ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Articles  (95)
  • synthesis  (95)
  • Springer  (95)
  • American Chemical Society
  • 1995-1999  (95)
  • Chemistry and Pharmacology  (95)
  • Nature of Science, Research, Systems of Higher Education, Museum Science
Collection
  • Articles  (95)
Publisher
Years
Year
  • 1
    ISSN: 1572-8870
    Keywords: Phosphazenes ; coordination chemistry ; synthesis ; electrochemical behavior ; transition metal ; cinnamonitrile cyclophosphazene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Hexakist 4-formylphenoxy cyclophosphazene (1) reacts with six equivalents of cyanomethylenetriphenylphosphorane to give hexakist 4-cinnamonitrile cyclotriphosphazene bearing 12 functional groups tsix nitriles and six olefins' able to coordinate up to 12 metals. In this way a series of polynuclear phosphazene metal derivatives (8–12) was prepared with different transition metals and in different oxidation states. Pt(0), Pt(II) and Rh(I). The analogous cinnamonitrile derivatives (3–7) were prepared and used as models for the characterization of corresponding phosphazene compounds. The redox properties of the complexes3–5 and8–10 as well as of the free cinnamonitrile2 and the free substituted cyclophosphazene1 have been investigated by cyclic voltammetry (CV) and controlled potential electrolysis (CPE) in aprotic media (THF, CH2Cl2, or NCMe 0.2M [NBu4][BF4]), at Pt electrodes. Cathodic processes have been detected only when the unsaturated C=C bond of the cinnamonitrile group is uncoordinated: hence, for compounds1. 4. and9. they are irreversible occur at potentialsE p red ca. −1.3 to ca. −1.9V vs SCE which are less cathodic than that exhibited by the free cinnamonitrile (2:E p red ca. −2.0 V vs SCE), and are believed to be centered at the electron-acceptor emptyπ * (C=C) orbital of each of the cinnamonitrile groups present in the molecule. Anodic processes are displayed only by complexes3. 5. 8. and10 with at least one Pt(0) site: they are irreversible, conceivably centered at such a metal center, and occur at potentials (E p bv ca. 0.7 1.2 V vs SCE) which are dependent on the electronic effects of the ligands, in particular the strong electron-withdrawing ability of the cyclophosphazene group. Complex10 undergoes dissociation in NCMe to form9 and possibly solvated [Pt(PPh3)2] species which adsorb at the electrode surface. No evidence for any redox process centered at the phosphazene ring has been found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 5 (1995), S. 123-133 
    ISSN: 1572-8870
    Keywords: Multifunctional polymer ; cyclolinear polycarbosiloxane ; polyvinyldimethylphenylsilane ; polyvinyldimethylchlorosilane ; replacement ; hydrolytic condensation ; synthesis ; characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Controlled synthesis of high molecular weight cyclolinear polycarbosiloxanes (PCCS) is considered, using the following reactions sequence: (1) anionic polymerization of vinyldimethylphenylsilane, (2) replacement of the Ph group in polyvinyldimethylphenylsilane (M n=83.900,M w/M n=1.48) by a Cl group to prepare polyvinyldimethylchlorosilane (PVMCS), and (3) hydrolytic intramolecular condensation of PVMCS. The formation of carbochain polymer with predominantly six-membered carbosiloxane rings is demonstrated (M n=81.400,M w/M n=1.54).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 8 (1998), S. 167-178 
    ISSN: 1572-8870
    Keywords: Poly(1,2-phenylenedithiocarbamate) ; poly(1,2-phenylenedithiocarbamate)–metal complexes ; synthesis ; characterization ; structure ; DC electrical conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Poly(1,2-phenylenedithiocarbamate) (PPDTC) was prepared by the reaction of 2-aminothiophenol with carbon disulfide followed by condensation through the removal of H2S gas. PPDTC was used as a ligand to prepare four poly(1,2-phenylenedithiocarbamate)–metal complexes of iron(II), cobalt(II), copper(II), and lead(II), by refluxing with the metal salts. The polymer and its metal complexes were investigated by elemental analyses, UV–visible and IR spectroscopy, inherent viscosity, and magnetic susceptibility. The DC electrical conductivity variation with the temperature in the range 298–498 K of PPDTC and its polymeric copper complex was measured. Both polymer and polymer metal complexes showed an increase in electrical conductivity with an increase in temperature: typical semiconductor behavior. The proposed structure of the complexes is (MLX2·mH2O) n .
