Influence of chloride anions on the electrodeposition and electroactivity of the polymer matrix in polypyrrole,poly(<Emphasis Type="Italic">N</Emphasis>-methylpyrrole) and polypyrrole derivatives functionalized by titanocene centers,in dry non-aqueous solutions

We report electrochemical studies on the influence of a small concentration of chloride ions on the electroactivity of the polymer matrix of polypyrrole (PPy), poly(N-methylpyrrole) [p(N-MePy)] and a poly(titanocene-propyl-pyrrole) derivative, p(Tc3Py) [Tc(CH₂)₃NC₄H₄; Tc=CpCpTiCl₂; Cp=C₅H₅; Cp=C₅H₄] in acetonitrile (AN), tetrahydrofuran (THF) and N,N-dimethylformamide (DMF). The polymer films were obtained on Pt disc electrodes from AN solutions of the monomers containing 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF₆) as the supporting electrolyte and then transferred to the corresponding monomer-free solution. Studies in Cl^–-containing solutions have shown that the p(Tc3Py) matrix is very sensitive to the presence of Cl^– ions in all the above solvents, namely that it was subjected to electrochemical degradation at potentials above 0.1 V vs. a Ag/0.01 M Ag⁺ in AN reference electrode. Degradation of the p(Tc3Py) matrix was also observed in chloride-free DMF+TBAPF₆ solutions. Addition of chloride ions to the AN solution containing pyrrole, N-methylpyrrole or Tc3Py inhibits the deposition of the polymer films. On the other hand, we have found that PPy and p(N-MePy) matrices after their deposition in chloride-free AN solutions show much more stable redox responses in contact with chloride and/or DMF solutions. Possible mechanisms of these effects are discussed.Abbreviations AN acetonitrile - Cp cyclopentadienyl - DMF N,N-dimethylformamide - N-MePy N-methylpyrrole - p(N-MePy) poly(N-methylpyrrole) - PPy polypyrrole - p(Tc3Py) poly[Tc(CH₂)₃NC₄H₄] - Py pyrrole - Tc titanocene=bis(cyclopentadienyl)titanium dichloride, Cp₂TiCl₂, or its radical CpCpTiCl₂ (Cp=C₅H₄) - Tc3Py titanocene-propyl-pyrrole, Tc(CH₂)₃NC₄H₄ - THF tetrahydrofuran Contribution to the 3rd Baltic Conference on Electrochemistry, Gdansk-Sobieszewo, Poland, 23–26 April 2003Dedicated to the memory of Harry B. Mark, Jr. (28 February 1934–3 March 2003)     

Adsorption of<Emphasis Type="Italic"> N</Emphasis>-dodecyl-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimethyl-3-ammonio-1-propanesulfonate (DDAPS), a model zwitterionic surfactant,on the Au(111) electrode surface

Electrochemical measurements including cyclic voltammetry, differential capacity, and chronocoulometry have been used to characterize the adsorption behaviors of the zwitterionic surfactant N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS) on the Au(111) electrode surface. The thermodynamics of the ideally polarized electrode have been employed to determine the Gibbs excess and the Gibbs energy of adsorption. The results show that the adsorption of DDAPS has a multistate character. The first two states are observed at potentials close to zero charge. At low bulk DDAPS concentrations, it corresponds to the formation of a film of nearly flat adsorbed molecules. At higher concentrations it is converted into a hemimicellar state. The second state is formed at negative potentials and charge densities close to 0 C cm^–2. It corresponds to a film of tilted molecules oriented with the hydrocarbon tail towards the metal and the polar head toward the solution.Dedicated to Professor Zbigniew Galus on the occasion of his 70^th birthday and in recognition of his many contributions to electrochemistry.     

Detection of <Emphasis Type="Italic">N</Emphasis>-monomethyl-lysine generated by metabolic transmethylation

Administration of radiolabelled deprenyl to rats resulted in the urinary elimination of a ¹⁴C-labelled N-monomethyl-lysine. An increased level of N-monomethyl-lysine was found following an oral dose of another drug, also containing an N-methyl group. The urine sample was treated with 9-fluorenylmethoxycarbonyl chloride and then subjected to high-performance liquid chromatography (HPLC); the radioactive fraction was identified as N-monomethyl-lysine by using HPLC-MS in electrospray mode. Identification of N-monomethyl-lysine in the radioactive fraction gives experimental proof of transmethylation from a well-known drug to an endogenous compound.     

Effect of Cu(II) on the electrochemically initiated reaction of thiols with<Emphasis Type="Italic"> N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-diethyl-<Emphasis Type="Italic">p</Emphasis>-phenylenediamine: methodology for the indirect voltammetric determination of Cu(II)

The effect of Cu(II) on the determination of homocysteine via its electrochemically initiated reaction with N,N-diethyl-p-phenylenediamine is examined. The presence of copper inhibited the detection process for homocysteine owing to a complexation reaction occurring. This provided an indirect route for the sensitive and selective determination of Cu(II), which produced a linear response over the range from 2.5 to 500 M and a limit of detection of 2.5 M. The detection pathway was examined in the presence of metallic and inorganic ions, with negligible interference observed.     

