Beitr?ge zur analytischen Chemie des Zirkoniums

Zusammenfassung In der vorliegenden Arbeit wird eine rasche und genaue spektrophotometrische Bestimmungsmethode für Mikrogrammengen Zirkonium mittels des Azofarbstoffes Solochrome Violet R besehrieben. Dieser Farbstoff bildet in 0,1 n salzsaurer Lösung mit Zirkonium einen rotvioletten Komplex, der bei einer Wellenlänge von 560 m, maximale Absorption aufweist. Mit dieser Methode kann noch 1 g Zirkonium/10 ml Meßlösung mit ausreichender Genauigkeit bestimmt werden.Wir danken Herrn Prof. Dr. F. Hecht für seine Unterstützung, die für das Zustandekommen dieser Arbeit von großer Bedeutung war.IV. Mitteilung siehe diese Z. 166, 181 (1959).     

Photooxidation of bis(ethylxanthato)nickel(II) containing aromatic nitrogen heterocyclic ligands in chloroform

The photochemistry of the complexes [Ni(Etxn)₂(N-N)] [Etxn=ethylxanthate,N-N=2,2-bipyridine(bpy), 4,4-dimethyl-2,2-bipyridine (4,4-Me-bpy), 1,10-phenanthroline (phen) or 2,2-bipyrimidine (bpym)] has been investigated. These complexes were not light sensitive in most solvents such as acetonitrile. Upon irradiation of chloroform solutions of these complexes, a photoredox reaction occurred giving the parent Ni(Etxan)₂. It is suggested that the reactive excited state is of the charge-transfer-to-solvent (CTTS) type. The energy of this state depends on the redox potentials of the solvent. When CHCl₃ as solvent was replaced by the stronger oxidant CCl₄, the photoactive wavelength region was shifted to the red. It was blue shifted when the weaker oxidant CH₂Cl₂ was used. From quantum yield measurements it is concluded that the photostability of the studied complexes decreases in the following order:bpym>phen>bpy>4,4-Me-bpy.

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Photooxidation von Bis(ethylxanthato)nickel(II) mit aromatischen Stickstoffheterocyclen enthaltenden Liganden in Chloroform

Zusammenfassung Es wurde die Photochemie der Komplexe [Ni(Etxn)₂(N-N) [Etxn=Ethylxanthat,N-N=2,2-Bipyridin (bpy), 4,4-Dimethyl-2,2-bipyridin (4,4-Me-bpy), 1,10-Phenanthrolin (phen) oder 2,2-bipyrimidin (bpym)] untersucht. Diese Komplexe waren in den meisten Lösungsmitteln wie etwa Acetonitril nicht lichtsensitiv. Bei Bestrahlung von Chloroformlösungen der Komplexe trat jedoch eine Photoreaktion auf, die zum Stammkomplex Ni(Etxn)₂ führte. Es wird vorgeschlagen, für den reaktiven angeregten Zustand einen Charge-Transfer-zu-Lösungsmittel (CTTS)-Typ anzunehmen. Die Energie dieses Zustands hängt vom Redoxpotential des Lösungsmittels ab. Bei Ersatz von CHCl₃ als Lösungsmittel durch das stärkere Oxidans CCl₄ wurde die photoaktive Wellenlänge nach Rot verschoben. Eine Blauverschiebung ergab sich hingegen, wenn das schwächere Oxidans CH₂Cl₂ verwendet wurde. Aus Messungen der Quantenausbeuten ergab sich die folgende Ordnung nach abnehmender Photostabilität der untersuchten Komplexe:bpym>phen>bpy>4,4-Me-bpy.

     

Synthesis,structural characterization and antimicrobial activities of cyclochlorotriphosphazene derivatives derived from N-(1-Naphthyl)ethylenediamine

Abstract

The nucleophilic substitution reactions of cylochlorotriphosphazene (N₃P₃Cl₆) with N-(1-Naphthyl)ethylenediamine resulted in the following formation of partially and fully substituted cyclotriphosphazene derivatives: 2,4,4,6,6-pentachloro-2-open-chain-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (3); 4,4,6,6-tetrachloro-2,2-spiro-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (4); 2,6,6-trichloro-2-open-chain-4,4-spiro-N-(1-Naphthyl)ethylendiamino-cyclotriphosphazatriene (5); 2,4-dichloro-2,4-ansa-6,6-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (6); and 2,4,6-trichloro-2,4,6-non-gem-open-chain-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (7); 2,2,4,4,6,6-tri-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (8); 2,4-dichloro-2,4-cis-open-chain-6,6-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (9); and 2,4,6,6-tetrachloro -2,4-ansa-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (10). The reactions produced the 4,4,6,6-tetrachloro-2,2-spiro-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (4) and 2,4,6,6-tetrachloro-2,4-ansa-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (10) derivatives as the major products in this system. The structures of the compounds were characterized by FT-IR, elemental analysis, TLC-MS, FT-IR, ¹H, and ³¹P NMR spectral data. All the derived compounds (3–10) were screened for antimicrobial activity by using the broth-agar microdilution technique for the determination of MIC and MCC values. In this context, the compounds were examined against three different human pathogens; Escherichia coli W3110, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231. Except compounds 6 and 9, the rest of the compounds exhibited significant antimicrobial activity on E. coli (W3110), S. aureus (ATCC 25923) and C. albicans (ATCC 1023). Among the synthesized derivatives, compound 4 is the most active agent against the referenced bacteria.     

