Synthesis of novel non-natural spiro[2.3]hexane amino acids,the conformationally restricted analogs of γ-aminobutyric acid

3-Methylenecyclobutanecarboxylic acid and its methyl ester were used as the starting compounds for the synthesis of new spiro[2.3]hexane amino acids, the conformationally rigid analogs of γ-aminobutyric acid, namely, 5-aminospiro[2.3]hexanecarboxylic and 5-amino-spiro[2.3]hexanephosphonic acids, promising modulators of GABAergic cascades in the human central nervous system. The methods developed for the synthesis of the target amino acids are based on the reactions of catalytic [1+2] cycloaddition of diazoacetic and diazophosphonic esters to 3-substituted methylenecyclobutanes, as well as on a modified Curtius reaction for the transformation of a carboxy group to the amine one.     

Zinc-containing derivatives of 2-aminopyrimidine

A platform containing three anticancer components is proposed. The components are a radioactive ⁶⁹mZn isotope and zinc complexes, where both zinc and ligand exhibit anticancer properties. Two zinc-containing complexes, namely (2-AP)₂ZnCl₂ and (2-AP)₂Zn(Sal)₂ (AP is 2-aminopyrimidine, Sal is salicylate) were synthesized and characterized. Their cytotoxicity with respect to some leukemia cell lines is demonstrated. Their stability in physiological solution and percentage of apoptosis (by flow cytometry) are investigated. Stable complexes of compounds with the isotope ⁶⁹mZn were characterized by TLC and autoradiography.     

Asymmetric Ir-catalyzed hydrogenation of 1,5-benzodiazepinones using mixtures of ligands

The catalytic hydrogenation of benzodiazepinones using metal complexes with phosphite and phosphoramidite ligands was carried out for the first time. The mixed-ligand catalytic systems containing a chiral phosphoramidite or phosphite in combination with an achiral phosphine were shown to exhibit a higher enantioselectivity compared to catalysts containing homocombinations of chiral ligands.     

Functional copolymers with triazole and acetate fragments

New functional copolymers of different composition with triazole and acetate fragments in the macromolecules were synthesized by free radical copolymerization of 1-vinyl-1,2,4-triazole with vinyl acetate. The reactivity of the comonomers was studied and the monomer copolymerization constants were calculated. The structure and composition of the copolymers were determined by elemental analysis, IR and ¹H NMR spectroscopy.     

Synthesis of complexes of N-vinylpyrrolidone–vinylamine or N-vinylpyrrolidone–allylamine containing macrocyclic polyligand 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA) with gallium-68 isotope and estimation of their in vivo distribution

Russian Chemical Bulletin - A method for radiolabeling the water-soluble N-vinylpyrrolidone copolymers with N-vinyl- and N-allylamine containing bifunctional chelation unit...     

NO-donating and hemolytic activity of tetranitrosyl iron complexes with ligands of the 2-mercaptopyridine series

Russian Chemical Bulletin - The NO-donating and hemolytic activity of the binuclear tetranitrosyl iron complexes (TNIC) with thiolate ligands of the composition [Fe2(SR)2(NO)4], where R is...     

Gas-phase fragmentation studies of biotinylated oligomannuronopyranosides under conditions of collisionally activated dissociation

Russian Chemical Bulletin - High-resolution electrospray ionization mass spectra (MS and MS/MS) of a series of glycoconjugates containing biotin and oligomannuronopyranosyl residues linked via a...     

Electrochemical oxidation of thrombin on carbon screen printed electrodes

The electrochemical oxidation of thrombin on the surface of carbon screen printed electrodes was studied. The electrochemical activity of thrombin was predicted, using bioinformation analysis, based on the data about the electrochemical properties of amino acids. The number of potentially electroactive amino acid residues, namely, tyrosine (Tyr), tryptophan (Trp), cysteine (Cys), histidine (His), methionine (Met), and cystine (Cys-Cys) located on the protein surface and orientated by their electroactive groups toward the electrode surface, i.e., accessible for electrochemical oxidation was calculated. The theoretical data were confirmed experimentally by cyclic and square-wave voltammetry. The available data on the protein structure allowed us to attribute the recorded electrochemical signals of thrombin oxidation to certain types of amino acid residue: the oxidation peak with a potential maximum at 0.7–0.8 V (vs. Ag/AgCl) was attributed to the oxidation of the Trp and Tyr residues; the wave in the range 1.0–1.2 V, to the oxidation of His; and the wave at 1.2–1.5 V, to the oxidation of Met and Cys-Cys. The electroanalysis based on the oxidation peak of the Tyr and Trp amino acid residues allowed to detect thrombin up to the concentration of 10^–7 M. The suggested strategy for predicting the electrochemical activity can be used for investigating the properties of many other proteins and peptides and serve as a basis for their quantitative determination when developing various sensor and biosensor devices.     

Transport properties of metacomposites in eutectic MAO<Subscript>4</Subscript>–V<Subscript>2</Subscript>O<Subscript>5</Subscript> systems (M = Ca,Sr; A = W,Mo)

Metal molybdates MMoO₄ (M = Ca, Sr) and their composites with vanadium oxide V₂O₅ were synthesized. An X-ray diffraction analysis confirmed that the obtained molybdates were single-phase, and the heterogeneous systems were two-phase. The temperature dependences of the total conductivity of the composites were studied. The ion transport numbers in the {CaMoO₄ · xV₂O₅} composites (x = 1–30 mol %) were studied by the EMF method. The conductivity of the composites at x ≤ 5 mol % was shown to be ionic. The conductivity of the composites was described using the mixing equation.     

Are metals made from molecules?

In the traditional view, covalently bound materials differ in a fundamental way from metallic substances. Though both are built from more basic units that are, in turn, constructed from a small number of atoms, for these two materials classes the nature of these units is thought to be quite different. For covalent solids and liquids, these units are considered to be molecular, meaning that they possess properties and bonding that are retained in the condensed phase and thus they continue to be identifiable within the larger system. For metallic materials, these basic units are considered to be mere constructs that are not observable against the delocalized bonding of metals or alloys. The perceived dissimilarity of metallic and covalently bound materials has fostered distinctly different approaches to their design and improvement. Here, the delocalized view of metallic bonding is examined. This examination suggests that much of the rationale used in the design of molecular materials my be applied to metals and alloys as well.