Crystal structure of 1-(2-pyridiniomethyl)-2,4-<Emphasis Type="Italic">bis</Emphasis>(phenylsulfonyl)benzene bromide

The crystal structure of 1-(2-pyridiniomethyl)-2,4-bis(phenylsulfonyl)benzene bromide, (C₂₄H₂₀NO₄S₂)⁺. Br^– (I) has been investigated by X-ray diffraction (XRD)analysis. The triclinic structure of I (space group P1, a = 7.863 , b = 8.350 , c = 9.043 , = 94.00°, = 97.81°, = 104.62°, Z = 1) was solved by direct methods and refined by full-matrix least-squares analysis in an anisotropic approximation to R = 0.048 for all 4570 reflections collected (CAD-4 automatic diffractometer, CuK ). The geometrical parameters of the organic cation were determined with a sufficient degree of accuracy. The crystal structure of I involves a very strong interionic hydrogen bond N⁺-HBr^–.Original Russian Text Copyright © 2004 by A. N. ChekhlovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 759–763, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Acid-base and complexation properties of <Emphasis Type="Italic">gem</Emphasis>-diphosphonic and <Emphasis Type="Italic">gem</Emphasis>-diphosphinic acids in aqueous solutions and micellar media of surfactants

Acid-base and complexation properties of gem-disubstituted phosphorus acids, viz., methylenediphosphonic, 1-hydroxyethylidene-1,1-diphosphonic, P,P-diphenylmethylene-diphosphinic, and P, P-diphenyl-1-hydroxyethylidene-1, 1-diphosphinic acids, were studied in aqueous solutions and in the presence of biomimetics (micelles of ionic surfactants). The dissociation constants of the acids and stability constants of complexes with magnesium(II) and copper(II) ions were determined in aqueous solutions and microheterogeneous media containing sodium dodecyl sulfate, cetylpyridinium chloride, or cetylpyridinium nitrate (ionic strength 0.1 mol L^–1, temperature 25°C).Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1919–1925, September, 2004.     

Hexafluoroacetone as Protecting and Activating Reagent. A New Approach to <Emphasis Type="Italic">N</Emphasis>-Glycosides

Summary. N-Glycosides of Asn and homologues have been synthesized starting from hexafluoroacetone-protected -activated Asp, Glu, and Aad derivatives and glycosylamines. The synthetic value of the new building blocks was demonstrated by the concise incorporation of N-glycosylated Asn, Gln, and Aad -amides into glycopeptides.     

A kinetic stability study of <Emphasis Type="Italic">M</Emphasis>N<Subscript>5</Subscript> (<Emphasis Type="Italic">M</Emphasis>=Li,Na, K,and Rb)

A structure and kinetic stability study on some complexes with the general formula MN₅, where M are the alkali-metal atoms, Li, Na, K, and Rb, has been carried by using hybrid density functional methods. Complex B (C_2v) with two points of attachment to the N₅ ring is the most energetically favored for all metals considered here. Pyramidal structures A (C_5v) are kinetically unstable and they rapidly rearrange to the most stable planar structures B. At the QCISD(T)/6-311 + G*//B3LYP/6-311 + G* + ZPE (B3LYP/6-311 + G*) level, the decomposition barrier heights of LiN₅-B, NaN₅–B, KN₅-B, and RbN₅-B are predicted to be 19.9, 22.0, 22.5, and 23.0 kcal/mol, respectively. In addition, the rate constants of the decomposition reaction MN₅-B MN₃ + N₂ (M + Li, Na, K, and Rb) are also predicted using conventional transition state theory and canonical variational transition state theory, respectively.     

Arjunolic acid derivative glycoside from the stems of <Emphasis Type="Italic">Hedera colchica</Emphasis>

Five triterpenoid saponins were isolated from the stems of Hedera colchica K. Koch, Araliaceae. Two of them are new natural substances. HCSt-A (1): 3-O--D-arabinopyranoside; 28-O--L-rhamnopyranosyl-(1 4)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl-arjunolic acid. HCSt-B (2): 3-O--D-xylopyranoside; 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl-hederagenin. The derivative of arjunolic acid is described for the first time in Araliaceae family. The chemical structures of isolated compounds were established on the base of chemical and 1D and 2D NMR experiments.Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 461–463, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Grafting of poly-<Emphasis Type="Italic">N</Emphasis>-methacryloylaminodeoxyglucose on poly-<Emphasis Type="Italic">N</Emphasis>-vinylpyrrolidone

A graft copolymer simulating glycoprotein was prepared by reaction of poly-N-methacryloylaminodeoxyglucose containing terminal amino group with a copolymer of N-vinylpyrrolidone and acrylic acid N-hydroxysuccinimide ester.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004, pp. 1356–1359.Original Russian Text Copyright © 2004 by Nazarova, Pavlov, Kever, Afanaseva, Panarin.     

