Galina I. Timofeeva

Mechanistic Investigation of the Asymmetric Addition of Trimethylsilyl Cyanide to Aldehydes Catalysed by Dinuclear Chiral (Salen)titanium Complexes

Titanium complexes 1 derived from chiral salen ligands are highly active precatalysts for the asymmetric addition of trimethylsilyl cyanide to aldehydes and ketones. Based on spectroscopic studies and the identification of adducts between complexes 1 and carbonyl compounds or trimethylsilyl cyanide, a catalytic cycle which explains the origin of the asymmetric induction is proposed. Kinetics studies have been carried out, the results of which are consistent with the proposed catalytic cycle.

Polymers based on ionic monomers with side phosphonate groups

A number of new ionic vinyl monomers composed of 1�vinylimidazolium cation with diethoxy� and dihydroxyphosphoryl groups and various anions—Br - , (CN)2N - , and (CF3SO2)2N - —are synthesized. The freeradical polymerization of the monomers in solutions of molecular and ionic solvents yields new polymer analogs of ionic liquids, and their molecularmass characteristics, solubility, heat resistance, thermal stability, and electrical conductivity are estimated. It is shown that the incorporation of bulky phosphorylalkyl side substituents into the vinylimidazolium polycation causes a decrease in the glasstransition temperature and an increase in the ionic conductivity of polymer salts. The highest ionic conductivity (2.6 × 10 -5 S/cm at 25°C) is exhibited by the polymer with the (CN)2N - anion.

Redox-Initiated Radical Polymerisation of Acrylamide in Moderately Frozen Water Solutions

The radical polymerisation of acrylamide initiated with a persulfate/tertiary amine redox pair was performed in liquid (+5 to +35°C) and moderately frozen (–10 to –30°C) aqueous solutions. The reaction in frozen systems resulted in the pronounced increase in the molecular weight of the polymer. The temperature dependence of the yield and molecular weight of cryogenically produced polyacrylamide were of extreme character with a maximum for both parameters in the vicinity of –12.5°C.

Dependence of the degree of association of water-soluble amino acid and peptide derivatives of fullerene[60] on pH and the ionic strength of a solution

The dependences of the degree of association of water-soluble amino acid and peptide derivatives of fullerene[60] on pH and the ionic strength of a solution were studied by the diffusion method. The degree of association of alanine, serine, arginine, and alanylalanine derivatives of fullerene increases both in acidic and in alkaline media compared to the initial aqueous solution. Using arginine and alanylalanine derivatives of fullerene as an example, it was demonstrated that the degree of association also increases as the ionic strength of a solution increases.

A study of the behavior of disubstituted methyl esters of peptide derivatives of fullerene C60 in aqueous solutions

Association of methyl esters of peptide-containing maleimidofullerenes in aqueous solutions was studied by the diffusion method. It was found that dissolution of these compounds follows a mechanism differing from that for the corresponding salts and that the degree of association of fullerene derivatives is affected most strongly by the structure of the molecule as a whole rather than by the peptide nature.

Molecular Mass Characteristics and Solution Behavior of Some Cardo Polybenzimidazoles

The behavior of dilute solutions of cardo polybenzimidazoles based on 3,3′4,4′-tetraaminodiphenyl ether; 3,3′,4,4′-tetraaminodiphenyl sulfone; and 4,4′-diphenylphthalidedicarboxylic acid in solvents of various natures has been studied by the methods of dynamic light scattering, sedimentation, and viscometry. All of the polymers have been found to contain a microgel fraction. For each fraction, the diffusion coefficient and the particle size are determined. The experimental characteristics of macromolecules correspond to the conformational rigidity calculated by a computer simulation procedure.

Three-dimensional polycondensation of monomers with ionomer-type interactions

Abstract The three-dimensional polycondensation of bifunctional hexamethylene diamine and trifunctional guanidine hydrochloride is studied. It is shown that the properties of this process do not follow the classical Flory theory. One of the most interesting features is the dependence of the critical extent of the polycondensation (i.e. the gel point) on the synthesis temperature. It is supposed that the reason for this is the different reactivity of the functional groups of guanidine hydrochloride and the different temperature coefficient of reactivity. As a result, some parts of the functional groups are excluded from the reaction. It is supposed that the reason for this is the ionomer character of the guanidinium links in the linear chains. Due to dipole-dipole interactions the ion pairs associated with the third functionality of these links aggregate into multiplets. Thus, reaction groups turn out to be effectively sterically screened and their ability to enter into the reaction with the formation of branching points becomes restricted.

Structuring in solutions of polydiphenylenesulfophthalide salts and their combined systems with a cationic surfactant

New derivatives of polydiphenylenesulfophthalide, namely its alkali-metal salts and interpolymer complexes with a cationic surfactant, are prepared via polymer-analogous transformations. It is shown that, depending on the type of solvent, solutions of polydiphenylenesulfophthalide salts may feature the properties of polyelectrolytes or ionomers. On the basis of dynamic laser light scattering data, the sizes of associates formed in solutions of salts of polydiphenylenesulfophthalide and its complexes with cetyl pyridinium chloride are determined. With the use of dynamic drop tensiometry, the values of surface tension of the aqueous solutions of lithium polydiphenylenesulfophthalide and its complexes with cetyl pyridinium chloride, as well as viscoelastic characteristics of adsorption layers formed at the solution/air interface, are measured.

Synthesis and characterization of cobalt ferrite nanoparticles in hybrid micelles of poly[styrene-block-(ethylene oxide)] and sodium dodecyl sulfate

Cobalt ferrite nanoparticles are synthesized in hybrid micelles of poly[styrene-block-(ethylene oxide)] and sodium dodecyl sulfate in water at room temperature. The nanoparticles are prepared by the chemical precipitation method via the exchange reaction between iron and cobalt salts with sodium dodecyl sulfate and the redox reaction under the action of an aqueous solution of methylamine. As evidenced by small-angle X-ray scattering, transmission electron microscopy, and ferromagnetic resonance examination, cobalt ferrite nanoparticles occurring in hybrid micelles of the block copolymer and sodium dodecyl sulfate are polydisperse (their size is 0.3–50 nm) and ferromagnetic.

Synthesis of hyperbranched polyphenylenes by suzuki reaction and their spectral characteristics

New monomer—1,3,5-tri(4-pinacolatoborolanephenyl)benzene (2) was obtained by Suzuki reaction of 1,3,5-tri(4-iodinephenyl)bensene (1) with bis-pinacolatodiborolane in the presence of [1,1′-bis(dydiphenylphosfino)-ferrocene]di-chloropalladium(II) as catalyst (PdCl2[dppf]). Hyperbranched polyphenylenes P1 and P3, which are blue light-emitting materials (410–430 nm), were also obtained by Suzuki reaction used different ratio of comonomers 1 and 2. Obtained polymers had a weight-average molecular weights of 4000–8000 and terminal iodine content of 27.5–14.2 wt % respectively. It was shown that polyphenylene’s quantum yields in solution decrease while iodine content increase.