Synthesis,structure, DNA interaction,and hydrolytic function toward bis(<Emphasis Type="Italic">p</Emphasis>-nitrophenyl) phosphate of a heterobinuclear macrocyclic complex

An asymmetrical bis-pyridine pendant-armed macrocyclic heterobinuclear complex, [ZnNiL](ClO₄)₂·CH₃CN (H₂L was derived from the condensation between 3,3′-((ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))bis(methylene))bis(2-hydroxy-5-methylbenzaldehyde) and 1.3-diaminopropane), has been synthesized and characterized by physico-chemical and spectroscopic methods. The asymmetric unit contains two complete macrocyclic complexes that are nevertheless quite similar to one another. The Zn–Ni separations, bridged by the two phenoxides, are 3.107 and 3.141 Ǻ, respectively. The phosphate hydrolysis catalyzed by the complex was investigated using bis(4-nitrophenyl)phosphate (BNPP) as the substrate. The catalytic rate constant (k _cat) is 1.64 × 10⁻³ s⁻¹ at pH 7.4 and 25 °C, which is 10⁸-fold higher than that of the corresponding uncatalyzed reaction. The interaction between the complex and calf thymus (CT) DNA was investigated by UV–vis absorption, viscosity experiments, and cyclic voltammetry. The complex shows good binding propensity to calf thymus DNA via intercalation with a binding constant of 5 × 10⁴ M⁻¹. The agarose gel electrophoresis studies show that the complex has a concentration-dependent DNA cleavage activity.     

Crystal structures of [Hg(<Emphasis Type="Italic">N</Emphasis>-ethylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>] and [Hg(<Emphasis Type="Italic">N</Emphasis>-propylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>]

Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu)₂(CN)₂] (1) and [Hg(Prtu)₂(CN)₂] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)–162.2(3)°. The structures are stabilized by N-H—S, N-H—N, and C-H—N intramolecular and intermolecular hydrogen bonds.     

A Schiff base ligand <Emphasis Type="Italic">N</Emphasis>-(2-hydroxylacetophenone)-3-oxapentane-1,5-diamine and its nickel(II) complex: synthesis,crystal structure,antioxidation, and DNA-binding properties

A new Schiff base ligand N-(2-hydroxylacetophenone)-3-oxapentane-1,5-diamine (HL) and its Ni complex, [Ni₂(L)₂(NO₃)₂], have been synthesized and characterized by physicochemical and spectroscopic methods. The X-ray crystal structure of [Ni₂(L)₂(NO₃)₂] shows it to be a dinuclear 2:2 complex, in which each Ni(II) atom is in a distorted octahedral geometry. The two Ni(II) atoms are dibridged by two phenoxo ligands, forming a Ni₂O₂ parallelogram-type moiety. The interactions between free HL and the complex with calf thymus DNA have been investigated, and the binding constant and linear Stern–Volmer quenching constant suggest that the two compounds bind to DNA via the intercalation mode. The binding affinity of the complex was higher than that of HL. Antioxidant assays in vitro showed that the Ni(II) complex possesses significant antioxidant activity.     

Halogenophilic and classical <Emphasis Type="Italic">Ad</Emphasis><Subscript><Emphasis Type="Italic">N</Emphasis></Subscript><Emphasis Type="Italic">E</Emphasis> mechanisms in nucleophilic vinylic substitution reactions involving the anions of transition metal carbonyls

The mechanism of the reaction of carbonylate anions ([M(CO) _n L]^–) with highly activated vinyl halides (Hal = Cl, Br, I) was investigated by the method of “anion traps” – the effect of proton donors on the composition of the reaction products. It was demonstrated that the reactions with PhCHal=C(Z)₂ (Hal = Br, I;Z=CN, CO₂Et) and PhCN=CClI take place through initial attack by the carbonylate at the halogen atom, the reactions with PhCCl=C(CO₂Et)₂ and PhCOCH=CHHal (Hal = Cl, I) take place through attack by the carbonylate at the π bond (Ad_NE mechanism), and in the case of E-and Z-PhCN=CHI the two mechanisms operate concurrently. The main laws determining the reaction mechanisms are analyzed.     

