Einsatz von Hochleistungs-Trennkapillaren in der GC.-EIMS./GC.-CIMS.-Analyse: Eine Möglichkeit zur massenspektrometrischen Doppelbindungscharakterisierung in komplexen Monoalkengemischen

In an attempt to determine position and substitution of double bonds in complex mixtures of straight-chain and branched monoalkenes without actually isolating the constituents, GC.-MS. analysis is performed after in-batch preparation of derivatives of a judiciously chosen type. Cyclic phenylboronates (4,5-substituted 2-phenyl-1,3,2-dioxaborols) are prepared from 1,2-diols which are, in turn, obtained from the original alkenes by treatment with osmium tetroxide. Chemical ionization mass spectrometry (CIMS.) is used in addition to conventional electron impact techniques (EIMS.) in sequential GC./CIMS.- and GC./EIMS.runs, yielding complementary structural information for the single components of the mixture. In order to cope with the potential severity of the separation problem, high-efficiency glass capillary columns were employed throughout. The performance of the system used is demonstrated by a complete double bond analysis of a 35-component mixture of monoalkenes in the C₅ to C₉ range.     

A theory of molecules in molecules

SCF wave functions have been calculated using a minimal atomic basis set of Gaussian lobe functions for the para-, meta-, and ortho-forms of the molecules C₆H₄XY, where X, Y can be either of CN, OH, or F. It is found that in all cases the total energies increase in the sequence meta-, para-, ortho-compound. For the molecules containing the CN group the energy differences are extremely small (0.1–1 kcal/mole) for the other molecules they are one to two orders of magnitude larger. The reliability of these results is discussed. The theory of molecules in molecules is applied to these cases. The wave function of C₆H₄XY is constructed from the fragments C₆H₅X and HY by transferring some of the localized orbitals of the wave functions of the fragments and recalculating the orbitals in the region of interaction. For the molecules containing the CN group the energy differences are too small so that they are not correctly reproduced except by the most exact calculations, which involve no approximations other than the transfer of localized orbitals. For the other molecules satisfactory results are obtained.     

The Enantioselective Synthesis of 3-Methoxy-1, 3, 5 (10)-estratrien-11, 17-dione by a Thermal Intramolecular Cycloaddition Reaction. Preliminary communication

The enantiomerically pure (+)-3-methoxy-1, 3, 5 (10)-estratrien-11, 17-dione 11 (with trans-anti-trans configuration) was synthesized in a highly stereocontrolled fashion from (±)-t-butyl 4-methoxy-1-benzocyclobutene carboxylate (8) and the (+)-carboxylic acid 6 , obtained from 4 in two steps, followed by one crystallization of the (+)-ephedrine salt. The key step 10→11 (Scheme 2) involves a thermal intramolecular cycloaddition reaction.     

Gezielte Synthese von Kohlenwasserstoff-verbrückten Komplexen. Nucleophile addition von Pentacarbonylrhenat und -manganat an π-gebundene Dien-, Cyclodien-, Trimethylenmethan-, Cycloheptatrienyl- und Alkin-Liganden

Pentacarbonyl-rhenate and -manganate react with the cationic complexes [cpMo(CO)₂(diene)]⁺, [cpMo(CO)₂(cyclopentadiene]⁺, [cpMo(CO)₂(cyclohexadiene)]⁺, [cpMo(CO)₂(trimethylenemethane]⁺, [(OC)₃Mo(η⁷-C₇H₇)]⁺, [cp(OC)-(Ph₃P)Mo(alkyne)]⁺ to give the corresponding heteronuclear hydrocarbon-bridged complexes.     

Über Phosphorstickstoffverbindungen. XXIX. Reaktionen von Diphenyltrichlorphosphoran mit Stickstoff enthaltenden Verbindungen

The reaction of diphenyltrichlorophosphorane with amides leads to (C₆H₅)₂P(Cl)?N-acyl compounds, whereas with amines salt-like compounds, [(C₆H₅)₂P(Cl)? NHR]Cl, are formed.     

Erprobte Verfahren zur Ultramikro-Elementaranalyse

Zusammenfassung Es wird über ein allgemein anwendbares Verfahren zur CH-Bestimmung mit Einwaagen von 0,4–1 mg berichtet. Die Verbrennung erfolgt in einer verkleinerten Pregl-Apparatur, wobei als Verbrennungs- und Treibgas Helium mit 5–10% Sauerstoff dient. Wasser und Kohlendioxid werden aus dem Gasstrom ausgefroren, in einer evakuierten zweiteiligen Meßapparatur fraktioniert umkondensiert und dort über ihre Drucke bestimmt.

---

Summary A generally applicable method is described for the determination of carbon and hydrogen with sample weights of 0.4 to 1 mg. The combustion is carried out in a very small, modified Pregl-apparatus, employing helium containing 5–10% oxygen as combustion and entraining gas. Water and carbon dioxide are removed from the gas stream by freezing. Then water and carbon dioxide are evaporated and fractional-condensed in a vacuum apparatus, where their quantities are determined by their pressures.

---

---

Die Versuche wurden außerordentlich sorgfältig von Herrn Nicklas durchgeführt.     

Supramolecular architectures of streptavidin on biotinylated self-assembled monolayers. Tracking biomolecular reorganization after bioconjugation

In this work we have studied the supramolecular bioconjugation of streptavidin (SAv) on biotinylated self-assembled monolayers. By using the quartz crystal microbalance technique with dissipation we were able to follow in real time the biomolecular reorganization within the film. The overall process could be described as an early stage involving a significant increase in surface coverage followed by another stage where the SAv layer slowly reached the asymptotic coverage. Finally, a reorganization process takes place in the bioconjugated film. These results on the kinetics of biomolecular reorganization can be described in terms of the Lifshitz-Slyozov law. These are the first experimental results demonstrating the complexity and the different time scales involved on the bioconjugation of SAv at solid-liquid interfaces. We consider that these findings could have strong implications on the molecular design of biosensing platforms.