Anodic oxidation of 9,9′-bifluorenylidene: electrochemical behaviour and physicochemical properties of relevant polymers

The physicochemical properties and electrochemical behaviour of polymers obtained by the anodic oxidation of the 9,9′-bifluorenylidene are presented together with the polymerization conditions.     

Triplet level-dependent photoluminescence and photoconduction properties of π-conjugated polymer thin films doped by iridium complexes

Triplet energy level-dependent decay pathways of excitons populated on iridium (Ir) complexes within π-conjugated polymeric matrices were studied by means of photoluminescence (PL) and photoconduction action spectroscopy. We chose a set of matrices, poly(9-vinylcarbazole) (PVK), poly[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl] (PF2/6), poly [2-(5′-cyano-5′-methyl-hexyloxy)-1,4-phenylene] (CNPPP), and poly [2-(5′-cyano-5′-methyl-hexyloxy)-1,4-phenylene-co-pridine] (CNPPP-py10 and CNPPP-Py20), having triplet energy levels ranging from 2.2 up to 3.0 eV. As Ir-complex dopants, we selected three phosphorescent emitters, iridium(III)bis(2-(2′-benzothienyl) pyridinato-N-acetylacetonate) (Ir(btp)₂acac), iridium(III)fac-tris(2-phenylpyridine) (Ir(ppy)₃), and iridium(III)bis[(4,6-fluorophenyl)-pyridinato-N,C^2′]picolinate (FIrpic), having triplet energy levels of 2.1, 2.5, and 2.7 eV, respectively. It was found that the triplet emission from the dopants, being populated via energy transfer from the matrices, was strongly dependent on the matching of triplet energy levels between matrix polymers and Ir-complexes. Photocurrent action spectra confirm effective exciton confinement at the dopants sites in the case of PVK matrix systems.     

Diinsertion of fluorenylidene into a sulfur-sulfur bond of diaryl disulfides

Upon irradiation (>340 nm) of a benzene solution of diazofluorene with di-p-tolyl- or di-p-anisyl disulfide, the corresponding 9,9′-bis(arylmercapto)bifluorenyl was afforded in moderate to good yield accompanied by formation of 9,9′-bis(arylmercapto)fluorene. The major reaction pathway is considered to be a disulfur ylide formation followed by two times of successive Stevens rearrangement or by concerted electron redistribution via [2,3]sigmatropic rearrangement.     

Congener profile and toxicity assessment of polychlorinated biphenyls in human adipose tissue of Italians and Chileans

Human exposure to polychlorobiphenyls (PCBs) in humans was determined by analyzing adipose tissue samples collected in 1996–1997 from two different localities: Siena (Italy) and Concepción (Chile). ΣPCBs was higher in Italian samples than that from Chile (493 and 53 ng/g wet wt., respectively). Thirty-seven different PCB congeners were identified in all samples. The prevailing PCB congeners in both groups were 22′44′5 pentachlorobiphenyl (IUPAC no. PCB 118), 22′344′5′ (PCB-138) and 22′44′55′ (PCB-153) hexachlorobiphenyls and 22′33′44′5 (PCB-170), 22′344′55′ (PCB-180) and 22′34′55′6 (PCB-187) heptachlorobiphenyls. PCB-153 accounted for more than 20% of the total PCB residue in both groups, while the remaining six congeners accounted for approximately 70%. Hexachlorobiphenyls were the most abundant congeners in all samples, with 42% of total residue in those from Italy and 43% in the Chilean samples, followed by heptachlorobiphenyls with 41 and 36% in Italian and Chilean samples, respectively. Average concentrations of non-ortho substituted coplanar congeners were below 1 pg/g wet wt. In the samples from Siena no noticeable differences were observed between the three average coplanar concentrations, while in those from Concepción 33′44′tetrachlorobiphenyl (PCB-77) was much higher than 33′44′pentachlorobiphenyl (PCB-126) and 33′44′55′hexachlorobiphenyl (PCB-169). For each sample the contribution to the total toxic equivalent values (ΣTEQs) of each non-ortho, mono-ortho and di-ortho substituted PCB congeners was assessed. The overall TEQs calculated for the monitored PCBs, were 10.16 pg/g wet wt. in Italian samples and 1.09 pg/g wet wt. in Chileans ones. In both groups the main contribution to ΣTEQs were the di-ortho substituted PCB congeners (Siena: 6.17 pg/g wet wt.; Concepción: 0.56 pg/g wet wt.) and the mono-ortho substituted PCB congeners (Siena: 3.97 pg/g wet wt.; Concepción: 0.50 pg/g wet wt.).     