Redox Behavior of Neptunium(V) in Tributyl Phosphate and <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-Dihexyl Octanamide Extractants Dissolved in <Emphasis Type="Italic">n</Emphasis>-Dodecane

Spectrophotometric investigations have been carried out on the disproportionation of Np(V) to form Np(IV) and Np(VI) in 1.1 mol⋅L⁻¹ solutions of tributyl phosphate (TBP) and in N,N-dihexyl octanamide (DHOA) in n-dodecane medium. The Np(V) was found to coordinate with Np(IV) in 1.1 mol⋅L⁻¹ TBP solution in n-dodecane to form a mixed valence “cation–cation” complex by bonding through an axial oxo group on Np(V). By contrast, this interaction was less prominent in the case of 1.1 mol⋅L⁻¹ DHOA solutions. The effect of 1-octanol, added as phase modifier, on the disproportionation behavior of Np(V) was also investigated. An attempt was made to calculate the disproportionation/reduction rate constants for Np(V) under the conditions of these studies. Absorbance measurements on the Np stripped from organic phases revealed the occurrence of Np(V) in the aqueous phase.     

<Emphasis Type="Italic">Z</Emphasis>-and <Emphasis Type="Italic">E</Emphasis>-conformers of <Emphasis Type="Italic">N</Emphasis>-chloroacetylcytisine

N-Chloroacetylcytisine was synthesized by acylation of (–)-cytisine. Stable Z- and E-conformers with respect to rotational isomerism around the N-12–CO bond were found in PMR spectra at room temperature. The point at which PMR resonances of the Z- and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated.     

Calculated properties of neutral and charged Al<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript>Co<Subscript><Emphasis Type="Italic">m</Emphasis></Subscript> clusters by density functional theory

Density functional calculations are performed to study the structures and electronic properties of Al _n Co _m clusters with n = 1–7 and m = 1–2. Frequency analysis is also performed after structural optimization to make sure that the calculated ground states are real minima. The corresponding total and binding energies, adiabatic electron affinities and ionization potentials are presented and discussed to aid the identification of our calculations. The BSSE correction is also considered in our calculation. Among Al _n Co _m , Al _n Co _m ⁻, and Al _n Co _m ⁼ clusters (n = 1–7 and m = 1–2), Al₄Co⁻, Al₆Co⁻, Al₂Co₂, and Al₆Co₂ are predicted to be more stable. Our results are consistent with the available experimental data.     

Preparation of a zwitterionic trichloroplatinum(II) complex with an alkylbipyridinum ligand and its reaction in dmso-<Emphasis Type="BoldItalic">d</Emphasis><Subscript>6</Subscript> solution

A zwitterionic trichloroplatinum(II) complex PtCl₃(4,4′-bpy-N-ⁿBu) (1) was prepared by an aqueous reaction of [4,4′-bpy-N-ⁿBu]Cl with K₂PtCl₄, and was characterized by ¹H-n.m.r. and IR spectroscopy as well as elemental analysis. Dissolving (1) into dmso-d ₆ at 25 °C yields a mixture of the complexes, cis-PtCl₂(4,4′-bpy-N-ⁿBu)(dmso-d ₆) (2-cis), trans-PtCl₂(4,4′-bpy-N-ⁿBu)(dmso-d ₆) (2-trans), [4,4′-bpy-N-ⁿBu]Cl and PtCl₂(dmso-d ₆)₂. Ratio of the products in the dmso-d ₆ solution changed depending on the temperature and the total concentration of the complexes. These compounds are in equilibrium via isomerization reaction between (2-cis) and (2-trans) and via displacement reaction of the alkylbipyridinium ligand of (2-cis) and (2-trans) with dmso-d ₆ to form [4,4′-bpy-N-ⁿBu]Cl and PtCl₂(dmso-d ₆)₂.     

