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Complexes of organotin compounds RSnCl with bisand trisphosphonate derivatives of 2,6-di- tert-butyl-4-methylphenol (ionol) were synthesized. X-ray diffraction studies were carried out for some of them. The redox properties of the synthesized compounds were characterized by cyclic voltammetry. Antioxidant/prooxidant activity of the complexes was studied using a new electrochemical method based on measuring the rate of hydrogen atom transfer to the stable radical 2,2´-diphenyl-1-picrylhydrazyl (DPPH). The data obtained were compared with the results of studying activity of the compounds during lipid peroxidation (LP) in biological samples. A correlation is observed between the results on antioxidant activity obtained by electrochemical DPPH test and using biological samples. Unlike the initial organotin compounds, the synthesized complexes have antioxidant activity, whereas phosphorus-containing phenols exhibit the properties of efficient antioxidants and chelating agents. [ABSTRACT FROM AUTHOR]

The temperature dependence of the heat capacity of a polycrystalline sample of the heterospin solvate [Cu(hfac)L]·0.5[1,4-(CF)CH] (L is 2-(1-butyl-1 H-pyrazol-4-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1 H-imidazole-3-oxide 1-oxyl) was studied in the range of 5-298 K. The results of the thermochemical study of this compound were shown to be in agreement with the data from magnetochemical and diffraction measurements providing evidence that, as the temperature changes, the complex undergoes phase transitions at 59 and 123 K. [ABSTRACT FROM AUTHOR]

Efficiency of poly( N-vinylimidazole) as the basic recyclable catalyst for the Michael addition of CH-acids to acrylonitrile, methyl acrylate, methyl vinyl ketone and methyl vinyl sulfone in water at ambient temperature was studied. In these reactions, formation of both 1: 1 and 1: 2 adducts is possible. [ABSTRACT FROM AUTHOR]

Electrochemical method for the evaluation of antioxidative activity of compounds based on their reaction with the stable radical, 2,2-diphenyl-1-picrylhydrazyl, was suggested with monitoring of the reaction by cyclic voltammetry (CVA). Antioxidative properties of new ferrocene derivatives Fc(L)R (where Fc is the ferrocenyl, R is the fragment of 2,6-di- tert-butylphenol or its aromatic analog, L is the spacer) were studied. Anodic oxidation of the compounds Fc(L)R, which contain azomethine and 2,6-di- tert-butylphenol moities, proceeds in three steps, that suggests a possibility of intramolecular proton-coupled electron transfer process. Conjugates of ferrocene and 2,6-di- tert-butylphenol are efficient antioxidants. [ABSTRACT FROM AUTHOR]

Abstract  New heterocyclic system, viz., 8,12-dehydro-8H,12H-[1,2,3]triazolo[2′,1′:1,2][1,2,3]triazolo-[4,5-f][1,2,3,4]benzotetrazine 2,4-dioxide, has been synthesized by thermolysis of 5-azido-6-(1,2,3-triazol-2-yl)benzotetrazine 1,3-dioxide, and its thermal stability and spectral properties have been studied. [ABSTRACT FROM AUTHOR]

Abstract  The properties of phenoxyl radicals generated by the oxidation of mono-, di-, and triphosphorus derivatives of 2,6-di(tert-butyl)-4-methylphenol (ionol) were studied by ESR. These compounds exist as conformers that are interconvertible with a temperature-dependent rate. Numerical processing of the ESR spectra gave the thermodynamic and activation parameters that characterize the interconversion of the conformers. The antioxidant activities of the compounds were studied in a model oxidation of oleic acid and with biological objects. These phenols efficiently inhibited radical oxidation reactions. [ABSTRACT FROM AUTHOR]

A series of new 1-[4-(aminosulfonyl)phenyl]-5-oxopyrrolidine-3-carboxylic acids were synthesized by the solvent-free condensation of 4-aminobenzenesulfonamides with itaconic acid at 140–165 °C. The synthesized compounds were examined for antimicrobial activity. [ABSTRACT FROM AUTHOR]

A reaction of complexes CoCl(dppe) (dppe is the 1,2-bis(diphenylphosphino)ethane) or CoCl(dppp) (dppp is the 1,3-bis(diphenylphosphino)propane) with [K][7,8- nido-CBH] upon reflux in benzene led to the mixed ligand closo-cobaltacarboranes [3,3-(PhP(CH)PPh)-3-Cl- closo-3,1,2-CoCBH] ( n = 2 and 3, respectively) in moderate yields (34 and 16%). The structure of the 18-electron complexes in solution and the solid state was studied by NMR and IR spectroscopy, the structure in the case of the closo-complex with dppe-ligand was confirmed by X-ray crystallography. [ABSTRACT FROM AUTHOR]

commo-Ferracarboranes and [8-{(nido-7″,8″-C2B9H11-9″(11″)-)Ph2PCH2CH2PPh2}-commo-3,3′-Fe-{1,2-C2H9B10}{1′2′-C2B9H11}] were prepared as minor products in the metallation reaction of [K]+[nido-7,8-C2B9H12]− with the 14-electron iron complex [Ph2P(CH2)2PPh2]FeCl2. The structures of the complexes were determined by single-crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

A series of new heterocyclic ensembles, derivatives of 5-oxo-1-(1,3,4-thiadiazol-2-yl)-pyrrolidine-3-carboxylic acid, was synthesized by heating 5-substituted 1,3,4-thiadiazol-2-amines and itaconic acid under solvent-free conditions or with the addition of acetic acid at 140–150 °C. The resulting acids can be used as building blocks in the synthesis of new potentially biologically active heterocyclic compounds. [ABSTRACT FROM AUTHOR]

