Dmitry E. Korshin

Self-assembly of an aminoalkylated resorcinarene in aqueous media: host–guest properties

A new water-soluble resorcinarene, with a negatively-charged lower rim and a positively-charged upper rim self-assembles into supramolecular oligomers to bind 1,5-diaminonaphthalene in water.

Electrochemical control of association and deposition of tetraviologen calix[4]resorcin

The association and deposition of tetraviologen calix[4]resorcin MVCA-C58+ can be controlled using the electrochemical reduction-reoxidation cycle of viologen units. The monomeric MVCA-C58+was converted into the highly molecular (MVCA-C54+·)n associate (π-polymer) by reducing it to the MVCA-C54+· tetra(radical cation) and completely returns to the starting monomeric state by reverse oxidation. The reduction to the neutral state MVCA-C50 allowed calixresorcin to pass from solution to precipitate and the reverse oxidation led to its returning in solution.

Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetra(methyl viologen) calix[4]resorcinol

Binding of an amphiphilic dianion 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane (APCO2−) with an amphiphilic octacation tetra(methyl viologen) calix[4]resorcinol (MVCA8+) in media containing different amounts of water and DMSO using NaClO4 or NaCl as supporting electrolytes was shown for the first time by cyclic voltammetry and spectrophotometry. The stoichiometry of the complex depends on the MVCA8+: APCO2− ratio, medium, and supporting electrolyte. A 1: 1 charge-transfer complex is mainly formed (λmax = 480 nm) in 30% DMSO at a ratio of the compounds of 1: 1. A similar 1: 1 complex of APCO2− with a model compound methyl viologen MV2+ (λmax = 482 nm) is formed under these conditions. A donor-acceptor interaction occurs between the acceptor viologen units and nitrogen-centered electron-donating fragments of the APCO2− dianion. An increase in the content of APCO2− in the solution leads to an additional binding of one (30 vol.% DMSO, water, NaClO4) or two (30 vol.% DMSO, water, NaCl) particles of APCO2− with the hydrophobic fragments of MVCA8+. The complexes aggregate to form insoluble precipitates in aqueous and water-DMSO media. A selective reversible electroswitching from the bound to free state of one of the three bound APCO2− particles was performed when reducing MVCA8+ to MVCA4·+ in a 30 vol.% DMSO/NaCl medium.

Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetramethylviologen calix[4]resorcin with a methyl radical in the resorcinol ring

The binding of the amphiphilic 1,5-bis(para-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane dianion (APCO2−) with the octacation of the amphiphilic tetramethylviologen calix[4]resorcin having a methyl radical in the resorcinol ring (MVCA-C18+) in 30% aqueous DMSO in a 0.1M NaCl supporting solution was studied by various methods. The dianion was bound at the upper rim of calixresorcin due to the donor-acceptor interactions between the viologen acceptor units and the nitrogen- and phosphorus-centered electron-donor fragments of APCO2− and at the lower rim due to hydrophobic interactions. The composition of the complex depended on the MVCA-C18+: APCO2− ratio. The complexes aggregated, forming insoluble precipitates. MVCA-C18+-APCO2− is a system with reversibly electro-switchable aggregation. The starting MVCA-18+ octacation partially bound APCO2−, a certain quantity of both substrates remaining in a free state in solution. The MVCA-C14+· tetraradical tetracation formed as a result of the reduction of MVCA-C18+ completely bound APCO2− due to hydrophobic interactions when the MVCA-C18+: APCO2− ratio was 1: 3. The reversible oxidation of MVCA-C14+· to the starting MVCA-C18+ octacation brought the system back to its starting state

pH-controlled photoinduced electron transfer in the [(Mo6Cl8)L6]-calix[4]resorcine-dimethylviologen system.

A pH-controlled photoinduced electron transfer in the supramolecular system [(Mo(6)Cl(8))L(6)]-calix[4]resorcine-dimethylviologen is reported.

Electrochemical switching of monomer—associate in the system tetraviologen calix[4]resorcinol—3,7-di(l-menthyl)-1,5-di(p-sulfonatophenyl)-1,5-diaza-3,7-diphosphacyclooctane

The possibility of controlling the association of tetraviologen calix[4]resorcinol (MVCA-C58+) with 3,7-di(l-menthyl)-1,5-di(p-sulfonatophenyl)-1,5-diaza-3,7-diphosphacyclooctane (APCO-22−) in the electrochemical cycle of reduction-reoxidation of viologen units was shown. Reduction to tetra(radical cation) MVCA-C54+· transforms monomeric MVCA-C58+ and APCO-22- into the associate (π-polymer) (xAPCO-22−·yMVCA-C54+·)n, which is completely returned by reoxidation to the initial state.

Synthesis of 3-Hydroxy-4-arylquinolin-2-ones Including Viridicatol via a Darzens Condensation – Friedel-Crafts Alkylation Strategy

The new efficient synthesis of biologically important 3-hydroxy-4-arylquinolin-2-ones through the Darzens condensation (epoxidation) of dichloroacetanilides with aromatic aldehydes followed by one-pot dechlorative epoxide-arene cyclization is described. This methodology has been utilized for the synthesis of naturally occurring viridicatol, a fungal metabolite isolated from the penicillium species.

5-(α-Halobenzyl)- and 5-Benzylidene-2,2-dimethyl-1,3-oxazolidin-4-ones in Synthesis of α-Hydroxy Acids

The reactions of acid hydrolysis of 5-(α-halobenzyl)- and 5-benzylidene-2,2-dimethyl-1,3-oxazolidin-4-ones were studied. A possibility of the synthesis of corresponding α-hydroxy acids was shown.