Crystal and molecular structure of copper(II) <Emphasis Type="Italic">trans</Emphasis>-bis-(2-(methylimino)-4-pentanonate)

Synthesis and X-ray diffraction study of trans-bis-(2-(methylimino)-4-pentanonato)Cu(II), which is methyl-substituted ketoiminate, is reported. Crystal data for CuN₂O₂C₁₂H₂₀: a = 7.374(1) , b = 9.171(1) , c = 10.823(2) ; = 96.51(1)°, = 106.12(1)°, = 96.81(1)°, space group P , Z = 2, d _calc = 1.38 g/cm³, d _exp = 1.37 g/cm³, R = 0.037. The structure is molecular and consists of isolated trans-complexes. The coordination polyhedron of the copper atom is intermediate between the square and tetrahedron; the average distances are Cu-O 1.91 and Cu-N 1.95 , the O-Cu-O and N-Cu-N trans bond angles are 145.5° and 150.3°, respectively. The O-Cu-N chelate angle is 94.6°. The calculated energies of van der Waals intermolecular interactions are compared with the thermogravimetric characteristics of the complex with ketoiminate and copper(II) ethylenediamine-bis-acetylacetonate.Original Russian Text Copyright © 2004 by I. A. Baidina, P. A Stabnikov, A. D. Vasiliev, S. A. Gromilov, and I. K. IgumenovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 706–712, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Analysis of the Temperature and Composition Dependence of Viscosimetric Properties of 2-Butanone <Emphasis Type="Bold">+</Emphasis> 2-Butanol Solvent Mixtures

Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0x_i1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(x_i), and =(T, x_i). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*^E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.     

Investigation of kernel oils of <Emphasis Type="Italic">Quercus robur</Emphasis> and <Emphasis Type="Italic">Quercus cerris</Emphasis>

The kernel oils of Quercus robur and Quercus cerris were obtained by Soxhlet extraction using petroleum ether. Oil yields were found to be 5.2–5.6% and 4.3–4.8% for Q. robur and Q. cerris kernel, respectively (expressed in g per 100 g of dried plant material). The physical and chemical constants, unsaponifiable matter and total fatty acids were determined. The total fatty acid composition of oils was determined by GC in the methyl ester form. Considering the composition and content of fatty acids, the examined kernel oils were very similar. Seven fatty acid components were identified in both oils: palmitic, stearic, arachidic, palmitoleic, oleic, linoleic, and -linolenic. In Q. robur and Q. cerris kernel oils the principal acids were oleic (44.3% and 43.0%, respectively) and linoleic (37.2% and 32.6%, respectively), followed by a significant amount of palmitic acid.Published in Khimiya Prirodnykh Soedinenii, No. 5, pp. 347–348, September–October, 2004.     

Synthesis of <Emphasis Type="Italic">N</Emphasis>-(2-vinyloxyethyl)pyrazoles

Alkylation of pyrazoles with 2,2-dichloroethyl ether under conditions of phase-transfer catalysis was studied. The monoalkylation products of 3(5)-methylpyrazoles at 190–200°C undergo intramolecular cyclization to form bicyclic salts. Conditions for dehydrochlorination of N-[2-(2- chloroethoxy)ethyl]pyrazoles into N-(2-vinyloxyethyl)pyrazoles were found.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1365–1367.Original Russian Text Copyright © 2004 by Attaryan, Martirosyan, Panosyan, Matsoyan.This revised version was published online in April 2005 with a corrected cover date.     

Amperometric determination of live <Emphasis Type="Italic">Escherichia coli</Emphasis> using antibody-coated paramagnetic beads

Detecting and enumerating fecal coliforms, especially Escherichia coli, as indicators of fecal contamination, are essential for the quality control of supplied and recreational waters. We have developed a sensitive, inexpensive, and small-volume amperometric detection method for E. coli -galactosidase by bead-based immunoassay. The technique uses biotin-labeled capture antibodies (Ab) immobilized on paramagnetic microbeads that have been functionalized with streptavidin (bead–Ab). The bead–Ab conjugate captures E. coli from solution. The captured E. coli is incubated in Luria Bertani (LB) broth medium with the added inducer isopropyl -D-thiogalactopyranoside (IPTG). The induced -galactosidase converts p-aminophenyl -D-galactopyranoside (PAPG) into p-aminophenol (PAP), which is measured by amperometry using a gold rotating disc electrode. A good linear correlation (R²=0.989) was obtained between log cfu mL^–1 E. coli and the time necessary to product a specific concentration of PAP. Amperometric detection enabled determination of 2×10⁶ cfu mL^–1 E. coli within a 30 min incubation period, and the total analysis time was less than 1 h. It was also possible to determine as few as 20 cfu mL^–1 E. coli under optimized conditions within 6–7 h. This process may be easily adapted as an automated portable bioanalytical device for the rapid detection of live E. coli.     