The complex investigation of paramagnetic (17-electron) iron and ruthenium closo-metallacarboranes with chelate diphosphine ligands 3,3-(PhP(CH)PPh)-3-Cl- closo-3,1,2-MCBH (M = Fe, n = 2, 3; Ru, n = 4), o-phenylenecycloboronated 3-Cl-3,3,8-[InlineMediaObject not available: see fulltext.] ( n = 3, 4; R = H or Me), and bis( o-cycloboronated) [InlineMediaObject not available: see fulltext.] ( n = 4, 5) was performed using cyclic voltammetry and matrix-activated laser desorption/ionization time-of-flight (MALDI-TOF) spectrometry. Some diamagnetic iron and ruthenium exo-nido- and commo-complexes were studied using the same methods. A relationship between the redox potentials of the metallacarborane complexes and their stability and transformations under the MALDI-TOF conditions was established. [ABSTRACT FROM AUTHOR]

New biologically active substances isolated from natural sources provide valuable information on structural motifs that are important for a specific type of activity and can also be used as drugs or serve as raw materials for chemical modification in order to develop new pharmaceuticals. This review considers natural antibiotics combining two pharmacophores in their structure: a redox-active naphthoquinone moiety and a membrane-active polyol macrolide. Data on their structures and the spectrum of biological activity are summarized. [ABSTRACT FROM AUTHOR]

Representatives of the new heterocyclic system, pyrimido[5’,4’:3,4]pyrrolo[1,2-f]phenanthridine, were obtained via the intramolecular C-H-arylation of 6-aryl-5-(2-bromophenyl) pyrrolo[3,4-d]pyrimidine-2,4-diones catalyzed by palladium complexes with N-heterocyclic carbene ligands (Pd/NHC). [ABSTRACT FROM AUTHOR]

Condensed pregnano[17,16-d]triazolines were produced in 1,3-dipolar cycloaddition of 16-dehydropregnenolone acetate with organic azides at 10 kbar. The structure of the synthesized compounds was determined by using two-dimensional NMR spectroscopy (1H—1H COSY, NOESY, HSQC, and HMBC). [ABSTRACT FROM AUTHOR]

New 3'-(4-chlorophenyl)-5',5'-dimethyl-2'-oxospiro[(2 H)-chromene-2,4'-1,3-oxazolidine] was synthesized to study the donor influence of the chlorine atom at the N-phenyl substituent on the structure and photochromic properties of 1,3-oxazolidine-containing spiropyrans. Photochemical properties of synthesized 1,3-oxazolidine derivatives were studied at room temperature in toluene. The X-ray diffraction parameters for the new compound were compared with the data obtained earlier for similar spiropyrans. [ABSTRACT FROM AUTHOR]

The femtosecond dynamics of excitation relaxation of the zinc porphyrinate trimer was studied by the pumping-scanning method. The obtained results were examined using semi-empirical quantum chemical calculations. The dynamics of excitation relaxation shows that the application of similar systems as models for studying photosystems and development of artificial analogs of natural photosynthetic centers is promising. An explanation for the observed coherent dynamics of exciton bands was proposed. [ABSTRACT FROM AUTHOR]

An approach to the synthesis of earlier unknown androstano[17,16-d]pyrazoles containing a monothiooxamide fragment at the nitrogen atom of the pyrazole ring has been suggested. The method is based on the reaction of NH-unsubstituted androstano[17,16-d]pyrazole with chloroacetyl chloride with subsequent involvement of the obtained N-chloroacetylpyrazole into the reaction with elementary sulfur in the presence of aromatic amines. The synthesized androstano[17,16-d]pyrazoles containing a monothiooxamide fragment at the nitrogen atom of the pyrazole ring exhibit high antiparasitic activity. [ABSTRACT FROM AUTHOR]

Abstract  The known organotin(IV) complexes with 2-mercaptopyrimidine (L) [Me2SnL2] (1), [Bun 2SnL2] (2), [Ph2SnL2] (3), and [Ph3SnL] (4) were synthesized using a new approach. The effect of the synthesized compounds on peroxidation of fatty acids (oleic and linoleic) was studied. Complexes 1–4 promote the peroxidation of oleic acid. Their effect on the enzymatic peroxidation of linoleic acid with lipoxygenase was compared with that of cisplatin and in vitro cytoxicity against sarcoma cancer cells was determined. The antiproliferative effect of complexes 2–4 was demonstrated. [ABSTRACT FROM AUTHOR]

Abstract  Reactions of photogenerated fluorine atoms with C60 fullerene molecules isolated in solid argon were studied by EPR spectroscopy in the temperature range from 15 to 25 K. Highly resolved anisotropic EPR spectrum of the FC60 ⋅ radical was obtained for the first time. The spectrum is characterized by low anisotropy of the g-tensor and by axially symmetric HFC tensor on 19F nuclei. The parameters of the HFC tensor for 19F magnetic nuclei were determined. The isotropic HFC constant A iso equals 202.8 MHz and the anisotropic magnetic dipole-dipole interaction constant A dip equals 51.8 MHz. Quantum chemical calculations of FC60 ⋅ radical showed that the PBE1/Λ22m method (PBE1 functional and the correlation triple-zeta basis sets augmented with polarization functions on inner atomic shells) provides good agreement between the theoretical magnetic parameters and experimental data. Specific features of the spin density distribution in the FC60 ⋅ radical are discussed. [ABSTRACT FROM AUTHOR]