Showing papers in "Russian Chemical Bulletin in 2010"

Antitumor activities of ferrocene compounds

Abstract: Data on the antitumor activities of ferrocene compounds and the results concerning the mechanisms of their action published between 1995 and 2010 are discussed. The biomedical aspects of the study of ferrocene derivatives are briefly analyzed.

Nitropyrazoles : 18. Synthesis and transformations of 5-amino-3,4-dinitropyrazole (Full Articles)

Abstract: A method of preparation of 5-amino-3,4-dinitropyrazole (1) from 3(5)-methyl-5(3)-nitro- and 3(5)-methyl-4,5(3)-dinitropyrazoles was developed, the key step of which was the Hofmann rearrengement of nitro- and dinitropyrazolecarboxamides. The protonation of 5-amino- 3,4-dinitropyrazole was studied by spectral methods (UV spectroscopy, NMR spectroscopy). In spite of low basicity of the amino group, compound 1 undergoes N-arylation, N-nitration, and annulation reactions with formation of dinitropyrazolo[5,1-a]pyrimidine derivatives and hitherto unknown dinitroimidazo[1,2-b]pyrazole derivatives. Diazotization of 1 leads to 5-diazo-3,4-dinitropyrazole (19), which exists in the form of the internal salt. Some reactions of this compound were studied and the formation of the corresponding 5-halogeno(azido)- 3,4-dinitropyrazoles under the action of the halide and azide ion was shown. Dinitropyrazolo- [5,1-c][1,2,4]triazine and 7-hydroxydinitro-4,7-dihydropyrazolo[5,1-c][1,2,4]triazine deriva- tives were obtained by the action of active methylene compounds on the betaine 19.

Antioxidant biomedicine: from free radical chemistry to systems biology mechanisms

Abstract: Natural and synthetic antioxidants are widely used in modern medicine. Some of them proved to be efficient geroprotectors, i.e., they extend the life span of laboratory animals when added to food or drinking water on a regular basis. In vitro, antioxidants inhibit free-radical chain oxidation reactions, resulting in oxidation of fatty acids, edible fats, etc. However, their efficiency as scavengers of oxygen free radicals in cells and tissues is negligible as compared with natural antioxidant enzymes. In vivo, antioxidants decrease the concentration of free radicals but they are not only and not so much direct inhibitors of free radical processes as physiologically active compounds that prevent the formation of oxygen radicals and free radical oxidation. For example, synthetic antioxidant dibunol (BHT) prevents the generation of the O2- radical as a by-product of mitochondrial electron transport, while flavonoids exert a preventive antioxidant action by inducing the expression of the antioxidant enzymes, superoxide dismutase and catalase. The endocrine system and regulatory transcription and translation factors play a significant role in the antioxidant therapy. Therefore, elucidating the molecular mechanisms of the "antioxidant prophylaxis" is a task of the molecular systems biology.

A new meroterpenoid from the marine fungus Aspergillus versicolor (Vuill.) Tirab.

Abstract: A new meroterpenoid asperdemin (1) and two known compounds, viz., diorcinol (2) and viridicatol (3), were isolated from the marine fungus Aspergillus versicolor. The structures of these compounds were established by NMR spectroscopy and high-resolution mass spectrome-try. The absolute stereochemistry of 1 was determined by modified Mosher’s method. The antimicrobial activity of the total extract from A. versicolor was attributed to diorcinol (2). Asperdemin exhibits weak cytostatic and membranolytic activities in developing embryos of the sea urchin Strongylocentrotus nudus.

