E. P. Zhil’tsova

Catalysis of nucleophilic substitution reactions in supramolecular systems

The factors determining the catalytic effect of supramolecular systems on the nucleophilic substitution reactions are analyzed. The role of the structural and phase transitions of nanoaggregates in the catalytic mechanism are determined. The substrate specificity is shown for different structures of the supramolecular composition.

Catalytic properties of micellar systems based on 4-aza-1-alkyl-1-azoniabicyclo[2.2.2]octane bromides

The catalytic effect of micellar systems based on alkylated 1,4-diazabicyclo[2.2.2]octanes on the alkaline hydrolysis of butyl chloromethyl 4-nitrophenyl phosphonate is reported. The catalytic effect is due to the reactants concentrating in the micellar phase. It increases with an increase in the hydrophobicity of the surfactant. The bicyclic surfactant manifests the higher efficiency than its cyclic and noncyclic analogues. The micellization properties of alkylated 1,4-diazabicyclo[2.2.2]octanes in aqueous solutions have been investigated by the NMR method. An increase in the hydrophobicity of the surfactant decreases the critical micelle concentration and increases the hydrodynamic radius and aggregation numbers of the micelles.

Catalytic properties of polymer-colloid complexes based on polyethyleneimines and mono- and diquaternized 1,4-diazabicyclo[2.2.2]octane derivatives in the hydrolysis of phosphorus acids esters

It is established by spectrophotometry that polyethyleneimines, mono- (MQD) and diquaternized (DQD) hexadecyl derivatives of 1,4-diazabicyclo[2.2.2]octane, and mixed polymercolloid systems based thereon catalyze the hydrolysis of p-nitrophenyl alkyl chloromethylphosphonates. The catalysis efficiency depends on the structures of substrate, 1,4-diazabicyclo-[2.2.2]octane derivatives, and polyethyleneimine, pH of the medium, and the temperature. In the case of MQD, the catalytic effect changes from 20 to 80-fold with an increase in the length of phosphonate alkyl radical from R = OEt to R = OC6H13; the DQDs exhibit lower catalytic activity compared to the MQD. The most efficient catalysis (up to 90-fold acceleration) is observed for a mixed polyethylene—dicationic surfactant system where the surfactant contains the hydroxyethyl fragment in the head group, which is due to a favorable effect of the micellar microenvironment of reagents.

Micellar and liquid-crystalline properties of bicyclic fragment-containing cationic surfactant

NMR spectroscopy is employed to study the aggregation of a cationic surfactant, 4-aza-1-cetyl-1-azoniabicyclo[2.2.2]octane bromide, in aqueous solutions. Self-diffusion coefficients are determined for micelles and monomers and the hydrodynamic radius and aggregation number are calculated for micelles. Polarization microscopy data demonstrate that the examined compound is an amphotropic substance. It is found that the lyotropic liquid-crystalline system is characterized by a wider temperature range of mesophase existence as compared to the thermotropic system.

Complex Formation and Self-Association in the Alkylated Polyethyleneimine Calix(4)resorcinarene Chloroform System

Complex formation and self-association in the system alkylated polyethyleneimine-calix[4]resorcinarene-chloroform were studied by UV spectrophotometry, dilecometry, and light scattering. The constant of complex formation of polyethyleneimine with calixarene was found to depend on the hydrophobicity of the components of the system and presence of surfactants.

Complex of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with copper dibromide: structure, aggregation, and biological activity

The aggregation and adsorption properties of a new complex of 1-hexadecyl-4-aza-1-azoniabicyclo[2.2.2]octane bromide with copper dibromide were studied by methods of conductometry, tensiometry, and dynamic light scattering. The critical micelle concentration, size of the aggregates, and adsorption characteristics at the water—air interface were determined. The antimicrobial and antifungal effects were established. The studied properties of the complex were compared with the properties of the ligand and cationic surfactants with a head group of the cyclic and acyclic types. The enhanced aggregation ability of the complex and its improved biological activity were shown.

Self-assembly of symmetrical and dissymmetrical dicationic surfactants in the solid phase and in solution

The effect of the spacer structure (linear, cyclic, bicyclic) and dissymmetry of alkyl fragment in a series of dicationic gemini surfactants on the ability to form thermotropic liquid crystals and on the micellar properties was studied. Transitions crystal-thermotropic liquid crystals-isotropic solution were studied using differential scanning calorimetry and optical microscopy. The self-diffusion coefficients of micelles and monomers of the dicationic dialkyl derivatives of 1,4-diazabicyclo[2.2.2]octane in water were determined by pulsed field gradient NMR spectroscopy. The effect of the surfactant structure on the values of critical micelle concentrations, hydrodynamic radii, and aggregation numbers of micelles was analyzed.

Supramolecular catalytic systems based on alkylated diquaternary 1,4-diazabicyclo[2.2.2]octane derivatives

The micellization and catalytic properties of the diquaternary 1,4-diazabicyclo[2.2.2]octane derivatives, viz., 1-alkyl-4-ethyl-1,4-diazoniabicyclo[2.2.2]octane dibromides (DAD) in water were studied by conductometry, viscosimetry, and spectrophotometry. The critical micelle concentrations and the semiaxial ratio of the micellar aggregates were determined. The character and strength of the effect of the DAD micelles on the alkaline hydrolysis of 4-nitrophenyl alkylchloromethylphosphonates depend on the surfactant and substrate structures, DAD concentration in solution, and temperature. An increase in the hydrophobicity of DAD and phosphonate increases the efficiency of catalysis.

Alkylated polyethyleneimine-cationic surfactant-calix[4]resorcinarene-chloroform catalytic system

The kinetics of phosphorylation of alkylated polyethyleneimine in chloroform in the presence of cationic surfactants with a cyclic or bicyclic head group and alkylated calix[4]resorcinarenes has been investigated by UV spectrophotometry. The catalytic activity of individual and mixed solutions of the amphiphilic admixtures depends on the structure of the constituents of the composition, on their concentrations in the solution, and on their relative amounts. In the presence of a calixarene, a decrease in the surfactant and polymer concentrations enhances the catalytic effect of the system.

Phosphorylation of polyethyleneimine in the solutions of calyx[4]resorcinolarene and its mixture with the surfactant

Phosphorylation of alkylated polyethyleneimine in chloroform in the presence of alkylated calyx[4]-resorcinolarenes with 2-hydroxyethoxy- and phosphorus-containing substituents and cetyl(3-hydroxypropyl)-dimethylammonium bromide was studied by means of the UV spectrophotometry. It was found that the character and the degree of the effect of calyxarene and its mixture with the surfactant depend on the hydrophobicity of macroring and the ratio of concentrations of components in the solution. The increase in the content of calyxarene and decrease in the concentration of polymer leads to the transformation of the catalytic action into the inhibiting one.