Alexey B. Kornev

Facile preparation of amine and amino acid adducts of [60]fullerene using chlorofullerene C60Cl6 as a precursor.

We report a general synthetic approach to the preparation of highly functionalized amine and amino acid derivatives of [60]fullerene starting from readily available chlorofullerene C(60)Cl(6). The synthesized water-soluble amino acid derivative of C(60) demonstrated pronounced antiviral activity, while the cationic amine-based compound showed strong antibacterial action in vitro.

The activity of [60]fullerene derivatives bearing amine and carboxylic solubilizing groups against Escherichia coli : a comparative study

We report a comparative investigation of the antibacterial activity of two water-soluble fullerene derivatives bearing protonated amine (AF) and deprotonated carboxylic (CF) groups appended to the fullerene cage via organic linkers. The negatively charged fullerene derivative CF showed no tendency to bind to the bacterial cells and, consequently, no significant antibacterial activity. In contrast, the compound AF loaded with cationic groups showed strong and partially irreversible binding to the negatively charged Escherichia coli K12 TG1 cells and to human erythrocytes, also possessing negative zeta potential. Adsorption of AF on the bacterial surface was visualized by atomic force microscopy revealing the formation of specific clusters (AF aggregates) surrounding the bacterial cell. Incubation of E. coli K12 TG1 with AF led to a dose-dependent bactericidal effect with LD50 = 79.1 µM. The presence of human erythrocytes in the test medium decreased the AF antibacterial activity. Thus we reveal that the water-soluble cationic fullerene derivative AF possesses promising antibacterial activity, which might be utilized in the development of novel types of chemical disinfectants.

Photodynamic activity of a hybrid nanostructure based on a polycationic fullerene derivative and phthalocyanine dye photosens

229 As known, fullerenes are photoexcited to a triplet state in 100% quantum yield, which then is deacti vated to generate, depending on the polarity of a medium, either singlet oxygen О2 or superoxide radi cal anions and other active radicals [1]. Numerous studies have addressed the photodynamic effect of fullerene and their derivatives: the generation of active radicals upon photoexcitation is responsible for dam age of DNA, proteins, and membranes, as well as for the suppression of the reproduction of tumor cells, viruses, and bacteria [2]. However, the efficiency of the photodynamic action of fullerenes and the pros pects for their application in medicine are essentially limited by the weak absorption by fullerenes of visible light, especially in the range 650–800 nm, which is most suitable for photodynamic therapy. The photodynamic effect of fullerenes can be con siderably enhanced by creating hybrid nanostructures − О2 . (HNSs) via the formation of a fullerene complex with a dye that efficiently absorbs visible light [3]. In such a complex, the dye can efficiently absorb light and transfer excitation energy or electron to the fullerene. Further excitation transfer or electron transfer from the fullerene to molecular oxygen will generate active oxygen species. The creation of such an HNS based on fullerene and a dye can thereby significantly enhance the efficiency of photodynamic therapy.

Estimation of membrane activity of water-soluble polysubstituted fullerene derivatives by luminescence methods

Patterns of the interaction between water-soluble polysubstituted fullerene derivatives (PFDs) and the lipid bilayer of phosphatidylcholine liposomes were investigated by applying triplet and fluorescent probes. Objective quantitative criteria have been proposed for the evaluation of membranotropic action of chemical substances, notably, fullerene derivatives that quench fluorescent probes with different localizations within the membrane. Thus, the defined criteria are the rate constants for the quenching of the fluorescence of triplet probes and the equilibrium constants for PFD-probe complexes, which characterize their stability. The localization of PFDs in the membrane was determined by comparing rate constants for the quenching of eosin phosphorescence and equilibrium constants for PFD-chromophore complexes. In addition, the efficiency of the interaction of PFDs with various sites of the phospholipid membrane has been seen to depend on the charge of addends that are attached to the polysubstituted derivatives.