Supramolecular systems based on 1-alkyl-4-aza-1-azoniabicyclo[2.2.2]octane bromides

Abstract: The aggregation in aqueous solutions of alkylated 1,4-diazabicyclo[2.2.2]octanes of various hydrophobicity and their adsorption at the water-air interface were studied by tensiometry, conductometry, potentiometry, viscosimetry, and ESR spectroscopy. The parameters of adsorption, critical micelle concentrations, concentrations of free counterions (bromide ions), and degree of binding of the counterions with micelles were determined. The intensification of the micelle formation ability of the surfactants with an elongation of the alkyl fragment was shown. The effective radii of ensembles of the hexadecyl and octadecyl derivatives were determined by the dynamic light scattering method. A relationship between the concentration dependences of the size of micelles and their shape was established.

Synthesis of polycationic lipids based on cholesterol and spermine

Abstract: The synthesis of cholesterol-based cationic lipids in which the hydrophobic steroidal fragment is linked to a spermine residue as the hydrophilic domain by ester or carbamate linkage is described.

New tin(iv) o-iminosemiquinone complexes

Abstract: New tin(iv) mono- and bis-o-iminosemiquinone complexes were obtained by the exchange reaction of radical anion lithium salt of 4,6-di-tert-butyl-N-(2,6-diisopropylphenyl)-o-imino-benzoquinone with tin(iv) organochlorides. The compounds synthesized were characterized by EPR spectroscopy and X-ray diffraction analysis. Substituents on the tin atom were found to affect stability of paramagnetic metal derivatives formed.

Surface tension of equilibrium spherical drops in the vapor phase

Abstract: The dependence of surface tension of equilibrium spherical drops in the vapor phase on their size at the saturation vapor pressure was studied The calculation was based on the lattice-gas model in the quasichemical approximation, which takes into account the correlation effects of the nearest interacting molecules The methods for calculation of the surface tension using a reference surface were considered The key method is the calculation using an equimolecular reference surface In the calculation by determining the force moment balance of the transition region, the reference surface is shifted toward the liquid phase of the drop, although the surface tension values are rather similar for both methods For equilibrium drops, the notion of tension surface was found to be absent The temperature dependences of the surface tension were studied The critical sizes of the drops corresponding to the conditions of drop stability as a condensed phase were elucidated

Synthesis and thermal stability of cubic ZnO in the salt nanocomposites

Abstract: Cubic zinc oxide (rs-ZnO), metastable under normal conditions, was synthesized from the wurtzite modification (w-ZnO) at 7.7 GPa and ∼800 K in the form of nanoparticles isolated in the NaCl matrix. The phase transition rs-ZnO → w-ZnO in nanocrystalline zinc oxide under ambient pressure was experimentally studied for the first time by using differential scanning calorimetry and high-temperature X-ray diffraction analysis. It was shown that the transition occurs in the temperature range from 370 to 430 K and its enthalpy at 400 K is −10.2 ± 0.5 kJ mol−1.

Two new paeciloxocins from a mangrove endophytic fungus Paecilomyces sp.

Abstract: Paeciloxocins A and B (2-(1-hydroxy-3-methylbutyl)- and 2-(1-acetoxy-3-methylbutyl)- 11-hydroxy-9-methyl-1-methoxy-5H,7H-dibenzo[b,g]-1,5-dioxocin-5-ones), viz., two new metabolites, were isolated from the mangrove fungus Paecilomyces sp. collected from the Taiwan Strait. Their structures were elucidated by spectral methods. Paeciloxocin A exhibited strong cytotoxicity against the hepG2 cell line.

Interaction between threonine and cadmium cation in [Cd(Thr) n ] 2+ ( n = 1–3) complexes: density functional calculations

Abstract: Structures corresponding to energy minima and the binding of cadmium cation to threo- nine (Thr) in model systems [Cd(Thr)n]2+ (n = 1–3) were studied theoretically. Quantum chemical computations were performed within the framework of the density functional theory using the B3LYP, BLYP, and P functionals. In the optimized structures of the complexes [CdThr]2+ and [Cd(Thr)2]2+, threonine acts as a bidentate ligand and cadmium binds to oxygen atoms of carbonyl and hydroxyl groups with the formation of one and two six-mem- bered rings, respectively. In the complex [Cd(Thr)3]2+, cadmium binds to three nitrogen atoms and three oxygen atoms of carbonyl groups in three Thr molecules to form three five-mem- bered rings.

