Andrei S. Potapov

Decomposition of reactive oxygen species by copper(II) bis(1-pyrazolyl)methane complexes

Two bis(1-pyrazolyl)alkane ligands, bis(3,5-dimethyl-1-pyrazolyl)methane and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methane, and their copper(II) complexes, bis(3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL1(NO3)2] and bis(4-iodo-3,5-dimethyl-1-pyrazolyl)methanedinitratocopper(II) [CuL2(NO3)2]·2H2O, were prepared. Physiochemical properties of the copper(II) complexes were studied by spectroscopic (UV–vis, IR, EPR) techniques and cyclic voltammetry. Spectroscopic analysis revealed a 1:1 stoichiometry of ligand:copper(II) ion and a bindentate coordination mode for the nitrate ions in both of the complexes. According to experimental and theoretical ab initio data, the copper(II) ion is located in an octahedral hexacoordinated environment. Both complexes were able to catalyze the dismutation of superoxide anion (

Synthesis of ditopic ligands containing bis(1H-pyrazol-1-yl)-methane fragments

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Coordination polymers with adjustable dimensionality based on CuII and bis-imidazolyl bridging ligand

) (pH 7.5) and decomposition of H2O2 (pH 7.5) and peroxynitrite (pH 10.9). In addition, both complexes exhibited superoxide dismutase (SOD) like activity toward extracellular and intracellular reactive oxygen species produced by activated human neutrophils in whole blood. Thus, these complexes represent useful SOD mimetics with a broad range of antioxidant activity toward a variety of reactive oxidants.

Synthesis of monomeric and oligomeric 1,1′-methylenebis-(1H-pyrazoles) contaning ethynyl fragments

Eleven new complexes of Cu(II) chloride and nitrate with bis(pyrazol-1-yl)propane and bis[2-(pyrazol-1-yl)ethyl]ether ligands were prepared and characterized by spectral and electrochemical methods. X-Ray crystal structure determination of bis[2-(3,5-dimethylpyrazol-1-yl)ethyl]etherdinitratocopper revealed a hepta-coordinated structure with the bis(pyrazole) ligand coordinated in a tridentate NNO-fashion and both of the nitrate ions in a bidentate fashion. Reaction of Cu(II) nitrate complexes with 2,2-bipyridyl led to the displacement of one of the nitrate ions into the outer sphere and the formation of mixed-ligand complexes. Mixed-ligand bipyridyl Cu(II) complexes demonstrated the highest superoxide dismutase (SOD)-like activity in a chemical superoxide anion-generating system, with IC(50) values in the low micromolar range. Density functional theory calculations showed that introduction of a bipypidyl ligand into the complexes dramatically lowered the lowest unoccupied molecular orbital (LUMO) energy level, which explains the increased SOD-like activity of these complexes compared to non-bipy species. These bipy complexes were also effective scavengers of reactive oxygen species generated by phagocytes (human neutrophils and murine bone marrow leukocytes) ex vivo. Thus, these bipy mixed-ligand complexes represent a promising class of SOD mimetics for future development.

Synthesis and oxidation of some azole-containing thioethers

New approaches have been proposed for the synthesis of compounds containing two bis(1H-pyrazol-1-yl)methane fragments. Nucleophilic replacement of the halogen atoms in appropriate tetrabromo derivatives by pyrazoles in the superbasic system KOH-DMSO gave ditopic chelating ligands: 1,1,2,2-tetrakis(1H-pyrazol-1-yl)ethane, 1,4-bis[bis(1H-pyrazol-1-yl)methyl]benzene, and 1,4-bis[bis(3,5-dimethyl-1H-pyrazol-1-yl)methyl]benzene. 1,4-Bis[bis(1H-pyrazol-1-yl)methyl]benzene was also synthesized by reaction of 1H-pyrazole with terephthalaldehyde in the presence of thionyl chloride. 1,1,2,2-Tetrakis(1H-pyrazol-1-yl)ethane was converted into the corresponding tetraiodo and tetranitro derivatives.

Synthesis of 1,8-di(pyrazol-1-yl)-3,6-dioxaoctane and its derivatives

New pyrazole-containing aldehydes, 1-ethylpyrazole-4-carbaldehyde, 1-ethyl-3,5-dimethylpyrazole-4-carbaldehyde, and 1,1’-methylenebis(3,5-dimethylpyrazole-4-carbaldehyde), were synthesized by the Vilsmeier reaction. Their reactions with primary amines (aniline, hydrazine, ethylenediamine, p-phenylenediamine, benzidine) gave the corresponding Schiff bases.

Synthesis and Cytotoxicity of bis(pyrazol-1-yl)-Alkane Derivatives with Polymethylene Linkers and Related Mono- and Dipyrazolium Salts

Abstract1,4-Bis(imidazol-1-yl)butane was synthesized from imidazole and 1,4-dibromobutane in an alkaline medium. A variation of the molar ratio of reagents in the system copper(II) chloride dihydrate and 1,4-bis(imidazol-1-yl)butane (bImB) upon heating in N,N-dimethylformamide resulted in the synthesis of two new coordination polymers [Cu(bImB)Cl2] (1) and [Cu(bImB)2Cl2] (2), which were structurally characterized. Product 1 was found to possess a chain structure, while structure 2 is built of neutral layers, with the dimensionality of the extended coordination structures being determined by the reaction conditions. The new compounds were characterized by IR spectroscopy, elemental analysis, and powder X-ray diffraction data.

Synthesis of New Bitopic Tetra(pyrazolyl)-Ligands with Neopentane and O-Xylene Backbones

Abstract1,1′-Methylenebis(1H-pyrazole) and 1,1′-methylenebis(3,5-dimethyl-1H-pyrazole) reacted with iodine in the presence of iodic acid to give the corresponding 4,4′-diiodo derivatives. Polycondensation of the latter with p-diethynylbenzene led to the formation of oligomeric compounds. 1,1′-Methylenebis(4-iodo-1H-pyrazoles) were converted into 4,4′-diethynyl derivatives by the Sonogashira and reverse Favorskii reactions, and their oxidative polycondensation in the presence of copper(I) chloride in pyridine also gave oligomeric products with a molecular weight exceeding 9000.