Pavel L. Padnya

Acetylcholinesterase biosensor for inhibitor measurements based on glassy carbon electrode modified with carbon black and pillar[5]arene

New acetylcholinesterase (AChE) biosensor based on unsubstituted pillar[5]arene (P[5]A) as electron mediator was developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. The AChE from electric eel was immobilized by carbodiimide binding on carbon black (CB) placed on glassy carbon electrode. The working potential of 200mV was obtained in chronoamperometric mode with the measurement time of 180 s providing best inter-biosensors precision of the results. The AChE biosensor developed made it possible to detect 1×10(-11)-1×10(-6) M of malaoxon, 1×10(-8)-7×10(-6) M of methyl-paraoxon, 1×10(-10)-2×10(-6) M of carbofuran and 7×10(-9)-1×10(-5) M of aldicarb with 10 min incubation. The limits of detection were 4×10(-12), 5×10(-9), 2×10(-11) and 6×10(-10) M, respectively. The AChE biosensor was tested in the analysis of pesticide residuals in spiked samples of peanut and beetroot. The protecting effect of P[5]A derivative bearing quaternary ammonia groups on malaoxon inhibition was shown.

Supramolecular “containers”: self-assembly and functionalization of thiacalix[4]arenes for recognition of amino- and dicarboxylic acids

New p-tert-butylthiacalix[4]arenes containing amide, tertiary amine and ammonium fragments in cone conformation were synthesized and characterized. The interaction of the p-tert-butylthiacalix[4]arenes with amino-, dicarboxylic acids and EDTA was studied by electron spectroscopy. The ability of the synthesized thiacalix[4]arenes to form supermolecules and supramolecular associates with guests was shown by dynamic light scattering. The formation of commutative and cascade supramolecular systems based on amphiphilic macrocycles was studied by UV spectroscopy and dynamic light scattering. It was shown that thiacalix[4]arene containing quaternary ammonium fragments with three methyl groups at the nitrogen form associates – “containers” containing glutamic acid as a guest.

Selective stepwise oxidation of 1,4-decamethoxypillar[5]arene

For the first time, the 1H and 13C{1H} NMR data were classified and analyzed for the pillar[5]arenes with one, two, three and five 1,4-benzoquinone fragments obtained in good yields. The empirical relationships established make it possible to define the relative position of the quinone and aryl fragments to each other in the oxidation products of any pillar[n]arenes.

Towards macrocyclic ionic liquids: novel ammonium salts based on tetrasubstituted p-tert -butylthiacalix[4]arenes

Water-insoluble ionic liquids based on p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim with amide and quaternary ammonium groups containing alkyl, phenyl, ester, phthalimide, glycine, alanine and glycylglycine groups in cone and 1,3-alternate conformations were synthesized. It was established that macrocycles containing quaternary ammonium fragments with alkyl, phenyl and ester groups at the nitrogen atom in cone conformation melt lower by 8–31 °C than 1,3-alternate stereoisomers. It was shown that the introduction of the bis(trifluoromethylsulfonyl)imide anion as a counterion in the structure of quaternary ammonium salts based on thiacalix[4]arenes led to a substantial decrease in the melting point of the above salts.

Synthesis and properties of chiral nanoparticles based on (pS)- and (pR)-decasubstituted pillar[5]arenes containing secondary amide fragments

Employing induced asymmetric synthesis, new decasubstituted pillar[5]arenes containing (R)-(+)- or (S)-(−)-1-phenylethane-1-acetamide fragments have been obtained and characterized. Using NTA and TEM, and circular dichroism spectroscopy, it was shown that the amidopillar[5]arenes synthesized form spherical chiral nanoscale aggregates in CHCl3. During heating, both positive and negative Cotton effects corresponding to nanoparticles in CHCl3 reversibly decrease. Keeping the nanoparticles at room temperature results in a decrease in their size and intensification of the Cotton effect.

Hybrid multicyclophanes based on thiacalix[4]arene and pillar[5]arene: synthesis and influence on the formation of polyaniline

For the first time, fragments of a pillar[5]arene were spatially preorganized with a thiacalix[4]arene core in a single multimacrocyclic structure. It was shown that the synthesized hybrid multicyclophanes bind aniline and do not interact with p-toluenesulfonic acid. Supramolecular assistance of the synthesized multicyclophanes in oxidative polymerization of aniline in aqueous p-toluenesulfonic acid solutions was studied. It was found that the use of the multicyclophane template in the reaction of the oxidative polymerization of aniline led to the formation of emeraldine with a higher molecular weight and a similar conductivity (1–2 mSm cm−1), which formed more stable emeraldine dispersions in acetone in comparison with traditionally obtained polyaniline.

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.

Synthesis of Water-Soluble Amino Functionalized Multithiacalix[4]arene via Quaternization of Tertiary Amino Groups

A convenient approach to the synthesis of multithiacalix[4]arene derivatives containing amino groups and phthalimide fragments by the formation of quaternary ammonium salts is presented. As the initial macrocycle for the synthesis of multithiacalix[4]arenes, a differently substituted p-tert-butylthiacalix[4]arene containing bromoacetamide and three phthalimide fragments was used in a 1,3-alternate conformation. The macrocycle in cone conformation containing the tertiary amino groups was found to be a convenient core for the multithiacalix[4]arene systems. Interaction of the core multithiacalix[4]arene with monobromoacetamide derivatives of p-tert-butylthiacalix[4]arene resulted in formation in high yields of pentakisthiacalix[4]arene containing quaternary ammonium and phthalimide fragments. The removal of phthalimide groups led to the formation of amino multithiacalix[4]arene in a good yield. Based on dynamic light scattering, it was shown that the synthesized amino multithiacalix[4]arene, with pronounced hydrophobic and hydrophilic fragments, formed dendrimer-like nanoparticles in water via direct supramolecular self-assembly.

Phase behaviour, structural properties and intermolecular interactions of systems based on substituted thiacalix[4]arene and nonionic surfactants

ABSTRACT Supramolecular organised materials were prepared from nonionic surfactants and the following macrocyclic ionic liquids: n-tert-butylthiacalix[4]arenes containing quaternary ammonium fragments with amino acid substituents. Tetraethylene glycol monododecyl ether and decadiethylene glycol monododecyl ether were used as nonionic surfactants. They form lamellar and hexagonal mesophases in aqueous media, respectively. Liquid crystal and structural properties of these systems were studied. Intermolecular interactions of system components leading to formation of lyomesophases were estimated. Molecular structure of thiacalixarene contributes to the formation of a hydrogen bonding with surfactants. This process, in turn, initiates formation of a denser packed hexagonal structure. Graphical Abstract

Effect of the alkylidene spacer and the p - tert -butylthiacalix[4]arene macrocyclic platform on the reactivity of the hydroxyl groups in the acylation reaction

A series of cone and 1,3-alternate p-tert-butylthiacalix[4]arenes tetrasubstituted at the lower rim simultaneously by the amide, ester, and carboxyl functions were synthesized. The reactivity of the synthesized compounds depends on the length of the alkylidene spacer. The N-(hydroxyethyl)amide derivatives do not react with succinic anhydride, whereas the N-(3-hydroxypropyl)amide derivatives react to form acylation products.