Fluorocarbohydrates Part XXV. Synthesis and structure of 2-deoxy-2-fluorolactose and related compounds

Experimental details describing the addition of CF₃OF to hexa- -accetyl- -lactal (I) are presented. Four fluorinated disaccharides: trifluoromethyl 3,6-di- -acetyl-2-fluoro-4- -(2′,3′,4′,6′-tetra- -acetyl-β-D-galactopyranosyl)-β- -mannopyrinoside (V), trifluoromethyl 3,6-di- -acetyl-2-deoxy-2-fluoro-4- -(2′,3′,4′,6′-tetra- -acetyl-β-D-galactopyranosyl)-α- -glucopyranoside (VI), 3,6-di- -acetyl-2-deoxy-2-fluoro-4- -(2′,3′,4′,6′-tetra- -acetyl-β- -galactopyranosyl)-β- -mannopyranosyl fluoride (VII), and 3,6-di- -acetyl-2-deoxy-2-fluoro-4- -(2′,3′,4′,6′-tetra- -acetyl-β-D-galactopyranosyl)-α- -glucopyranosyl fluoride (VIII) were isolated from the product mixture. The profound changes in both the rate and the major products of the addition, compared to those reported for related monosaccharide glycals, are discussed in relation to the steric influence exerted by the presence of the non-reducing (galactoside-B) ring of the disacchride glycals. The configuration and the confirmation of the fluorinated portion of the adducts were assigned on the basis of ¹⁹F.m.r. spectroscopic parameters and the structural     

Hetrocyclic Thiones and Their Analogs in Reactions of 1,3-Dipolar Addition: V. Reactions of 2,3,3-Triphenyl-1-thioxophthalimidine with Nitrile Imines

2,3,3-Triphenyl-1-thioxophthalimidine reacted with nitrile imines along the pattern of [3+2]-cycloaddition affording 2,3,3,3′,5′-pentasubstituted benzo[c]pyrrolidine-1-spiro-2′-(2′,3′-dihydro-1′,3′,4′-thiadiazoles). The reaction is regioselective and involves the exocyclic C=S bond.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 772–775.Original Russian Text Copyright © 2005 by Budarina, Labeish, Bel’skii, Galishev.     

Structure-Property Relationship in Bispyrrolizidine Photochromic Compounds Derived from Indolo[4,5-<Emphasis Type="Italic">e</Emphasis>]- and -[7,6-<Emphasis Type="Italic">g</Emphasis>]indoles

The spirocyclic compounds bis[2′,3′-bis(methoxycarbonyl)-5′,6′,6′ -trimethylspirofluoren-9,4′-(1′-aza-2′-cyclopentene)][1′,5′ -a]indolino[4,5-e]indoline and bis[2-,3′-bis(methoxycarbonyl)-5′,6′,6′ -trimethylspiro-fluoren-9,4′-(1′-aza-2′-cyclopentene)][1′,5′ -a]indolino[7,6-g]indoline exhibit photochromic properties with various half-lifes. The AM1 method was used to correlate the structural and electronic properties, on the one hand, and photochromic properties, on the other, and to explain reasons for the difference in the photochromism of the two compounds.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 670–673.Original Russian Text Copyright © 2005 by Samsoniya, Trapaidze, Tsikoliya, Machaidze, Esakiya.     

Synthesis of 3-(3″-Aminobenzoylamido)-1-(2′,4′,6′-trichlorophenyl)pyrazol-5-one,an Intermediate in the Synthesis of the Purple Component of Color Photographic Materials

Catalytic reduction of 3-(3″-nitrobenzoylamido)-1-(2′,4′,6′-trichlorophenyl)pyrazol-5-one with hydrogen and hydrazine hydrate to 3-(3″-aminobenzoylamido)-1-(2′,4′,6′-trichlorophenyl)pyrazol-5-one, the key intermediate in the synthesis of the purple component of color photographic and motion-picture materials, was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 284–286.Original Russian Text Copyright © 2005 by Yutilov, Smolyar, Minkina.     

C-Glucosylflavonoid biosynthesis from 2-hydroxynaringenin by Desmodium uncinatum (Jacq.) (Fabaceae)

[2′,3′,5′,6′-²H₄]-2-Hydroxynaringenin is synthesised and incubated with commercially available UDP-glucose and the crude protein extract from Desmoduim uncinatum leaves. The organic extract produces isotopically labelled [2′,3′,5′,6′-²H₄]-vitexin and [2′,3′,5′,6′-²H₄]-isovitexin. Repeating the experiment with denatured protein or replacing the 2-hydroxynaringenin with [2′,3′,5′,6′-²H₄]-apigenin or [2′,3′,5′,6′-²H₄]-naringenin results in no observable incorporation. 2-Hydroxynaringenin is therefore the substrate for C-glucosylflavonoid biosynthesis in D. uncinatum.     