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis surveys from Japan 3 (1999), S. 119-126 
    ISSN: 1572-8803
    Keywords: organozeolite ; microporous and mesoporous material ; inorganic-organic composite ; synthesis ; phosphonate ; aluminomethylphosphonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Attempts in developing organozeolites, namely microporous and mesoporous crystalline inorganic-organic composites with a zeolite-like three-dimensional framework and organic moieties covalently connected to the framework, are briefly reviewed. MCM-41 type mesoporous materials modified by organic functional groups have been prepared by use of organosiloxane as a part of Si sources and by post-modification of the purely inorganic materials using organosiloxane. Also, the incorporation of organic moieties into the zeolite frameworks has been tried. Recently, several novel metal organophosphonates with a three-dimensional framework, which can be regarded as organozeolites, have been prepared. Along with these new attempts, the authors' studies in preparation, structural analysis and gas adsorption properties of microporous aluminomethylphosphonates are introduced.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1572-8773
    Keywords: chrysobactin ; Erwinia chrysanthemi ; immunoassay ; siderophore ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Chrysobactin (α-N-(2,3-dihydroxybenzoyl)-d-lysyl-l-serine), a siderophore that is essential for systemic virulence by plant pathogenic Erwinia chrysanthemi, was synthesized with high diastereomeric purity. Chrysobactin was prepared by coupling the N-hydroxysuccinimide ester of α-N-(2,3-dibenzyloxybenzoyl)-ε-N-Cbz-d-lysine with l-serine benzyl ester followed by deprotection via hydrogenolysis. Optically pure chrysobactin was obtained with 98% overall yield. A monoclonal antibody to ferric chrysobactin was developed and characterized as IgM. The antibody reacts with chrysobactin, ferric chrysobactin and less strongly with ferric dihydroxybenzoic acid. The antibody reacts weakly with the siderophores ferrichrome, A, ferric pseudobactin and ferric rhodotorulic acid. This antibody was used in a competitive immunoassay to detect ferric chrysobactin at 10−8 to 10−10 mol. This immunoassay may provide a useful method for the detection of chrysobactin in plant samples.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 7 (1997), S. 1-18 
    ISSN: 1572-8870
    Keywords: Alternating copolymers ; cis and trans stilbenes and oligomeric dimethylsilylenes ; synthesis ; spectral properties ; photoisomerization and degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of perfectly alternating copolymers containing oligomeric dimethylsilylene and cis or trans stilbene units has been prepared by the condensation polymerization of silyl ditriflates with the corresponding stilbene dianion. As expected, the spectral characteristics and the polymer processability were very different for the isomeric polymers. Evidence of σ–π interaction was obtained from absorption measurements and the excited state of the Si4 catenates was characteristic of a polar charge transfer state. The polymers are all photoactive and irradiation in the long-wavelength absorption band leads to cis–trans isomerization followed by complete disappearance of the long-wavelength (λ〉300 nm) absorption. The latter was not observed for the monomeric model compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inorganic and organometallic polymers and materials 9 (1999), S. 63-77 
    ISSN: 1572-8870
    Keywords: Octamethylcyclo-di(meta-silphenylenesiloxane) ; poly(silphenylene-siloxane) ; synthesis ; X-ray structure ; 4-dimethylaminopyridine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Octamethylcyclo-di(meta-silphenylenesiloxane) 1 (cyclic meta-dimer) was synthesized from 1,3-bis(dimethylhydroxysilyl)benzene 7 in a dilute THF solution, in the presence of a catalytic amount of 4-dimethylaminopyridine (DMAP). In contrast, only small amounts of the cyclic meta-dimer 1, cyclic meta-trimer 2, cyclic meta-tetramer, etc. were obtained when the condensation reaction was carried out with the catalyst n-hexylamine 2-ethylhexoate or sodium hydroxide. The major product in these reactions is polymer 8. The structure of compound 1 was confirmed by X-ray crystallography. This cyclic molecule is most likely unstrained since the X-ray structure reveals that the Si–O–Si bond angle is 142.1(1)° which is similar to that in most unstrained siloxane compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Topics in catalysis 4 (1997), S. 249-260 
    ISSN: 1572-9028
    Keywords: mesoporous materials ; synthesis ; pore size ; activity ; selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The development of ordered mesoporous solids is revised. Acid, base, and redox catalytic properties are presented together with their application for a series of organic reactions of fundamental and practical interest. Finally it is explained that it is possible to make use of the high surface and regular porosity of MCM–41 to prepare supported metals, and bifunctional catalysts. The above properties together with the presence of a large number of surface silanol groups allow the grafting of catalytically active transition metal complexes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1572-8773
