Vitaliy V. Yanilkin

Crystal violet dye in complexes with amphiphilic anionic calix[4]resorcinarenes: binding by aggregates and individual molecules.

Here, we report on a systematic study of six calix[4]resorcinarene macrocycles bearing eight carboxylic groups on the upper rim and four different lower rim substituents that are either aliphatic (2, 4, and 5) or alkylaromatic (1, 3, and 6). The macrocycles were studied in their individual aqueous solutions and in the presence of triphenylmethane dye crystal violet. It was found that binding of crystal violet with aggregated macrocycles shields it from the bulk of solution, preventing its discoloration under basic conditions and electrochemical reduction on the glassy carbon electrode. Most efficient shielding, reducing the rate of discoloration more than 173 times, as compared to solution with no macrocycle, was achieved with 6 forming aggregates of average 72 molecules in 0.1 mM solutions.

Methylviologen mediated electrosynthesis of gold nanoparticles in the solution bulk

Electrosynthesis of gold nanoparticles (AuNp) was carried out by methylviologen mediated reduction of Au(I) at potentials of the MV2+/MV˙+ redox couple in water/0.1 M NaCl medium, in the absence and in the presence of stabilizers. In all the cases, AuNp are formed in the solution bulk and are not deposited on the cathode. In the absence of stabilizers, AuNp (14–100 nm) coalesce to give aggregates of various shapes that eventually form a deposit. Sonication reversibly destructs the deposit into nanoparticles. In the presence of alkylamino-modified silicate nanoparticles (SiO2–NHR, 120–160 nm), spherical AuNp (≤20 nm) are bound as inclusions in the SiO2–NHR surface layer. Polyvinylpyrrolidone (40 000 D) stabilizes spherical AuNp with a mean diameter of 5–14 nm. All the particles were characterized by electron microscopy methods (SEM, STEM) and X-ray powder diffraction (XRPD).

Highly active Pd–Ni nanocatalysts supported on multicharged polymer matrix

In this article, we report the synthesis of mono- and bimetallic Pd–Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications. The morphology and catalytic properties of the composites depend on the Pd–Ni ratio. In the Suzuki–Miyaura coupling reaction, the composite with an equal amount of palladium and nickel is the most active and the reaction occurs within six hours in water at room temperature.