Koordinationschemie makrocyklischer liganden—I : Kernresonanzspektroskopische untersuchungen über die lösungsstruktur und das komplexierungsverhalten makrocyklischer aminopolyaether

From the highly refined proton-NMR spectra of monocyclic and bicyclic aminopolyethers, signal shifts have been observed which indicate conformation changes in the ligand moiety. Their dependence on solvent, coordinated cation and anion is discussed, and an interpretation of the spectra is put forward on the basis of dynamic symmetry patterns.     

Evaluation of parameters critical to observing proteins inside living Escherichia coli by in-cell NMR spectroscopy

Our recently developed in-cell NMR procedure now enables one to observe protein conformations inside living cells. Optimization of the technique demonstrates that distinguishing the signals produced by a single protein species depends critically on protein overexpression levels and the correlation time in the cytoplasm. Less relevant is the selective incorporation of (15)N. Poorly expressed proteins, insoluble proteins, and proteins that cannot tumble freely due to associations within the cell cannot yet be observed. We show in-cell NMR spectra of bacterial NmerA and human calmodulin and discuss limitations of the technique as well as prospects for future applications.     

Schwingungsspektren und Kraftkonstanten von Hexamethyldisilan,Hexaphenyldisilan und 1,1,1-Trimethyl-2,2,2-triphenyldisilan

The Raman and infrared spectra of (CH₃)₃SiSi(CH₃)₃ (I), (CD₃)₃SiSi(CD₃)₃, (C₆H₅)₃SiSi(C₆H₅)₃ (II), (CH₃)₃SiSi(C₆H₅)₃ (III), and (CD₃)₃SiSi(C₆H₅)₃ are reported. Assignments are based on symmetry G ₃₆ ⁺ (free internal rotation) forI, D_3d forII, and C_3v forIII. Normal coordinate treatment has been done using some simplifications in the phenyl coordinates. The SiSi stretching force constant inI amounts to 1,65 N/cm. In compoundsII andIII strong vibrational coupling is elucidated byPED calculations.     

Exact spin-pairing energies at the crossovers in octahedral d 4, d 5, d 6, and d 7 transition metal complexes

Exact spin-pairing energies are calculated by direct diagonalization of the relevant ligand field plus interelectronic repulsion matrices for the configurations d ⁴, d ⁵, d ⁶, and d ⁷ of octahedral transition metal ions. The results are presented in terms of /B as function of = C/B for the range of values =3.0 to 8.0. Comparison with the quantity resulting from a simplified approach in which configuration interaction is neglected or considered on an approximate basis only reveals significant differences. Useful estimates of spin-pairing energies are provided, in addition, on the basis of empirical magnetic and electronic spectral data.

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Zusammenfassung Exakte Spinpaarungsenergien für die Konfigurationen d ⁴, d ⁵, d ⁶ und d ⁷ oktaedrischer Übergangsmetallionen werden durch direkte Diagonalisierung der entsprechenden Matrizen des Ligandenfeldes sowie der Elektronenwechselwirkung berechnet. Die Ergebnisse für /B werden in Abhängigkeit von = C/B für den Wertebereich =3.0 bis 8.0 angegeben. Ein Vergleich mit der Größe , die bei einer vereinfachten Behandlung unter Vernachlässigung oder näherungsweiser Berücksichtigung der Konfigurationswechselwirkung erhalten wird, zeigt auffallende Unterschiede. Nützliche Abschätzungen der Spinpaarungsenergie werden außerdem unter Benutzung empirischer magnetischer und elektronenspektroskopischer Daten erhalten.

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Résumé Les énergies exactes de couplage de spin sont calculées par diagonalisation directe du champ de ligand correspondant en plus des matrices de répulsion électronique pour les configurations d ⁴, d ⁵, d ⁶ et d ⁷ des ions octaédriques des métaux de transition. Les résultats sont présentés en termes de /B en fonction de = C/B dan l'intervalle =3,0 à 8,0. On trouve des différences significatives par comparaison de avec les valeurs résultant d'une approche simplifiée sans interaction de configuration ou avec interaction de configuration approchée. De plus, des estimations des énergies de couplage de spin sont obtenues à partir de données empiriques magnétiques et spectrales.

     

Untersuchung der Temperaturabhängigkeit derg ik -Tensoren von Polyäthyleneinkristallen

Zusammenfassung Es wurden die Kristallitgröße und die Änderungen der parakristallinen Gitterstörungen aus den Linienbreiten des Röntgenweitwinkeldiagramms von lösungskristallisiertem linearem Polyäthylen bei den Temperaturen 15°K, 73°K, 173°K und Zimmertemperatur bestimmt. Es wurde eine Zunahme der Gitterstörungen mit fallender Temperatur gefunden.

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Summary The crystallite size and the paracrystalline distortions in polyethylene single crystals were evaluated by the measurement of the linewidth in the X-ray wide angle diagram at four different temperatures (15°K, 73°K, 173°K and 297°K). An increase of the lattice distortions with decreasing temperature was found.