Omega chrome black blue G as a colorimetric reagent for the microdetermination of various cations

Summary Omega Chrome Black Blue G has been found to be a suitable colorimetric reagent for the detection of cobalt and for the determination of copper, cobalt, cadmium, lead and magnesium. The effects of time, p_H, temperature, and foreign ions on the absorbancy are investigated. The reagent is practically suitable for the determination of microgram amounts of cobalt in presence of nickel and other ions which evoke a red colour.The reagent is not suitable for the determination of nickel, calcium, strontium, and zinc.     

Amperometric determination of live <Emphasis Type="Italic">Escherichia coli</Emphasis> using antibody-coated paramagnetic beads

Detecting and enumerating fecal coliforms, especially Escherichia coli, as indicators of fecal contamination, are essential for the quality control of supplied and recreational waters. We have developed a sensitive, inexpensive, and small-volume amperometric detection method for E. coli -galactosidase by bead-based immunoassay. The technique uses biotin-labeled capture antibodies (Ab) immobilized on paramagnetic microbeads that have been functionalized with streptavidin (bead–Ab). The bead–Ab conjugate captures E. coli from solution. The captured E. coli is incubated in Luria Bertani (LB) broth medium with the added inducer isopropyl -D-thiogalactopyranoside (IPTG). The induced -galactosidase converts p-aminophenyl -D-galactopyranoside (PAPG) into p-aminophenol (PAP), which is measured by amperometry using a gold rotating disc electrode. A good linear correlation (R²=0.989) was obtained between log cfu mL^–1 E. coli and the time necessary to product a specific concentration of PAP. Amperometric detection enabled determination of 2×10⁶ cfu mL^–1 E. coli within a 30 min incubation period, and the total analysis time was less than 1 h. It was also possible to determine as few as 20 cfu mL^–1 E. coli under optimized conditions within 6–7 h. This process may be easily adapted as an automated portable bioanalytical device for the rapid detection of live E. coli.     

Synthesis of 4-hydroxy-4,5-dihydro-1,2,4-triazol-5-ones

Summary A series of hydroxamic acid ethoxycarbonylhydrazides was obtained by reactions of ester ethoxycarbonylhydrazones with hydroxylamine. The corresponding 3-substituted 4-hydroxy-4,5-dihydro-1,2,4-triazol-5-ones were synthesized by cyclization of these hydroxamic acid derivatives in basic medium.

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Synthesen von 4-Hydroxy-4,5-dihydro-1,2,4-triazol-5-onen

Zusammenfassung Durch Reaktion von Esterethoxycarbonylhydrazonen und Hydroxylamin wurde eine Reihe von Hydroxamsäureethoxycarbonylhydraziden gewonnen; Cyclisierung dieser Verbindungen durch Base gab die entsprechenden 3-substituierten 4-Hydroxy-4,5-dihydro-1,2,4-triazol-5-one.

     

Ordering of Kekulé structures using nonadjacent numbers

Kekulé indices and conjugated circuits are computed for 36 Kekulé structures, together with two VB quantities associated with the corresponding factor graphs (previously called submolecules). These latter quantitites are nonadjacent numbers of Hosoya and the reciprocal of the connectivity indices of Randi?. It was found that the index of Hosoya successfully orders a set of Kekulé structures belonging to the same hydrocarbon in a parallel order as their Kekulé indices and branching indices. This substantiates the relation between VB and MO theories. A code is derived by summing contributions of nonadjacent numbers in all Kekulé stuctures of a hydrocarbon. The order of the resulting codes is found to be identical to the order of the molecular properties (resonance energies, π-energies, and eigenvalues) of the hydrocarbons.     

The Behavior of 3,3-Diphenylindan-1,2-dione Towards Alkyl Phosphites

The reaction of 3,3-diphenylindan-1,2-dione with trimethyl phosphite in dry benzene at room temperature for about 15 h led to the formation of a mixture containing dimethyl (3,3-diphenyl-2-methoxy-1-indenyl)phosphate and dimethyl (3,3-diphenyl-1H-2-oxo-1-indanyl)phosphate, whereas with triisopropyl phosphite, diisopropyl (3,3-diphenyl-2-isopropoxy-1-indenyl)phosphate is the only product. Treatment of the dione with dialkyl phosphites under different experimental conditions gave dialkyl (3,3-diphenyl-1-hydroxy-2-oxo-1-indanyl)phosphates. Reaction mechanisms are presented which account for the experimental results. Structural assignments of the new compounds are based on the spectroscopic evidences and two examples were elucidated by X-ray crystallography.     

Computation of dynamic adsorption with adaptive integral,finite difference,and finite element methods

Analysis of diffusion-controlled adsorption and surface tension in one-dimensional planar coordinates with a finite diffusion length and a nonlinear isotherm, such as the Langmuir or Frumkin isotherm, requires numerical solution of the governing equations. This paper presents three numerical methods for solving this problem. First, the often-used integral (I) method with the trapezoidal rule approximation is improved by implementing a technique for error estimation and choosing time-step sizes adaptively. Next, an improved finite difference (FD) method and a new finite element (FE) method are developed. Both methods incorporate (a). an algorithm for generating spatially stretched grids and (b). a predictor-corrector method with adaptive time integration. The analytical solution of the problem for a linear dynamic isotherm (Henry isotherm) is used to validate the numerical solutions. Solutions for the Langmuir and Frumkin isotherms obtained using the I, FD, and FE methods are compared with regard to accuracy and efficiency. The results show that to attain the same accuracy, the FE method is the most efficient of the three methods used.