    Keywords: Gram-negative bacteria ; inositol ; mycobacteria ; siderophore analog ; synthesis ; tricatecholate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A novel 1,3,5-triamino-myo-inositol derivative ispresented as a readily available scaffold for the design oftripodal siderophore mimetics.Based on this scaffold, various hexadentate catecholate-type siderophoreanalogs weresynthesized by attaching the catechols to the inositol scaffold via spacer units of differentstruc-tureand length. The potential to tune the polarity of the inositol containing siderophoreanalogs has also beendemonstrated by varying the protection group strategy. The siderophoreactivity of the prepared siderophoreanalogs was examined by cross-feeding tests withvarious Gram-negative bacteria and mycobacteria.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 38 (1996), S. 245-249 
    ISSN: 1572-879X
    Keywords: ferri-silicate ; gallo-silicate ; zeolites ; molecular sieves ; synthesis ; mesitylene isomerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ferri- and gallo-silicate analogues of NCL-1, a high silica large pore zeolite, have been synthesized and characterized through spectroscopic methods (XRD, IR, ESR and solid state MAS NMR), ion exchange capacity, adsorption (n-hexane, 1,3,5-trimethylbenzene and water), BET surface area and catalytic activity and selectivity in Brønsted acid catalyzed conversion of 1,3,5trimethylbenzene measurements. These data were compared with those exhibited by Al-NCL-1 analogue. During 1,3,5-trimethylbenzene (mesitylene) isomerization into 1,2,4-trimethylbenzene (pseudocumene), the conversion decreased in the order: Al〉 Ga-〉 Fe-NCL-1 (at the same reaction temperature, WHSV and time on stream). However, the selectivity for pseudocumene and isomerization selectivity (vis-á-vis disproportionation) followed the reverse order at comparable conversion level.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    ISSN: 1572-8803
    Keywords: pyridine bases ; synthesis ; catalyst ; pentasil zeolite ; ZSM-5 ; shape selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Pyridine bases are widely used in pharmaceuticals, insecticides, and herbicides due to their high bioactivity. In this paper, in addition to the conventional synthesis methods for pyridine bases, recent advances in the gas phase synthesis of pyridine bases over the shape selective catalysts (ZSM-5) are described.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 58 (1999), S. 393-401 
    ISSN: 1572-8943
    Keywords: dinuclear Ni(II) complex ; non-isothermal kinetics ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Crystal of the complex Ni2L (ClO4)2 was obtained by reaction of Ni(ClO4)2 and macrocyclic ligand H2L, where L2− is the dinucleating macrocycle with two 2,6-di(aminomethyl)-4-methyl phenolate entities combined by the same two lateral chains, –(CH2)2–NH–(CH2)2–, at the amino nitrogens. The thermal decomposition processes of the title complex were studied in a dynamic atmosphere of dry argon using TG-DTG. The kinetic analysis of the first and second thermal decomposition steps were performed via the TG-DTG curves, and the kinetic parameters were obtained from analysis of the TG-DTG curves with integral and differential methods. The most probable kinetic function was suggested by comparison of the kinetic parameters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 50 (1997), S. 785-793 
    ISSN: 1572-8943
    Keywords: double sulfates ; lanthanides ; synthesis ; thermal studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract On evaporation at room temperature of an aqueous reaction mixture of Ln(III) sulfate and ethanolammonium sulfate in a molar ratio higher than 1∶16, crystal products with a waxy feel were obtained. They were identified by means of the X-ray powder diffraction patterns and it was concluded that they are isostructural. The results of elemental analysis and the mass losses by TG analysis indicated the formation of double sulfates with general formula: (HOCH2CH2NH3)4Ln2(SO4)5·4.5H2O (Ln=La, Ce, Pr or Nd) Their thermal decompositions in static atmosphere in the temperature range from ambient up to 1173 K took place in a similar way, and mainly Ln2O2SO4 was obtained as final product. The exception was the Ce compound, which decomposed to CeO2. The double sulfates decomposed in many not well-differentiated steps. From the mass losses occurring during thermal decomposition, the mode of thermal decomposition was presumed. The X-ray powder diffraction patterns of Ln2O2SO4 (Ln=La, Pr and Nd) show that they are also isostructural.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 285-296 
    ISSN: 1572-8943
