Reaktionen von π-Organokomplexen des Nickels mit tertiären Phosphanen

Reactions of π-Organonickel Complexes with Tertiary Phosphanes In a hexane solution Ni(C₅H₅)₂ reacts with PBu₃ or Ph₂PBu forming the nickel(O) complexes Ni(PBu3)₄ or Ni(Ph₂PBu)₄ (A). Under the same conditions only one cyclopentadienyl ligand is substituted by PhPBu₂ and the nickel(I) compound (C₅H₅)Ni (PhPBu₂)₂ (B) is obtained. Products of the reactions between B and α,α′-dipyridyl, hydrogen chlorid in ether, or Ni(PhPBu₂),Cl₂ are Ni(dipy)₂, [PhPHBu₂]₂[NiCl₄], or (C₅H₅) Ni(PhPBu₂)₂Cl. By the reaction with HgCl₂ a cyclopentadienyl compound of an unknown structur is formed. The compound Ni(PhPBu₂)₄ which is analogous to A is synthesized by the reduction of bis(acety1acetonato)-nickel with Et₂AlOEt in the presence of PhPBu₂ or by the reaction of bis (cyclooctadiene-1,5)-nickel with PhPBu₂.     

Die Massenspektren der Pyrrolidide einiger aliphatisch-alicyclischer Carbonsäuren

The mass spectra of the pyrrolidides of some long-chain carboxylic acids with alicyclic residues attached to their ω-end are discussed and compared with the spectra of the corresponding esters. Fragmentation triggered by the pyrrolidide group generates a series of peaks, which clearly exhibits the size and the structure of the carbon chain.     

Polarographie schwefelhaltiger Proteine

Zusammenfassung An kristallisierten Enzymen des biologischen Stoffwechsel wird gezeigt, daß bei der Polarographie nur die schwefelhaltigen Proteine katalytische Wasserstoffwellen geben. Von den in der Literatur beschriebenen Doppelstufen der Proteine besitzt nur die im negativeren Potentialbereich liegende Welle die eigentliche katalytische Funktion. Die erste Vorwelle von Proteinen verschwindet, wenn die polarographische Messung bei 0° C durchgeführt wird.In Proteinen sind nur Disulfidgruppen katalytisch wirksam. Sogenannte reine Sulfhydryl-Enzyme haben keinen katalytischen Effekt. Typische SH-Enzyme können jedoch polarographisch als p-Chloromercuribenzoatkomplexe gemessen werden.Durch Harnstoffzusatz bei der polarographischen Messung von Proteinen gelingt es, zwischen maskierten und freien Sulfhydryl- oder Disulfidgruppen an Enzymen zu definieren.Auszug aus der Dissertationsschrift H. Katzlmeier, Technische Hochschule München (1959).     

31P- und 195Pt-NMR-Untersuchungen an Diplatin(I)-Komplexen des Typs [Pt2(μ-SPR2)2L2] (L = PR3, PhP(OPh)2, P(OPh)3, CNR)

³¹P and ¹⁹⁵Pt N.M.R. Investigations on Diplatinum (I) Complexes of the Type [Pt₂(μ-SPR₂)₂L₂] (L = PR₃, PhP(OPh)₂, P(OPh)₃, CNR) ³¹P-, ¹⁹⁵Pt-chemical shifts and ¹⁹⁵Pt–³¹P- resp. ³¹P–³¹P-coupling constants of a series of doubly bridged diplatinum(I) complexes are reported. ³¹P-coordination chemical shifts of the terminal ligands of complexes of type [Pt₂(μ-SPR₂)₂(P′R₃′)₂] and some of the various coupling constants are strongly influenced by the π-acceptor strength of these ligands. J(¹⁹⁵Pt–¹⁹⁵Pt) is found to change the sign among the series of complexes investigated. Thermal singlett triplet exitation giving rise to the paramagnetism of these complexes observed by preliminary EPR-measurements and confirmed by EHT-calculations is deduced from the large values of ²J(P–P′) and ³J(P′P′) as well as the unusually high temperature dependence of some coupling constants and other NMR features. The chemical stability of the doubly bridged core, the coordination shifts of the bridging phosphorus atoms and EHT-calculations suggest a view of aromaticity of the [Pt₂(μ-SPR₂)₂](M–M) unit of these complexes.     

Influence of Test Specimen Geometry and Water Soaking on the In Vitro Cytotoxicity of Orthocryl®, Orthocryl® LC,Loctite® EA 9483 and Polypropylene

Depending on their composition, plastics have a cytotoxic potential that needs to be evaluated before they are used in dentistry, e.g., as orthodontic removable appliances. Relevant guidelines set out requirements that a potential new resin in the medical field must meet, with a wide scope for experimental design. In the present study, test specimens of different geometries consisting of varying polymers (Orthocryl^®, Orthocryl^® LC, Loctite^® EA 9483, Polypropylene) were soaked for different periods of time, then transferred to cell culture medium for 24 h, which was subsequently used for 24-h cultivation of A549 cells, followed by cytotoxicity assays (WST-1, Annexin V-FITC-propidium iodide (PI) flow cytometry). In this context, a reduction in the cytotoxic effect of the eluates of test specimens prepared from Orthocryl^® LC and Loctite^® EA 9483 was particularly evident in the Annexin V-FITC-PI assay when the soaking time was extended to 48 h and 168 h, respectively. Consistent with this, a reduced release of potentially toxic monomers into the cell culture medium, as measured by gas chromatography-mass spectrometry, was observed when the prior soaking time of test specimens of all geometries was extended. Remarkably, a significant increase in cytotoxic effect was observed in the WST-1 assay, which was accompanied by a higher release of monomers when the thickness of the test sample was increased from 0.5 to 1.0 mm, although an elution volume adapted to the surface area was used. However, further increasing the thickness to 3.0 mm did not lead to an increase in the observed cytotoxicity or monomer release. Test specimens made of polypropylene showed no toxicity under all test specimen sizes and soaking time conditions. Overall, it is recommended to perform toxicity studies of test specimens using different geometries and soaking times. Thereby, the influence of the different specimen thicknesses should also be considered. Finally, an extension of the test protocols proposed in ISO 10993-5:2009 should be considered, e.g., by flow cytometry or monomer analysis as well as fixed soaking times.     

Measurement of frequency differences between visible laser lines up to 170GHz using metal-insulator-metal point contact diodes

Frequency differences of up to 170 GHz between a cw dye laser and a krypton laser at 568 nm were measured by mixing laser and microware radiation with a metalinsulator-metal point contact diode. Beat signals are well above noise and there is still great potential for improvement when better microwave oscillators are used. From the measurements reported it follows that the diode can be used for determining still higher frequency differences of visible laser radiation.