Silver-containing nanocomposites based on galactomannan and carrageenan: synthesis, structure, and antimicrobial properties

Abstract: Water-soluble silver-containing nanocomposites based on biocompatible polysaccharides, galactomannan and carrageenan, were synthesized for the first time. A complex of physicochemical methods was employed to establish the phase composition, the average size of metal nanoparticles, and the morphology of new nanobiocomposites. The obtained nanomaterials possess high antimicrobial activity.

Directed synthesis and immunoactive properties of (2-hydroxyethyl)ammonium salts of 1-R-indol-3-ylsulfanyl(sulfonyl)alkanecarboxylic acids

Abstract: A general method for the synthesis of 1-alkyl(allyl)(benzyl)-substituted (indol-3-yl)-sulfanylalkanecarboxylic acids and hexane-1,6-diyl(1,4-phenylenemethylene)bisindol-3-ylsulfanylalkanecarboxylic acids from the corresponding N-substituted indoles and bisindoles, thiourea, iodine, and halogencarboxylic acids was developed. The oxidation of substituted (indol-3-yl)sulfanylalkanecarboxylic acids for the first time afforded their analogs containing the sulfonyl group. New (2-hydroxyethyl)ammonium salts of 1-R-indol-3-ylsulfanyl(sulfonyl)-alkanecarboxylic acids, which are structural analogs of highly active immunomodulators of indacetamin and VILIM, were synthesized. Among the studied (2-hydroxyethyl)ammonium salts of 1-R-indol-3-ylsulfanylacetic and -sulfonylalkanecarboxylic acids, the compounds exhibiting high dose-dependent antiproliferative activity by the ability to affect the spontaneous and mitogen-stimulated splenocyte proliferation of mice in vitro were found.

Antioxidant properties of terpene-substituted phenols

Abstract: Antioxidant activity of terpene-substituted phenols and their aminomethyl derivatives as compared to the activity of standard antioxidants, ionol and trolox, has been studied by spectrophotometry (by the ability to react with the stable radical of 2,2-diphenyl-1-picrylhydrazyl) and coulometry (by the ability to react with a bromine radical).

Structure and properties of μ2-S-[bis(benzenethiolato)tetranitrosyldiiron] in solution

Abstract: Dinuclear iron tetranitrosyl complex with the composition [Fe2(SPh)2(NO)4] (1) was synthesized and its single crystals and polycrystals were studied by X-ray diffraction, IR spectroscopy, and elemental analysis. The decomposition products of complex 1 were investigated by electrochemical method and mass spectrometry. The mass spectrum of a solution of complex 1 shows two groups of ions: the primary decomposition products of 1 in solution (the complex ions [Fe(SPh)(NO)2(NO2)]−, [Fe(SPh)2(NO)]−, and [Fe(SPh)2(NO)2]−) and a series of the ions [FeO2 + n(NO)]− and [FeO3 + n(NO)]− (n = 0–4), which are formed in secondary reactions. The structures of the complexes, which were formed through the Fe-NO bond dissociation and the replacement of the NO ligand by aqua and oxygen ligands in complex 1, and the structure of the complex [FeO3]− were studied by quantum chemical modeling.

Kinetics and mechanism of thermal polymerization of hexafluoropropylene under high pressures

Abstract: The basic kinetic parameters of thermal polymerization of hexafluoropropylene, namely, general rate constants, degree of polymerization, and their temperature and pressure dependences in the range of 230–290 °C and 2–12 kbar (200–1200 MPa) were determined. The activation energy (E act = 132±4 kJ mol−1) and activation volume (ΔV 0 ≠ = −27±1 cm3 mol−1) were calculated. The activation energy of thermal initiation of polymerization was estimated. The reaction scheme based on the assumption about a biradical mechanism of polymerization initiation was proposed.