    Keywords: alanine ; complexes of rare earth bromides ; synthesis ; TG-DTG ; thermal decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The complexes of rare earth bromides with alanine, REBr3·3Ala·nH2O (RE=Ce, Pr, Sm, Eu, Gd and Tb, n=3; RE=Dy and Y, n=2.5 Ala=alanine), were prepared and characterized by means of chemical analysis, elemental analysis, molar conductivity, thermogravimetry, IR spectra and X-ray diffraction. The thermal decomposition in N2 of these complexes was studied by means of TG-DTG techniques from ambient temperature to 1000°C. During heating, the hydrated complexes of Ce, Pr and Y lose waters in one step, but the hydrated complexes of Sm, Eu, Gd, Tb and Dy lose waters in two steps. Then anhydrous complexes lose 2.5 alanine molecules except the complexes of Eu which lose three alanine molecules. Apparently, only be complex of Eu has an intermediate, EuOBr. All complexes finally decompose to oxides.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 577-584 
    ISSN: 1572-8943
    Keywords: nicotinamide ; phenazone ; synthesis ; thermal decomposition ; zinc complex
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New zinc complex compounds of general formula ZnL2,X2 {X=CI, Br; L=phenazone(phen), nicotinamide(nam)} were synthesized. The new compounds were characterized by elemental analysis, IR spectroscopy and DTA, TG/DTG methods. Thermal properties of the new compounds were investigated. It was found that nicotinamide, phenazone and ZnCl2 or ZnBr2 are released during the thermal decomposition of the compounds. Mass spectroscopy has been used for the determination of the thermal decomposition intermediate products.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    ISSN: 1572-8951
    Keywords: Bichromophoric molecules ; intramolecular energy transfer ; synthesis ; fluorescence ; X-Ray structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The design, structures and spectral properties of a number of bichromophoric molecules are presented. These bichromophoric molecules are composed of an aromatic ring connected by two methylene chains to an α-diketone moiety. Both absorption and emission spectra can be attributed to a superposition of the individual spectra of the separate chromophores. The critical transfer radius for electronic energy transfer from the aromatic (donor) chromophore to the α-diketone (acceptor) chromophore was calculated from the spectral overlap between the fluorescence spectrum of the aromatic moiety and the absorption spectrum of the α-diketone moiety. The results show that this series of molecules is well suited for a mechanistic study of short-range intramolecular electronic energy transfer.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    ISSN: 1572-9001
    Keywords: X-ray structure ; benzoxazine ; synthesis ; potassium channel modulators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract With the aim of discovering new molecules with K+ channel modulating properties, we have synthesized analogues of cromakalim, an important molecule which shows specific affinity toward the K+ channels, by replacing the benzopyrane ring with a benzoxazine moiety. As a part of this study, we have synthesized and characterized, in solution and in the solid state as well, the compound ethyl [2,2-dimethyl-6-(Δ2-thiazolin-2-yl)-4H-l,4-benzoxazin-3-one-4-yl]butyrate (V). This compound exhibits in the solid state the following parameters: molecular formula C19H24N2O4S, triclinic, space group $$P\bar 1$$ , Mw = 376.5, a = 12.581(3) Å, b = 5.485(4) Å, c = 14.612(2) Å, α = 91.85(2), β = 108.9(3), γ = 82.04(4), V = 944.7 Å3, Z = 2, d = 1.323 g·cm−3. We describe here the synthesis and discuss the solid-state conformation of this new molecule; when tested on rat aorta ring precontracted with phenylephrine, the compound showed a concentration-dependent relaxation comparable to that measured for cromakalin taken as reference drug.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 46 (1996), S. 515-520 
    ISSN: 1572-8943
    Keywords: SiO2-aerogel ; synthesis ; thermal stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Aerogels are extremely porous high-tech materials based on inorganic oxides, especially silica. The paper describes synthesis and properties of SiO2-aerogel, and changes occurring during heating of SiO2-aerogel in the temperature range from 20 to 1000°C. Four thermoanalytical methods were used: Thermodilatometry, Differential thermal analysis, Thermogravimetry and Derivative thermogravimetry.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 49 (1997), S. 1255-1261 
    ISSN: 1572-8943
    Keywords: barium cerate ; oxalate coprecipitation ; proton conductor ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The decomposition process of barium, cerium and neodymium oxalates in air was investigated by DTA-TG. Decomposition of an oxalate coprecipitate precursor and formation of barium cerate were examined in air, N2 and CO2 atmospheres, respectively, by employing DTA-TG and XRD. The results showed that, in air, cerium oxalate could easily be decomposed to CeO2 below 350°C and Nd2O3 could be obtained at 670°C, while a high temperature of 〉1400°C was needed to obtain BaO. Although some amount of BaCeO3 was formed at 500°C in air, at 650°C in N2 and at 800°C in CO2, single perovskite phase of BaCeO3 could only be obtained at a much higher temperature.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 173 (1997), S. 1-5 
