Boris Shivachev

Crystal structure and properties of the copper(II) complex of sodium monensin A

The preparation and structural characterization of a new copper(II) complex of the polyether ionophorous antibiotic sodium monensin A (MonNa) are described. Sodium monensin A binds Cu(II) to produce a heterometallic complex of composition [Cu(MonNa)(2)Cl(2)].H(2)O, 1. The crystallographic data of 1 show that the complex crystallizes in monoclinic space group C2 with Cu(II) ion adopting a distorted square-planar geometry. Copper(II) coordinates two anionic sodium monensin ligands and two chloride anions producing a neutral compound. The sodium ion remains in the inner cavity of the ligand retaining its sixfold coordination with oxygen atoms. Replacement of crystallization water by acetonitrile is observed in the crystal structure of the complex 1. Copper(I) salt of the methyl ester of MonNa, 2, was identified by X-ray crystallography as a side product of the reaction of MonNa with Cu(II). Compound 2, [Me-MonNa][H-MonNa][CuCl(2)]Cl, crystallizes in monoclinic space group C2 with the same coordination pattern of the sodium cation but contains a chlorocuprate(I) counter [CuCl(2)](-), which is linear and not coordinated by sodium monensin A. The antibacterial and antioxidant properties as two independent activities of 1 were studied. Compound 1 is effective against aerobic Gram(+)-microorganisms Bacillus subtilis, Bacillus mycoides and Sarcina lutea. Complex 1 shows SOD-like activity comparable with that of the copper(II) ion.

Positron lifetime computations of defects in nickel containing hydrogen or helium

Positron lifetime of defects in nickel containing hydrogen or helium has been calculated, using Monte-Carlo, density-functional theory and local-density approximation. It is found that the values of positron lifetime in voids are lowered by the presence of hydrogen or helium. The calculations show a correlation between the microvoid size in nickel and the value of the positron lifetime. With the growth of the void size the difference in the positron lifetime for clusters containing hydrogen or helium becomes significant. Calculations show a saturation of the positron lifetime for microvoids containing more than 45 hydrogen atoms and around 30 helium atoms. A dependence between the positron lifetime and the ratio of hydrogen or helium atoms to the number of vacancies in nickel voids is established.

Antimycobacterial activity of novel hydrazide-hydrazone derivatives with 2H-chromene and coumarin scaffold.

This study reports the synthesis of new 2H-chromene or coumarin based acylhydrazones, which were evaluated for their in vitro antimycobacterial activity against reference strain Mycobacterium tuberculosis H37Rv and compared to the first-line antituberculosis drugs, isoniazid (INH) and ethambutol (EMB). The most active compounds 7m (MIC 0.13μM), 7o (MIC 0.15μM) and 7k (MIC 0.17μM) demonstrated antimycobacterial activity at submicromolar concentration level and remarkably minimal associated cytotoxicity in the human embryonic kidney cell line HEK-293T. Structure-activity relationship for this class of compounds has been established.

Anthracene-Derived Bis-Aminophosphonates: Crystal Structure, In Vitro Antitumor Activity, and Genotoxicity In Vivo

Abstract The X-ray crystal structures of the anthracene-derived bis-aminophosphonates 4.4′-bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminodiphenylmethane (1) and 1,3-bis [N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminobenzene (3) are reported. The X-ray analyses demonstrated that both compounds crystallize in a centrosymmetric manner containing a meso-form (1) and a pair of enantiomers (3). The cytotoxic potential, genotoxicity, and antiproliferative activity of bis-aminophosphonates 1 and bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]benzidine (2), as well as their subcellular distribution in a tumor cell culture system, are also discussed. Compounds 1 and 2 showed optimal antiproliferative activity to human tumor cells from colon carcinoma line HT-29. In vitro and in vivo safety testing revealed that the compounds exert lower toxicity to normal cells as compared with well-known anticancer and cytotoxic agents. Supplemental materials are available for this article. Go to the publishers online edition ofPhosphorus, Sulfur, and Silicon and the Related Elementsto view the free supplemental file. GRAPHICAL ABSTRACT

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

The crystal structures of 3-amino-cycloheptanespiro-4′-imidazolidine-2′,5′-dione (I) {systematic name: 3-amino-1,3-diazaspiro[4.6] undecane-2,4-dione} and 3-amino-cyclooctanespiro-4′-imidazolidine-2′,5′-dione (II) {systematic name: 3-amino-1,3-diazaspiro[4.7] dodecane-2,4-dione}, have been determined. In both compounds the polar hydantoin groups cause molecules to aggregate via N-H...O and N-H...N interactions, forming a layer structure, in which the cycloalkane rings project outwards from the central, more polar, region. The observed molecular structure is compared with that calculated by density functional theory methods.

A microporous titanosilicate for selective killing of HeLa cancer cells

Structural distribution of zinc(II) ions in the pore system of three silicate molecular sieves has revealed an unprecedented application of the microporous titanosilicate Zn–ETS-4 as a non toxic, highly efficient and selective inhibitor of HeLa cancer cells.

Synthesis and crystal structure of a Pt(II) complex with 3-amino-5-methyl-5-phenylhydantoin

The reaction of K2PtCl4 with 3-amino-5-methyl-5-phenylhydantoin (amphh, L) and KI in aqueous ethanol yields dark violet crystals of a binuclear platinum(II) complex. The molecular structure of the complex was determined by single-crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group with a = 8.458(3), b = 11.016(2), c = 16.249(3) (Å), α = 94.630(14), β = 100.63(2), γ = 108.55(4)° and Z = 2. The structure consists of [K2L4]2+ cations and [Pt2I6]2− anions bridged by K–I bonds to form quasi-one-dimensional chains along the b axis. Chains are linked by K+ ··· π(Ph) interactions and N–H ··· O hydrogen bonds. The complex is compared with data for related structures.

2-(3-benzoyl-1-pyridinio)-3,4-dioxocyclobutenolate.

The title compound, C16H9NO4, also known as the 3-benzoylpyridinium betaine of squaric acid, exhibits a dipolar electronic ground-state structure with a positively charged pyridinium fragment and a negatively charged squarate moiety. In the molecule, the two aromatic rings are twisted by 56.03 (2) degrees relative to one another. The three-dimensional packing of the molecules is stabilized by C-H...O short contacts.

[(4,4-Dimethyl-2-oxo-1,3-oxazolidin-3-yl)methyl]phosphonic acid.

The title compound, C6H12NO5P, was synthesized as an intermediate phase in a search for new N-(phosphonomethyl)glycine derivatives. The molecules are held together by O-H...O hydrogen bonds, forming chains along the b axis in the crystal structure. The observed molecular structure is compared with that calculated by the density functional theory method.

3-Carb­oxy­phenyl­boronic acid–theophylline (1/1)

The title two-component molecular crystal [systematic name: 3-(dihydroxyboranyl)benzoic acid–1,3-dimethyl-7H-purine-2,6-dione (1/1)], C7H7BO4·C7H8N4O2, comprises theophylline and 3-carboxyphenylboronic acid molecules in a 1:1 molar ratio. In the crystal, molecules are self-assembled by O—H⋯O and N—H⋯N hydrogen bonds, generating layers parallel to (-209). The layers are stacked through π–π [centroid–centroid distance = 3.546 (2) Å] and C—H⋯π interactions.