Reactions of <Emphasis Type="Italic">N</Emphasis>-aroxycarbonyltrichloroacetimidates with nucleophilic phosphorus derivatives

Aryl N-aroxycarbonyltrichloroacetimidates (Ar = Ph, 4-FC₆H₄) react with diphenylphosphinite according to the scheme of the aza-Perkow reaction to give the corresponding aryl N-(1-aroxy-2,2-dichloro-vinyl)-N-diphenylphosphinoylcarbamates. The structure of one of these compounds was confirmed by single crystal X-ray diffraction analysis. In the case of electron-accepting substituents (Ar = 4-O₂N₆H₄), the primary product undergoes mild -elimination to give nitrophenyl diphenylphosphinate and 1-nitrophenoxy-2,2-dichlorovinyl isocyanate. The reaction of trichloroacetimidates with triethyl phosphite yields a mixture of O- and N-phosphorylation products.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 11, 2004, pp. 1797–1803.Original Russian Text Copyright © 2004 by Rassukanaya, Onysko, Sinitsa, Bolbut, Chernega.This revised version was published online in April 2005 with a corrected cover date.     

Solvolysis of allylic prostaglandin mesylates: moderate 1,3-<Emphasis Type="Italic">syn</Emphasis>-stereoselectivity

The stereochemistry of S _N2 and S _N2 substitutions of the allylic mesyloxy group in mesylates of prostaglandin allylic epimeric 13- and 15-alcohols under the action of various nucleophiles (H₂O, MeOH, AcOH, LiBr) was studied. The substitution accompanied by rearrangement occurs with moderate (1.4–1.6 : 1) syn-stereoselectivity with respect to the configuration of the mesyloxy group, which increases with decreasing temperature and depends only slightly on the nature of the nucleophile.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2510–2518, November, 2004.     

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.     

<Emphasis Type="Italic">In vitro</Emphasis> inhibitory effect of polyoxometalates on human tumor cells

H₇[NiV₁₃O₃₈] was synthesized from K₇[NiV₁₃O₃₈] using an ion exchange method. Then Pr₂H[NiV₁₃O₃₈] was obtained by double decomposition of H₇[NiV₁₃O₃₈] with Pr₂(CO₃)₃. The actual amount of praseodymium measured by elemental analysis coincides with the designed amount of praseodymium in Pr₂H[NiV₁₃O₃₈]. The i.r. spectra suggested that the [NiV₁₃O₃₈]^7– anion did not collapse after the ion exchange and double decomposition. The ⁵¹V n.m.r. spectrum of Pr₂H[NiV₁₃O₃₈] showed four peaks and their ratio of the relative intensity was 4:4:4:1. This result agrees with the chemical environment of V atoms in the [NiV₁₃O₃₈]^7– anion. In vitro antitumor activities of polyoxometalates on several human tumor cells have been investigated using the MTT method. Pr₂H[NiV₁₃O₃₈] is the most effective polyoxometalate tested in this study for inhibiting KB cell. Pr₂H[NiV₁₃O₃₈] also showed remarkable inhibitory effect on some other tumor cells: HCT, Bel, B₁₆, BCAP and ESCL cells. These results indicate that Pr₂H[NiV₁₃O₃₈] is a potent broad spectrum antitumor agent. The structure type of polyoxometalates greatly influences their antitumor activity: the order of structure type for inhibiting KB cell is: [NiV₁₃O₃₈]^7–>[Mo₇O₂₄]^6–>Anderson structure Keggin structure Dawson structure. Moreover, the nature of the polyatom in the polyoxometalates also greatly influences their antitumor activity: the polyatom order for inhibiting KB cell is: V>Mo W. On the other hand, the nature of the counter cation and the heteroatom in the polyoxometalates exerted a relatively small influence on the inhibitory effect against the KB cell, although the praseodymium salt of [NiV₁₃O₃₈]^7– showed a higher antitumor activity than its potassium salt.     

Alkaloids of <Emphasis Type="Italic">Arundo donax</Emphasis> L.

The structure of a new dimeric indole alkaloid, arundarine, isolated from the roots of the plant Arundo donax L. (Poaceae) was determined. On the basis of spectroscopic data, arundarine was identified as 5-[3-(2-dimethylaminoethyl)indol-1-yl]-6-hydroxy-N ²-methyl-1,2,3,4-tetrahydro--carboline.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1697–1699, August, 2004.For Part 14, see Ref. 1.