Heterocycles 51: Liphophilicity investigation of some thiazole chalcones and aurones by experimental and theoretical methods

Reversed‐phase thin‐layer chromatography and reversed‐phase high‐performance liquid chromatography were used for lipophilicity determination of a library of 30 thiazole chalcones and aurones previously synthetized in our laboratory. The experimental lipophilicity data have been compared with theoretical lipophilicity parameters estimated by various computational methods. Good correlations between the experimental and calculated lipophilicity parameters have been found for both investigated classes of compounds. Correlations between the lipophilicity of the thiazole chalcones and aurones and their antiproliferative activity were discussed. The methodologies and data gathered in this study will contribute to the lipophilicity studies of chalcones and aurones derivatives, two important classes of compounds in medicinal chemistry.     

Unprecedented Vilsmeier formylation: expedient syntheses of the cruciferous phytoalexins sinalexin and brassilexin and discovery of a new heteroaromatic ring system

[reaction: see text]. A very concise first synthesis of sinalexin was achieved by regioselective formylation of 1-methoxyindoline-2-thione under Vilsmeier conditions followed by unprecedented ammonia workup. Similar formylation of indoline-2-thione yielded brassilexin and a novel pentacyclic heteroaromatic compound resulting from condensation of the Vilsmeier adduct of indoline-2-thione. Both sinalexin and brassilexin displayed strong antifungal activity against several pathogens of crucifers.     

Flow effects in nucleus-nucleus collisions at (4.5×A) GeV/c

The multiplicity distributions of the negative particles are analysed using the moments method, for obtaining some experimental information on the possibility to observe flow processes and correlation between the particles in nucleus-nucleus collisions. The role of the collision geometry is important. The calculations are compared with experimental results for nucleus-nucleus collisions at (4.5×A) GeV/c obtained at the Synchrophasotron from JINR Dubna.Presented (by the first author) at the International School-Workshop Relativistic Heavy-Ion Physics, Prague (Czech Republic), 19–23 September 1994.     

Thermal radical initiator derivatives based on O‐imino‐isourea: Synthesis,polymerization, and characterization

The new thermal radical initiators (TRIs) with linear and cyclic type groups based on derivatives of O‐imino‐isourea have been designed and synthesized. The radical polymerization property of the synthesized TRI derivatives as a radical initiator in n‐butyl acrylate was monitored by differential scanning calorimetry analysis. TRI derivatives with linear type groups, such as 3‐PenDCC, 3‐HexDCC, and 4‐HepDCC, showed peak temperatures (T_peak) of 80–84 °C, whereas those with cyclic type groups, such as C‐PenDCC, C‐HexDCC, and C‐HepDCC, exhibited a wide T_peak distribution in the 74–87 °C range. The polymerization efficiency using new TRIs in n‐butyl acrylate was elaborately identified from the molecular weights and conversion obtained using gel permeation chromatography analysis and NMR spectroscopy. To consider their possible application to automotive clearcoats, the real‐time evolution of the rheological properties of clearcoat resins during the crosslinking process with newly synthesized TRI derivatives was measured, confirming the different crosslinking kinetics of TRI derivatives in real thermal curing process. The results were found to be well correlated with data from the radical polymerization experiments of TRIs. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3593–3600.     

Film characteristics of anodic oxidized AZ91D magnesium alloy by applied power

This study examined the film characteristics of an anodized AZ91D magnesium alloy by varying the direct current and pulse frequency conditions. In order to evaluate the effect of the pulse frequency on film formation, anodic oxidation was carried out by applying direct current and pulse current at a current density of 300 mA/cm². Compared with the sample groups treated with the direct current, a large number of small arcs were generated continuously on the film treated with the pulse current and the film formation rate was found to increase. Homogeneous and compact pores were formed with increasing frequency, and the rate of formation was increased rapidly to the arrival voltage. The film thickness increased and the surface roughness decreased with increasing anodic oxidation time at a fixed frequency of 125 Hz. However, treatment for more than 3 min led to decomposition of the oxidized film onto the previously formed film, which caused an increase in the number of cracks and pores within the film. The most uniform and smallest pores were acquired when the surface was anodized for 3 min at a current density and frequency of 300 mA/cm² and 125 Hz, respectively. X‐ray diffraction revealed the formation of MgO and Mg₂SiO₄ peaks, with a relative decrease in peak intensity for the MgO and Mg substrate. The Vickers hardness value was higher on the treated groups than on the untreated group, and the potentiodynamic polarization test revealed satisfactory corrosion resistance through a decrease in corrosion density and a large improvement in the corrosion potential. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and Evaluation of Antimicrobial Activity of Some New Hetaryl‐Azoles Derivatives Obtained from 2‐Aryl‐4‐methylthiazol‐5‐carbohydrazides and Isonicotinic Acid Hydrazide

A series of new 1,3,4‐oxadiazole/thiadiazole and 1,2,4‐triazole derivatives have been synthesized starting from 2‐aryl‐4‐methylthiazol‐5‐carbohydrazides and isonicotinic acid hydrazide. All the newly synthesized compounds were characterized by IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The synthesized compounds were screened for their antibacterial and antifungal activity, assessed as growth inhibition diameter. Some of them showed good antibacterial activity against gram positive Staphylococcus aureus, while the antibacterial activity against Listeria monocytogenes, Escherichia coli, and Salmonella typhymurium and antifungal activity against Candida albicans was modest. None of the tested compounds showed inhibitory activity against gram positive bacteria Enterococcus faecalis and Bacillus cereus and against gram negative bacteria Pseudomonas aeruginosa.     

Effect of intramolecular energy transfer on the rate of unimolecular isomerization: HCN --HNC

This paper reports calculations of the rate of isomerization of HCN - HCN based on the theory of Gary and Rice as extended by Zhao and Rice. The major task is to determine the effect of intramolecular energy transfer on the prediction of the rate of isomerization. Both the full three-dimensional (3D) system and the reduced two-dimensional (2D) system obtained from freezing CN bond at 1.159 A are analyzed to check the validity of the freezing bond approximation. Meanwhile, RRKM rates are calculated to test RRKM choice of the transition state by comparing to Gary-Rice three-state model. The comparison shows that the rates from 2D model and 3D model are differing up to 20% with 2D rates consistently larger. The intramolecular energy transfer modifies the isomerization rate for HCN system up to 30% that is modestly small by the expectation. The isomerization rate predicted from RRKM theory is greater than those of Gary-Rice three-state model theory up to 65%, and it overstimates the rates under all consider