    ISSN: 1573-4919
    Keywords: human ; cytotrophoblast ; syncytiotrophoblast ; culture ; iso-transferrins ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Transferrin (Tf) mRNA was recently demonstrated in rat and mouseplacental tissue. Rat placental cells were shown to secrete transferrin. Thecell type with which Tf mRNA was associated was not investigated. Wetherefore studied the ability of immunopurified human term cytotrophoblastcells in culture to synthesize Tf, by means of pulse-label experiments with35S-methionine and report that these cells do synthesize Tf. Tf mRNA wasdemonstrated in the cell lysates by means of RT-PCR. Tf isolated fromcytotrophoblast and syncytiotrophoblast cells was shown to be different fromboth maternal and fetal serum Tf with respect to the distribution ofisoforms as demonstrated by means of iso-electric focusing. The iso-electricpoints were found at lower pH values (pH 5.0-5.4), compared to theiso-electric points of maternal and fetal serum Tf, suggesting a higherdegree of sialylation and glycan chain complexity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 1573-4919
    Keywords: apolipoprotein B ; synthesis ; secretion ; clearance ; nonsense ; mutation ; mRNA metabolism ; apoB48
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Low levels of cholesterol are protective against development of coronary artery disease. Heterozygous hypobetalipoproteinemic individuals expressing truncated apolipoprotein (apo)B as a result of mutation in the capob gene have low levels of cholesterol and apoB in their plasma. To study the molecular mechanism of low levels of apoB in these individuals, we employed a previously reported knock out mouse model generated by targeted modification of the apob gene. The heterozygous, apoB-100/B-81, mice express full length and truncated apoB, B-81, and have 20 and 35% lower levels of total cholesterol and apoB, respectively, when compared to WT (apoB-100/B-100) mice. The majority of the truncated apoB, B-81, fractionated in the VLDL- density range. The mechanism of low levels of apoB in B-100/B-81 mice was examined. Total hepatic apoB mRNA levels decreased by 15%, primarily due to lower levels of apoB-81 mRNA. Since apoB mRNA transcription rates were similar in B-100/B-100 and B-100/B-81 mice, low levels of mutant apoB-81 mRNA occurred by enhanced degradation of apoB mRNA transcript containing premature translational stop codon. ApoB synthesis measured on isolated hepatocytes decreased in B-100/B-81 mice by 35%, while apoB-48, apoE, and apoAI syntheses remained unchanged. Metabolic studies using whole animal showed a 32% decrease in triglyceride secretion rates, consistent with the apoB secretion rates. Inhibition of receptor-mediated clearance of apoB-81-containing particles resulted in greater relative accumulation of apoB-81 in plasma than apoB-100, suggesting enhanced clearance of apoB-81-containing particles. These results demonstrate that low levels of apoB in heterozygous hypobetalipoproteinemic mice occurs by low rates of apoB secretion, and increased clearance of truncated apoB. Similar mechanisms appear to contribute to low levels of apoB in hypobetalipoproteinemic humans.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Topics in catalysis 9 (1999), S. 13-34 
    ISSN: 1572-9028
    Keywords: boralites ; synthesis ; characterization ; isomorphous substitution ; boron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis, physico-chemical characterization and catalytic activity of boron-containing molecular sieves (boralites) are reviewed and discussed. Incorporation of boron in the silica framework of several phases has been assessed by structural and spectroscopic evidence. Compared with the aluminosilicate parent compounds, boralites display weaker acid strength sufficient, however, for catalyzing several reactions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Topics in catalysis 9 (1999), S. 59-76 
    ISSN: 1572-9028
    Keywords: synthesis ; silica zeolites ; framework density ; phase selectivity ; connectivity defects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recent advances in the synthesis of all-silica and high-silica crystalline molecular sieves in fluoride media, with special regard to low framework density phases, are presented. The fundamental differences between the synthesis in hydroxide and fluoride media with respect to the properties of the materials obtained and the phase selectivity of the crystallization are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    Springer
    Topics in catalysis 9 (1999), S. 93-103 
    ISSN: 1572-9028
