Synthesis and X-ray structural analysis of a unique Co-crystallization complex of [NaSal]2DB24C8 and [KSal]2DB24C8

Sodium salicylate (NaSal where Sal=2-hydroxybenzoate), when mixed with dibenzo-24-crown-8 (DB24C8) yields a bimetallic complex [NaSal]₂DB24C8 in most polar organic media, while potassium salicylate (KSal) under similar conditions shows a tendency to yield 11 or 21 complexes depending upon medium or synthesis. However, the presence of both NaSal and KSal together results in a unique mixed cation complex of composition NaKSal₂DB24C8. This product melts sharply (190-92°C) without decomposition, displays IR spectral characteristics comparable to those of [Na(Sal)]₂DB24C8, and is stable in aqueous media as shown by the detectable cation effect on the UV absorption bands of Sal and DB24C8. Single crystal X-ray analysis of NaK(Sal)₂DB24C8 reveals that the system represents a co-crystallization complex of individual (KSal)₂DB24C8 and (NaSal)₂DB24C8 molecules. The crystals are monoclinic,P2₁/c,a=19.976(2) Å,b=9.031(1) Å,c=25.541(5) Å,=122.065(9)°, ų,T=298 K,Z=2+2, CuK =1.5418 Å, and 2 (2.5°–100°). FinalR factor for the 3012 observed reflections (F>3) is 0.092. Both the Na₂- and K₂-molecules possess crystallographic centers of symmetry with one metal and its associated anion on each side of the crown ring. However, the conformations of the crowns are very different in the two molecules, with the K₂-crown being nearly planar and the Na₂-crown being quite puckered. Four oxygen atoms from the DB24C8 (KO, 2.680–2.908 Å) and three carboxyl oxygen atoms (KO, 2.472–2.708 Å) from separate salicylate ions coordinate with each potassium. Three oxygens from the crown (NaO, 2.536–2.65 Å) and three carboxyl oxygens (NaO, 2.31–2.563 Å) coordinate with each sodium. The salicylate ions lie on opposite sides and nearly perpendicular (77.2°, Na₂-molecule; 82.7° K₂-molecule) to each crown but coordinate to both of the metal ions within a molecule. The K⁺K⁺ and Na⁺Na⁺ distances in the respective molecules are 3.95 and 3.34 Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82044 (18 pages).     

碘酸钾存在下极谱催化波法测定陈皮甙

基于陈皮甙在ＫＩＯ３存在下产生的极谱催化波，拟定了测定陈皮甙的新方法。在 ０．５５ ｍｏｌ／Ｌ ＨＡｃ－０．０１ｍｏｌ／Ｌ　ＮａＡｃ（ｐＨ ４．００±０．０５）－１．０×１０～（－３）ｍｏｌ／Ｌ ＫＩＯ３缓冲溶液中，陈皮甙催化波的峰电位为－１．３５ Ｖ（ｖｓ，ＳＣＥ），它的一阶导数峰峰电流与陈皮甙浓度在２．６ × １０～（－７）～２．６ × １０～（－６）ｍｏｌ／Ｌ范围内呈线性关系（ｒ＝０．９９７０，ｎ＝６）。本方法比现有的电化学方法灵敏度高一个数量级。可用于直接测定中草药贯众水提液中陈皮甙含量。     

Hygrometric Determination of Water Activities, Osmotic and Activity Coefficients, and Excess Gibbs Energy of the System MgSO4–K2SO4–H2O

Ternary aqueous solutions of MgSO₄ and K₂SO₄ have been studied by the hygrometric method at 25°C. The relative humidity of this system is measured at total molalities from 0.35 mol-kg^–1 to about saturation for three ionic-strength fractions (y = 0.25, 0.50, and 0.80 of MgSO₄. The data allow calculation of water activities and osmotic coefficients. From these measurements, the Pitzer ionic mixing parameters are determined and used to predict the solute activity coefficients in the mixture. The results are used to calculate the excess Gibbs energy at total molalities for ionic-strength fraction y.     

Crystal structure of KAsUO<Subscript>6</Subscript>·<Subscript>3</Subscript>H<Subscript>2</Subscript>O at 100 and 293 K

The crystal structure of KAsUO₆·3H₂O was solved at 100 K and 293 K. KAsUO₆·3H₂O at T = 100 K: tetragonal, P4/ncc, a = 7.2037(6) Å, c = 17.811(2) Å; Z = 4, R1 = 0.0263, wR2 = 0.0546, for 618 independent reflections; at T = 293 K: tetragonal, P4/ncc, a = 7.1600(4) Å, c = 17.746(1) Å; Z = 4, R1 = 0.0263, wR2 = 0.0433 for 427 independent reflections. The results of X-ray analysis are compared with our previous data on heat capacity of this compound, and changes that take place in the structure at elevated temperature are considered.     

Electronic structure and chemical bonding in K<Subscript>2</Subscript>V<Subscript>3</Subscript>O<Subscript>8</Subscript>

The calculations of the electronic structure of layered polyvanadate K₂V₃O₈ were made employing the spin-polarized tight-binding LMTO method. Calculated magnetic moment for K₄V₆O₁₆ compound phase equals 1.97 μ_B. V-O interactions were established to be dominating in the chemical bonding generation in this polyvanadate according to the estimated crystal orbital overlap population. The covalent bonds V(2)-V(2) in V(2)₂O₇ groups and electron density localization on vanadium atoms in isolated pyramids V(1)O₅ were found.     

