Volume 21, Issue 7

Beim Beschuß von Diboran mit Krypton-Ionen werden Borwasserstoff-Anionen gebildet. Mit einem Massenspektrometer wurden folgende negative Ionen identifiziert: [ΒΗ 4 ] ⊖ , [Β 2 Η 7 ] ⊖ , [B 2 H 5 ] ⊖ , [Β 3 Η 8 ] ⊖ , [B 3 H 7 ] ⊖ , [B 4 H 9 ] ⊖ , [Β 4 Η 8 ] ⊖ , [B 5 H 10 ] ⊖ . Die experimentellen Ergebnisse werden auf der Grundlage der Lipscomb sehen Theorie diskutiert. Für die bisher unbekannten Ionen werden chemische Strukturformeln vorgeschlagen.

Unter Zugrundelegung eines Modelles des harmonischen Oszillators und starren Rotators werden die thermodynamischen Funktionen von Thionyl- und Seleninylhalogeniden für den idealen Gaszustand im Temperaturbereich zwischen 200 und 2000 °K berechnet. Weiterhin werden mit Hilfe der Methode von Lippincott-Stutman die molekularen Polarisierbarkeiten aus einem semi-emprischen δ-Funktionen-Potentialmodell berechnet. Im Falle des SOCl 2 stimmt der theoretisch berechnete Wert gut mit dem experimentell ermittelten überein.

1 H-, 19 F- und 31 P-KMR-Daten werden für einige Alkylamide, das Pyrrolidid und das Phenylhydrazid der Difluorthiophosphorsäure mitgeteilt.

Die Umsetzung von Methylenchlorid mit Alkalisulfid führt in alkoholisch-wäßrigem Medium zu Polythioformaldehyden. In Abhängigkeit vom Wassergehalt erhält man bevorzugt hochpolymere oder niedermolekulare Formen. Dabei wurden neben dem bekannten Trithian erstmals ein tetramerer und pentamerer Thioformaldehyd erhalten. Die spontane thermische Polymerisation eines „Rohtetrathians“ wird beschrieben. Die Verwendung von Na 2 Se bzw. H 2 Se anstelle von Na 2 S liefert verschiedene polymere Methylenselenide.

This research has shown that the complexes of aromatic alpha amino dicarboxylic acids and of 2-amino-3-naphthoic acid are stable to about the same degree as those of the methyl substituted anthranilic acids. Infrared data show that of the thirty-three possible compounds, eighteen exist as coordination complexes; none of these has been previously reported. Stability series have been predicted, and in the case of 2-amino-3-naphthoic acid, the sequence was identical with that of methyl substituted anthranilic acids; in the case of 3-aminophthalic acid, the order was considerably different, and no valid sequence could be derived for 2-aminoterephthalic acid. As expected, the 2-amino-3-naphthoic acid acted as a bidentate ligand, whereas the two substituted phthalic acids behaved as tridentates, although the structures assigned were different. In each case, coordinated water was possible, but often the relative unavailability of the coordination positions and the presence of varying amounts of water in the lattice of these very insoluble complexes made determination difficult. In most cases, at least one molecule of water was present.

Two new complexes of platinum (II) with alpha amino acids have been prepared and characterized; these are diaquobisarginatoplatinum (II) and diaquotrishistidinatodiplatinum (II) chloride. Efforts to prepare similar complexes with lysine and serine using similar synthetic techniques failed to produce separable compounds. Infrared data, analytical results for carbon and hydrogen, and melting point information support the structures postulated in this report; no success was achieved in determining molecular weight by the Rast method.

