Chromatographic separation and molecular modelling of triazines with respect to their inhibition of the growth of L1210/R71 cells.

The potential anti-cancer activity of triazines was characterized by the inhibition of the growth of L1210/R71 cells. The retention times for fifteen triazine derivatives were measured by high-performance liquid chromatography on octyl silica and silica gel columns. The slope and intercept values of the plot of the logarithmic capacity factor versus acetonitrile concentration were calculated from the reversed-phase retention measurements. The adsorption properties of the compounds were characterized by the retention data obtained on silica gel columns using high and low concentrations of ammonium salts in the hydro-organic mobile phase. The non-polar, non-polar unsaturated and polar surface areas, the surface energies, the dipole moments and the Van der Waals radii of the molecules were calculated from their chemical structures after energy minimization on the basis of molecular mechanics. Correlation analysis of these parameters showed that the inhibitory effect is dependent on the polar and non-polar surface areas of the molecules. The reversed-phase slope showed a significant correlation with the difference between the accessible and the total non-polar surface areas of the compounds, whereas the intercept values correlated with the non-polar accessible surface area. The adsorption properties of the triazines on silica gel cannot be described by the molecular parameters investigated here.     

Structural Investigation of Guest-to-Host and Ligand-Ligand Interactions in Werner Clathrates of [Ni(4-Etpy)4(NCS)2]⋅ nG Type (G = Naphthalene Derivatives). The Crystal Structure of [Ni(4-Etpy)4(NCS)2]⋅1-Methylnaphthalene

The stoichiometry and spectral properties of [Ni(4-Etpy)4(NCS)2]nG clathrates have been studied where n = 2 for G = 1-BrN (N = naphthalene), n = 1 or 2 for G = 1-MeN, and n = 0.5 for 2-MeN and 2-BrN. The complexes under study show electronic absorption spectra typical of an octahedral environment of the Ni(II) central atom. The differences found in IR spectra for the (CN) and (Ni–-NNCS) vibrations are discussed. The crystal structure of [Ni(4-Etpy)4(NCS)2]1-MeN was determined by X-ray diffraction and refined to R = 0.0586. Discrete non-centrosymmetric [Ni(4-Etpy)4(NCS)2] molecules form layers of a host structure and the space between the layers is occupied by 1-MeN. The relationship between interatomic distances in the host complex of similar clathrates are discussed.     

Direct reading thermometric analysis

According to the direct reading thermometric method the concentration of the component to be determined is established from the temperature variation of the sample solution obtained on adding to it an excess of a reagent which reacts selectively with the respective component. Under suitably chosen experimental conditions the concentration of the respective component is determined from a single measured value. Since the established measurement technique requires little manual work and the respective components may be determined from the sample solution directly without any separations, the method in its present form is chiefly suitable for rapid serial analyses.

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Zusammenfassung Bei der thermometrischen Methode mit Direktablesung wird die Konzentration der gesuchten Komponente aus der Temperaturänderung der Probelösung bestimmt, die nach Zugabe eines Überschusses von einem selektiv reagierenden Reagens wahrnehmbar ist.Unter geeigneten Versuchsbedingungen kann man die Konzentration der gesuchten Komponente aus einem einzigen Meßwert, nämlich der Temperaturänderung der Probelösung bestimmen. Da die ausgearbeitete Meßtechnologie wenig Arbeit erfordert und die gesuchten Komponenten ohne jede Trennung direkt bestimmt werden können, ist die Methode in ihrer jetzigen Ausführungsart hauptsächlich zu betriebsmäßigen Serien-Schnellanalysen geeignet.

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Résumé Selon la méthode thermométrique à lecture directe, on détermine la concentration du constituant cherché d'après la variation de température de la solution échantillon que l'on additionne d'un excès de réactif sélectif de celui-ci. Dans les conditions expérimentales appropriées, une seule mesure suffit pour déterminer la concentration du constituant cherché. Comme la technique de mesure qui a été mise au point demande peu de travail et comme on peut doser sans aucune séparation les constituants étudiés, la méthode dans sa forme actuelle se prête en premier lieu aux dosages en séries industriels.

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Infrared study of adsorption of methanol,deuterated methanol and ethylene on the surface of ZSM-5 type zeolite

The surface species resulting in exposing of the ZSM-5 zeolite at elevated temperatures to methanol, deuterated methanol or ethylene have been studied by IR method.The three-step adsorption at 150°, 300°, 420° C or one-step adsorption at 420° C have been carried out in order to prepare the samples for IR. In all cases the most prominent band appeared in the range 1495–1515 cm^?1; besides two bands at about 1470 and 1370 cm^?1 have been observed. On the basis of Greenler's results and of the shift values of the bands in our spectrum of adsorbed deuterated methanol it was supposed that the band 1495–1515 cm^?1 is due to the OCO group from the surface species. Moreover these species would involve both oxygen atoms from the surface of zeolite but not from OH groups of methanol.     