Reactions of sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide with alkyl halides and silicon and tin chlorides

Abstract: Reactions of sodium 3,4,5-triphenyl-1,2-diphosphacyclopentadienide with primary alkyl bromides, secondary alkyl iodides, and silicon and tin chlorides gave stable 1-substituted 1,2-diphospholes. In a solution of 3,4,5-triphenyl-1-trimethylstannyl-1,2-diphosphacyclopenta-2,4-diene, the Me3Sn group migrates between two phosphorus atoms.

Synthesis of fluoromethyl-containing analogs of antitumor alkaloid luotonin A

Abstract: A convenient method for the synthesis of hitherto unknown 3-bromomethyl-2-chloro-4-fluoromethylquinolines has been developed. Coupling of 3-bromomethyl-2-chloro-4-trifluo-romethylquinoline with 4(3H)-quinazolinone with subsequent intramolecular Heck cyclization leads to 7-trifluoromethylluotonin, an analog of the antitumor alkaloid luotonin A. 7-Trifluo-romethylluotonin retains the antitumor activity including apoptosis of cultured tumor cells and inhibiting DNA-topoisomerase I.

Synthesis, structures, and conductivities of salts (BEDT-TTF)[9,9′(12′)-I2-3,3′-Co(1,2-C2B9H10)2] and (TTF)[9,9′,12,12′-I4-3,3′-Co(1,2-C2B9H9)2]

Abstract: The radical cation salts of tetrathiafulvalene (TTF) and bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) with iodo derivatives of cobalt bis(dicarbollide), (TTF)[9,9′,12,12′-I4-3,3′-Co(1,2-C2B9H9)2] and (BEDT-TTF)[9,9′(12′)-I2-3,3′-Co(1,2-C2B9H10)2], respectively, were synthesized and their crystal structures were determined. The introduction of iodine atoms into the lower rim of the dicarbollide ligands, unlike the substitution at the upper rim, leads to insignificant changes in the crystal structure and the conductivity of the radical cation salts compared to the analogous salts based on unsubstituted cobalt bis(dicarbollide).

Inhibiting effect of 6-methyluracil derivatives on the free -radical oxidation of 1,4-dioxane

Abstract: The antioxidation activity of 5-substituted 6-methyluracils was quantitatively estimated in the model system of initiated radical-chain oxidation of 1,4-dioxane. The rate constants of the reactions of 1,4-dioxane peroxide radicals with 6-methyluracil (1), 6-methyl-5-piperidinouracil (2), 6-methyl-5-morpholinomethyluracil (3), 6-methyl-5-morpholinouracil (4), 6-methyl-5-methylaminouracil (5), 5-ethylamino-6-methyluracil (6), and 5-hydroxy-6-methyluracil (7) were measured. Among compounds 1–7, derivative 7 is most efficient with an inhibition rate constant of (5.2±0.1) · 104 L mol-1 s-1 (60 °C).

Spin-adduct of the P4 ·− radical anion during the electrochemical reduction of white phosphorus

Abstract: The radical anion P4·− was detected and identified by the ESR method as a spin-adduct with nitrone during the electrochemical reduction of white phosphorus in the presence of a spin trap, viz., α-phenyl-N-tert-butylnitrone, in a special electrolysis cell with a helical platinum working electrode in the potentiostatic mode. The character of the behavior of P4·− and the spin trap during electrochemical reduction was monitored by cyclic voltammetry directly in the electrolysis cell, and the spin-adduct formed was detected by ESR.

