S. E. Solov’eva

Cooperative intramolecular hydrogen bond and conformations of thiocalix[4]arene molecules

The joint FTIR spectroscopic study and ab initio quantum-chemical calculations (HF/3-21G and PBE/TZ2P methods) showed that thiocalix[4] arene molecules adopt the cone conformation in CCl4 solutions. The weakening of the cooperative intramolecular H bond in thiocalix[4]arenes compared to the corresponding calix[4]arenes can be due to the larger thiocalixarene macrocycle, bifurcated hydrogen bond in it, and electron density transfer from the bridging S atom to the benzene ring.

Extraction of cesium and americium with p-alkylcalix[8]arenes from alkaline solutions

Previously unknown isononylcalix[8]arene was synthesized from commercially available isononylphenol. The properties of the product (solubility, extraction ability, tendency to aggregation) were compared with those of the known tert-butylcalix[8]arene. The extraction of 137Cs, 99mTc, and 241Am from alkaline carbonate solutions with solutions of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) in tetrachloroethylene was studied. The dependence of the distribution ratios on pH of the aqueous phase in the interval from 11 to 13.9 and on the nature of functional groups in the calixarene core was determined. The composition of extractable solvates of cesium and americium with calix[8]arenes was found. Calix[8]arenes extract cesium from alkaline solutions more efficiently than p-tert-butylphenol, their nonmacrocyclic analog, does. tert-Butylcalix[8]arene exhibits the highest performance, which may be due to formation of aggregates 5.7 ± 0.8 nm in diameter in the organic phase at pH 13.5 of the aqueous phase. The isononyl derivative exists in the monomeric form (particle diameter 1.9 ± 0.5 nm).

Electrochemical properties of n-sulfonatothiacalyx[4]arene complexes with Fe3+ and [Co(dipy)3]3+ ions

The electrochemical properties of n-sulfonatothiacalyx[4]arene (H4XNa4) complexes with [Co(dipy)3]3+ and Fe3+ ions were studied by means of cyclic voltammetry in aqueous solution at pH 2.5. The observed single-electron reduction of [Co(dipy)3]3+ bound extraspherically to the upper rim and Fe3+ ion bound intraspherically to the lower rim of n-sulfonatothiacalyx[4]arene in binary [Co(dipy)3]3+ · H3X5−, H3X5− · Fe3+, and ternary [Co(dipy)3]3+ · H3X5− · Fe3+ heterometal complexes was more difficult than in the free state. The reversible single-electron transfer to the metal ion results in lower binding energy ([Co(dipy)3]3+, ΔΔG0 = 3.9 kJ/mol) or in full fast dissociation of the complex (Fe3+). The ternary complex in the solution forms the aggregates, in which inner encapsulated Fe(III) and Co(III) ions are not reduced on the electrode. Their quantitative reduction takes place by the relay mechanism of intra- and intermolecular electron transfer through electrochemically generated [Co(dipy)3]2+ outer ions.

Composite materials on the basis of phenylenecarboxylate framework MOF-5 and calix[4]arenes with various structures

A comparative study of the texture and adsorption characteristics of newly synthesized composite materials based on 1,4-benzenedicarboxylate metal-organic framework MOF-5 and calix[4]arenes with various structures was performed.

Template synthesis in the Cu(II)-dihydrazinomethanethione-acetone ternary system

Complex formation in the Cu(II)-dihydrazinomethanethione (H2NHN-CS-NHNH2)-acetone ternary system in an ethanol solution containing CuCl2, dihydrazinomethanethione, and acetone, as well as on contact of gelatin-immobilized copper(II) hecacyanoferrate(II) with alkaline (pH >10) aqueous solutions containing the above organic compounds was studied. It was found that template synthesis is realized in both cases but gives different products: in the first case, a heteroligand chelate of CuL1(OH) with 9-hydrazino-9-mercapto-4,6,6-trimethyl-2,3,7,8-tetraazanona-3,8-dienethiohydrazide and hydroxide ion is formed, while in the second, a chelate of CuL2 with 2,8,10,10,16-pentamethyl-3,4,6,7,11,12,14,15-octaazaheptadeca-2,5,7,12,15-pentaene-5,13-dithiol. In both cases, dihydrazinomethanethione and acetone function as ligsons. A scheme of involved processes is suggested.

Mild template synthesis of a macrocyclic Cu(II) chelate complex with 1,10-diamino-1,10-dimercapto-5,6-dimethyl-4,7-diazadeca-1,4,6,9-tetraene-3,8-dithione in Cu2[Fe(CN)6]-gelatin-immobilized matrix implantates

Complexation in Cu2[Fe(CN)6]-gelatin-immobilized matrix implantates in contact with alkaline (pH > 10) aqueous solutions containing propane-1,3-dithioamide and butane-2,3-dione, as well as with an ethanolic solution containing the same organic compounds, was studied. It was found that room-temperature complexation in the gelatin matrix gives a macrocyclic complex CuL1with a tetradentate N,S,S,N-donor ligand via a template synthesis, while complexation in solution at room and higher temperatures yields only a bischelate Cu(II) complex with monodeprotonated propane-1,3-dithioamide. Schemes of the complexation processes were proposed. It was demonstrated that when propane-1,3-dithioamide and butane-2,3-dione are in direct contact in solution, the above N,S,S,N-donor ligand was formed in neither the presence nor the absence of Cu2+.

Synthesis and fluorescent properties of thiacalix[4]arenes containing terpyridyl fragments at the lower rim

New thiacalix[4]arenes tetrasubstituted by terpyridyl fragments at the lower rims in the 1,3-alternate stereoisomeric form were synthesized. The molecules interact with EuIII and TbIII in the DMF solution to form highly luminescent nanoscale (21–26 nm) metal-organic structures with the 2: 1 metal-to-ligand stoichiometry and a narrow particle size distribution.

1,3-Cyclohexadiene hydrogenation in the presence of a palladium-containing catalytic system based on an MOF-5/calixarene composite

A palladium-containing material based on the new metal-organic framework structure MOF-5/20% calix[4]arene have been synthesized and characterized by physical and chemical methods for the first time. The catalytic activity of the 3% Pd/MOF-5/20% calix[4]arene composite in partial 1,3-cyclohexadiene hydrogenation into cyclohexene is fairly high and is comparable with that of the 5% Pd/C reference catalyst.

Synthesis and structure of lower rim-substituted alkynyl derivatives of thiacalix[4]arene

Lower-rim substituted bis- and tetrakis(alkynyloxy)thiacalix[4]arenes in cone and 1,3-alternate configurations were synthesized by the Mitsunobu reaction, and their structure was determined using homoand heteronuclear one- and two-dimensional NMR techniques. Bis(prop-2-yn-1-yloxy)thiacalix[4]arene was found to exist in conformational equilibrium whose position depends on the temperature and reaction conditions.

Synthesis, structure, and properties of a new representative of the family of calix[4]arene-containing [MnII2MnIII2]-clusters

A new representative of calix[4]arene-containing tetranuclear manganese complexes of the [MnII2MnIII2] type was obtained. According to the data of magnetoochemical studies, the complex exhibits properties of molecular magnet at the temperature below 5 K. Parameters of the exchange interaction and the activation energy were determined. The influence of the peripheral environment on the magnetic properties of the tetranuclear manganese framework in the structure of the complex was revealed.