新型镨-铁-钼系和铈-铁-钼系氮化物的结构和磁性

对于轻稀土,特别是铈和镨,难以形成具有ThMn_(12)型结构的釜属间化合物,本文通过适当的热处理,制备成功单相的CeMo_(1.5)Fe_(10.5)和PrMo_(1.5)Fe_(10.5)及其氮化物,特别是PrMo_(1.5)Fe_(10.5)N_x,c轴为易磁化方向,并具有高居里温度、高各向异性场和高饱和磁化强度,可开发为有应用价值的新型磁体。     

催化极谱法连续测定岩石中钨和钼

本文提出了在二苯基乙醇酸-二苯胍-氯酸钠催化极谱体系测钨后,加入少许钛铁试剂,使钼产生一个极灵敏的导数波。谊波形尖锐、对称,便于测量钼。建立的连测体系简便灵敏,用于岩石样品中钨和钼的测定,取得了满意的效果。     

磷钼蓝光度法测定钼

利用磷钼杂多酸测磷,这是众所周知的,但用于钼的测定,还未见报道。本文提出在含MoO_4~(2-)溶液中,过量PO_4~(3-)的存在下使之形成磷钼杂多酸,经抗坏血酸还原后,直接用于钼的测定,方法十分简便。在测定波长690nm处,摩尔吸光系数为7.0×10~2,钼量在0—12mg/mL范围内符合比尔定律,满足高含量钼快速分析的要求。方法用于钼铁中钼的测定,获得较为满意的结果。     

2-羟基萘甲醛苯甲酰腙作配体的钼和钒两个化合物的合成和晶体结构

2-羟基萘甲醛苯甲酰腙(H₂L)由2-羟基萘甲醛和苯甲酰肼在乙醇溶液中制得。利用H₂L分别合成了钼和钒的配合物，[MoO₂(EtOH)L](1) 和 [VO(OMe)L(MeOH)](2)，并测定了它们的晶体结构。配合物1和2是类似的结构单元，钼和钒都采取扭曲的八面体配位构型。     

硫粉为硫源,多元醇辅助合成硫化钼纳米片

MoS₂ nanosheets are prepared with sulfur powder and Na₂MoO₄ by a one-pot two-phase method at 170-200 ℃ for 8 h. In addition, a three-step growth mechanism based on the aggregation and coalescence model is proposed. The reassembly of sulfur powder ensures the transformation from sulfur powder to H₂S to reduce Na₂MoO₄ and plays a key role in the successful preparation of MoS₂ nanosheets. The as-prepared MoS₂ nanosheets are rich in unsaturated sulfur atoms, probably resulting from the dislocation cores of the MoS₂ nanosheets, which have been found to be beneficial for hydrogen evolution reaction catalysis. The method and growth mechanism adopted in this study may be applied to other transition metal dichalogenides for similar structures. The facile and green method provides an alternative for the preparation of MoS₂ nanosheets.     

钼磷酸铵及钼磷酸掺杂的聚合物电解质

以聚氧乙烯(PEO)为基质,掺杂适量的钼磷酸铵或钼磷酸,制备出PEO-(NH₄)₃PMo12O₄₀及PEO-H₃PMo12O₄₀质子导电聚合物电解质膜,测定了其电导率.讨论了加入(NH₄)₃PMo12O₄₀及H₃PMo12O₄₀对PEO构型及Keggin阴离子的影响,分析了PEO-(NH₄)₃PMo12O₄₀及PEO-H₃PMo12O₄₀复合膜质子电导提高的原因.其中PEO-(NH₄)₃PMo12O₄₀质子导电聚合物电解质复合膜的室温电导率最高可达1.4×10_-3S/cm.     

钼与社会

钼及其合金的优异机械性能与良好的物理化学性能,使其倍受工业各部门的青睐,导致85%的钼用于制备铁基合金;钼及其含氧化合物为化学石油工业的重要催化剂;二硫化钼则被誉为“润滑之王”;钼还被用于制备无机颜料。钼在生命系统中为必须的微量元素,它能促进植物生长发育,提高农作物产量;对人类防治一些癌症也有一定作用。预计本世纪末,世界对钼将出现供不应求的趋势。     