Reaction and relaxation of vibrationally excited molecules: a classical trajectory study of Br + HCl(υ′) and Br + DCl(υ′) collisions

a quasiclassical trajectory study has been carried out to investigate the dynamics of collisions between Br + HCl (1 υ′ 4) and Br + DCl (υ′ = 2,3). For HCl (υ′ 2) and DCl (υ′ = 3), the endoergic reaction producing Cl + HBr occurs readily, and at approximately the same rate as vibrational deactivation in non-reactive collisions. For HCl(υ′ = 2) and DCl(υ′ = 3), where the initial vibrational energies are similar to |ΔE₀ for the reaction, the rates of both reactive and inelastic processes are quite strongly temperature dependent but the ratio of reactive to inelastic encounters is not a strong function of T. Comparison of the calculated results for Br + HCl(υ′ = 1) with experimentally determined rates strongly suggests that, at least at low temperatures, removal of HCl(υ′ = 1) by Br atoms occurs predominantly via electronically non-adiabatic vibrational relaxation.     

Synthesis, characterization and crystal structure determination of platinum(IV) complexes containing, bipyridine derivatives and chloride, [Pt(5,5′-dmbipy)Cl4] and [Pt(6-mbipy)Cl4]

The complex [Pt(5,5′-dmbipy)Cl₄] (1) (5,5′-dmbipy is 5,5′-dimethyl-2,2′-bipyridine) was prepared from the reaction of H₂PtCl₆·6H₂O with 5,5′-dimethyl-2,2′-bipyridine in methanol. The same method was employed to make [Pt(6-mbipy)Cl₄] (2) (6-mbipy is 6-methyl-2,2′-bipyridine). Both complexes were characterized by elemental analysis, IR, UV–Vis, ¹H NMR, ¹³C NMR and ¹⁹⁵Pt NMR spectroscopy. Their solid state structures were determined by the X-ray diffraction method.     

Dilactone Formation by Chromic Anhydride Oxidation of the Germacranolide Stizolicin

The sidechain of the germacranolide stizolicin was oxidized by CrO₃ in Py to form a lactone. The structure of the product was established as 4,5α-epoxy-7α,5,6,8β(H)-germacr-1(10),11(13)-dien-8α (3′-oxo-2′,5′-dihydrofuran-3′-carboxylyl)-12,6-olide using spectral data.__________Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 117–118, March–April, 2005.     

Approaches to wired terpyridine: Bithienyl alkynyl derivatives of 2,2′:6′,2″-terpyridine and their ruthenium(II) complexes

Two approaches to the formation of ruthenium(II) complexes containing ligands with conjugated 2,2′:6′,2″-terpyridine (tpy), alkynyl and bithienyl units have been investigated. Bromination of 4′-(2,2′-bithien-5′-yl)-2,2′:6′,2″-terpyridine leads to 4′-(5-bromo-2,2’-bithien-5′-yl)-2,2′:6′,2″-terpyridine (1), the single crystal structure of which has been determined. The complexes [Ru(1)₂][PF₆]₂ and [Ru(tpy)(1)][PF₆]₂ have been prepared and characterized. Sonogashira coupling of the bromo-substituent with (TIPS)CCH did not prove to be an efficient method of preparing the corresponding complexes with pendant alkynyl units. The reaction of 4′-ethynyl-2,2′:6’,2″-terpyridine with 5-bromo-2,2′-bithiophene under Sonogashira conditions yielded ligand 2, and the heteroleptic ruthenium(II) complex [Ru(2)(tpy)][PF₆]₂ has been prepared and characterized.     