Synthesis of graft copolymers of wood and <Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone

Lignocellulose copolymers with grafted lactam rings were prepared by graft copolymerization of wood with N-vinylpyrrolidone initiated by Fe²⁺-H₂O₂. The principal features of their formation were investigated as functions of reactant concentrations, temperature, and polymerization time. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 174–176, March–April, 2008.     

Molecular structure of <Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">o</Emphasis>-and <Emphasis Type="Italic">p</Emphasis>-hydroxybenzyl)cytisine

The molecular structures of N-(o-and p-hydroxybenzyl)cytisine were investigated by NMR spectroscopy, x-ray structure analysis, and molecular modeling. It was found that NMR resonances of the OH and aromatic protons in N-(o-hydroxybenzyl)cytisine were doubled because of the presence of two conformers in solution. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 165–168, March–April, 2008.     

Low-temperature thermodynamic properties of <Emphasis Type="Italic">L</Emphasis>-cysteine

Heat capacity C _p(T) of the orthorhombic polymorph of L-cysteine was measured in the temperature range 6–300 K by adiabatic calorimetry; thermodynamic functions were calculated based on these measurements. At 298.15 K the values of heat capacity, C _p; entropy, S _m⁰(T)-S _m⁰(0); difference in the enthalpy, H _m⁰(T)-H _m⁰(0), are equal, respectively, to 144.6±0.3 J K⁻¹ mol⁻¹, 169.0±0.4 J K⁻¹ mol⁻¹ and 24960±50 J mol⁻¹. An anomaly of heat capacity near 70 K was registered as a small, 3–5% height, diffuse ‘jump’ accompanied by the substantial increase in the thermal relaxation time. The shape of the anomaly is sensitive to thermal pre-history of the sample.     

X-ray photoelectron and auger spectroscopic study of the chemical composition of BC<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>N<Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> films

X-ray photoelectron and Auger spectroscopy are used to investigate the chemical composition of BC _x N _y films synthesized by PECVD from different initial gas mixtures in the temperature range 473–723 K. Main principles and features of the film formation are found. It is shown that the chemical composition of BC _x N _y films significantly depends on the synthesis parameters, which enables targeted control of their physical properties. The obtained data are discussed.     

Molecular properties of the copolymers of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diallyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethylammonium chloride and maleic acid

The hydrodynamic and conformational properties of molecules of poly(N,N-diallyl-N,N-dimethylammonium chloride) and N,N-diallyl-N,N-dimethylammonium chloride-maleic acid copolymers of different compositions in solutions with various ionic-strength and pH values, as well as of the polyelectrolyte complex based on the copolymer with dodecyl sulfate anions in chloroform, are studied. For poly(N,N-diallyl-N,N-dimethylammonium chloride) molecules in a 1 M NaCl solution, the Kuhn segment length and the hydrodynamic diameter of the chain are estimated as A = 3.9 nm and d = 0.48 nm, respectively. In acidic solutions with pH 3.5, the copolymers demonstrate behavior typical for polyelectrolytes. In an alkaline solution with pH 13, when 1 M NaCl is added to the solution of the copolymer containing 29 mol % maleic acid units, there is an antipolyelectrolyte effect that manifests itself as an increase in the intrinsic viscosity of the copolymer and in the hydrodynamic radius of its molecules. It is found that an increase in the fraction of maleic acid units in the copolymer from 12 to 42 mol % brings about a reduction in the equilibrium rigidity of its macromolecules from 4.1 to 2.2 nm. The equilibrium rigidity of polyelectrolyte-complex molecules is higher than that of initial copolymer molecules owing to steric interactions arising between the aliphatic chains of dodecyl sulfate anions. In an electric field, the molecules of the complex are oriented owing to the induced dipole moment resulting from the displacement of dodecyl sulfate anions along the chain contour.     

