl O and azomethine N atoms of two tridentate ligands to form two stable five‐membered rings sharing one side in keto‐mode and two water molecules. The coordination polyhedron around Pr³⁺ was described as a monocapped square antiprism geometry. In an individual molecule, four tridentate ligands were coordinated by two negative univalent (HL) and two bivalent forms (L) respectively. Two negative univalent ligands were coordinated via μ₂‐bridging mode.     

改性凹凸棒的制备及对砷离子的吸附研究

针对日益严重的砷离子污染问题，本文采用灵敏简便的原子荧光分析法，探究了凹凸棒石粘土吸附剂对砷离子的吸附性能，测定了pH、吸附时间、砷离子的初始浓度等因素对凹凸棒石粘土负载铁氧化物对砷离子吸附能力的影响，并通过SEM、EDX、FTIR对所制得的吸附剂进行了表征研究，同时进行了吸附动力学和吸附等温模型的分析。研究结果表明，改性后的凹凸棒对砷离子的吸附性能有了显著提升，在较低浓度时吸附效率可达98%，该吸附符合Langmuir等温吸附模型和准二级动力学方程。