Determination of electron affinity of carbonyl radicals by means of negative ion mass spectrometry

Appearance energies of [M-H](-) ions from carbonyl compounds R-CO-R' (R,R' = H, CH(3), NH(2), OH) have been measured by means of negative ion mass spectrometry in resonant electron capture mode. Values of electron affinity of the corresponding radicals, CH(2)&dbond;C(X)O, NH&dbond;C(X)O and O&dbond;C(X)O, have been determined. Copyright 1999 John Wiley & Sons, Ltd.     

The multi-functional aspect of scanning holographic microscopy: a review(Invited Paper)

Recent developments in scanning holographic microscopy that offer the prospects of new quantitative tools and imaging modalities in bio, micro, and nano sciences are reviewed. The versatility of the method is emphasized. Scanning holography can operate in an incoherent mode for fluorescence imaging, in a coherent mode for quantitative phase imaging, or in a tomographic mode for axial sectioning and rejection of the out-of-focus haze. Possible applications are illustrated with examples, and future prospects ...     

Primitive Illumination Systems for Families of Convex Bodies in the Plane

Let F= {C₁,C₂,...,C} be a family of ndisjoint convex bodies in the plane. We say that a set Vof exterior light sources illuminates F, if for every boundary point of any member of Fthere is a point in Vsuch that is visible from ,i.e. the open line segment joining and is disjoint from F. An illumination system Vis called primitive if no proper subset of Villuminates F. Let p_max(F) denote the maximum number of points forming a primitive illumination system for F, and letp_max(n) denote the minimum of F) taken over all families Fconsisting of ndisjoint convex bodies in the plane. The aim of this paper is to investigate the quantities p_max(F) and p_max(n).     

Reaction mechanism and structure of products in photochemical transformations of copper(ii) heptafluorobutyrate in methanol

The mechanism of photochemical transformations of copper(II) heptafluorobutyrate in methanol is studied. The structure of products and intermediate compounds is investigated. Photolysis occurs as a two- step process. The first step involves changes in the coordination sphere of the Cu(II) ion. The second step is photoreduction of Cu(II) forming metallic copper and Cu(II) fluoride as a complex with methanol. In the presence of oxygen, the first step is reversible. A scheme of these processes is suggested. Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 662–668, July–August, 1997.     

Complexation of Co(II) with phosphonomethylaminosuccinic acid in solutions

Complexation in the Co(II)-phosphonomethylaminosuccinic acid (H₄L) system in aqueous solutions at component ratios of 1 : 1 and 1 : 2 and c _Co(II) = 1 × 10^?2 mol/L was studied by electronic absorption spectroscopy. The formation of various protonated complexes of the general formula Co(H _n L) _m (OH) _q (n = 3?0; m = 1?C2; q = 0?C2) was found, and their stability constants and distribution diagrams were calculated. It was demonstrated that the bis complexes have the structure of a distorted octahedron, and the octahedron ?? tetrahedron rearrangement of the coordination polyhedron occurs in the equimolar complexes at pH > 8.     

Complex formation of Fe(III) with tartaric acid by the method of nuclear magnetic relaxation

An investigation was made of the system Fe(III)-tartaric acid at an equimolar ratio of the components by the method of nuclear magnetic relaxation. The formation of monomer and dimer complexes FeH_ntar and Fe₂(H_ntar)₂ (n = 3–0), as well as a mixed ligand complex Fe₂(H₃tar)(H₂tar), was established, and their stability constants were determined. The diagrams of the distribution of complex forms as a function of the pH were calculated according to the values of the stability constants. Questions of the monomer dimer transition of the investigated complexes in solution are discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 4, pp. 492–497, July–August 1987.     

Reaction of N-alkylglycolurils with electrophilic reagents

The N-hydroxymethylation, N-acetylation, and N-acetoxymethylation of mono-, di-, and trialkylglycolurils by reaction with the electrophilic reagents formaldehyde and acetaldehyde have been studied. General methods have been developed for the preparation of mono-, di-, and tri-N-hydroxymethylglycolurils by treatment of differently substituted N-alkylglycolurils with formaldehyde (as hemiformal in methanol) and the synthesis of di-N-and tri-N-acetyl-or N-acetoxymethylglycolurils via the electrophilic substitution of hydrogen atoms for an acetyl group at the nitrogen or oxygen atoms in the hydroxymethyl groups of glycolurils using acetic anhydride. The regioselectivity of the reaction of the 2-t-Bu-and 2-c-C₆H₁₁-glycolurils with formaldehyde has been shown to yield a 4,6-di(hydroxymethyl) derivative. It was found that the hydroxymethylation of 2,4-and 2,6-dialkylglycolurils occurs regioselectively with a stoichiometric ratio of glycoluril to hemiformal and permits preparation of their mono-and dihydroxymethyl derivatives. The enantiomeric analysis of the obtained compounds has been carried out for the first time using HPLC on chiral phases. X-ray analysis has been carried out on the previously unreported racemic 2,6-diacetoxymethyl-4,8-dimethylglycoluril. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 411–423, March, 2006.     

Micellar free radical initiators

The effect of the nature of the surfactant, peroxide (ROOH), and medium on the rate of radical initiation in a surfactant-ROOH mixed micellar system has been studied. Cationic surfactants, as distinct from anionic and nonionic ones, have been found to catalyze ROOH decomposition to form radicals. Cationic surfactants in an organic medium exhibit higher catalytic effect than in an aqueous solution. The catalytic activity of the surfactants is strongly dependent on the counterion nature. The highest catalytic activity is shown by cetyltrimethylammonium chloride.