Volume 25, Issue 12

Die monomolekulare Schicht eines Cyaninfarbstoffes, in der die Farbstoffchromophorebenen senkrecht, die Chromophorlängsachsen parallel zur Schichtebene stehen, wurde zwischen monomolekularen Schichten von Cadmium-Arachidat in einen Kondensator eingebaut. Aus der Absorptionsänderung bei Anlegen einer Spannung an den Kondensator wurden Dipolmoments- und Polarisierbarkeits-Änderungen beim Übergang vom Grundzustand zum angeregten Zustand des Farbstoffmoleküls bestimmt. Die Polarisierbarkeits-Änderung beim Übergang zum angeregten Zustand eines Moleküls konnte damit erstmals direkt experimentell ermittelt werden. Die betrachteten Meßgrößen wurden auf Grund des Elektronengasmodells theoretisch berechnet. In allen Fällen wurde beim Vergleich mit den experimentellen Daten eine Übereinstimmung im Vorzeichen und eine ungefähre Übereinstimmung im Absolutwert festgestellt

Mit Hilfe einer Drucksprungapparatur wurde die Kinetik von Ni-L-Tartrat und von racemischem Nickeltartrat bei 25°C untersucht. Dabei wurde das bereits bekannte 3 Reaktionsschema Ni 2⊕ + T 2⊖ ⇄ NiT (1) und NiT⇄(NiT) 2 (2) zugrundegelegt. Aus den Ergebnissen geht eindeutig hervor, daß die Reaktion (2), die zur Bildung des Doppelkomplexes (NiT) 2 führt, stereospezifisch ist, d. h. es entstehen nur die Komplexe (Ni-D-T) 2 und (Ni-L-T) 2 , nicht aber der gemischte Doppelkomplex (Ni 2 -ᴅ-T-ʟ-T). An Hand von Atommodellen wird gezeigt, daß sich nur aus zwei Ni-D-T-bzw. aus zwei Ni-L-T-Einheiten ein spannungsfreies Modell des Doppelkomplexes aufbauen läßt, bei dem gleichzeitig alle 4 Carboxylatgruppen in der energetisch günstigeren trans-Stellung angeordnet sind. Somit ist einzusehen, daß ein Komplex (Ni 2 -ᴅ-T-ʟ-T) nicht nachgewiesen werden kann

14 N chemical shifts are reported for nitriles, isocyanides and complexes with nitriles, isocyanides, and isohydrocyanic acid. The correlation of the 14 N coordination shifts with the metal-ligand back bonding as known from IR-investigations is discussed. While pi bonding seems to be insignificant in isocyanide complexes with metal cations, such as Fe 2⊕ , 14 N-NMR measurements suggest an increase of pi bond order on going from isocyanide carbonyl complexes to compounds in which isonitriles are the only ligands bound to zerovalent metals

The infrared and Raman spectra of aqueous alkaline Zn(II) solutions and of crystalline tri-, tetra- and hexahydroxo zincate(II) and tetra- and hexahydroxocadmate(II) salts, respectively, are reported and discussed. Between 5 ᴍ and 15 ᴍ NaOH concentrations only the tetrahedral [Zn(ΟΗ) 4 ] 2⊖ -ion is present in solution. Direct coordination of H 2 O to Zn(II) does not take place in an essential order of magnitude at any concentration

Redox-Reaktionen zwischen Jodboranen einerseits und Brom. Schwefel oder Dimethylsulfoxid andererseits liefern neben elementarem Jod Bromborane, 1.2.4.3-5-Trithiadiborolane, Borsulfine und Boroxine

Die Reaktion von S 2 Cl 2 mit H 2 Se liefert die beiden Achtringe S 6 Se 2 und S 5 Se 3 nebeneinander. Sie sind einfach voneinander zu trennen. Selen-Selen-Bindungen liegen darin nicht vor

Der von SILLEN am BiOCl-Gitter beobachtete Übergang von der Stöchiometrie ABX zur AB 2 X 2 wurde nunmehr auch bei intermetallischen Phasen gefunden. In diesem Zusammenhang gelang es, eine Reihe neuer Vertreter des ThCr 2 Si 2 -Typs darzustellen und strukturell zu charakterisieren