Nano-composites SnO(VO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>) as anodes for lithium ion batteries

Nano-composites of SnO(V₂O₃) _x (x = 0, 0.25, and 0.5) and SnO(VO)_0.5 are prepared from SnO and V₂O₃/VO by high-energy ball milling (HEB) and are characterized by X-ray diffraction (XRD), scanning electron microscopy, and high-resolution transmission electron microscopy techniques. Interestingly, SnO and SnO(VO)_0.5 are unstable to HEB and disproportionate to Sn and SnO₂, whereas HEB of SnO(V₂O₃) _x gives rise to SnO₂.VO _x . Galvanostatic cycling of the phases is carried out at 60 mA g⁻¹ (0.12 C) in the voltage range 0.005–0.8 V vs. Li. The nano-SnO(V₂O₃)_0.5 showed a first-charge capacity of 435 (±5) mAh g⁻¹ which stabilized to 380 (±5) mAh g⁻¹ with no noticeable fading in the range of 10–60 cycles. Under similar cycling conditions, nano-SnO (x = 0), nano-SnO(V₂O₃)_0.25, and nano-SnO(VO)_0.5 showed initial reversible capacities between 630 and 390 (±5) mAh g⁻¹. Between 10 and 50 cycles, nano-SnO showed a capacity fade as high as 59%, whereas the above two VO _x -containing composites showed capacity fade ranging from 10% to 28%. In all the nano-composites, the average discharge potential is 0.2–0.3 V and average charge potential is 0.5–0.6 V vs. Li, and the coulombic efficiency is 96–98% after 10 cycles. The observed galvanostatic cycling, cyclic voltammetry, and ex situ XRD data are interpreted in terms of the alloying–de-alloying reaction of Sn in the nano-composite “Sn-VO _x -Li₂O” with VO _x acting as an electronically conducting matrix.     

Synthesis and characterization of <Emphasis Type="Italic">N</Emphasis>-tolyglycosylamines

N-Tolylglycosylamines were synthesized from o-, m-, and p-toluidines and aldoses (D-glucose, D-galactose, D-mannose, L-rhamnose, D-xylose, and L-arabinose). The anomeric and isomeric compositions of the synthesized products were established using ¹³C NMR methods. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 333–335, July–August, 2008.     

Formation of a Hydroxo-bridged Dinuclear Ru(III)/Ru(III) Complex from <Emphasis Type="Italic">N</Emphasis>-Methylimidazole and [Ru<Emphasis Type="Italic">Cp</Emphasis>(CH<Subscript>3</Subscript>CN)<Subscript>3</Subscript>]<Superscript>+</Superscript>

Summary. The reaction of [RuCp(CH₃CN)₃]PF₆ with 1 equiv of N-Me-imidazole results in the quantitative formation of [RuCp(¹N-N-Me-imidazole)(CH₃CN)₂]PF₆ (1) featuring a ¹N rather than a ¹C bound N-Me-imidazole ligand. According to DFT/B3LYP calculations, ¹N coordination of N-Me-imidazole is preferred over ¹C coordination by 25.5kJ/mol. Upon exposure to air 1 reacts with oxygen and water to afford the novel hydroxo-bridged dinuclear complex of [Ru₂Cp₂(¹N-N-Me-imidazole)₂(-OH)₂](PF₆)₂ (2) featuring a metal-metal single bond. The dimeric nature of 2 was confirmed by a single-crystal X-ray structure analysis.     

Synthesis,structure, and properties of <Emphasis Type="Italic">N</Emphasis>-(nitramino)phthalimide

N-(Nitramino)phthalimide R₂N-NHNO₂ (R₂NH is phthalimide) was synthesized by nitration of N-aminophthalimide with nitronium tetrafluoroborate. The structure of this compound was established by X-ray diffraction and confirmed by ¹H, ¹³C, and ¹⁴N NMR spectroscopy. The methylation of this compound with diazomethane affords a mixture of N-methyl (R₂N-NMeNO₂) and O-methyl (R₂N-N=N(O)OMe) isomers. The latter compound contains the previously unknown high-nitrogen-oxygen fragment. The thermal decomposition of N-(nitramino)phthalimide in vacuo at 80–100 °C gives 2H-3,1-benzoxazine-2,4(1H)-dione (isatoic anhydride) as the major product. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 625–630, March, 2008.     

