Solubilization of Biologically Active Heterocyclic Compounds by Biocompatible Microemulsions

Russian Journal of Physical Chemistry A - Microemulsions based on biocompatible components with high water content are applied to increase the solubility of medicinal drugs of the heterocyclic...     

Catalytic Effect of Micellar Systems Based on Hydroxypiperidinium Surfactants in the Hydrolysis of a p-Nitrophenyl Phosphonate

Kinetics and Catalysis - The aggregation behavior, solubilization effect, and catalytic activity of hexadecylpiperidinium surfactants (including ones functionalized with hydroxyl substituents) have...     

Mixed systems based on the cationic surfactant with a butyl carbamate fragment and nonionic surfactant Tween 80: Aggregation behavior and solubilization properties

Mixed micelles are formed in the binary compositions based on the cationic surfactant functionalized by the butyl carbamate fragment and nonionic surfactant Tween 80 in aqueous solutions. The aggregation parameters of the formed micelles (critical micelle concentration, size, and surface potential) depend on the component ratio in the system. The solubilization effect of individual and mixed micelles on the drugs of the heterocyclic series, indomethacin and 1-[5-(4-chlorophenyl)-3-phenylpyrrol-2-yl)]benzimidazol-2(3H)-one, was quantitatively characterized.     

Zeolite Synthesis in the Presence of Metallosiloxanes for the Quantitative Encapsulation of Metal Species for the Selective Catalytic Reduction (SCR) of NOx

Metal encapsulation in zeolitic materials through one-pot hydrothermal synthesis (HTS) is an attractive technique to prepare zeolites with a high metal dispersion. Due to its simplicity and the excellent catalytic performance observed for several catalytic systems, this method has gained a great deal of attention over the last few years. While most studies apply synthetic methods involving different organic ligands to stabilize the metal under synthesis conditions, here we report the use of metallosiloxanes as an alternative metal precursor. Metallosiloxanes can be synthesized from simple and cost-affordable chemicals and, when used in combination with zeolite building blocks under standard synthesis conditions, lead to quantitative metal loading and high dispersion. Thanks to the structural analogy of siloxane with TEOS, the synthesis gel stabilizes by forming siloxane bridges that prevent metal precipitation and clustering. When focusing on Fe-encapsulation, we demonstrate that Fe-MFI zeolites obtained by this method exhibit high catalytic activity in the NH₃-mediated selective catalytic reduction (SCR) of NO_x along with a good H₂O/SO₂ tolerance. This synthetic approach opens a new synthetic route for the encapsulation of transition metals within zeolite structures.     

The crystal structure of new quantum memory‐storage material Sc1.368Y0.632SiO5

Monoisotopic scandium yttrium oxyorthosilicate crystals as a material for quantum memory storage with high optical quality were grown by the Czochralski method. This material, of composition Sc_1.368Y_0.632SiO₅, is characterized by congruent melting and a melting point 60 K below the temperature for the ideal solid‐solution series Y₂SiO₅–Sc₂SiO₅. The structure of the crystals was refined on the basis of high‐quality single‐crystal X‐ray diffraction data. Sc_1.368Y_0.632SiO₅ belongs to B‐type RE₂SiO₅ (space group C2/c). Scandium and yttrium cations are distributed among two 8f sites with coordination numbers 7 and 6 for which the occupancy parameters ratios Sc:Y and average bond lengths are, respectively, 0.473:0.527 and RE1—O = 2.305 (2) Å, and 0.895:0.105 and RE2—O = 2.143 (2) Å. It is shown that the character of the occupancy of the positions of the cations with coordination numbers (CN) 6 and 7 for these solid solutions can be approximated by a polynomial dependence, the magnitude of the coefficients of which depends on the difference in the ionic radii of the cations. A preliminary electron paramagnetic resonance (EPR) study shows that activator ions with a large ionic radius at a concentration less than 0.1% occupy a position with CN = 7.