Das potentielle vierzähnige Phosphin C [CH 2 P (C e H 5 ) 2 ] 4 wirkt gegenüber den zweikernigen Metallcarbonylen Co 2 (CO) 8 und Mn 2 (CO) 10 als lediglich dreizähniger Reaktionspartner und bildet mit ihnen unter Valenzdisproportionierung und CO-Eliminierung ein bicyclisches Dicarbonyl-kobalt (I) -Kation bzw. Tricarbonyl-mangan (I) -Kation sowie die entsprechenden Anionen [Co (CO) 4 ] ⊖ und [Mn (CO) 5 ] ⊖ . Letztere lassen sich durch Umsetzungen mit Na [B (C e H 5 ) 4 ] gegen [B (C 6 H 5 ) 4 ] ⊖ austauschen. Die Strukturen der neuen Verbindungen werden in Zusammenhang mit Leitfähigkeitsmessungen, an Hand der IR- und Raman - aktiven (CO) - und (MC) -Valenzschwingungen sowie der (MCO) -Deformationsschwingungen (M = Metall) diskutiert. Für das schon länger bekannte [Mn (CO) 5 ] ⊖ -Ion wird auf Grund der IR- und Raman - Daten eine Rassenzuordnung mitgeteilt

As known from various biological important macrocycles (porphyrines, corrines) the single heterocycle C 4 H 5 N is able to form pyrrolyl compounds with a transition metal-to-nitrogen bond. These can be synthesized from metal halides and LiPyrr in ether or THF under anaerobic conditions. Binary and coordination compounds as well as Cp-derivatives of both Ti and Ni, their chemical, magnetic, IR- and PMR-spectroscopic properties are described to confirm the structures

All accessible NMR shifts δ 31 P of phosphorus surrounded by four nitrogen atoms are compiled systematically. They cover the relatively wide range from -40 to +50 ppm. All shift differences observed correlate well with changes in nitrogen hybridization: in the order p 3 → sp 3 → sp 2 → sp for nitrogen δ 31 P (N 4 ) is shifted to a higher field. In particular, δ 31 P (N 4 ) is a linear function of the degree of substitution, when phosphazeno groups are substituted by amino groups in open chain or cyclic systems. This is also true of δ 31 P (0 4 ) in alkoxy or phenoxy/phosphoroxy substitution series

Im Dreistoffsystem Calcium-Lithium -Silicium wurde eine Phase der Zusammensetzung Ca 1.65 Li 1.85 Si 4,0 aufgefunden und strukturell aufgeklärt. Das Siliciumteilgitter besteht aus nahezu regulären, ebenen Siliciumsechsecken, die in 1.4-Stellung durch zwei Siliciumatome miteinander verknüpft sind

The Raman spectra of four molecules absorbing in the visible region (SnJ 4 , GeJ 4 , TiBr 4 , and TiJ 4 ) are presented. They were excited with a quasi-continuous ruby laser and recorded with a special electronic detection system. Except for TiJ 4 , complete Raman spectra of crystal powder pellets could be obtained for the first time. The assignment reported by previous authors was confirmed by accurate polarization studies of solutions or pure liquid. The assignment is also in the solid state possible on the basis of Td point group symmetry. The fundamental vibrations of TiJ 4 in solutions are: ν 1 (A 1 ) =162, ν 2 (E) =51, ν 3 (F 2 ) =319 and ν 4 (F 2 ) Y = 67 cm -1

The preparation of 2-bromacetoacetamides and their copper chelates is described. The stability constants of these compounds were determined by potentiometric pH-measurements. The change of stability constants by the substituents of the amide group is interpreted

The preparation of 2-chloroacetoacetanilides and the preparation of their metal chelates is described. The dissociation constants of the chelating agents and the stability constants of the copper chelates were determined by potentiometric pH-measurements

A series of buffers, for methanol p.A. (water content 0,05%), were prepared and measured potentiometrically. The series, covering a pH*-range of 2.4-12.4, consists of ten buffers which are tabulated in steps of 0.2 pH*-units