Synthesis of cobalt bis(dicarbollide) conjugates with natural chlorins by the Sonogashira reaction

Abstract: Boron neutron capture therapy (BNCT) is one of the new and promising methods for cancer treatment. 1—4 The further development of this method is inseparably associ� ated with the design of new boroncontaining drugs that can selectively accumulate in the tumor tissue. Amino ac� ids, peptides, nucleotides, and some other molecules trop� ic to tumors can be used as molecules performing the tar� geted boron transport to the tumor. The ability of porphy� rins to be accumulated in cancer cells is well known. This ability in combination with the photoinduced generation of reactive oxygen species makes it possible to use them as photosensitizers in anticancer photodynamic therapy (PDT). 5—7 Photosensitizers based on natural chlorophylls with the enhanced tropicity to tumors, low toxicity, and an intense absorption in the nearIR spectral region, provid� ing the laser radiation action on deeply localized layers of cancer tissues, are of special interest. Therefore, synthesis of conjugates of polyhedral boron compounds with natural porphyrins is a topical issue. 8—16 The porphyrin fragment in these compounds provides the transportation of the bo� roncontaining conjugate to cancer cells and a possibility of visualization of the tumor. The subsequent irradiation of the cells with thermal neutrons and their interaction with the 10 B isotope of boron compounds selectively accu� mulated in cancer cells should result in the selective de� struction of malignant neoplasms. In the present work, the Sonogashira reaction, which is actively employed in modern organic chemistry, 17,18 was used for the synthesis of boroncontaining conjugates of natural porphyrins.

ESR study of paramagnetic derivatives of sterically hindered di-o-quinone with the tetrathiafulvalene bridge

Abstract: The paramagnetic derivatives of 4,4′,7,7′-tetra-tert-butyl-2,2′-bis-1,3-benzodithiol-5,5′,6,6′-tetraone (1), viz., radical anion salts of the alkali metals (Li, Na, K) and cobaltocenium cations, chelated mono-o-semiquinone complexes with different metal fragments (Tl, TlMe2, SnPh3, Mn(CO)4, Mn(PPh3)(CO)3), a number of copper(I) complexes with sterically hindered phosphines as well as binuclear heterometallic derivatives of triphenylantimony(V) o-semiquinone-catecholate with the analogous paramagnetic centers, were studied by ESR spectroscopy. The reaction of di-o-quinone 1 with sodium amalgam resulted in the formation of all reduced forms including quinone-semiquinone, disemiquinone, semiquinone-catecholate, and dicatecholate. A radical cation with the unpaired electron localized on the tetrathiafulvalene (TTF) fragment, which resulted from the oxidation of di-o-quinone 1, was detected by ESR spectroscopy.

Reactions of diazo esters with electron-deficient alkenes in the presence of Lewis acids

Abstract: 1,3-Dipolar cycloaddition reaction of diazo esters to electron-deficient dipolarophiles to yield the corresponding 1- or 2-pyrazolines was found to be significantly accelerated with Lewis acids (Yb(OTf)3, Sc(OTf)3, GaCl3, EtAlCl2). The use of GaCl3 as the catalyst leads to the acceleration not only of the 1,3-dipolar cycloaddition reaction, but also subsequent insertion of the CHCO2Me electrophilic fragment of methyl diazoacetate into the N-H bond of 2-pyrazolines formed. Such Lewis acids as SnCl4, BF3, TiCl4, and In(OTf)3 are not efficient in the described processes, since they rapidly decompose starting diazo compounds.

Solubilization of carbon nanoparticles, nanotubes, nano-onions, and nanodiamonds through covalent functionalization with sucrose

Abstract: Water solubilization of carbon nanoparticles (nanocarbons), single-walled nanotubes (SWCNTs), nano-onions (NOs) and nanodiamonds (NDs) has been achieved through their covalent functionalization by fluorination and subsequent derivatization with sucrose The covalent bonding of sucrose to the surface of the fluorinated nanocarbons was attained by a one-step fluorine substitution reaction with sucrose-derived lithium monosucrate under sonication in DMF at room temperature This chemical process provides a simple, inexpensive, and easily scalable method for hydrophilic chemical modification of SWCNT, NO, and ND surfaces to produce sucrose-functionalized nanocarbons that become soluble in water, DMF, ethanol, and other polar solvents The sucrose-functionalized nanocarbon particles are expected to be biocompatible due to the abundance of hydroxyl groups available for hydrogen bonding and further chemical modification Relevant examples have been given