    Keywords: mixed-bonded ; aluminophosphates ; open-framework ; layered ; synthesis ; structure ; hydrothermal ; solvothermal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structural features, the synthesis and the role of templates in the synthesis for mixed-bonded open-framework aluminophosphates and related layered materials will be reviewed in this article. These aluminophosphate materials differ from the (4,2)-connected aluminophosphates and zeolites in that they contain TO5 and/or TO6 primary building units or terminal T-O bonds (T stands for Al or P). The extra ligands for the TO5 and TO6 units in the aluminophosphates with framework Al/P = 1 are either bridging OH groups or H2O molecules in most cases whereas the terminal T-O bonds are either P-OH or P=O species with P=O bonds being prevalent in layered aluminophosphates. Most of TO5 or TO6 containing aluminophosphates are prepared using a cyclic amine or a diamine as the structure directing agent (template), and the aluminophosphates with Al/P〈1 or the layered materials tend to form from an alcoholic medium. Both synthetic conditions and templates play a critical role in determining the composition and structural feature of these materials.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 1573-1561
    Keywords: Eriocrania cicatricella ; Eriocrania sparrmannella ; Eriocraniidae ; Lepidoptera ; sex pheromone ; EAG ; GC-EAD ; mass spectrometry ; synthesis ; evolution ; (Z)-4-hepten-2-one ; (2R)-heptan-2-ol ; (2R)-(Z)-4-hepten-2-ol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Extracts from different body parts of adult femaleEriocrania cicatricella (Zett.) were tested for electrophysiological activity on conspecific male antennae. Extracts from the Vth abdominal segment, containing a pair of exocrine glands, elicited the largest electroantennographic response when compared to extracts of other body parts. Female extracts were analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). The EAD active peaks were identified as (Z)-4-hepten-2-one, (2R)-heptane-2-ol, and (2R)-(Z)-4-hepten-2-ol by coinjection on a gas chromatography and by comparison of mass spectra with those of synthetic standards. In field tests, a blend of these three pheromone components was highly attractive to conspecific males, and a subtractive assay confirmed that the unsaturated alcohol is the major pheromone component, whereas no definite behavioral activity could be assigned to the ketone or the saturated alcohol. A bait containing the two alcohols withS-configuration was attractive to maleE. sparrmannella (Bosc), whereas no males ofE. cicatricella were found in these traps. The sex pheromone compounds inE. cicatricella are chemically similar to pheromones reported in Trichoptera and they are produced in homologous glands.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 1573-1561
    Keywords: Calomyrmex sp. males ; mandibular gland secretion ; 3,5,6-trimethyltetrahydropyran-2-ones ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relative configuration of a δ-lactone isolated from the mandibular gland extracts of Calomyrmex sp. males has been determined to be (3SR,5RS,6SR)-3,5,6-trimethyltetrahydropyran-2H-one after the synthesis of the four possible racemates and comparison of their mass spectra and gas chromatographic properties with those reported in the literature for the natural product.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 831-836 
    ISSN: 1573-4846
    Keywords: aerogel ; silica-zirconia ; synthesis ; sintering ; pore distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A solution of zirconium propoxide stabilized by methoxyethanol is mixed with silicon ethoxide in ethanol and hydrolyzed by small amounts of neutral, basified or acidified water. The obtained silica-zirconia gel is dried in supercritical conditions, yielding an aerogel. The modifications of the aerogel porous texture as a function of chemical composition and thermal treatment are investigated using adsorption-desorption isotherms analysis, mercury porosimetry, electron-microscopy and X-ray diffraction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 8 (1997), S. 831-836 
    ISSN: 1573-4846
    Keywords: aerogel ; silica-zirconia ; synthesis ; sintering ; pore distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A solution of zirconium propoxide stabilized by methoxyethanol is mixed with silicon ethoxide in ethanol and hydrolyzed by small amounts of neutral, basified or acidified water. The obtained silica-zirconia gel is dried in supercritical conditions, yielding an aerogel. The modifications of the aerogel porous texture as a function of chemical composition and thermal treatment are investigated using adsorption-desorption isotherms analysis, mercury porosimetry, electron-microscopy and X-ray diffraction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 15 (1999), S. 201-209 
    ISSN: 1573-4846
    Keywords: sol-gel ; synthesis ; protoenstatite ; 29Si-NMR ; freeze-drying
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Three different magnesium silicate sols were prepared from Mg(OMe)2 and TEOS for which hydrolysis with H2O2 and H2O was under stoichiometric, stoichiometric, or over stoichiometric. Xerogels were prepared from the sols by simple evaporation, spray-drying, or freeze-drying. The freeze-dried precursor formed mostly protoenstatite, a high-temperature polymorph of enstatite (MgSiO3) that is generally not stable at room temperature; the other precursors formed mixtures of protoenstatite and clinoenstatite. The three xerogels and their calcined products were studied with XRD, HTXRD, BET, carbon analysis, TG/DTA and29 Si-NMR. Residual carbon was found to be an important factor in the crystallization, and 29Si-NMR spectroscopy was found to be a better tool than XRD to assess the phase purity of protoenstatite.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    Springer
