Rhodium catalysed [2+2+2] cycloadditions of acetylenes

Wilkinson's catalyst RhCl(PPh₃)₃ is an effective catalyst (0.5 – 2 mole %) for the rapid intermolecular trimerisation of 1,6-heptadiynes with monoacetylenes under mild conditions.     

Hydrotalcite catalysed [4+2] cycloaddition reactions of nitroso- and azo-alkenes

The generation of nitroso- and azo-alkenes and their [4+2] cycloaddition reactions with furan and ethyl vinyl ether, producing dihydro-1,2-oxazines and tetrahydropyridazines, by the use of catalytic Mg:Al 3:1 hydrotalcite, is described. The absence of an organic solvent, the catalytic quantities of Ht required together with its regeneration and reuse, may be regarded as environmentally friendly, greener and economically advantageous over the usual methods.     

Crystal Structure of LiClO4

Single crystals of LiClO₄ were obtained during attempts to prepare lithium containing rare earth perchlorates from a lithium perchlorate melt. In the crystal structure of LiClO₄ (ortho‐rhombic, Pnma, Z =4, a = 865.7(1), b = 691.29(9) pm, c = 483.23(6), R_all = 0.0273) the Li⁺ ions are in distorted octahedral coordination of oxygen atoms. The octahedra are linked via common edges to chains according to ¹[LiO_2/1O_4/2] which run in the [010] direction. The perchlorate ions are almost ideal tetrahedra.     

偶联剂原位改性SiO2提高PEO/LiClO4/SiO2电导率

偶联剂原位改性SiO2提高PEO/LiClO4/SiO2电导率;PEO;聚合物电解质;偶联剂;SiO2;电导率     

Cocrystallization of Cu2+ with NH4Cl by the anomalous isomorphism mechanism

In the ammonium chloride crystallization region of the NH₄Cl−CuCl₂−H₂O−CH₃ON system, cocrystallization of the impurity with the main substance occurs by epitaxial adsorption of complexes of varying composition. In NH₄Cl crystals, the Cu²⁺ impurity forms oriented interlayers (ingrowths) simultaneously at the macro-and microlevels. The ratio between the two trapping forms depends on the growth conditions. St. Petersburg State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 35, No. 5, pp. 70–78, September–October, 1994. Translated by L. Smolima     

4-Mercaptophenylacetic acid functionalized Mn2+-doped ZnS nanoparticles fluorescence quenching caused by the addition of Cu2+

This paper reports that 4-mercaptophenylacetic acid functionalized Mn²⁺-doped ZnS nanoparticles (4-MPAA-ZnS-Mn²⁺ NPs) as fluorescent probes for the detection of copper ions in solution. The fluorescence quenching was due to the aggregation of copper ions with 4-MPAA-ZnS-Mn²⁺ NPs. These aggregations were confirmed by using UV lamp, UV–visible spectroscopy and dynamic light scattering (DLS). These 4-MPAA-ZnS-Mn²⁺ NPs were applied as fluorescent probes to detect copper ions in aqueous solution.     

高氯酸锂与1,3-氮氧杂环-戊-2-酮形成的二元熔盐电解质

制备了高氯酸锂(LiClO4)与1,3-氮氧杂环-戊-2-酮(OZO)形成的二元熔盐电解质, 虽然先导物具有较高的熔点, 但二者可形成均一、稳定的共熔体系, 测试结果表明该熔盐体系具有低的共熔温度(-50 益). 红外光谱分析表明OZO 通过Li—O 键与LiClO4中Li+配位而破坏了LiClO4的离子键,形成很大的配位阳离子,削弱了阴阳离子间的库伦作用力; 同时Li—O 配位也导致OZO 分子间的氢键断裂, 因而体系的共熔温度较之纯物质熔点显著降低, 部分样品室温下以液体状态稳定存在. 采用交流阻抗法和循环伏安法对其电化学性质进行研究, 结果显示, 配比n(LiClO4):n(OZO)=1:4.5 的样品室温(25 ℃)电导率为0.66×10^-3 S·cm^-1, 80 ℃电导率为7.33×10^-3 S·cm^-1; 其电化学稳定电位窗口约为3.5 V.     

Metallation of rigid 2-aryl-1,3-dioxanes

Regioselective metallation and alkylation/acylation of 2-aryl-1,3-dioxanes was achieved in high yield.     

Ring opening polymerization of tetrahydrofuran catalysed by maghnite-H+

The cationic ring-opening polymerization of tetrahydrofiiran using maghnite-H~+ is reported.Maghnite-H~+,is a non-toxic solid catalyst issued from proton exchanged montmorillonite clay.Polytetrahydrofuran,also called "poly(butandiol) ether",with acetate and hydroxyl end groups was successfully synthesized.Effects of reaction temperature, weight ratio of initiator/monomer and reaction time on the conversion of monomer and on the molecular weight are investigated.A cationic mechanism of the reaction was proposed.This chemistry can be considered as a suitable route for preparing poly(THF) as a soft segment for thermoplastic elastomers.     

Rhodium catalysed [2+2+2] cycloadditions- an efficient regiospecific route to calomelanolactone

A short regiospecific synthesis of calomelanolactone has been devised in which the key step is a [2+2+2] cycloaddition.     

