Three‐dimensional hydrogen‐bonded framework structures in flunarizinium nicotinate and flunarizinediium bis(4‐toluenesulfonate) dihydrate

The structures of two salts of flunarizine, namely 1‐bis[(4‐fluorophenyl)methyl]‐4‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazine, C₂₆H₂₆F₂N₂, are reported. In flunarizinium nicotinate {systematic name: 4‐bis[(4‐fluorophenyl)methyl]‐1‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazin‐1‐ium pyridine‐3‐carboxylate}, C₂₆H₂₇F₂N₂⁺·C₆H₄NO₂⁻, (I), the two ionic components are linked by a short charge‐assisted N—H...O hydrogen bond. The ion pairs are linked into a three‐dimensional framework structure by three independent C—H...O hydrogen bonds, augmented by C—H...π(arene) hydrogen bonds and an aromatic π–π stacking interaction. In flunarizinediium bis(4‐toluenesulfonate) dihydrate {systematic name: 1‐[bis(4‐fluorophenyl)methyl]‐4‐[(2E)‐3‐phenylprop‐2‐en‐1‐yl]piperazine‐1,4‐diium bis(4‐methylbenzenesulfonate) dihydrate}, C₂₆H₂₈F₂N₂²⁺·2C₇H₇O₃S⁻·2H₂O, (II), one of the anions is disordered over two sites with occupancies of 0.832 (6) and 0.168 (6). The five independent components are linked into ribbons by two independent N—H...O hydrogen bonds and four independent O—H...O hydrogen bonds, and these ribbons are linked to form a three‐dimensional framework by two independent C—H...O hydrogen bonds, but C—H...π(arene) hydrogen bonds and aromatic π–π stacking interactions are absent from the structure of (II). Comparisons are made with some related structures.     

A simple hydrated salt with a complex hydrogen‐bonding network: tetrakis(5‐amino‐3‐carboxy‐4H‐1,2,4‐triazol‐1‐ium) hexachloridocadmate(II) tetrahydrate

In the title cadmium chloride salt, (C₃H₅N₄O₂)₄[CdCl₆]·4H₂O, the asymmetric unit comprises two N‐protonated 5‐amino‐3‐carboxy‐4H‐1,2,4‐triazol‐1‐ium cations, half a [CdCl₆]⁴⁻ anion and two molecules of water. The Cd²⁺ cation is located on a centre of inversion and is coordinated by six chloride anions, forming a distorted octahedron. In the crystal structure, alternating layers of cations and anions are arranged along the [101] direction, forming a three‐dimensional supramolecular network via a combination of hydrogen‐bonding and aromatic stacking interactions.     

固蓝盐B分光光度法测定药物中抗坏血酸

探讨了一种简便的选择性高的药物中抗坏血酸的测定方法。该方法是基于在酸性介质中抗坏血酸和固蓝盐B的反应,产物的最大吸收为420nm.摩尔吸光系数为1.31×10~4L·mol~(-1)·cm~(-1).方法已应用于某些药物中抗坏血酸的测定,结果与碘量法一致,回收率为98.4％～105％,相对标准偏差低于3.7％。     

New amidines from intramolecular cyclization in triflic acid of nitroketene aminals with a tethered phenyl ring

Nitroketene aminals with a tethered phenyl group underwent an intramolecular cyclization in trifluoromethanesulfonic acid to afford the corresponding N-(3-ethyl-hydrohydroxyiminobenzocyclo-alkenylidene)methylamine trifluoromethanesulfonate. The yields were fair to good excepted for the starting compound 1-[N-ethyl-N-(2-phenylethyl)amino]-1-methylamino-2-nitroethene.     

基于推测弹性的双寡头研发AJ模型最优成本缩减决策

文章通过将推测弹性引入AJ模型,首先考察一致性推测弹性对双寡头企业研发策略的影响,从而得出有推测的双寡头市场结构下的研发均衡结果,然后将零一致性推测弹性的均衡成本缩减量与AJ模型的结果进行对比,最后给出一致性推测弹性和溢出系数之间的关系对研发绩效的影响效果.     

Solid polymers doped with rare earth metal salts. II. Thermal behavior and morphology of the neodymium acetate–poly(ethylene oxide) system

Samples of poly(ethylene oxide), PEO, doped with neodymium acetate, Nd (Act)₃, were prepared and found to be microphase separated. At an EO/Nd (Act)₃ molar ratio no less than 4, wide-angle x-ray diffraction (WAXD) patterns and small-angle x-ray scattering (SAXS) data suggest that bulk Nd (Act)₃ and ionic clusters are both absent. It is inferred from differential scanning calorimetry (DSC) thermograms that in the presence of PEO, Nd (Act)₃ forms an amorphous phase which is different from the amorphous phase formed by Nd (Act)₃ alone. The tighter binding of CH₃COO^- to Nd³⁺, in comparison to Cl^-, appears to be responsible for the lack of true dissolution of Nd (Act)₃ in PEO, a behavior clearly distinct from a number of polymer-metal salt complexes reported in the literature. © 1993 John Wiley & Sons, Inc.     

工频趋肤效应及其应用

通过对圆柱型导线中传导电流密度分布公式的推导和讨论，说明在频率很高或频率虽低（例如工频５０Ｈｚ）但导线截面较大都会产生很强的趋肤效应，进而通过实例讨论了工频趋肤效应的一些特点和应用。     

Enantiomeric enrichment of partially resolved N-methyl-amphetamine

The enantiomeric enrichment of N-methyl-amphetamine (MA) was tried by eight different preparative separation methods. The enrichment process was also studied by thermoanalitical methods (DSC,TG). There is no enantiomeric enrichment during fractional distillation and selective extraction of the liquid base. The enantiomeric mixture of MA·HCl can be enriched by crystallization or by sublimation. The most effective enrichment can be achieved by fractional crystallization or distillation of the reaction mixture after partial salt formation with hydrochloric acid. The separation is less effective in case of fractional steam distillation and selective extraction when the enantiomer and the racemate are distributed between two liquid phases. This supports the general experience that having a solid phase in the system makes enantiomer separation more efficient.This revised version was published online in November 2005 with corrections to the Cover Date.     

Structure and photochromic properties of a single-crystalline spiro[indolinepyranopyridinium] salt

The molecular and crystal structure of single crystalline 5’-hydroxymethyl-1,3,3,7’, 8’-pentamethylspiro[indoline-2,2’-[2H]-pyrano[3,4-b]pyridinium] iodide (1) was studied. The crystal structure is composed of cation layers separated by iodide ions and provides a sufficient volume for the phototransformation of compound 1. The spectroscopic and photochromic properties of this compound in the crystalline state were investigated. Upon irradiation with light at 270–370 nm, up to 600 layers of single crystals are subjected to photochromic transformations. The quantum yield of formation of the open form is ∼0.1, and the quantum yield of decoloration is 0.04. After ten reversible photocyclizations, the absorption of the colored form was decreased by 10%. The photochromic properties were related to the single-crystal structure. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2050–2055, September, 2005.