In the γ-radiolyse of N 2 O saturated aqueous solutions of 2-deoxy-D-ribose (8·10 -3 mol/l) the following products (G-values) are formed: 2-deoxy-ᴅ-erythro-pentonic acid (and its γ-lacton) (1) (2,5), 2.5-dideoxy-ᴅ-erythro-pentonic acid (8) (0.6 3 ), 2-hydroxy-oxa-cyclohexanone-(4) (5) (1,1 5 ), 2-hydroxy-oxa-cyclohexanone- (5) (6) (1,0), 3-hydroxyglutaraldehyde (7) (0,5 5 ), further, α-hydroxy-carbonyl compounds 2-4 (0,2) and possibly malonaldehyde (≦ 0,1). The formation of the products can be explained by the attack of the water radicals (˙OH and ˙H) on the 2-deoxy-ᴅ-ribose to give primarily 2-deoxyribosyl radicals. These radicals may disproportionate directly, rearrange or eliminate water analogous to those from ethylene glycol 1 . The main product 1 stems from a disproportionation reaction of primary 2-deoxyribosyl radicals, 8 has a rearranged radical as a precursor, while in the formation of 5-7 primary 2-deoxyribosyl radicals split off water before disproportionation. The mechanism are discussed in detail

In the γ-radiolysis of aqueous N 2 O-saturated solutions of ethylene glycol (0,1 M) the following products (G-values at 20°C) were found: succinaldehyde (1,7 S ), glycolaldehyde (1,0 5 ), acetaldehyde (1,2), 3,4-dihydroxybutanal (0,2 2 ), and erythritol (0,1 5 ). Radicals from the water radiolysis (H˙ and ˙OH) attack ethylene glycol and yield ˙CHOH -CH 2 OH radicals. These radicals readily split off water yielding ˙CH 2 - CHO radicals [reaction (3)]. All products can be explained by disproportionation or dimerization of these two radicals. Material balance of products formed with respect to the primary yields of ˙H and ˙OH radicals from water radiolysis was obtained. ˙CHOH-CH 2 OH -+ CHO-CH 2˙ +H 2 O. (3) CHO-CH 2˙ +CH 2 OH-CH 2 OH→CHO-CH 3 +˙CHOH-CH 2 OH. (9) In contrast to the yields of the other products the acetaldehyde yield depends strongly on ethylene glycol concentration and temperature. With increasing temperature and ethylene glycol concentration the chain (3) - (9) - (3) becomes more and more important

The syntheses of the dibenzoquinolizinium-salts 3, 13, 16, 20 and 25 which are of spectroscopic interest are described. Their electronic excitation spectra will be published later by Perkampus and coworkers in this journal

We could prove that the system spiropyran/acid/pyrylium salt follows the equilibrium relation Spiropyran+acid ⇄ pyrylium salt. This color reaction can be used as an indicatory system. In this case the acid has to be produced instandaneously within the system. For this the spiropyran is mixed with a HX-donor which splits off a hydrogen halide HX by uv-irradiation. The coloration mechanism of layers consisting of spiropyran + HX-donor+matric forming polymer depends on the wavelength of the actinic radiation. Long wavelength uv-irradiation shows energy transfer, while only short wavelength uv-irradiation causes the primary process in the HX-donor

Die Geschwindigkeitskonstanten zweiter Ordnung für die Reaktion einfacher SH-Verbindungen sowie Imidazol-SH-Verbindungen mit Bromacetamid bei pH 7 und verschiedenen Temperaturen wurden bestimmt und daraus die Aktivierungsenergien sowie mit Hilfe der pK SH -Werte die pH-unabhängigen Geschwindigkeitskonstanten ermittelt. Die Ergebnisse zeigen, daß die nucleophile Reaktivität von SH-Gruppen durch ideal benachbarte Imidazolreste erhöht werden kann. Der Mechanismus dieser Aktivierung wird kurz diskutiert. - Eine nähere Untersuchung der Reaktivität von 4-Brom-5-nitroimidazol, das in der Literatur als Alkylierungsmittel vorgeschlagen wurde, zeigte, daß diese Verbindung unter den gewählten Bedingungen nicht mit SH-Gruppen reagiert