    Molecular diversity 4 (1998), S. 149-153 
    ISSN: 1573-501X
    Keywords: combinatorial ; cyclic peptides ; cyclization ; dipeptides ; diversity ; macrocycles ; orthogonally protected lysine ; solid phase ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple and efficient synthesis of novel 14-membered macrocycles from a resin-bound orthogonally protected lysine residue is described. Reductive alkylation of the lysine α-nitrogen introduces the first diversity element. Acylation of the resultant secondary amine with an Fmoc-amino acid introduces the second diversity element providing a resin-bound protected di-peptide precursor. Removal of the Fmoc-group is followed by acylation with a succinic anhydride to introduce the final diversity elements. Removal of the methyltrityl-group from the amino group followed by macrocyclization provides the desired macrocycles, after TFA cleavage, in excellent yield and purity.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    ISSN: 1573-9171
    Keywords: stannyl-substituted ; 1-germacyc lope nta- 2,4-diene ; stannyl-substituted 1-germacyclopent-3-ene ; synthesis ; reactivity ; photolysis ; germanium-tin bond cleavage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Previously unknown stannyl-substituted germanium heterocycles, 1, 1 -bis(trimethylstannyl) 2,3,4,5-tetraphenyl-l-germacyclopenta-2,4-dienc and 1,1-bis(trimethylstannyl)-3,4-dimethyl-1-germacyclopent-3-ene were synthesized, and their photolysis and chemical transformations were Studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 163-166 
    ISSN: 1573-9171
    Keywords: palladium ; carbonylphosphine clusters ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Several methods for the synthesis of the Pd38(CO)28L12 cluster (L = PEt3) by treatment of Pd10(CO)12L6 with CF3COOH-Me3NO, CF3COOH-H2O2, Pd(OAc)2-Me3NO, and Pd2(dba)3 mixtures (dba is dibenzylideneacetone) were proposed. The tri-n-butylphosphine analog, Pd38(CO)28(PBu3)12, was synthesized by the reaction of Pd10(CO)14(PBu3)4 with Me3NO. The reaction of Pd4(CO)5L4 with Pd2(dba)3 yields clusters with an icosahedral packing of the metal atoms, Pd34(CO)24L12 and Pd16(CO)13L9.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1929-1932 
    ISSN: 1573-9171
    Keywords: long-chain diacetylenic acids ; N-pyridyl andN-pyrimidylamides of alkanediyni cacids ; long-chain derivatives of nitroxyl radicals ; synthesis ; monolayers ; Langmuir-Blodgett films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Acyl derivatives of 2-aminopyridine, 2-aminopyrimidine, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl were obtained from long-chain diacetylenic acyl chlorides and the corresponding heterocyclic compounds. Spreading isotherms of monolayers on a water surface show that lengthening of the hydrocarbon chain and replacement of the pyridyl groups in these compounds by the more hydrophilic pyrimidyl groups render the films more condensed. Long-chain acyl derivatives of nitroxyl radicals form monolayers possesing a low collapse pressure. ESR spectra of Langmuir-Blodgett films of these radicals before and after photopolymerization were recorded.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    ISSN: 1573-9171
    Keywords: α,β-dehydro-α-amino acids ; Wittig-Horner reaction ; diastereoselectivity ; triethylamine ; (Z)-3-aryl-2-(carbobenzoxyamino)acrylates ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The Wittig—Horner reaction of CbzNHCH(CO2Me)P(O)(OMe)2 (1) with ArCHO (2) in the presence of Et3N as a base affords methyl (Z)-3-aryl-2-(carbobenzoxyamino)acrylates (3) with high degrees of diastereoselectivity (Z)/(E) 〉 10∶∶1. One recrystallization of the crude product is sufficient to obtain isomerically and chemically pure (Z)-3.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 2371-2374 
    ISSN: 1573-9171
    Keywords: silacyclobutanes ; ferrocenyl-derivatives ; 9-carbazolyl-derivatives ; fluoro-derivatives ; synthesis ; polymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis and polymerization of silacyclobutane derivatives with ferrocenyl, 9-carbazolyl, and pentafluorophenyl fragments in substituents have been carried out. The effect of the replacement of H atoms by F in pendant groups of the polysiltrimethylene main chain on the glass transition temperature has been studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 381-383 
    ISSN: 1573-9171
    Keywords: 2-alkoxyhexafluoropropyl-2-isocyanates ; synthesis ; ureas ; carbamates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A convenient preparative method for the synthesis of 2-alkoxyhexafluoropropyl-2-isocyanates is proposed. The reactions of the isocyanates with amines and alcohols are studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1210-1214 
    ISSN: 1573-9171
