Alena A. Vavilova

MALDI-TOF MS and Morphology Studies of Thiacalixarene-Silsesquioxane Products of Oligo- and Polycondensation

For the first time condensed silsesquioxane derivatives of tetratrialkoxysilyl compounds have been characterized by MALDI-TOF mass spectrometry. Tetrasubstituted p-tert-butyl thiacalix[4]arene derivatives containing organosilicon fragments with variable stereochemistry were chosen as organosilicon compounds for polycondensation. Information obtained from mass spectra was used to deduce both the structures of oligomeric derivatives, as well as the structure of silsesquioxane framework. The morphology of formed polysilsesquioxanes was investigated by scanning and transmission electron microscopy.

p-tert-Butylthiacalix[4]arenes functionalized by N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide fragments: synthesis and binding of anionic guests

New p-tert-butylthiacalix[4]arenes, which are mono-, 1,2-di- and tetrasubstituted at the lower rim containing N-(4’-nitrophenyl)acetamide and N,N-diethylacetamide groups in cone and partial cone conformations have been synthesized. Their complexation ability towards a number of tetrabutylammonium salts n-Bu4NX (X = F−, Cl−, Br−, I−, CH3CO2 −, H2PO4 −, NO3 −) was studied by UV spectroscopy. The effective receptor for the anions studied as well as selective receptors for F−, CH3CO2 − and H2PO4 − ions, which based on the synthesized thiacalix[4]arenes, have been obtained. It was shown that p-tert-butylthiacalix[4]arene tetrasubstituted at the lower rim by N-(4’-nitrophenyl)acetamide moieties bonded to the anions studied with association constants within the range of 3.55 × 103–7.94 × 105 M−1. Besides, the binding selectivity for F−, Cl−, CH3CO2 −, and H2PO4 − anions against other anions was in the range of 4.1–223.9. Substituting one or two fragments in the macrocycle with N,N-diethylacetamide groups significantly reduces the complexation ability of the receptor. In contrast to the 1,3-disubstituted macrocycle containing two N-(4’-nitrophenyl)acetamide moieties, the 1,2-disubstituted thiacalix[4]arene, which contains only one such fragment and a N,N-diethylacetamide moiety, selectively binds F− anions.

Tetracarboxylic acids on a thiacalixarene scaffold: synthesis and binding of dopamine hydrochloride

For the first time thiacalix[4]arene derivatives in 1,3-alternate conformation simultaneously containing amide, carboxyl and hydroxyl groups capable of forming 1 : 1 stoichiometry complexes with dopamine hydrochloride were obtained. The efficiency of dopamine hydrochloride binding was evaluated by a number of spectral methods. Using the methods of fluorescent, UV-Vis and NMR spectroscopy, the mechanism of interaction of the synthesized macrocycles with dopamine has been studied. It was shown that quenching of dopamine fluorescence by the studied macrocycles is carried out through a static mechanism.

Systems Based on Calixarenes as the Basis for the Creation of Catalysts and Nanocontainers

Increasing efficiency of chemical catalysis, as well as new directions for the control of chemical reactions, is of great importance in the further progress of chemical technologies and the pharmaceutical industry. One of the modern methods developed to solve this problem assumes carrying out reactions in nanoreactors, in which the reagents are concentrated in compartments of few nanometers in size. Currently, various micro- and nanostructured media, such as amphiphilic macrocyclic compounds (including calixarenes, resorcinarenes, and cyclodextrins) and micellar solutions and emulsions, are used as nanoreactors. This chapter describes systematized data on reactions in solutions containing various calixarene and resorcinarene derivatives, which increase the rate of a large number of reactions by acting as nanoreactors. Usually, the type of functional substituent determines the rate of reaction, for example, its controllable increase or decrease.