Aerobic oxidation of cumene catalysed by 4-alkyloxycarbonyl-N-hydroxyphthalimide

4-Hexyloxycarbonyl-, 4-dodecyloxycarbonyl- and 4-hexadecyloxycarbonyl-N-hydroxyphthalimides were synthesised using trimellitic anhydride chloride as the starting material. The obtained lipophilic derivatives of N-hydroxyphthalimide were applied as catalysts of the cumene oxidation reaction with oxygen performed in polar acetonitrile, in non-polar tert-butylbenzene and in the absence of a solvent. The courses of reactions catalysed by N-hydroxyphthalimide and its derivatives were compared.      

PEO/LiClO_4纳米SiO_2复合聚合物电解质的电化学研究

将实验室制备的纳米二氧化硅和市售纳米二氧化硅粉末与PEO LiClO4复合 ,制得了复合PEO电解质 .它们的室温离子电导率可比未复合的PEO电解质提高 1～ 2个数量级 ,最高可以达到 1 2 4× 10 - 5S cm .离子电导率的提高有两方面的原因 :一是无机二氧化硅粉末的加入抑制了PEO的结晶 ,是二氧化硅粉末和聚合物电解质之间形成的界面对电导率的提高也有一定的作用 .在进一步加入PC EC(碳酸丙烯酯 碳酸乙烯酯 )混合增塑剂后制得的复合凝胶PEO电解质 ,可使室温离子电导率再提高 2个数量 ,达到 2× 10 - 3 S cm .用这种复合凝胶PEO电解质组装了Li|compositegelelectrolyte|Li半电池 ,并测量了该半电池的交流阻抗谱图随组装后保持时间的变化 ,实验观察到在保持时间为 144h以内钝化膜的交流阻抗迅速增大 ,但在随后的时间内逐渐趋于平稳 ,表明二氧化硅粉末的加入可以有效地抑制钝化膜的生长     

Fluorescence quenching of naphthols by Cu2+ in micelles

Effect of the micelles of anionic, cationic and non-ionic surfactants on the fluorescence quenching of 1- and 2-naphthols has been studied in the presence of copper ion. The excited state lifetime, dynamic and static quenching constants for these systems have been determined. Fluorescence quenching in water and SDS micelle is due to the collision of the fluorophore with the quencher with a small static component. The negatively charged naphtholate ions in the excited state are quenched with significantly higher rates than the neutral naphthol molecules, which are located further inside the mesophase. CTAB micelle is less effective than the SDS micelle for fluorescence quenching. The effect of CTAB on water-assisted excited-state deprotonation has been investigated in the presence of ZnSO₄. For TX-100 micelle there is negligible quenching even at higher concentration of the quencher.     

ChemInform Abstract: Pseudopotential Investigations on the Molecules Cu2Si2, Cu2Sn2, Cu4Si4, and Cu4Sn4

show the equilibrium structures to be the butterfly arrangement for the Cu₂X₂ clusters and the heterocubane arrangement for the Cu₄X₄ clusters.     

Cu2+ in trigonal-bipyramidaler Koordination: Die Struktur des CuGaInO4

Cu²⁺ in Trigonal-bipyramidal Coordination: Structure of CuGaInO₄ CuGaInO₄ crystallizes in space group R3 m with the hexagonal unit cell parameters a = 335.4(3) and c = 2481(5) pm (Z = 3). The anions form a 12-layer structure with the sequence (31)₃. Indium has a position between cubically packed oxygen layers and possesses a (trigonally-compressed) octahedral coordination. Cu²⁺ and Ga³⁺ – with positions near to the oxygen layers of hexagonal sequence – have a trigonal-bipyramidal coordination (distorted: C_3v). Polyhedra of the same kind form layers by mutual connections via common edges. Polyhedra of different kind are connected with each other along the 3 -axis by common corners.     

脯氨酸与Cu、Cu~+和Cu~(2+)配位体系的计算研究

运用M06-2X和ωB97XD方法分别在6-311++G(2d,p)和TZVP基组水平上,对脯氨酸(Pro)的15种构象与Cu、Cu+和Cu2+形成的多种配合物的几何结构、能量学特征、振动光谱和电子结构等进行计算研究.四种水平得到20种[Pro-Cu]、16种[Pro-Cu]+和16种[Pro-Cu]2+稳定结构.[Pro-Cu]和[Pro-Cu]+体系中出现12种Pro构象,而[Pro-Cu]2+体系中出现11种Pro构象,三种体系中最稳定的结构都不是由能量最低的Pro构象生成的.在结构CI3、CI4、CII7和CII8中,Pro的羧基氢转移到亚氨基氮形成两性离子与Cu双配位结合.[Pro-Cu]0/1+/2+体系四种水平计算相对能差范围逐渐增加,结合能分别在-60.0--5.0 kJ·mol-1、-340.0--170.0 kJ·mol-1和-1100.0--860.0 kJ·mol-1范围,配位体系中Pro的变形能逐渐增加.N―H和O―H键伸缩振动频率普遍发生红移,配位体系中部分电荷从Pro转移到Cu上,在[Pro-Cu]2+体系中单配位结构中电荷转移最多,约为单位负电荷.