Cobalt(II) porphyrazine catalysed reduction of nitrite

Studies on the catalytic reduction of nitrite on carbon electrodes modified with Co(II) tetra-2,3-pyridinoporphyrazine (CoTppa, 1), N,N′,N′′,N′′′-tetramethyltetra-2,3-pyridinoporphyrazine ([CoTm-2,3-tppa]⁴⁺, 2) and Co(II) N,N′,N′′,N′′′-tetramethyltetra-3,4-pyridinoporphyrazine ([CoTm-3,4-tppa]⁴⁺, 3) are reported. There is a close correspondence between the proximity of the methyl groups to the porphyrazine ring and the catalytic activity of the porphyrazine complexes. Bulk electrolysis gave ammonia and hydroxylamine as some of the products. The catalytic activity of the cationic complex, 3, towards the detection of low concentrations of nitrite (<10⁻⁹ M) in water containing sodium sulfate, was compared with the activities of the anionic cobalt(II) tetrasulfophthalocyanine ([CoTSPc]⁴⁻, 4) and the mixed [Co^IITm-3,4-tppa]⁴⁺·[CoTSPc]⁴⁻ (5) complexes. Complex 5 showed the best catalytic activity of the three in that large currents were obtained for very low concentrations of nitrite.     

X-ray Crystal and Ab Initio Structures of 3′,5′-di-O-Acetyl-N(4)-Hydroxy-2′-Deoxycytidine and Its 5-Fluoro Analogue: Models of the N(4)-OH-dCMP and N(4)-OH-FdCMP Molecules Interacting with Thymidylate Synthase

The crystal and molecular structures of the 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine molecule and its 5-fluoro congener have been determined by X-ray single crystal diffraction. The 3′,5′-di-O-acetyl-N(4)-hydroxy-5-fluoro-2′-deoxycytidine molecule crystallizes in the space group C2 with the following unit cell parameters: a = 21.72 Å, b = 8.72 Å, c = 8.61 Å, and β = 90.42^∘. 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine also belongs to the monoclinic space group C2 and the unit cell parameters are: a = 39.54 Å, b = 8.72 Å, c = 22.89 Å, and β = 95.26^∘. The non-fluorine analogue demonstrates a rare example of crystal structure with five symmetry-independent molecules in the unit cell. All the molecules in both crystal structures have the sugar residue anti oriented with respect to the base, as well as have the N(4)-OH residue in cis conformation relatively to the N(3)-nitrogen atom. In addition to the molecular geometries from X-ray experiment, the optimized molecular geometries have been obtained with the use of theoretical ab initio calculations at the RHF/6-31G(d) level. The corresponding geometric parameters in the molecules of 3′,5′-di-O-acetyl-N(4)-hydroxy-2′-deoxycytidine and its 5-fluoro congener have been compared. The differences including the C(5)=C(6) bond shortening and C(4)—C(5)—C(6) angle widening in the fluorine analogue are discussed in this paper in relation to the molecular mechanism of enzyme, thymidylate synthase, inhibition by N(4)-hydroxy-2′-deoxycytidine monophosphate and its 5-fluoro congener.     

Isotachophoretic determination of stability constants of Ho and Y complexes with diethylenetriaminepentaacetic acid and 1,4,7,10-tetraazadodecane-N,N′,N″,N-tetraacetic acid

The method of capillary isotachophoresis with conductivity detection was applied for the determination of the physico-chemical characteristics (conditional stability constants log β′) of holmium and yttrium complexes with DTPA (diethylenetriaminepentaacetic acid) and DOTA (1,4,7,10-tetraazadodecane-N,N′,N″,N-tetraacetic acid). The log β′ determination is based on the linear relation between the stability constants of lanthanide–DTPA (lanthanide–DOTA) complexes and the reduction of the zone of the complex owing to the bleeding phenomena (liberating free metal ion). The stability constants calculated using this relationship are comparable with the literary data obtained by other methods for both holmium (log β′_Ho–DTPA=21.9, log β′_Ho–DOTA=24.5) and yttrium complexes (log β′_Y–DTPA=21.2, log β′_Y–DOTA=24.4). Capillary isotachophoresis was applied for the determination of the optimum composition of the reaction mixture (metal:ligand ratio) as well.     

Synthesis of Tricyclic Spiro Compounds on the Basis of Alloocimene

Cyclization of 2- and 5-(2-methyl-1-propenyl)-3-cyclohexene-1-spiro-1′-cyclopentan-2′-ols and 2- and 5-(2-methyl-1-propenyl)-3-cyclohexene-1-spiro-1′-cyclohexan-2′-ols in the presence of orthophosphoric acid leads to formation of isomeric tricyclic spiro compounds.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 1, 2005, pp. 40–42.Original Russian Text Copyright © 2005 by Balbolov, Skumov, Mitkova.     