Das C-5-Proton 1.4-disubstituierter 1.2.4-Triazoliumsalze ist sehr beweglich. Der beobachtete große Einfluß 3-ständiger Substituenten auf die nichtklassische C-H-Acidität wird mit der Acceptorwirkung des N-2-Atoms erklärt

Tetracyanoethylene was added to dihydroresorcine and dimethyldihydroresorcine which yielded 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3,4,4-tricarbonitriles by cyclization. Dimethyl-dihydro-resorcine-monoimine together with tetracyanoethylene eliminated HCN and resulted in a 7,7-dimethyl-tetrahydro-quinoline derivative. The structures were proved by alkaline degradation and by IR- and NMR-spectroscopy

Es wurden Schmelzkurven sowie ORD- und ZD-Spektren von DNS-Lösungen verschiedenen Salzgehaltes gemessen. In Übereinstimmung mit den aus der Literatur bekannten Daten wurde mit abnehmendem Salzgehalt eine Destabilisierung der DNS-Doppelhelix gefunden, die Doppelstrangstruktur und die Basenaufstockung bleiben jedoch weitgehend erhalten. Die Doppelstrangstruktur wird bei niedrigen Ionenstärken erst nach thermischer oder Säuredenaturierung zerstört. Die Basenaufstockung wird dabei ebenfalls reduziert. Hohe Salzkonzentrationen (4,5 ᴍ NaCl) bewirken Strangtrennungen und ungeordnete Basendesorientierungen. Ein Vergleich der Absorptions-, ORD- und ZD-Daten zeigt, daß die Art der Konformationsänderungen von der Art der äußeren Einwirkungen abhängt

Aquocob (III) alamin (B 12a ) reagiert mit Kohlenmonoxid in alkoholischen Lösungen zu Kobaltalkyloxycarbonyl-cobalaminen. Die Reaktion läuft bei Zimmertemperatur ab, wird jedoch durch Wärme beschleunigt. Die Struktur der genannten Corrinoide ergibt sich daraus, daß diese auch aus Cob (I) alamin (B 12s ) durch die Reaktion mit den entsprechenden Chlorkohlensäureestern erhalten werden können. Die dargestellten Corrinoide haben erwartungsgemäß ein gemeinsames Absorptionsspektrum, welches dem des Cyanocobalamins ähnelt

The uropygial (preen) gland fat of the rook (Corvus frugilegus) is a mixture of ester waxes of which 2-methyl-substituted fatty acids with a chain length of C 16 -C 22 are shown to be the acidic components. The alcoholic components are n-alkanols with a chain length of C 6 -C 12 . As to the 32nd order of the natural system the uropygial gland fat seems to differ in the single families already if compared with that of the common sparrow

The acidic and alcoholic components of the uropygial gland wax from the tufted duck (Aythya fuligula) were investigated by a combination of GLC and mass spectrometry. Main components of the acidic part of the waxes are 2,4,6-trimethyl-nonanoic (39.0%) 2,4,6-trimethyl-octanoic (8.7%) and 2,6-dimethyl nonanoic acid (5.9%). Besides, 2,4,8-, 2,6,8-, and 2,6,10-trimethyl-substituted fatty acids occur. As minor components 2-methyl- and homologous series of 2,4-, 2,6-, 2,8-, and 2,10-dimethyl-substituted fatty acids could be detected. Main components of the wax alcohols were n-hexadecanol and n-octadecanol. As minor components 2-, 6-, 10-, 12-, and 14-methyl-branched primary alkanols occur. The tufted duck shows an uropygial gland wax which is typical for the 17th order of the natural system

Digestion of the electron transport particle fraction of Rhodospirillum rubrum with the proteases chymotrypsin, trypsin, subtilisin and pronase resulted in a release of protein from the membranal system. The solubilization was, however, limited to only 15 - 18 percent of the total protein, being the same with each of the four proteases. The enzymes catalyzing electron transfer which are located on these particles were not solubilized by the proteolytic digestion but were found to become differently inactivated already with low protease concentrations. The proteolytic attack revealed differences in the specificity of proteolysis between chymotrypsin and the other proteases

Drei Substanzen aus dem Hautdrüsensekret des südamerikanisches Frosches Leptodactylus pentadactylus wurden auf ihre Hemmwirkung für das Wachstum von Pilzen und Bakterien getestet. Dabei wurde gefunden, daß Spinaceamin und Bufotenin eine Hemmwirkung besitzen; bei Histamin wurde keine Hemmung beobachtet

