Synthesis, structural and spectral studies of Cu(II) and V(IV) complexes of a novel Schiff base derived from pyridoxal. Antimicrobial activity

A novel Schiff base, N-(4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one)pyridoxaldimine (HL·HCl), was prepared and structurally characterized on the basis of elemental analyses, ¹H and ¹³C NMR, and IR spectral data. The synthesis and characterization of several Cu(II) (1-6) and V(IV) (7) complexes with N-(4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one)pyridoxaldimine are reported. The composition and structures of the copper(II) and vanadium(IV) complexes were proposed based on elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic and EPR spectroscopy. In addition, the structures of the ligand and the complex [CuL(H₂O)₂]NO₃·2.25H₂O (1) have been determined by single-crystal X-ray diffraction, showing that the Cu(II) center has a distorted square-pyramidal geometry. The ligand and the complexes were also tested for their in vitro antibacterial activity.     

The impulse photopyroelectric method for thermal characterization of electrically conducting polymers

For electrically conducting polypyrole films, the thermal diffusivity and thermal conductivity were obtained by modeling the signals from the photopyroelectric flash technique with a one-dimensional four-layer system. This method has a number of advantages over the sinusoidal excitation: wide thickness range, fast acquisition, simple and cheap setup. This first thermal characterization of polypyrole films shows an increasing thermal conductivity with dopant ion concentration.     

Decomposition of the Space of Regular Operators

Let E be a directed vector space with the Riesz decomposition property and F be a complete v?ctor lattice. It is proved that if G is a solid subspace of E then the subspace of all regular operators annihilating on G is a component in the space of all regular operators from E into F.¹²     

Spectroscopic study on nystatin conformational modifications generated by its interaction with the solvent

Conformational transformations of the tetraenic nystatin chromophore under the influence of solvents and UV irradiation have been studied by absorption, fluorescence and wide-line NMR spectroscopy.     

Tartrazine,a new selective reagent for zirconium

A new method for determining zirconium is described, in which tartrazine serves as reagent. The precipitate can be ignited to ZrO₂ or weighed as the complex. The reagent appears to be very selective, and can be used for the determination of zirconium in alloys and ores.     

Electron impact mass spectrometry of phenyl thiophosphoroorganic amides

The interpretation of the electron impact mass spectra of methyl phenyl phosphinomorpholinylamidothioate, O-methyl phenyl phosphonomorpholinylamidothioate, phenyl phosphonomorpholinylamidochloridothioate and O-ethyl phenyl phosphonomorpholinyhimidothioate is presented. Elucidation of the fragmentation pathways was aided by exact mass measurements and observation of peaks due to metastable transitions detected for the first and last of the above compounds.     

Thermal behavior of some new chromium complexes with potential biological importance

Summary This paper reports the investigation of the thermal stability of three new complexes of Cr(III) with acrylate anion, [Cr₂(C₃H₃O₂)₄(OH)₂(H₂O)₄], [Cr₃O(C₃H₃O₂)₆(C₃H₄O₂)₃](C₃H₃O₂)×5H₂O and [Cr₂(C₃H₃O₂)₅(OH)] ×2H₂O, respectively. This type of complexes is important in proper carbohydrate and lipid metabolism of mammals. The thermal decomposition steps were evidenced. The thermal transformations are complex processes according to TG and DTG curves including dehydration and oxidative degradation of acrylate ion processes. The final product of decomposition is the chromium(III) oxide.     

Die photokolorimetrische Bestimmung des Palladiums mit 2-Mercapto-5-Anilin-1,3,4,-thiodiazol

Zusammenfassung Pd(II) gibt mit 2-Merkapto-5-anilin-1,3,4-thiodiazol eine Komplexverbindung; diese ist löslich und intensiv gelb gefärbt. Das stöchiometrische Verhältnis der beiden Komponenten beträgt 12. Die Komplexkonstante hat den Wert 4,17·10^–10. Eine empfindliche kolorimetrische Bestimmungsmethode für 0,12 bis 30 ppm Pd(II) wurde angegeben. Das UV-Spektrum der Komplexverbindung wurde ermittelt und der molare Extinktionskoeffizient bestimmt.

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Summary 2-Mercapto-5-aniline-1,3,4-thiodiazole yields a complex compound with palladium(II). This product is soluble and has an intense yellow color. The stoichiometric ratio of the components is 12; the complex constant is 4,17 ·10^–10. A sensitive colorimetric method for determining 0.12–30 ppm of palladium(II) is given. The ultraviolet spectrum of the complex compound has been mapped and also the molar extinction coefficient has been determined.

     

Carbon Cavity Microelectrode for Electrical Wiring of Enzyme by Insoluble Electroactive Species in Aqueous Media

The carbon cavity microelectrode (CME), exhibiting a volume of 4×10^?6 cm³, offers a genuine alternative for immobilizing and connecting enzymes in aqueous electrolytes by powder of insoluble redox materials. In the present work, the electrochemical behavior of two redox species such as ferrocene (Fc) and tetrathiafulvalene (TTF) was investigated with CME to evaluate their potentialities in the electrical wiring of enzymes. For this purpose, powder of two enzymes, glucose oxidase (GOx) and horseradish peroxidase (HRP), was independently mixed with an insoluble redox material and forced to fill the single micro cavity of a carbon electrode covered by an inert insulator. The presence of the electroactive species, as well as the enzyme wiring was investigated by cyclic voltammetry. The amperometric detection of glucose was carried out by potentiostating the TTF/GOx and the Fc/GOx microelectrodes at 0.25 and 0.35 V respectively. The amperometric detection of H₂O₂ by the TTF/HRP microelectrode was performed at ?0.1 V vs. SCE.     

Time-resolved photocurrent generation in a photoelectrochemical cell with phthalocyanine

The kinetics of photocurrent generated in the photoelectrochemical cell (PEC) with phthalocyanine (Pc) dyes in the microsecond time scale was discussed. The shape of the kinetics is rather complex and it was discussed in terms of molecular phenomena and electrochemical processes occurring after laser flash illumination. Time constants were calculated from the photocurrent decay curves and at least three time components were well recognized (rise in 0.40 micros, declining in 0.40-0.45 micros and secondary increase in about 2 micros). The shape of the kinetics was discussed in terms of dye singlet and triplet state participation in photocurrent generation and also in terms of creation of the Helmholtz-Goy double layer at the dye layer-semiconductor interface. The alteration in shape of the Helmholtz-Goy double layer in photoelectrochemical cell after laser pulse was also discussed.