Porous homo- and heterochiral cobalt(II) aspartates with high thermal stability of the metal-organic framework

Abstract: Metal-organic coordination polymers with the compositions [Co2(L-asp) 2-(bpy)] · MeOH · H2O (1), [Co2(L-asp)2(bpe)] · 0.28(bpe) · H2O (2), and [Co2(d-asp)(l-asp)-(bpa)] · 0.25(bpa) · 1.5H2O (3) (H2asp is aspartic acid, bpy is 4,4′-bipyridine, bpe is trans-bis(4- pyridyl)ethylene, and bpa is 1,2-bis(4-pyridyl)ethane) were synthesized on heating cobalt(II) as-partate and N-donor ligands (bpy, bpe, or bpa) in an aqueous-methanol mixture. The structures of compounds 1⁗ash;3 were established by X-ray diffraction analysis and confirmed by X-ray powder crystallography, IR spectroscopy, thermogravimetry, and elemental analysis. The stability of the synthesized coordination polymers was studied. It was shown that they retain the framework structure on heating to 300 °C.

Branched oligothiophene silanes with the efficient nonradiative energy transfer between the fragments

Abstract: The synthesis of new dendrimers and branched oligothiophene silanes containing bithiophene groups at the periphery and quaterthiophene fragments at the center of the molecule is described. Specific features of bithiophene silane bromination were shown, and the conditions for the efficient synthesis of methyltris(5-bromo-2,2′-bithiophen-5-yl)silane have been found for the first time. The optical properties of the synthesized compounds were studied. The efficiency of the electron excitation energy transfer between the fragments of branched bi-and quaterthiophene silanes was measured.

One-pot synthesis of trifluoromethyl- and nitroso-substituted pyrazolines and pyrazoles and their tuberculostatic activity

Abstract: 3-Trifluoromethyl-substituted 4-nitrosopyrazolines and 4-nitrosopyrazoles were prepared by a one-pot synthesis from trifluoromethyl-containing 1,3-diketones, sodium nitrite in acetic acid, and hydrazines (hydrazine hydrate, methylhydrazine). 3-Trifluoromethylpyrazolines can be converted to pyrazoles on heating. The use of phenylhydrazine in these reactions led to the formation of regioisomeric 4-hydroxyimino-5-(trifluoromethyl)pyrazoline. The structure of heterocycles synthesized was established using X-ray diffraction study, 1H and 19F NMR spectroscopy. The obtained products exhibited considerable tuberculostatic activity.

EPR spectroscopy of thermally induced and light-induced spin transitions in heterospin exchange clusters of compounds Cu(hfac)2LR

Abstract: The review summarizes the results of EPR investigations of magneto-structural anomalies occurring in exchange-coupled copper-nitroxide clusters belonging to the family of compounds Cu(hfac)2LR. The key features and potential of EPR spectroscopy in studies of such systems, the methods developed to determine the exchange constants, and experiments using the optical switching of magnetic parameters in the heterospin exchange clusters studied are discussed.

Luminescence properties of mesoporous chromium(III) terephthalate and inclusion compounds of cluster complexes

Abstract: The luminescence properties of mesoporous chromium(III) terephthalate [Cr3O(C8H4O4)3F(H2O)2] (MIL-101) were discovered, and the luminescence spectra were detected at temperatures from 20 to 290 K. By the interaction of MIL-101 with solutions of anionic clusters [Mo6Cl14]2- (Mo6) and [Re6S8(CN)6]4- (Re6) new hybrid materials Mo6MIL-101 and Re6MIL-101 were synthesized, the nanoporous framework of which contains ca. 3.5 and 1.5 clusters per cage, respectively. The synthesized hybrid materials possess the luminescence properties different from those of the initial framework and cluster complexes.