钼体系催化剂中钼的光度测定

钼体系催化剂是一类重要的催化剂。催化剂中钼的含量对催化剂的活性起着重要作用,快速准确地测定其中钼的含量对于催化剂的研究是很必要的。硫氢酸盐光度法是测定钼常用的方法,具有操作简便、结果准确之优点。由于该催化剂只能在氮气保护下溶于汽油,遇到空气和水时钼即析出,故不能直接用文献[1]介绍的方法测定钼体系催化剂中钼。本文对汽油在无水乙醇中的溶解情况进行试验,表明催化剂的汽油溶液能溶于无水乙醇,而且稳定,从而解决了试样的稀释、分取和储存等问题。本法将钼的硫氰酸盐光度法应用到钼体系催化剂中钼的测定,得到了满意的结果。仪器与试剂 72型分光光度计;50％硫氰酸钾溶     

基于磷钼蓝反应测定钴-钼催化剂浸渍液中钼离子含量

基于磷钼蓝反应测定钴-钼催化剂浸渍液中钼离子含量。建立了一个流动注射-磷钼蓝分光光度法测定高浓度钼离子的含量,优化后的条件为:1酸度调节剂为0.5mol·L-1硫酸溶液;2载流为超纯水;3反应试剂为120g·L-1磷酸二氢钾、100g·L-1抗坏血酸及0.3mol·L-1硫酸的混合液;4总流量为2.8 mL·min-1;5酸度调节盘管长度为20cm;6反应盘管长度为250cm。三氧化钼的质量浓度在10.0~300.0g·L-1范围内与峰高呈线性关系,检出限(3s/k)为2.0g·L-1。方法用于钴-钼催化剂钼浸渍液的分析,回收率在99.7%~105%之间,测定值的相对标准偏差(n=11)小于1%。     

Ab initio studies of the conformations of ethynyl formate, cyano formate and related ethynyl and cyano compounds

The optimized geometries, relative free energies and related thermodynamic properties, harmonic frequencies, and dipole moments have been calculated at the HF and MP2 levels for ethynyl formate (1a), ethynyl acetate (1b), cyano formate, HCO₂CN (1c), cyano acetate (1d), S-ethynyl thioformate (2a), S-ethynyl thioacetate (2b), S-cyano thioformate (2c), S-cyano thioacetate (2d), N-ethynylformamide (3a), N-ethynylacetamide (3b), N-cyanoformamide (3c), and N-cyanoacetamide (3d) with the gaussian 98 program. For ethynyl formate, the calculation for 25 °C at the MP2/6-311++G(df,pd) level predicts that the Z isomer is more stable by 1.23 kcal/mol. For S-ethynyl thioformate, calculations at the MP2/6-311++G(2d,2p) level predict that the E isomer is favored by 0.71 kcal/mol at 25 °C. The E isomers of N-ethynylformamide and N-ethynylacetamide were found at all levels to be more stable than the Z isomers at 25 °C. For cyano formate and cyano acetate, calculations at the MP2/6-311++G(df,pd) level predict that the Z isomers are more stable at 25 °C by 1.50 and 2.72 kcal/mol, respectively. At this level and temperature, the Z isomers of 2c, 2d, 3c, and 3d are predicted to have free energies of 0.46, −0.07, 1.22, and 2.28 kcal/mol, respectively, relative to the E conformations. Z to E free-energy barriers at 25 °C of 8.63, 10.64, 17.63, 7.39, and 14.03 kcal/mol were calculated for 1a, 2a, 3a, 1c, and 3c at the HF/6-311G(d,p) level, and at the HF/6-311+G(d,p) level, the free-energy barrier for 2c was 7.08 kcal/mol.     

Synthesis and spectral properties of malononitrile-based merocyanine dyes

Di-, tetra-, and hexamethine merocyanines derived from malononitrile and heterocycles with moderate (dyes 1–6), strong (7–9), and weak (10 and 11) electron-releasing ability were synthesized. The electronic structures of merocyanines 10 and 11 are similar to the neutral polyene state, whereas those of 7–9 are similar to the ideal polymethine state. These tendencies become more pronounced with increasing length of the polymethine chain. The merocyanines derived from heterocyclic residues with weak or moderate electron-releasing ability exhibit a positive solvatochromism, whereas those with strong electron-releasing ability show a negative solvatochromism. An increase in the polarity of the solvent makes the former compounds more similar to polymethines, whereas the latter become more similar to polyenes bearing opposite charges on the end groups. The nature of the factors (nonspecific solvation, specific nucleophilic and electrophilic solvation, and vibronic interactions) responsible for the observed characteristic features was analyzed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2726–2735, December, 2005.     

