Complexes of the selected transition metal ions with 4-methoxycinnamic acid

In this study, 4-methoxycinnamates of Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Nd(III) and Gd(III) were synthesised. From the infrared (IR) spectra analysis of complexes, sodium salt and according to the spectroscopic criteria the carboxylate groups seem to be bidentate chelating. The complexes of 4-methoxycinnamates lose the water molecules in one or two steps. The final products of their decomposition are oxides of the respective metals. The enthalpy values of dehydration process were determined. The FTIR spectra of the gas phase products indicate that the decomposition of the complexes is connected mainly with the release of molecules of water (H₂O), carbon dioxide (CO₂), carbon monoxide (CO), methane (CH₄) and other hydrocarbons. The analysed compounds follow the Curie?CWeiss law. The magnetic moment values experimentally determined change as follows: from 5.90??? _B to 6.27??? _B for Mn(II) complex, from 4.57??? _B to 4.99??? _B for Co(II) complex, from 3.68??? _B to 3.30??? _B for Ni(II) complex, from 1.87 ?? _B to 1.96 ?? _B for Cu(II) complex, from 3.06??? _B to 3.51??? _B for Nd(III) complex, and from 6.91??? _B to 6.90??? _B for Gd(III) complex.     

Copper (II) chloride / tetrabutylammonium bromide catalyzed oxidation of 2,6-diisopropylnaphthalene and 4,4′-diisopropylbiphenyl

The oxidation processes of 2,6-diisopropylnaphthalene and 4,4′-diisopropylbiphenyl with oxygen in the presence of a catalyst, composed of copper(II) chloride and tetrabutylammonium bromide, were investigated. It was found that, in essence, only one isopropyl group undergoes oxidation, and obtained mixtures contained mainly peroxide, alcohol, ketone and only small amounts of hydroperoxide.      

Quantitative analysis of crystallization kinetics by light depolarization technique. Possibilities and limitations

The kinetics of isothermal crystallization of various polymers was investigated by light depolarization technique (LDT) using the new setup with direct registration of depolarization ratio. Experimental data were analyzed using new method proposed by Ziabicki who shown that degree of crystallinity is a non-linear function of degree of depolarization, crystal thickness, and its birefringence. Other experimental methods were involved providing supplementary information on crystal thickness (SAXS) and allowing comparison of crystallization kinetics (WAXS, DSC). The advantage of LDT relies on high sampling rate allowing on-line measurements and lack of inertia effects that exist in other methods like calorimetry. The limitations of the applicability of the method are discussed. The method needs supplementary information not only on crystal thickness but also on variable optical birefringence of real crystals. Our results show that LDT can be used in a simple way for investigation of crystallization kinetics at relatively high temperatures, providing large and perfect crystals. In such a case it is sufficient to use crystal intrinsic birefringence and final crystal thickness typical at particular temperature of crystallization. On the other hand, depolarization ratio combined with measurements by other methods (crystallinity and crystal thickness) can be used for estimation of crystal birefringence.     

Thermal Stability and Flammability of Polypropylene-Silsesquioxane Nanocomposites

This article presents a study of the thermal stability of polypropylene-based nanocomposites filled with tetrasilanolphenyl silsesquioxane (phPOSS). Nanofillers were introduced into a polypropylene matrix in three different amounts: 2, 5, and 10 wt.%. Investigations were carried out by means of thermogravimetric analyses conducted in inert and oxidizing atmospheres, Fourier transform-infrared spectroscopy, scanning electron microscopy, and flammability UL-94 test. The addition of phPOSS into the polymeric matrix increased thermal stability in comparison to neat iPP and introduced significant changes in the flammability of iPP/phPOSS nanocomposites.     

Microwave-assisted guanidinylation in solid phase peptide synthesis: comparison of various reagents

The guanidinylation of a peptide chain on a polymeric support under microwave conditions using derivatives of thioureas—S-alkylisothioureas, pyrazole-carboxamidine, and guanidine as guanidinylating reagents is described. The best results are obtained with N,N′-di-Z-S-methylisothiourea and N,N′-di-Z(2-Cl)-S-methylisothiourea. It is found that guanidinylation with reagents containing Boc groups is accompanied by side reactions.     