Linear free-energy relationships and the density functional theory: an analog of the hammett equation

Density functional theory has been applied to describe electronic substituent effects, especially in the pursuit of linear relationships similar to those observed from physical organic chemistry experiments. In particular, analogues for the Hammett equation parameters (sigma, rho) have been developed. Theoretical calculations were performed on several series of organic molecules in order to validate our model and for comparison with experimental results. The trends obtained by Hammett-like relations predicted by the model were found to be in qualitative agreement with the experimental data. The results obtained in this study suggest the applicability of similar correlation analysis based on theoretical methodologies that do not make use of empirical fits to experimental data can be useful in the study of substituent effects in organic chemistry.     

The influence of the extrapolation method on enthalpies of solution at infinite dilution

Analyses have been performed on solution enthalpy data for KCl and NaCl in water at 298.15 K in the molality range below 1 mol kg^?1. In order to calculate the enthalpy of solution at infinite dilution. ΔH^∞, the available data have been extrapolated using five different methods. The influence of the extrapolation method on ΔH^∞ has been discussed taking into account the discrepancies between the different data sets.     

Ultrasound effects on the Mn(III) - promoted addition of amidoalkyl radicals to olefins

Amidoalkyl radicals, generated from amides by Mn(OAc)₃ in acetic acid react with phenyl substituted alkenes to generate five-membered lactones or lactams. Ultrasound at ambient temperature significantly accelerates these single electron transfer reactions even when compared with conventional conditions under reflux or simple mechanical stirring. In some cases sonication leads to unusual products.     

Screening the origin and weathering of oil slicks by attenuated total reflectance mid-IR spectrometry

The combination of attenuated total reflectance-fourier transform mid-infrared spectrometry (ATR-FTMIR) and multivariate pattern recognition is presented as a fast and convenient methodology to ascertain the source product an oil slick comes from and to evaluate the extent of its weathering. Different types of hydrocarbons (including crude oils, several heavy distillates and the Prestige's heavy fuel oil) were spilled on metallic containers designed ad hoc and their fate monitored by ATR-FTMIR. Not only environmental conditions were considered for weathering but artificial IR- and UV-irradiation. Pattern-recognition studies revealed that the different hydrocarbons clustered at different locations on the score plots and that the samples corresponding to each oil became ordered according to the extent of their weathering. Among them, fuel oil samples coming from the recent disaster of the Prestige tanker off the Galician shoreline showed a distinctive behaviour. Comparison of natural-, IR- and UV-weathering of a crude oil showed that IR solar radiation can be important in oil-weathering, in addition to broadly-reported UV degradation.     

The synthesis of 4‐amino‐3‐(2‐pyridyl)pyrazolo[5,1‐c][1,2,4]triazine and some of its derivatives

A mixture of both geometrical isomers of hydrazones 3a‐3e was obtained by the coupling reactions of pyrazole‐3‐diazonium salts 2a‐2d and benzenediazonium chloride 2e with 2‐pyridylacetonitrile 1 . Hydrazones 3a‐3d were cyclized to the corresponding 4‐amino‐3‐(2‐pyridyl)pyrazolo[5,1‐c][1,2,4]triazines 4a‐4d.     

Kinetic analysis of thermogravimetric data,V

The statistical analysis of activation energy and of logZ values derived from thermogravimetric data for 134 decomposition reactions of bisdioximatocobalt(III) complexes shows the validity of a linear compensation law, i.e. both the effects of heating rate and of the nature of the ligand manifest themselves in the kinetic compensation effect. The parametera of the compensation law is sensitive to ligand effects and its value is influenced both by the nature of the coordinated dione-dioxime and by the nature of the outer sphere anion X, which replaces an ammonia molecule in the thermal decomposition reaction.

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Zusammenfassung Die statistische Analyse der aus den thermogravimetrischen Resultaten erhaltenen Aktivierungsenergiewerte und log Z-Werte von 134 Zersetzungsreaktionen der verschiedenen bisdioxamato Kobalt(III) Komplexen zeigte die Gültigkeit eines Gesetzes der linearen Kompensation, d.h. der Effekt der Heizungsgeschwindigkeit und der Natur des Liganden verursachten in erster Näherung den kinetischen Kompensationseffekt. Parametera des Kompensationsgesetzes (1) repräsentiert den Ligandeffekt. Sein Wert wird durch die Natur des koordinierten Dion-dioxims und des Anions X in der äußeren Sphäre beeinflußt, das ein Aminmolekül während der thermischen Zersetzungsreaktion ersetzt.

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Résumé L'analyse statistique des valeurs des énergies d'activation et de celles de logZ obtenues à partir des résultats thermogravimétriques de 134 réactions de décomposition des complexes différent de bisdioximato-cobalt(III) montre la validité d'une loi de compensation linéaire du type (1); ceci signifie que l'effet de la vitesse de chauffage et celui de la nature du ligand sont responsables en première approximation de l'effet de compensation cinétique. Le paramètrea de la loi de compensation est sensible aux effets du ligand et la nature de la bis-dioxime coordonnée ainsi que la nature de l'anion X dans la sphère externe remplaÇant une molécule d'aminé durant la réaction de décomposition thermique influencent sa valeur.

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logZ, 134 - (III), . a - X, .