Quantitative chemical analysis of electrolytes in aqueous solutions exploiting the Donnan dialysis process

Chemical analysis of electrolytes in aqueous solutions is performed with a dialyzer consisting of two selective membranes: a cation and an anion-exchange membrane. The dialyzer actually functions like a galvanic cell when dialysis is carried out. The current that appears in the cell is measured. Since the dialysis process is caused by the concentration gradient, the current measured also depends on the concentration gradient. For proper conditions, it becomes possible to determine the concentration. The method may compete in some aspects with ion-selective potentiometry. The text was submitted by the authors in English.     

Self‐assembly of p‐tert‐butyl thiacalix[4]arenes and metal cations into nanoscale three‐dimensional particles

The shape of supramolecular aggregates based on stereoisomers of p‐tert‐butyl thiacalix[4]arenes functionalized with secondary, tertiary amide and hydrazide groups at the lower rim in cone, partial cone and 1,3‐alternate conformations with several metal cations were investigated by atomic force microscopy. The examined p‐tert‐butyl thiacalix[4]arenes form host–guest complexes; dimers, spherics ellipsoids and elongated nanoscale particles depending on the conformation of macrocycles, the nature of the binding centers and the nature of the metal cation. Only associates formed by p‐tert‐butyl thiacalix[4]arenes with morpholide groups at the lower rim in cone conformation with silver cations exhibited a higher antimicrobial activity. Copyright © 2012 John Wiley & Sons, Ltd.     

Flow injection analysis with amperometric detection for measurements of proton activities in solutions of strong acids and strong bases

 Flow injection and reversed flow injection analysis with amperometric detection were used for the determination of the concentrations of strong acids and strong bases and the pH of the solutions. The amperometric detection was based on the reduction current of hydrogen ion or water molecules. A platinum indicator electrode cathodically polarized at a constant potential was employed, choosing the potential in the rising part of the current/potential curve. On the basis of the experimental data an equation was developed for the calculation of the concentrations of the strong acids and strong bases and the pH by a non-linear regression computer program. Received: 26 October 1995/Revised: 3 April 1996/Accepted: 14 April 1996     

Silver-catalyzed one-pot synthesis of arylnaphthalene lactones

Arylnaphthalene lignan lactones are valuable natural products with promising anticancer and antiviral properties. In an effort to simplify their synthesis, we investigated a one-pot multicomponent coupling reaction between phenylacetylene, carbon dioxide, and 3-bromo-1-phenyl-1-propyne. After the corresponding 1,6-diyne was generated in situ, cyclization afforded the desired product. The level of regioselectivity was enhanced through the tuning of electronic properties. The use of cinnamyl bromide which led to the formation of a 1,6-enyne intermediate was also studied.     

Titrimetric analysis with adding the titrant by means of electrodialysis

A titration method is developed that titrant is added continuously to the analyte by electromigration through an ion exchange membrane. A constant rate of the titrant addition is achieved by keeping the electric current constant. Analyte amount then is proportional to the titration time. The method is applied to the most widely used titrations with a visual end point indication.     

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An N-heterocyclic carbene adduct of diatomic tin, :Sn[double bond, length as m-dash]Sn:

Reduction of an N-heterocyclic carbene (NHC) adduct of SnCl(2), viz. [(IPr)SnCl(2)] (IPr = :C{N(Dip)C(H)}(2); Dip = 2,6-diisopropylphenyl), with a magnesium(i) dimer, has afforded the first NHC complex of a row 5 element in its diatomic form, [(IPr)Sn[double bond, length as m-dash]Sn(IPr)]; a computational analysis of the complex indicates that it comprises a singlet state, doubly bonded tin(0) fragment, :Sn[double bond, length as m-dash]Sn:, datively bonded by two NHC ligands.