Ruthenium(II) <Emphasis Type="Italic">N</Emphasis>-heterocyclic Carbene Complexes in the Transfer Hydrogenation of Ketones

Six ruthenium-N-heterocyclic carbene complexes (2–7) have been prepared and the new compounds characterized by C, H, N analyses, ¹H-n.m.r. and ¹³C-n.m.r. The reduction of ketones to alcohols via transfer hydrogenation was achieved with catalytic amounts of complexes (2–7) in the presence of t-BuOK.     

The group-theoretical structure of the atomic g shell: connection with the alternating group <Emphasis Type="Italic">A</Emphasis><Subscript>6</Subscript> as <Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript>(9)

The special projective linear groups PSL(2ℓ + 1) or L ₂(2ℓ + 1) of order 2ℓ(2ℓ + 1)(ℓ + 1) can be used to study atomic shells of electrons with angular momentum quantum number ℓ corresponding to the atomic p, d, f, and g shells for ℓ = 1, 2, 3, 4, respectively. For the atomic g shell the group L ₂(9) is isomorphic with the alternating group A ₆ on six objects of order 360 or the symmetry group of the 5-dimensional simplex, a 5-dimensional analogue of the tetrahedron with 6 vertices and 15 edges. This leads to the subgroup chain SO(9) ⊃ SO(5) ⊃ L ₂(9) for the atomic g shell analogous to the subgroup chain SO(7) ⊃ G ₂ ⊃ L ₂(7) ≈⁷ O for the atomic f shell. In the L ₂(9) group only the representations of spherical harmonics or sums thereof, Γ(Y_ℓ), with dimensions dim Γ(Y_ℓ) or dim Γ(Y_ℓ) ± 1 divisible by 9 are found to be individually reducible to irreducible representations (irreps) or sums of irreps of L ₂(9). This leads to term groupings such as S, PD, G, PF, DH, L, PK, DI, FH, M, FI, PO, DN, HK, R, etc., of increasing total dimension for the irreps of SO(9) for various g ⁿ configurations in the atomic g shell.     

Determination of epoxides by high-performance liquid chromatography following derivatization with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethyldithiocarbamate

A reversed-phase, high-performance liquid chromatography (RP-HPLC) method that allows quantitation of low levels of epoxides has been described. The method involved derivatization of epoxides using 100- to 1,000-fold excess N,N-diethyldithiocarbamate (DTC) at 60 °C for 20 min at neutral pH. The unreacted DTC was then decomposed to CS₂ and diethyl amine by acidification of the reaction mixture to pH 2 using orthophosphoric acid. The first two steps could be performed in the same reaction vessel by sequential addition of reagents. In the final step, an aliquot (20 μL) of the derivatized sample was analyzed for the presence of stable esters of DTC by RP-HPLC using a Supelcosil LC-18-S (150 × 4.6-mm) column and a mobile phase consisting of 40% (v/v) acetonitrile in water at a flow of 1 mL min⁻¹. Using UV detection at 278 nm, the epoxides gave linear responses in the concentration range of 0.25 to 50 μM. The method is robust, and as low as 5 pmol of the analyte could be successfully detected and quantified with recoveries of ≥94%. Following a minimal pretreatment such as ultrafiltration (molecular weight cutoff 5,000 Da), the method is suitable for analysis of epoxides in complex physiological fluids (e.g., fetal bovine serum). The method has been rigorously evaluated and adapted in our laboratory for routine analysis and determination of stability of epoxides of 1,3-butadiene and other alkenes added to cell cultures.