Synthesis and structure of novel copper(II) complexes with pyrazole derived ligands and metal–ligand interaction in solution

Two new ligands of the coumarin type have been synthesized and characterized by ¹H, ¹³C NMR, IR and MS. The crystal and molecular structures of ligand 2, determined by the X-ray diffraction method, are presented. With copper(II) these ligands create solid complexes of the type CuLCl₂, where L is 5-(2-hydroxybenzoyl)-3-methyl-1-(2-pyridinyl)pyrazol-4-carboxylic acid methyl ester (2) or 3-methyl-1-(2-pyridinyl)-1H-chromene[4,3-c]pyrazol-4-on (3). The new copper(II) complexes have been characterized by elemental analysis and solid state FT-IR. The protonation constants of ligands 2 and 3 have been determined in 5% v/v 1,4-dioxane–water solution (25 °C). The coordination modes in the complexes with copper(II) are discussed for 2 on the basis of potentiometric and UV–Vis data.     

Symbolic Dynamics of the Piecewise Linear Standard Map

The symbolic dynamics of the sawtooth map is extended to the dissipative piecewise linear standard map. The ordering rules of foliations are derived, and the admissibility condition for allowed symbolic sequences is obtained. A symbolic analysis is given for invariant circles of the piecewise linear standard map without dissipation.     

新概念下的Sn掺杂(La1-xSrx)2Cu1-xSnxO4超导体的M(o)ssbauer谱研究

对新概念指导下而设计的(La1-xSrx)2Cu1-xSnxO4超导体进行了119SnM(o)ssbauer谱研究.对不同掺杂量样品的系统研究表明,M(o)ssbauer谱实验结果进一步证实了Sn以Sn4+价态存在并占据Cu晶位,不存在占据La晶位的Sn2+离子. Sn4+离子附近的局域晶格畸变较小,但是随Sn掺杂量有增加趋势.在对La2CuO4母体进行Sr和Sn同时掺杂所引入的载流子对超导电性的影响存在新的机制.在新的额外氧机制下,讨论了Sn掺杂所导致的额外氧对超导电性的影响.     

Catalytic combustion of carbon particulates over perovskite-type oxides

A Cu/Cr₂O₃ catalyst was prepared by co-precipitation method, studied in methanol dehydrocoupling to methyl formate in different gas streams and characterized by BET, XRD, TPR, TPD of NH₃ and CO₂, etc. The results demonstrate that the catalyst can catalyze the dehydrocoupling of methanol to methyl formate in high efficiency,e. g. 99% selectivity to methyl formate at 48% conversion of methanol. The results further indicate that metallic copper might be the active species for the formation of methyl formate     

Contracted Gaussian-type basis functions revisited. III. Atoms K through Kr

Six minimal basis sets of contracted Gaussian-type functions (GTFs) are developed for the third-row atoms K through Kr. The smallest and largest sets for transition metal atoms are (3333/33/3) and (8433/84/8), respectively, where a slash distinguishes the s, p, and d symmetries and single-digit figures in the parentheses denote the numbers of primitive GTFs. The two largest sets, (7433/74/7) and (8433/84/8), surpass the (62111111/33111/311) set of Schaefer et al. in the associated total energies. Our (8433/84/8) set is also superior to their (842111/631/411) set. The quality of the present basis sets is tested by self-consistent field (SCF) and configuration interaction (CI) calculations on the Cu₂ molecule. As the accuracy of the basis set increases, SCF calculations show a decrease in the dissociation energy and an increase in the equilibrium internuclear distance. The same tendencies are found in the results of CI calculations with and without a Davidson correction. All the present basis sets are freely available at the internet address: http://202.35.198.41/∼htatewak/. Received: 17 June 1998 / Accepted: 4 August 1998 / Published online: 23 November 1998     

Small band gap and high ionic conduction in Cu2S

Far-infrared reflectivity spectra of Cu₂S have been measured from 20 to 700 cm⁻¹ at several temperatures through the superionic transition temperature T_c. Many bands and two broad bands were observed at low and high temperatures, respectively. From the spectra, we determined optical dielectric constant _∞, the angular frequencies of longitudinal (LO) and transverse (TO) optical phonons, and transverse effective charge. Based on these values, we suggest significant role of small band gap for high ionic conduction with small activation energy and the possibility of lattice distortion arising from an enhanced effective charge. Anomalous temperature dependence has been found for _∞ and TO–LO splitting.     

流动注射蒸气发生原子吸收光谱测定痕量铜

建立了流动注射蒸气发生原子吸收光谱测定铜的新方法。使含有微量邻菲咯啉的样品溶液与硼氢化钠溶液汇合并反应生成蒸气态物质。在Ar载气下随反应液进入气液分离器分离 ,并进入石英管原子化器在 1 0 0 0℃下检测。在 5 0 0 μL进样体积下 ,铜的检出限为 1 8μg·L- 1 ,相对标准偏差为 2 6%(n =1 1 ,c=1 0 0 μg·L- 1 )。采样频率为 1 4 4样·h- 1 。分析标准参考物质大米粉和头发样品中的铜 ,结果与标准值一致     

基本物理化学常数的CODATA最新推荐值

文章给出了由国际科学技术数据委员会（简称CODATA）推荐的基本物理化学常数及转换因子的1998的自洽组的数值,供国际上普遍使用。新推荐值的村准不确定度,与1986年推荐值的相应不确定度比较,在多数情况下,前约为后者的1／5至1／12,而在某些情况下,则为其1／160,然后,几科在所有情况下,1998年数值与1986年相应值之差的绝对值均小于1986年数值的标准不确定度的两倍。     

Complementarity of universal calibration SEC and 13C NMR in determining the branching state of polyethylene

The quantitation of long‐chain branching (LCB) and short‐chain branching (SCB) in polyethylene (PE) was accomplished with a combination of carbon nuclear magnetic resonance (¹³C NMR) spectroscopy and size exclusion chromatography (SEC) with universal calibration. We demonstrate how the spectroscopic and chromatographic techniques can supplement each other, as neither is capable individually of completely describing the molecular architecture imparted by the various types of branching. The essential lack of impact of SCB on the hydrodynamic volume imposes a limit on SEC for determining this type of branching, whereas highly effective LCB in the PE molecule may not offer a statistically large enough amount of long chains for accurate determination by NMR. A variety of examples are given for PE, showcasing the advantages and shortcomings of each analytical method and their complementarity. Additionally, the importance of choosing an appropriate linear standard and viscosity shielding ratio (ϵ) for the Zimm–Stockmayer branching calculations employed for analyzing SEC data is emphasized with an examination of the effect on the results of using a branched standard and various ϵ values. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 3120–3135, 2000