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Mit 3 Abbildungen

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Vorgetragen auf der Arbeitssitzung des Fachausschusses Physik der Hochpolymeren in der Frühjahrstagung 1970 des Regionalverbandes Hessen-Mittelrhein-Saar der Deutschen Physikalischen Gesellschaft in Darmstadt, 10.–13. März 1970.     

Preconcentration of manganese,cobalt, yttrium,zirconium, niobium,ruthenium, europium and protactinium by various hydroxides

Summary The removal of trace elements from dilute water solutions by hydroxide precipitates was investigated. The co-precipitation yields of manganese, cobalt, ruthenium, europium and protactinium onto beryllium, zinc, iron, lanthanum and titanium hydroxides were studied in the pH region from 3 to 11, while those of manganese, cobalt, yttrium, zirconium, niobium, ruthenium, europium, and protactinium onto the same hydroxides were investigated in sea-water media. The influence of some other factors, such as the presence of neutral electrolyte and NH₄ ⁺ ions, aging of hydroxide precipitates etc. on the co-precipitation yields were also examined.

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Zusammenfassung Die Entfernung von Spurenelementen aus verdünnten wäßrigen Lösungen durch Hydroxidniederschläge wurde untersucht. Die mitgefällten Anteile Mn, Co, Ru, Eu und Pa in den Hydroxiden von Be, Zn, Fe, La und Ti wurden im pH-Bereich 3–11 untersucht, während die Anteile von Mn, Co, Yt, Zr, Nb, Ru, Eu und Pa in den gleichen Hydroxiden in Meerwasser studiert wurden. Der Einfluß einiger anderer Faktoren auf die Mitfällung, wie die Anwesenheit neutraler Elektrolyte und von NH₄-Ionen, die Alterung der Hydroxidniederschläge usw. wurden ebenfalls geprüft.

     

A CNDO/INDO crystal orbital model for transition metal polymers of the 3d series—basis equations

The crystal orbital formalism in the tight-binding approximation is combined with a recently developed CNDO/INDO model for transition metal species of the 3d series in order to allow band structure calculations on the Hartree-Fock (HF) SCF level for one-dimensional (1D) chains with organometallic unit cells. The band structure approach based on the CNDO and INDO approximation can be used for any atom combination up to bromine under the inclusion of the 3d series. The matrix elements for the tight-binding Hamiltonian are derived for an improved CNDO and INDO framework. The total energy of the 1D chain is partitioned into one-center contributions and into two-center increments of the intracell and intercell type. Semiempirical band structure calculations on simple model systems are compared with available ab initio data of high quality.     

Prospects of thermal analysis in polymer research

A survey and an analysis of the publications concerned in thermal analysis (TA) published in four renowned journals during the years 1965–1974 were performed. The published data were evaluated from three points of view: TA methods used for polymers, properties and phenomena studied by TA methods, types of polymers investigated by TA methods. From the statistical data were derived the future trends for the application of particular TA methods in polymer science.     

Extraktion von 3d-Metallionen mit zweizähligen Sulfonamiden. I. Liganden mit Schwefel bzw. heterocyclisch gebundenem Stickstoff als zweitem Haftatom

Extraction of 3d-Metal Ions by Bidendate Sulfonamides. I. Ligands with Sulfur or Heterocyclic Nitrogen as a Second Donor Atom The properties of 2-acetylpyridine-p-toluensulfonylhydrazone (APSH - H), arensulfonylthioureas (I), and the esters of arensulfonylmonothiocarbamic acid (II) or arensulfonyldithiocarbamic acid (III) as extractants for the late 3d-metal ions are proved. APSH-H is comparable to the proprietary extractant LIX 34. But, because of the special structure of the corresponding 1,2-chelates, the pH_1/2-values of nickel(II) and cobalt(II) are ≈2 units lower. The pK_s-values, measured in dioxane-water mixtures (75 per cent v/v), increase in the order III < II < I. In aqueous solutions compounds of type III are acids of medium strength. In the case of compounds of type I the substituents of the non-sulfonated nitrogen have a strong influence on the pK_s-values (ΔpK_s = 4.6). Among the late 3d-elements, the ligands II and III extract only copper(II) (pH_1/2 ～2.7 or ～1.6), the ligands I extract zinc(II), cobalt(II), and nickel(II) as well, but not iron(II) and iron(III). The reasons of this unique behaviour are discussed.     

The influence of “two-phase” synthesis conditions on blown film extrusion of LDPE

LDPE synthesized under two-phase conditions is known to have a good balance of blown film properties. Good optical properties and high impact strength are characteristic for two-phase LDPE grades. In order to obtain systematic information, LDPE was synthesized at several different pressures with two different melt index levels. Blown film was extruded at different output rates and melt temperatures. The influence on haze and dart drop impact was studied. Two-phase conditions were found to improve haze and dart drop impact and the improvement was impressive, especially for the low melt index grades. By increasing the output rate, the dart drop values were further improved. The influence of melt temperature on dart drop impact goes through an optimum and overall haze decreases with increasing melt temperature. For films made from two-phase grades, dart drop impact decreases as internal haze increases. For corresponding internal haze values, the films made from single-phase grades have lower dart drop values and they are somewhat scattered.