G. M. Fazleeva

Electrochemical reduction and oxidation of fullerenopyrrolidines* and the ESR spectra of paramagnetic intermediates

Electroreduction and electrooxidation of monosubstituted N-methyl[60]fullerenopyrrolidines were studied by cyclic voltammetry and potentiostatic microelectrolysis in the cavity of an ESR spectrometer. Stepwise reversible transfer of three electrons to the fullerenopyrrolidine molecule results in the formation of stable radical anions (according to ESR, g = 2.0000, ΔH = 0.8 G), dianions, and radical trianions (according to ESR, g = 2.0015, ΔH = 1.5 G). The reduction potentials vary over narrow limits depending on the nature of the substituents in the pyrrolidine fragment of the compounds. Electrooxidation is irreversible and occurs in either one or two steps. For compounds containing the aniline, indole, or phenol fragment, the first step is associated with oxidation of these fragments and only after that, is the fullerenopyrrolidine core oxidized. Oxidation of the pyrrolidine fragment is substantially more difficult than that of tertiary amines.

Reactions of carbanions of bis(dialkoxyphosphoryl)bromomethane with fullerenes C60 and C70

The reactions of carbanions of bis(dialkoxyphosphoryl)bromomethanes with fullerenes C60 and C70 afforded new bis(dialkoxyphosphoryl)methanofullerenes C60 and C70, respectively, whose structures were established by spectroscopic methods.

Synthesis and properties of new triazole methanofullerenes under the “click-chemistry” conditions

The “click-chemistry” methods were used for the first time to synthesize new 1,2,3-triazole derivatives of fullerene, promising for the study of their biological activity, as well as for the preparation of new fullerene-containing materials on their basis. The purity and composition of the compounds synthesized were confirmed by MALDI-TOF mass spectrometry and HPLC, their structures were confirmed by a combination of 2D NMR homo- and heteronuclear correlation.

Novel water-soluble methanofullerenes C60[C13H18O4(OH)4]6 and C60[C9H10O4(OH)4]6: Promising uncouplers of respiration and phosphorylation

Here, we report for the first time on two novel water-soluble polyol-methanofullerenes which uncouple respiration and oxidative phosphorylation. A cytofluorimetric JC-1-based ratiometric assay was used to quantify mitochondrial potential Ψm in Yarrowia lipolytica cells exposed to the fullerenes tested. Both methanofullerenes significantly downregulated Ψm, thereby decreasing the subset of cells with high mitochondrial potential compared with intact control cells. The Ψm-low subset of Yarrowia lipolytica cells resulted from methanofullerenes exposure preserved physiological cell size and granularity patterns.

Spin-adducts of radicals ·P(O)(OPri)2 and ·CMe3 with pyrrolidino[60]fullerenes studied by ESR spectroscopy

The addition of the ·But (R1) and ·P(O)(OPri)2 (R2) radicals to pyrrolidino[60]fullerenes C60CH2NMeCHX (X = C6H4N(CH2CH2Cl)2, 2,6-(But)2C6H2OH, PhC6H4, and indol-3-yl) was studied by ESR spectroscopy. The rate constants of R1 radical addition to these compounds and dimerization of spin-adducts of the R1 radicals with pyrrolidino[60]fullerenes were determined. Pyrrolidino[60]fullerenes manifest considerably higher reactivity toward the R1 radicals than fullerene C60 and methanofullerenes C60CX1X2 (X1 = X2 = CO2Et; X1 = CO2Me, X2 = OP(OMe)2, X1 = X2 = OP(OEt)2).

Synthesis and structure of allylated derivatives of fullerenes C60 and C70

New chromatographically pure monoand hexamethanofullerenes C60 and C70 containing active allylic groups were synthesized by Bingel—Hirsch reaction. These compounds are promising for the studies of biological activity, as well as for obtaining on their basis new fullerenecontaining materials. The purity and composition of the synthesized compounds were confirmed by MALDI-TOF mass spectrometry and HPLC, their structure was established by 1H and 13C NMR spectroscopy and X-ray diffraction.

Synthesis of new phosphorylated fullerene C60 derivatives soluble in polar solvents

A directed synthesis of new phosphorylated methanofullerenes containing acetonide fragments was accomplished for the first time, their chemical structure was confirmed by a combination of spectroscopic methods. Removal of the acetonide protection produced new phosphorrylated diol methanofullerenes, their structure and properties were studied. The diol methanofullerenes are well soluble in polar solvents, including a mixture of DMSO-water (1: 9).

Synthesis of new functionally substituted fullerenopyrrolidines

New fullerenopyrrolidines were synthesized by the three-component reactions of fullerene C60, N-methylglycine, and aromatic aldehydes, viz., N,N-bis(2-chloroethyl)-4-aminobenzaldehyde, N-(2-chloroethyl)-N-methyl-4-aminobenzaldehyde, indole-3-carbaldehyde, 4-phenylbenzaldehyde, and anthracene-9-carbaldehyde. The structures of the resulting compounds were established by spectroscopic methods.

Water-soluble polyol-methanofullerenes as mitochondria-targeted antioxidants: Mechanism of action

The mechanism of an antioxidant action of water-soluble polyol - methanofullerenes C60[C9H10O4(OH)4]6 and C60[C13H18O4(OH)4]6 as the mild uncouplers of an oxidative phosphorylation and respiration is postulated. According to this mechanism, hydroxyl group of methanofullerenols can be protonated under excess of protons in the intermembrane space of hyperpolarized mitochondria. Protonation of fullerene derivatives is confirmed by the decrease in their negative Zeta potential in the pH below 5.4. Heavily protonated methanofullerenols become positively charged and move into the mitochondrial matrix. As a consequence, the proton gradient is dissipated, which causes a decrease in mitochondrial transmembrane potential (ΔΨm) and reduction in ROS production.

Novel fluorene-containing fullerenes C60: synthesis and structures

Reactions of fullerene C60 with fluorene-2-carbaldehyde or 2,7-diacetylfluorene in toluene gave novel spiromethanofullerenes containing a reactive free formyl group. A novel fluorene-containing fullerenopyrrolidine was obtained by the Prato reaction. The purity and compositions of the compounds obtained were confirmed by MALDI TOF mass spectrometry and HPLC. Their structures were confirmed by 2D homo-and heterocorrelation NMR techniques.