Methyl 3-amino-2,3,6,-trideoxy-L-hexopyranosides in DFT level theory conformational studies

Geometry optimizations at the B3LYP level of density functional theory are reported for the (1)C4 and (4)C1 conformations of four theoretically possible alpha and beta methyl 3-amino-2,3,6-trideoxy-L-hexopyranosides. The Gibbs free energies, relative Gibbs free energies, and geometry parameters are presented for all the optimized structures. Conformational analysis of the pyranose ring is performed for each stereoisomer on the basis of calculated rotamer populations. It is demonstrated that the alpha/beta-L-arabino, alpha/beta-L-lyxo, and alpha-L-ribo stereoisomers adopt the (1)C4 conformation, whereas beta-L-ribo and alpha/beta-L-xylo stereoisomers remain in (1)C4 <==> (4)C1 conformational equilibrium. The preference of the alpha over the beta anomers is due to the endo-anomeric effect. The factors affecting the stability of pyranose ring conformations are discussed, as is the influence of hydrogen bonds on the orientation of the hydroxyl and amino groups. Figures of the most stable conformers are presented.     

On isometric stability of complemented subspaces of L p

We show that the Rudin-Plotkin isometry extension theorem inL _pimplies that whenX andY are isometric subspaces ofL _pandp is not an even integer, 1≤p<∞, thenX is complemented inL _pif and only ifY is; moreover, the constants of complementation ofX andY are equal. We provide examples demonstrating that this fact fails whenp is an even integer larger than 2.     

Synthesis and Hemostatic Activity of New Amide Derivatives

Eight dipeptides containing antifibrinolytic agents (tranexamic acid, aminocaproic acid, 4-(aminomethyl)benzoic acid, and glycine—natural amino acids) were synthesized in a three-step process with good or very good yields. DMT/NMM/TsO⁻ (4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium toluene-4-sulfonate) was used as a coupling reagent. Hemolysis tests were used to study the effects of the dipeptides on blood components. Blood plasma clotting tests were used to examine their effects on thrombin time (TT), prothrombin time (PT), and the activated partial thromboplastin time (aPTT). The level of hemolysis did not exceed 1%. In clotting tests, TT, PT, and aPTT did not differentiate any of the compounds. The prothrombin times for all amides 1–8 were similar. The obtained results in the presence of amides 1–4 and 8 were slightly lower than for the other compounds and the positive control, and they were similar to the results obtained for TA. In the case of amide 3, a significantly decreased aPTT was observed. The aPTTs observed for plasma treated with amide 3 and TA were comparable. In the case of amide 6 and 8, TT values significantly lower than for the other compounds were found. The clot formation and fibrinolysis (CFF) assay was used to assess the influence of the dipeptides on the blood plasma coagulation cascade and the fibrinolytic efficiency of the blood plasma. In the clot formation and fibrinolysis assay, amides 5 and 7 were among the most active compounds. The cytotoxicity and genotoxicity of the synthesized dipeptides were evaluated on the monocyte/macrophage peripheral blood cell line. The dipeptides did not cause hemolysis at any concentrations. They exhibited no significant cytotoxic effect on SC cells and did not induce significant DNA damage.     

Determination of the anomeric configuration of glycosyl esters of nucleoside pyrophosphates by fast-atom bombardment tandem mass spectrometry

Very low energy collision-induced dissociation of the deprotonated molecules of glycosyl esters of nucleoside pyrophosphates results in distinct fragmentation patterns that depend on the cis-trans configuration of the phosphodiester and 2″-hydroxyl groups of the glycosyl residue. In tandem mass spectrometry, sugar nucleotides with cis configuration produce only one, very abundant fragment that corresponds to nucleoside monophosphate, whereas nucleotides with trans configuration give weak signals for the nucleoside di- and monophosphates and their dehydration products. This empirical rule holds for sugar nucleotides that have a free 2″-hydroxyl group and no alternative charge location. Owing to its simplicity, sensitivity, and tolerance of impurities, fast-atom bombardment-tandem mass spectrometry represents a suitable method for determination of the anomeric linkage of glycosyl esters of nucleoside pyrophosphates if the absolute configuration of glycosyl residue is known and the compound fulfills the above-mentioned requirements.