Preparation of Neutral Ionophores for Alkali and Alkaline Earth Metal Cations and their application in ion selective membrane electrodes

The preparation of a series of non-cyclic, uncharged ligands able to selectively complex alkali and alkaline earth metal cations is described. These molecules are designed to be used as carriers for cations through membranes. Some of the compounds show high Ca²⁺ and Na⁺ selectivity, respectively, in liquid membrane electrodes.     

Measurement of gamow-teller strength for 176Yb --> 176Lu and the efficiency of a solar neutrino detector

We report a 0 degrees 176Yb(p,n)176Lu measurement at IUCF where we used 120 and 160 MeV protons and the energy dependence method to determine Gamow-Teller (GT) matrix elements relative to the model independent Fermi matrix element. The data show that there is an isolated concentration of GT strength in the low-lying 1(+) states making the proposed Low Energy Neutrino Spectroscopy detector (based on neutrino captures on 176Yb) sensitive to pp and 7Be neutrinos and a promising detector to resolve the solar neutrino problem.     

Beschreibung des visko-elastischen Verhaltens des polymeren Mischsystems Phenolnovolakharz-Nitrilkautschuk (PF/NBR) mit Hilfe der Van-der-Poel-Gleichung

Zusammenfassung Morphologische Untersuchungen an dem polymeren Mischsystem Phenolnovolakharz-Nitrilkautschuk haben gezeigt, daß diese Mischungen eine Struktur aufweisen, in der harte kugelige PF-Teilchen in einer Kautschukmatrix bzw. weiche Kautschukteilchen in einer Harzmatrix eingebettet sind. Mit Hilfe der morphologischen und mechanisch-dynamischen Untersuchungen wird versucht, das viskoelastische Verhalten von Polyblends mit der Van-der-Poel-Gleichung zu beschreiben. Es konnte gezeigt werden, daß bis zu ModulwertenGhart/Gweich ~ 100 eine gute Übereinstimmung mit der Van-der-Poel-Gleichung gefunden wird. Hohe Modulverhältnisse der harten Einlagerungskomponente zur weichen KomponentenGhart/Gweich ~ 1000, wie sie im kautschukelastischen Bereich auftreten, zeigen eine Übereinstimmung mit der Van-der-Poel-Gleichung nur bei einer Volumenkonzentration der harten EinlagerungskomponenteV _f < 0,3. Diese Ergebnisse werden mit anderen bekannten theoretischen Überlegungen über den Zusammenhang zwischen Elastizitätsmodul und Zusammensetzung von Verbundwerkstoffen verglichen.Schlüsselwörter Phenolnovolakharz-Nitrilkautschuk-System, viskoelastisches Verhalten, Torsionspendel, Van-der-Poel-Gleichung

---

Summary Morphological investigations of the polymer compound-system novolak resin-nitril rubber (PF/NBR) have shown, that these mixtures exhibit structures, in which hard spherical particles are embedded in a rubber matrix, respectively soft rubber particles in a resin matrix.An attempt was made to describe the viscoelastic behaviour of these polyblends by means of morphological and dynamic-mechanical investigations with the relation given by Van der Poel.Up to ratios of the moduliGhard/Gsoft ~ 100 a good agreement with the Van-der-Poel equation was found. In the rubber elastic region at ratiosG hard/G soft ~ 1000 this agreement was found for volume concentrations of the phenolic componentV _f ~ 0.3 only.The results are compared with other existing theories on the correlation between elastic modulus and composition of compound materials.

Mit 7 Abbildungen und 6 Tabellen     

The diffraction of elastic waves by an imperfect fusion bond

We consider diffraction by a semi-infinite crack located alonga fusion interface between two differing elastic media. Twotypes of crack, namely open and partially closed cracks, areinvestigated. An open crack is modelled by a stress-free contactboundary condition and a partially closed crack is modelledby a spring contact boundary condition. For the latter, thejump in the stress across the crack is assumed to be proportionalto the jump in the displacement across the crack. This situationarises in, for example, a K-weld where the fine grain of theparent material (for example, ferritic or forged austeniticsteel) is in stark contrast with the coarse-grained weld metal(for example, austenitic weld metal). In the metal weld thedirection of the grain axis varies through the metal. However,diffraction is a local phenomenon and so the austenitic steelis assumed to have a zonal axis so that it may be modelled bya transversely isotropic composite. The ferritic or forged austeniticsteel will be modelled as an isotropic material.     

Metal Cation Transport Studies Comparing Dibenzo-18-crown-6 (DB18C6) with N,N,N′,N′-Tetrakis (n-propyl)-2,3- naphthalenedioxydiacetamide (NPr)

The previously synthesized3,6-dioxa-4,5-disubstitutedoctanedicarboxamides including NPr bind cationsin methanol in the order: Ca²⁺ > Sr²⁺ >Ba²⁺ > Mg²⁺ > Na⁺,K⁺. These compounds also extract Group II cations better thanGroup I cations from water to dichloromethane. In contrast, thesediacetamides were found by W. Simon et al., to sense Na⁺ >Ca²⁺ when they were incorporated into ion-selective electrodesusing a low dielectric constant solvent. It was of interest to determine theorder of Group I and Group II cation transport rates of these compoundsusing a three-phase system with a liquid organic phase of low dielectricconstant. We now report that NPr transports thiocyanates in such a systemusing dichloromethane in the order K⁺ (7.2) >Ca²⁺ (6.6) > Ba²⁺ (5.8) > Na⁺(1). The transport rate for KSCN with DB18C6 is 20.5 times faster than withNPr.     

The preparation and properties of neutral diamide ionophores for group IIa metal cations

The preparation of a series of neutral ligands featuring ether and N-methyl-N-carbethoxypentylamide groups is described. These ligands as well as related ones bearing other diamide groups are shown to selectively chelate Group IIA cations by picrate extraction from water to methylene chloride. The changes in UV absorption of aromatic rings and amide groups in the ligands upon titration with metal salts in methanol allow the estimation of the stoichiometry of complexation and the ordering of cation binding. The observed selectivity sequences of cation extraction and binding are briefly discussed. Preliminary proton and ¹³C NMR studies on the effect of addition of Group IIA cation salts to several of the ligands in methanol suggest that most of the complexation occurs at the central ether and amide groups. ¹³C NMR T₁ changes by the Inversion Recovery Fourier Transform method are in agreement with the cation-induced shift data.     

Synthesis of N-(2-Hydroxy-1-phenoxyacetyl)- prolylproline and Related Cation Binding and Molecular Mechanics Studies

The synthesis of N-(2-hydroxy-1-phenoxyacetyl)prolylproline 2 from 2-acetoxyphen-oxyacetic acid is described. A firstsynthesis led toN-(2-acetoxy-1-phenoxyacetyl)prolylproline methylester 8b that fragmented upon attempted esterhydrolysis with 1N NaOH. A second synthesis gave thecorresponding benzyl ester 13, which wasconverted to 2 by deacylation of the phenolicacetoxy group with pyrrolidine followed byhydrogenolysis of the ester. Cation binding by 2 in methanol and related molecular mechanics (MM)geometric optimizations are discussed.