Stepwise formation constants of folic acid, N-[p-[[ (2-amino-4-hydroxy-6-pteridyl) methyl] amino] benzyl] glutamic acid, with the carcinogenic metal ions, aluminium (III), chromium (III), beryllium (II), lead (II) and uranium (VI) have been determined at 30 °C, and at various ionic strengths, viz. 0.01 ᴍ, 0.05 ᴍ, 0.10 ᴍ, maintained by potassium nitrate solution. The formation of the chelate is evident from the shift between the (i) ligand and (ii) ligand and metal titration curves. From the values for the stepwise protonation constants and metal-ligand stability constants at various ionic strengths, thermodynamic formation constants were evaluated by extrapolation to zero ionic concentration. Logarithms of the overall thermodynamic stability constants (log K μ=0 ) are: 20.40 for H-; 15.15 for Al-; 10.10 for Cr-; 9.35 for Be-; 6.50 for Pb-; 9.00 for U-chelates. Corresponding free energy changes (ΔF 0 ) are -28.47, -21.14, -14.09, -13.05, -9.07, -12.56 K · Cal · mol -1 respectively

From Agrobacterium tumefaciens, strain B6, a clone B6Ri could be isolated which grows well in presence of 150 ug/ml rifampicin. Moreover B6Ri does not alter the rifampicin in the medium (quantity, spectrum in visible light, ability to inhibit the growth of B6). B6Ri is able to induce crown-galls on leaves of Kalanchoe in the presence of 100 µg/ml rifampicin. Therefore the rifampicin-mediated inhibition of crown-gall induction by B6 is not a consequence of any influence of the drug on the host cell

Seed proteins of the 50 pea mutants induced by neutron radiation were investigated electrophoretically. The proteins were isolated in two fractions: insoluble (in water) seed proteins (Fraction I) and soluble proteins (Fraction II). The protein patterns from fraction II of 11 mutants differed from that of the initial line. However, no patterns from fraction I differed from that of the initial line. It is evident, that the fasciation mutans do not have the “γ”-Band in the protein pattern

A series of NH-acidic 2-anilino-3,5-dinitro-thiophenes (II), 2-anilino-3,4-dinitro-5-halo-thiophenes (VI), and some 3,5-dinitro-thienole-derivatives (IX, X) were synthesized. Compounds II and VI are potent uncouplers of oxidative phosphorylation in rat liver mitochondria. The most active comcounds yielded a 50% uncoupling at a concentration of 10 -7 ᴍ. With some of the 2-anilino-3,5-dinitro-5-halo-thiophenes (BDCT or DDCT), added to respiring liver mitochondria, a transitory uncoupling of energy-linked reactions could be observed which is comparable to the phosphorylating cycles produced by ADP. The mechanism of this effect is discussed

In Sinapis alba seedlings the cell elongation is inhibited by 5-FUDR. At a concentration of 10 -5 ᴍ FUDR reduces the incorporation of 3 H-cytidine into the DNA of the hypocotyl by 50% in 24 hours; if, however, the labeling begins two hours after application of FUDR the inhibition amounts to 63 per cent. In the cotyledons the corresponding values are 73 and 79 per cent. On the contrary, FUDR enhances the incorporation of 14 C-thymidine into DNA by 48% and 44% in the hypocotyl and cotyledons, respectively. These experiments suggest that FUDR inhibits DNA synthesis by blocking the thymidine pool (or thymidine-5-phosphate pool)

Treatment (1-3 h ) of corn root tips with 5 × 10 -5 ᴍ tetraphenylboron (TPB) caused characteristic changes of the membrane structure in the outer layers of the root cortex cells. The mitochondria had lost their inner structure. At the double membrane of the mitochondria and at the membrane plasmalemma, tonoplast, and endoplasmatic reticulum there appeared numerous osmiophilic globuli (ca. 50 nm). The permeability of the membranes seemed to be increased extremely. It is suggested that the lipoproteine complex of the membranes was destroyed by interaction of TPB with ammonium groups of the membrane constituents