One-pot multicomponent synthesis of 1,2,3,4-tetrasubstituted pyrroles catalyzed by [NMPH]CH3SO3

A general method for the synthesis of 1,2,3,4-tetrasubstituted pyrroles by [NMPH]CH₃SO₃ is reported. A full factorial design was performed in order to obtain a more robust and statistically correct optimum condition. The products were obtained in moderate to excellent yields. The developed methodology is very simple, cost-effective, and applicable for tri- and tetra-component reactions.     

Magnetic resonance studies of copper (II) sorbitol complex,in solution,reveal a supramolecular structure compatible to the crystal structure

Although the Cu²⁺-sorbitol complex [Cu²⁺-Sorb] structure in crystalline state has been determined by X rays, it is not known in solution, where most studies of this complex are performed. Therefore, the goal of this work was to obtain information about the structure of this complex in aqueous solution using nuclear magnetic resonance and electron paramagnetic resonance spectroscopies. The magnetic resonance results indicate that the complex is formed at approximately pH 12. In this pH the sorbitol ¹H relaxation times were so short (broad line) that was not possible to use standard nuclear magnetic resonance parameters (nuclear Overhauser effect and spin–spin coupling constants values) to solve the three-dimensional structure. However, valuable structural information about the complex in solution was obtained. The relaxation results indicate that the Cu²⁺ ions are buried in the structure and not accessible to solvent; the ¹H and ¹³C spectra shows strong paramagnetic shift effect indicating short distance between these nuclei and Cu²⁺ in the structure. No electron paramagnetic resonance signal was observed in pH 12 indicating strong Cu²⁺- Cu²⁺ dipolar interaction, compatible to Cu²⁺-Cu²⁺ distances measured in crystal, from 1.148 to 1.393 Angstroms. The complex self-diffusion coefficient (D) of 1.58 × 10⁻¹⁰ m²/s value, determined by Diffusion-Ordered Spectroscopy, is compatible to a molecular weight of 3–6 KDa. Therefore, these results corroborate that the [Cu²⁺-Sorb] complex is assembled in solution, at pH 12, with several structural parameters compatible to the toroidal hexadecacuprate supramolecular structure determined in solid state.     

A theoretical NMR study of polymorphism in crystal structures of azoles and benzazoles

The NMR chemical shifts of two azoles and one benzazole whose crystal structures present polymorphism have been computed using the GIPAW approach. ¹⁵N and ¹³C nuclei have been studied. Statistical analysis of the computed ¹³C and ¹⁵N chemical shifts indicates that the GIPAW chemical shifts reproduce with a high degree of accuracy those experimentally reported. This methodology can be used to identify other polymorphic crystal structures.     

Evaluation of selected buffers for simultaneous determination of ionic and acidic pesticides including glyphosate using anion exchange chromatography with mass spectrometric detection

Ion chromatography coupled with mass spectrometry is an established technique for determination of ionic analytes, however, sophisticated buffer removal equipment is required to eliminate inorganic compounds from the eluate before introduction into the ion source of mass spectrometer. A standard high‐performance liquid chromatography coupled with tandem mass spectrometry setup using an ion exchange column (Metrosep® A Supp 5) is proposed as an alternative approach. For that reason, some buffers including non‐volatile carboxylic acid based solutions have been evaluated for simultaneous trace determination of ionic and acidic pesticides including glyphosate in the same extract without a need for sophisticated buffer removal equipment. Two differently designed ionisation sources were compared qualitatively for the application of non‐volatile buffers. The study revealed that the choice of buffers had a strong influence on matrix effects in case of spiked extract injections. Finally, pesticides with very different physicochemical properties (logP < 0, logP ≥ 0) and structures (containing carboxylate, phosphonate, azolide, azanide, phenolate, bromate, and chlorate moieties) were quantified in spiked beer and oat extracts with acceptable recoveries (80–110%) using tandem mass spectrometry detection with AB SCIEX QTRAP 5500 instrument after separation using edetate buffer.     

Determination of uranium and thorium in sediments from Cananéia-Iguape system,Brazil

Journal of Radioanalytical and Nuclear Chemistry - The Cananéia-Iguape system is a complex of lagoon and estuarine channels located in the south of state of São Paulo. This system...     

Synthesis,thermal behavior,and spectroscopic study of the solid nalidixate of selected light trivalent lanthanides

Journal of Thermal Analysis and Calorimetry - Solid-state [Ln(nal)3]·nH2O compounds, where Ln represents light trivalent lanthanide (La to Sm, except Pm), nal is nalidixate (C12H11N2O3), and n...     

Quality standardization of herbal medicines of Spondias dulcis Parkinson using analytical and microbiological analysis

Journal of Thermal Analysis and Calorimetry - The solid–liquid phase equilibrium for binary system of 2,4,6-trimethylphenol (TMP) and 2,5-dimethylphenol (DMP) was built by differential...     

Effects of polyphenol removal methods on the in vitro exsheathment inhibitory activity of Lysiloma latisiliquum extracts against Haemonchus contortus larvae

It has been suggested that the anthelmintic (AH) activity of tannin-rich forages is related to their tannin content. However, reports on tropical fodders such as Lysiloma latisiliquum describe the same AH activity after the addition of tannin-blocking agents, suggesting that the activity either depends on the method of tannin blocking/removal or is due to other type of secondary metabolites. This study compared both the effect of the drying process of the plant material and the effect of different polyphenol removal methods on the AH activity of L. latisiliquum acetone-water extracts when tested against Haemonchus contortus. The results showed that the extraction of oven-dried (OD) leaves of L. latisiliquum yielded a CT-free extract with high AH activity. However, polyphenol-free fractions showed similar or lower AH activity levels as of those original OD extract. HPLC analysis confirmed that common polyphenolic metabolites are not responsible for the AH activity of L. latisiliquum.