Elucidation of activity of copper and copper oxide nanomaterials for electrocatalytic and photoelectrochemical reduction of carbon dioxide

Copper- and copper oxide–based materials are, in principle, promising components (supports, reactive sites, and visible light–absorbing semiconductors) of electrocatalysts and photocathodes for reduction of carbon dioxide. Electrochemical and photoelectrochemical approaches are generally suitable for the low-temperature CO₂-conversion to carbon-based simple organic fuels or utility chemicals.Different concepts of utilization, including nanostructuring, doping, admixing, preconditioning, modification, or functionalization of various copper- and copper oxide–based systems for catalytic electroreduction and photoelectrochemical reduction of CO₂ are elucidated, as well as important strategies to enhance the systems' overall activity and stability are discussed.     

溶质迁移研究进展

溶质迁移研究已成为水文地质等领域的一个重要研究课题。综述了溶质迁移研究进展,重点介绍了溶质迁移在地下水污染与防治、土壤盐碱化防治、海水入侵和咸水入侵防治等方面的研究现状,并指出应进一步研究的问题。     

Studies of some monocyclic and bicyclic arylacetonitriles

The high-resolution (1)H, (13)C, (1)H-(1)H COSY and (1)H-(13)C COSY NMR spectra have been recorded in CDCl(3) for arylacetonitriles 1-12 and analyzed. The arylacetonitriles 3-7 exist in two isomeric forms E (methyl group is anti to cyano group) and Z (the methyl group is syn to cyano group) in solution. Normal chair conformation with equatorial orientations of phenyl rings at C-2 and C-6 for monocyclic nitriles 1 and 2, epimeric chair structure EC (axial configuration of methyl group at C-3) for both the E and Z isomers of arylacetonitrile derivatives (3-7) and a distorted boat form, B(3), for the N-acylacetonitrile derivatives (8-10) have been proposed based on NMR data. The bicyclic nitriles 11 and 12 exist in twin chair conformations in solution. DFT calculations and chemical shifts also support these conformations. Geometry optimizations for 1-12 were carried out according to density functional theory using B3LYP/6-31G(d,p) basis set and for 1 and 8 the theoretical geometrical parameters have been compared with those of single crystal measurements.     

Coupled calculation of vibrational frequencies and intensities

The combination of normal coordinate analysis with intensity calculations gives quantitative information about molecular force fields and the assignments of vibrational frequencies. Calculations of vibrational intensities by means of a standard CNDO/2 version give rise to satisfactory results for the IR intensities. However, the calculated Raman intensities often differ strongly from the experimental data. Inclusion of 2p-polarization functions on hydrogen in the usually used valence basis set is quite successful to obtain improved molecular polarizabilities as well as Raman intensities.     

Potentiometric and thermodynamic studies of 2-mercapto-5-(2-hydroxynaphthylideamino)-1,3,4-thiadiazole and its metal complexes

Summary Proton-ligand dissociation constant of 2-mercapto-5-(2-hydroxynaphthylideamino)-1,3,4-thiadiazole (MHT) and the stepwise stability constants of its metal complexes were determined potentiometrically in 40 mass/mass% ethanol-water mixture containing 0.1 M KCl. The stabilities of the complexes follow the order: Cu²⁺>Ni²⁺>Co²⁺>Mn²⁺. The dissociation constant (pK^H) of MHT and the stability constants (logK) of its metal complexes were determined at different temperatures and the corresponding thermodynamic parameters were calculated and discussed. The proton dissociation process is non-spontaneous, endothermic and entropically unfavoured. The formation of the metal complexes was found to be spontaneous, endothermic and entropically favoured.     

ChemInform Abstract: Matrix IR Investigations of Molecular SPBr.

SPBr, generated according to the scheme, is cocondensated with excess argon at 15 K. In the matrix IR spectrum the two stretching vibrations and the overtone of the bending mode are observed.     

大型仪器公共技术服务中心管理经验介绍

结合中国科学院长春应用化学研究所公共技术服务中心建设情况,从运行管理模式、大型仪器设备共享措施、科技支撑队伍建设等方面介绍了中心如何推动大型仪器设备开放共享工作.     

ICP-AES法测定烟花爆竹中禁限用药物

以5%HNO3处理烟花爆竹内药物样品,以ICP-AES法测定样品中K、Na、P、Mg、Ba、Cu、B、Sr、Sb、Ga、Ge、Al、Ti、Mn、Pb、As 16种元素。比较了不同酸、不同浓度时样品的处理方法,5%HNO3为最佳样品处理条件。对4个不同厂家产品进行了测定和加标回收研究,测定结果的相对标准差小于5%(n=5),各元素的回收率在93.4%～114.3%之间。