Organic disulfides, mercaptans, sulfides and hydrogen sulfide have been exposed to γ-radiation in glasses of methyltetrahydrofuran or hydrocarbons at -196 °C. Absorptions have been observed which are attributed to either radicals of the type RS· or to addition complexes of these radicals to S-containing molecules or ions (for example to RS-SR- radical ions). In the case of disulfides. the S-radicals were produced by dissociative capture of electrons from the ionization of the glassy solvent. In the case of mercaptans, the sulphur radicals were formed via H-abstraction by free radicals from the radiolysis of the solvent, when the irradiated glasses were slowly warmed up. HS was formed this way in H 2 S containing irradiated glasses. The electron capture in benzylmercaptan, dibenzyldisulfide, and dibenzylsulfide partially leads to the benzylradical. Several new absorption bands have been observed which are tentatively attributed to negative ions: C 6 H 5 SH ⊖ from phenylmercaptan (8100 A), C 6 H 5 SC 6 H 5 e from diphenylsulfide (broad absorption over the visible range), C 6 H 5 CHS ⊖ from dibenzylsulfide (~ 3900 A). Carbontetrachloride simultaneously present in the glass was found to inhibit all reactions of free electrons, while the reactions of free radicals during warming up were not suppressed. Glasses of a methylcyclohexane-isopentane mixture containing olefins were found to absorb strongly between 7000 and 9000 A. These absorptions are attributed to positive ions. The absorption of ionized or protonated olefins occurs at longer wave lengths with decreasing number of Η-atoms at the carbon atoms of the double bond. Absorption by positive ions was also observed for diphenyldisulfide (8500 A), and for diallyldisulfide (6840 A). Small amounts of substances which can readily be protonated (such as n-propanol or methyltetrahydrofuran) decrease the intensity of the absorption bands of positive ions.

Es wurde die Kinetik des Abbaus von 5-Bromuracil in wäßriger Lösung bei p H = 6,5 durch Bestrahlung mit γ-Strahlen unter N 2 , O 2 und N 2 O untersucht. Die Ergebnisse werden an Hand der Radikaltheorie wäßriger Lösungen diskutiert und eine Hypothese zur Ursache der Strahlensensibilisierung lebender Zellen durch Bromuracil abgeleitet.

Die Darstellung von Aroxylradikalen mit para-ständiger Sauerstoffbrücke -O-R (darunter 13 C- und 17 O-markierter Verbindungen) wird beschrieben. Ihre ESR-Spektren lassen eine Beeinflussung der freien Spindichte-Verteilung im Aroxylring durch den Rest R erkennen. Ist R ein Phosphatoder Phosphinsäurerest, so beobachtet man eine zusätzliche 31 P-Hyperfeinstruktur. Der zweibindige Sauerstoff vermag also das freie Elektron „in den Substituenten R zu leiten“; formal können diese Radikale als „mesomere O-C-P-Radikale“ betrachtet werden. Dementsprechend besitzt das freie Elektron am Sauerstoffatom selbst eine endliche s-Spindichte, wie durch Einbau des Isotops 17 O in die Sauerstoffbrücke bewiesen werden konnte.

Hydroxytriazenes are very weak acids. The conventional potentiometric and conductometric method cannot be employed for determining their ionisation constants. However, these compounds show a distinct colour change in acid and alkaline media. Ultra-violet absorption studies of these compounds have been made 1 . The absorption maximum at 305 mµ of 3-hydroxy-3-methyl-1-phenyltriazene shifts to 335 mµ in an alkaline solution. The following equilibrium possibly exists: (molecular form, absorption peak at 305 mµ) (anion form, absorption peak at 335 mµ) This change in absorption maximum with PH has been used in determining the ionisation constants of fourteen hydroxytriazenes employing Robinson’s spectrophotometric method

S. cerevisiae- Zellen wurden mit NNMG behandelt. Der Anteil auxotropher Mutanten unter den überlebenden Zellen nahm mit der Einwirkungszeit und dem Grad der Abtötung bis auf 30% zu. Viele der NNMG-induzierten Mutanten wachsen schlecht. Die Abtötungskurven sind nicht linear bei Auftragung im halblogarithmischen Maßstab.

The photodynamic inactivation of nucleic acids with pyronin, methylene blue, thiopyronin and furocoumarines has been studied. The template efficiency of DNA in RNA-Polymerase reaction was found to be decreased after the treatment of DNA with these compounds. However, the magnitude of their inhibiting capacity varied from one compound to the other. Psoralen and thiopyronin were found to be the most active inhibitors followed by xanthotoxin and methylene blue respectively. At a lower temperature the inhibiting capacity of thiopyronin was considerably decreased but that of psoralen remained nearly unaffected. We have also tried to show evidence for a complimentary code in t-RNA through a specific destruction of guanine with thiopyronin.