氟钽酸钾中碳存在形式的探讨

本文从氟钽酸钾（Ｋ２ＴａＦ６）的生产工艺论述了有机物存在于Ｄ２ＴａＦ６的可能性。通过Ｋ２ＴａＦ６低温通氧燃烧前后测定碳的结果比较，以及Ｘ射线能谱仪表面分析结果，证实了碳的来源是残留的有机萃取剂。     

Chemiluminescence Method for the Determination of Glutathione in Human Serum Using the Ru(phen)3 2+ – KMnO4 System

A simple, rapid and specific chemiluminescence (CL) method for the determination of glutathione has been developed. The method is based on the enhanced CL of the reaction between Ru(phen)₃ ²⁺ (phen = 1,10-phenanthroline) and KMnO₄ by glutathione in HCl medium. Under the optimum conditions, the response is linearly proportional to the concentration of glutathione between 1.5 × 10⁻⁷ and 1.0 × 10⁻⁵ mol L⁻¹. The dection limit for glutathione (5.8 × 10⁻⁸ mol L⁻¹) is about 10 and 200 times better than those of the spectrophotometric method using Ellman regent and the Lucigenin – CL method, respectively. The final procedure allows the determination of glutathione in human serum with recoveries of 92%–108%. A satisfactory agreement was obtained with a mean relative difference of 2.5% compared to the HPLC method.     

Electroconduction of Potassium Orthophosphate Modified with Triple-Charged Cations

Solid electrolytes in the systems K_{3 – 3x} Me _x PO₄ (Me = Sc, Y, In, La, Nd, Gd, Tb) are synthesized. Their phase composition and the temperature and concentration dependences of their electroconductivity are studied. In all the systems there form solid solutions based on K₃PO₄, which have a high potassium cation conductance. The latter is due to the formation of potassium vacancies at substitutions 3K⁺ Me³⁺ and, at lower temperatures, to stabilization of a high-temperature -modification of potassium orthophosphate. The electroconductivity of synthesized solid solutions, which equals (4–7) × 10^–3 and 10^–1 S cm^–1 at 300 and 700°C, is similar to that of solid electrolytes K_{3 – x} P_{1 – x} E _x ^VIO₄ and K_{3 – 4x} E _x ^IVPO₄.     

Potassium and sodium 2,6-di-tert-butylphenoxides and their properties

The crucial factor of the reaction of 2,6-di-tert-butylphenol with alkali hydroxides is temperature, depending on which two types of potassium or sodium 2,6-di-tert-butylphenoxides are formed. These types exhibit different catalytic activity in the alkylation of 2,6-di-tert-butylphenol with methyl acrylate. More active forms of 2,6-Bu^t ₂C₆H₃OK or 2,6-Bu^t ₂C₆H₃ONa are synthesized at temperatures higher than 160 °C and are predominantly the monomers, which dimerize on cooling. The data of ¹H NMR, electronic, and IR spectra for the corresponding forms of 2,6-Bu^t ₂C₆H₃OK and 2,6-Bu^t ₂C₆H₃ONa isolated in the individual state are in agreement with cyclohexadienone structure. In DMSO or DMF, the dimeric forms of 2,6-di-tert-butylphenoxides react with methyl acrylate to form methyl 3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate in 64–92% yield. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2138–2143, December, 2006.     

Preparation of dibenzofuran-type amorphous polyetherketone by novel etherification reaction

4-Fluorobenzophenone reacted with potassium carbonate in the presence of silica catalyst in diphenyl sulfone solvent to yield 4,4′-dibenzoyldiphenyl ether. This new etherification reaction was extended to three difluoro aromatic ketones. 4,4′-Bis(4-fluorobenzoyl)diphenyl ether ( I ) reacted with potassium carbonate to yield a crystalline poly(oxy-1,4-phenylene-carbonyl-1,4-phenylene) (PEK) and 4,4′-bis{4-[4-(4-fluorobenzoyl)phenoxy]benzoyl}benzene ( II ) gave a crystalline poly(oxy-1,4-phenylene-carbonyl-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene-carbonyl-1,4-phenylene)(PEKEKEKK). 2,8-Bis(4-fluorobenzoyl)dibenzofuran ( III ) or 2,8-bis(4-chlorobenzoyl)dibenzofuran ( IV ) reacted with potassium carbonate to yield a poly(oxy-1,4-phenylene-carbonyl-2,8-dibenzofuran-carbonyl-1,4-phenylene) (PEKBK). The PEKBK was a noval amorphous polymer with the glass transition temperature of 222°C and it showed excellent thermal stability [T. Tanabe and I. Fukawa, Jpn. Pat., Kokai 64–74223 (1989)]. Several amorphous dibenzofuran type polyetherketone copolymers were prepared by coplycondensation of III with 4,4′-difluorobenzophenone ( V ) or 1,4-bis(4-fluorobenzoyl)benzene ( VI ) [T. Tanabe and I. Fukawa, Jpn. Pat., Kokai 1153722 (1989)]. © 1992 John Wiley & Sons, Inc.