Effect of introduction of heterocyclic moieties into polymer backbone on gas transport properties of fluorinated poly(ether imide) membranes

The effects of incorporation of heterocyclic moieties into fluorinated poly(ether imide) membranes on their gas transport properties were investigated. Four novel fluorinated poly(ether imide) (PEI) membranes were prepared from four different bis(ether amine)s namely, 4,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]biphenyl (BAQP); 1,4-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl] benzene (BATP); 2,6-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]pyridine (BAPy) and 2,5-bis[3′-trifluromethyl-4′(4′′-aminobenzoxy)bezyl]thiophene (BATh), and a fluorinated dianhydride, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane (6FDA) as a common dianhydride. Gas transport properties of these membranes were measured to investigate the effect of chemical structure on gas permeation and diffusion processes over four different gases (e.g., CH₄, N₂, O₂ and CO₂) at different temperatures (e.g., 35, 45 and 55 °C) at an applied pressure of 3.5 bar. It has been found that at 35 °C the permselectivities of BAPy and BATh based polymeric membranes (6.4 and 6.6, respectively) toward O₂ relative to N₂ are higher in comparison to BAQP and BATP (5.5 and 5.3, respectively) containing PEI membranes. The permeability coefficient of CO₂ for BAPy and BATh (51.92 and 45.31, respectively at 35 °C) based PEI membranes were observed to be much higher than BAQP and BATP based membranes (36.61 and 33.51, respectively at 35 °C) with comparable selectivity values of CO₂ relative to CH₄. All these membranes exhibit higher CO₂/CH₄ selectivity than those of common glassy polymers e.g., cellulose acetate, polysulfone and polycarbonate. The order of permeability of these gases was found as CO₂ > O₂ > N₂ > CH₄. The temperature dependency of permeation and diffusion processes enables to calculate the activation energies of the permeation and diffusion processes for these four different gases through four PEI membranes.     

5′,8-Cyclopurine-2′-deoxynucleosides: Molecular structure and charge distribution – DFT study in gaseous and aqueous phase

Oxidatively generated damage to DNA frequently appears in the human genome as an effect of aerobic metabolism or as the result of exposure to exogenous oxidizing agents. Due to these facts, it has been decided to present the structural propriety and charge distribution of 5′,8-cyclo-2′-deoxyadenosine/guanosine (cdA, cdG) in their 5′R and 5′S diastereomeric forms. For all points of quantum mechanics studies presented, the density functional theory (DFT) with B3LYP parameters on 6-311++G** basis set level was used. The 2-deoxyribose moiety of cyclopurines has adopted the ₀T¹ conformation in their cationic, neutral and anionic forms. The natural population analysis (NPA) of charge distribution between purine/2-deoxyribose moieties exhibited positive/positive value for cations, positive/negative for neutral molecules. NPA data for anionic forms showed negative/negative values in gas (exclude (5′S)cdG) and positive/negative in water. The dipole moments of 5′,8-cyclopurine-2′-deoxynucleosides were found as follows: 7.83(5′R)cdG, 6.86(5′S)cdG, 3.99(5′R)cdA, 1.99(5′S)cdA in the gaseous phase, 11.29(5′R)cdG, 9.99(5′S)cdG, 6.44(5′R)cdA, 4.14(5′S)cdA in the aqueous phase.     

The Study of <Emphasis Type="Italic">cis-trans</Emphasis> Equilibrium and Complexation with DNA of <Emphasis Type="Italic">meso</Emphasis>-Substituted Carbocyanine Dyes

The effect of DNA was studied on cis-trans equilibrium and spectral and fluorescent properties of a number of meso-substituted carbocyanine dyes: 3,3′-diethyl-9-thiomethylthiacarbocyanine iodide (K1), 3,3′-diethyl-9-methoxythiacarbocyanine iodide (K2), 3,3′-9-triethylthiacarbocyanine iodide (K3), 3,3′-dimethyl-9-ethyloxacarbocyanine iodide (K4), 3,3′-9-triethyl-5,5′-dimethyloxacarbocyanine iodide (K5), and 3,3′,9-triethyl-6,6′-dimethoxyoxacarbocyanine iodide (K6). Equilibrium between the cis and trans isomeric forms was detected for the thiacarbocyanine dyes in a number of organic solvents, with a shift of the equilibrium toward the cis-isomer caused by an increase in the solvent polarity. The oxacarbocyanines are present only in the form of trans-isomers in both polar and nonpolar solvents. Interaction of the dyes with DNA leads to the formation of stable noncovalent complexes. The complexation of the thiacarbocyanine dyes results in a shift of the isomeric equilibrium and occurs predominantly via the cis-form of the dye. The oxacarbocyanine dyes produce complexes with DNA in the initial trans-form.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 4, 2005, pp. 280–286.Original Russian Text Copyright © 2005 by Pronkin, Tatikolov, Anikovskii, Kuz’min.