The influence of benzimidazoles with saturated hydrocarbon side chains at C-2 on photosynthetic reactions of isolated spinach chloroplasts was investigated. They show little or no inhibition of the Hill- reaction, but are effective uncouplers depending on the length of the side chain. 2-Alkylbenzimidazoles with a side chain of at least eight and not more than fourteen carbon atoms uncouple non-cyclic and cyclic photophosphorylation at a concentration of less than 10~ 5 -m., 2-decyl-benzimidazole being the most potent uncoupler. Alkyl-benzimidazoles with less than seven or more than fourteen carbon atoms in the side chain do not uncouple photophosphorylation at 10~ 5 -m. N-Methyl-2-undecyl-benzimidazole is less effective as uncoupler than 2-undecyl-benzimidazole but is an inhibitor of oxygen evolution. 2-Undecyl-benzimidazole stimulates the Hill - reaction in the absence of the phosphorylation system and shifts the p H -optimum to a lower value, as expected from an uncoupler. Long chain alkylamines (C 10 -C 14 ) are uncouplers at lower concentrations (5 ·10 -5 -m.) than short chain amines.

The photosynthetic activity of particles obtained by lysozyme treatment of lyophilized cells from the blue-green alga Anacystis is described. Particles washed once catalyze cyclic photophosphorylation with PMS * and menadion as cofactor at a rate of about 150 and 70 μmoles ATP/h/mg chlorphyll, respectively, a Hill - reaction with ferricyanide coupled to ATP-formation, and pseudocyclic photophosphorylation. The ratio of ATP formed to two electrons transferred is 1 to 3. Repeated washing of the particles removes the phycocyanin without impairment of PMS catalyzed cyclic photophosphorylation, which is not inhibited by DCMU and antimycin and requires 10 -3 -m. NH 4 Cl or 10 -5 -m. desaspidin for uncoupling.

The radiosensitivity of dry bacteriophage was determined in vacuo at temperatures varying continuously between 100 ° and 300 °K using 2 MeV protons. Moreover, the influence of added cystamine and of base substitution by 5-bromouracil was investigated in the same range of temperatures. The variation of total cross section σ(Τ) with temperature is given by the expression: σ(T) =σ 0 ·(1+5,3. e-E a RT ) ±15 per cent. The constant σ 0 is 3,3.10 -12 cm 2 for normal Tl phage, 4,9.10 -12 cm 2 for base substituted Tl phage, 1,3.10 -12 cm 2 for Tl phage in presence of cystamine, and 1,6.10 -12 cm 2 for base substituted Tl phage in presence of cystamine; E a amounts to 1 kcal/mole in all four cases. The correlation between inactivation cross section σ and temperature T shows that two mechanisms of inactivation are present, one (σ 0 ) being independent of temperature, the other having an activation energy of about 1 kcal/mole. The first mechanism is ascribed to direct radiation action, while the temperature dependent component probably originates from small diffusible radicals.

The electromicroscopical structure and quinone composition of the osmiophilic, globular, lipiderich plastid inclusions were investigated in several plants. The localisation of the osmiophilic globuli in the plastid stroma and their behaviour toward fixation agents are described. The isolated globuli - here termed plastoglobuli - contain high amounts of lipophilic chloroplasts quinones and apparently no chlorophylls or carotenoids. There exist considerable differences in the relative quinone concentrations of chloroplasts and isolated plastoglobuli. The possible function of plastoglobuli is discussed.

The function of the osmiophilic stroma component of plastids - termed plastoglobuli 1 - has not yet been explained satisfactory. The changing plastoglobuli content during thylakoid-formation in proplastids of etiolated barley seedlings gives some evidence on their function. Before thylakoiddifferentiation proplastids of barley seedlings contain great numbers of plastoglobuli if grown in the dark. During thylakoid-formation, which can be induced in proplastids of etiolated plants by light flashes, the number of plastoglobuli decreases. Thus the plastoglobuli in proplastids of etiolated plants seem to possess the function of an extra-thylakoidal lipid pool, from which the lipids are taken for the synthesis of thylakoids.

From chloroplasts of Antirrhinum majus and Spinacia oleracea the structural proteids were isolated with anhydrous formic acid. These glycoproteids contain 3 - 5% carbohydrates. After hydrolysis the sugar constituents were examined by thin-layer- and gas-liquid chromatography. The sugars identified were galactose, glucose, mannose and xylose; galactose was found to be present as the predominant sugar. The carbohydrates of the soluble structural proteid have another sugar composition than those of the insoluble lamellar proteid of chloroplasts.