Photodynamic Activity of Hybrid Nanostructure on the Basis of Polycationic Fullerene Derivative and Xanthene Dye Eosine Y

It has been shown by the use of steady-state and time-resolved fluorimetry and kinetic phosphorescent spectroscopy that a polycationic fullerene derivative forms complexes with eosine Y in solution due to electrostatic interactions. It has been found that singlet excited states of eosine Y are effectively quenched due to either the excitation energy transfer or electron transfer from the dye to the fullerene core. This leads to a substantial increase in the photodynamic activity of the fullerene derivative and the dye in the structure of the complex when it is excited by light in the absorption band of the dye.

Heterometallic Palladium(II)–Indium(III) and −Gallium(III) Acetate-Bridged Complexes: Synthesis, Structure, and Catalytic Performance in Homogeneous Alkyne and Alkene Hydrogenation

The reaction of Pd3(OOCMe)6 with indium(III) and gallium(III) acetates was studied to prepare new PdII-based heterometallic carboxylate complexes with group 13 metals. The heterometallic palladium(II)-indium(III) acetate-bridged complexes Pd(OOCMe)4In(OOCMe) (1) and Pd(OOCMe)4In(OOCMe)·MeCOOH (1a) were synthesized and structurally characterized with X-ray crystallography and extended X-ray absorption fine structure in the solid state and solution. A similar Pd-Ga heterometallic complex formed by the reaction of Pd3(OOCMe)6 with gallium(III) acetate in a dilute acetic acid solution, as evidenced by atmospheric pressure chemical ionization mass and UV-vis spectrometry, was unstable at higher concentrations and in the solid state. Complex 1 catalyzes the liquid-phase-selective phenylacetylene and styrene hydrogenation (1 atm of H2 at 20 °C) in acetic acid, ethyl acetate, and N, N-dimethylformamide solutions, while no Pd metal was formed until alkyne and alkene hydrogenation ceased.

Membranotropic and relaxation properties of water-soluble gadolinium endometallofullerene derivatives

The membranotropic and relaxation properties of novel water-soluble gadolinium endometallofullerene derivatives (EMFD) were studied. Localization of EMFD in membranes and EMFD-induced changes in the membrane structure were determined by measuring the emission quenching of pyrene as a fluorescent probe. It was demonstrated that EMFD efficiently interact with pyrene molecules in model membranes, thus changing their microviscosity. Pulsed 1H NMR experiments revealed that the hydroxylated endometallofullerene Gd@C82(OH)∼30 has the highest relaxivity (R1 = 7.390 L mol−1 s−1) among the test EMFD and that its efficiency is 3.6 times that of the commercial MRI contrast agent Magnevist. The data obtained suggest that these EMFD are promising for use as low-toxicity contrast agents for magnetic resonance imaging.

Unusual platinum complexes in the gas phase

Previously unknown cationic platinum complexes Pt(C5H4N)(C5H5N)+ and Pt(C5H4N)+, where platinum atom forms an unusual three-membered metallacycle with a deprotonated pyridine molecule, were detected in the gas phase by mass spectrometry and structurally characterized by DFT quantum-chemical calculations.

Behavior of octa(benzo-15-crown-5)- and tetrasulfophthalocyanines in the presence of water-soluble C60 compounds

Octa[(4′-benzo-15-crown-5)oxy]phthalocyanine was shown to dissolve in the presence of water-soluble fullerene compounds C60Cl(NHCH2CH2NH3+)5(−OOCCF3)5 or C60Cl(C6H4CH2CH2COONa)5. The solubilization of phthalocyanine was attributed to the possibility of formation of the hydrogen bonds N-H...O(CH2) and coordination of the sodium cations inside the cavities of the crown ether fragments for the cationic and anionic fullerene derivatives, respectively. Solubilization of the crown-containing phthalocyanine with participation of water-soluble fullerene compounds proceeded with the formation of aggregated forms. A monomeric form of nickel tetrasulfonated phthalocyaninate in the presence of an equimolar amount of C60Cl(NHCH2CH2NH3+)5(−OOCCF3)5 in 50% ethanol is transformed into a dimeric form. The structures of the fullerene-containing compounds and their state in solution facilitate the stacking aggregation of phthalocyanines.