    Keywords: copper carboxylates ; synthesis ; structure ; discotic mesomorphism ; phase transition ; textures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis, structure, and mesomorphism of a new series of copper carboxylates are described. The influence of periphery of the chelate node on the appearance of discophase is studied. A stacked hexagonal structure of copper erucate is proved. The effect of restructuring of the chelate node in this compound after its isothermic exposure, causing the loss of mesomorphism is revealed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    ISSN: 1573-9171
    Keywords: alkylferrocenes ; alkylferrocenium cations ; synthesis ; cyclopalladation ; micellar media ; electrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Absract Simple methods have been developed for the preparation of a series ofn-alkylferrocenes H(CH2) n Fc (n = 3, 5–8, or 12) based on Friedel-Crafts acylation of ferrocenes followed by reduction of the corresponding ketones with Zn amalgam. The properties of H(CH2) n Fc and the corresponding ferrocenium ions in micellar aqueous solutions and the behavior of water-soluble cations H(CH2) n Fc+ in the absence of micelles were studied by cyclic voltammetry. In all cases, the formal redox potentials of ferrocenes (E o′) increase linearly asn increases up to 8. Whether micelles are present or not, the corresponding correlation equation has the following form:E o′= α + βn, where β = 29 mV in all cases. The synthesis of (±)-1-ethyl-2-methylferrocene from racemic α-dimethylaminoethylferrocene is reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 623-629 
    ISSN: 1573-9171
    Keywords: (S)-prolinol ; chiral 1-amino-1,3-dienes ; generation andin situ transformation ; chiral cyclohexa-1,3-dienes and hexahydronaphthalenes ; synthesis ; monoalkylidenemalonates ; [4+2] cycloaddition ; stereoselectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 3-Methyl- and 3-phenylbut-2-enal in the presence of (S)-prolinol (0.1 eq.) in benzene or THF react with the acidic monoesters of alkenylidene, and arylmethylidene-, and alkylidenemalonic acids at −10 to +22 °C to give optically active esters of 4,6-disubstituted cyclohexa-1,3-diene-l-carboxylic acids in moderate (10–43 %) yields. The enantiomeric purity of the products formed from the lint two types of acidic ylidenemalonates varies from 28 to 68 % and is higher than that observed in the case of related alkylidenemalonates. Under similar conditions cyclohexylideneacetaldehyde affords optically active derivatives of 1,5,6,7,8,8a-hexahydronaphthalene as mixtures ofcis andtrans isomers. The enantiomeric purity and absolute configuration of the cyclohexadienes thus obtained were determined using1H NMR spectroscopy in combination with chiral solvating agents.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 654-661 
    ISSN: 1573-9171
    Keywords: crown ether styryl dyes ; synthesis ; complexation ; anion-“capped” complexes ; [2+2] photocycloaddition ; cyclobutane derivatives ; 1H NMR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract New crown ether styryl dyes (trans-1c,d) containing the 18-crown-6 ether fragment were synthesized. Interaction oftrans-1c,d dyes, as well as their analogs,trans-1a,b containing the 15-crown-5 ether fragment, with Ca(ClO4)2 in MeCN afforded supramolecular structures (dimeric complexes). Competing reactions,trans-cis-photoisomerization with the formation of anion-“capped” complexes ofcis-1a—d and [2+2] autophotocycloaddition with the formation of cyclobutane derivatives8a—d and9c, were observed on photolysis of solutions of complexes oftrans-1a—d with Ca2+. Preorganization oftrans-isomers in dimeric complexes with Ca2+ determined the regio- and stereoselectivity of each of the two directions of the photocycloaddition and the efficiency of the reaction.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 667-670 
    ISSN: 1573-9171
    Keywords: long-chain 2-alkadiynylpyridines ; synthesis ; Langmuir-Blodgett films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four pathways of synthesis of 1-(2-pyridyl)heptacosa-12,14-diyne, using 10-bromodecan-1-ol and acetylene or tetradec-1-yne and 2-methylbut-3-yn-2-ol along with α-picoline as initial compounds, were studied and compared. It was shown that direct introduction of a completely formed unsaturated hydrocarbon chain into an α-picoline molecule by alkylation of its lithium derivative is the most appropriate method for preparation of long-chain 2-alkadiynylpyridines.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 1573-9171
    Keywords: ansa-zirconocene dichlorides ; synthesis ; molecular structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A mixture ofrac- andmeso-2,2′-propylidene-bis(η5-indenyl)zirconium dichlorides was obtained in 95% yield. The compounds were separated, and their structures were established by X-ray structural analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    ISSN: 1573-9171
    Keywords: sodium alkyls ; lithium alkyls ; NMR ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 1H,23Na, and7Li NMR spectra of 2-ethyl hexylsodiurn, 2-ethylhexyllithium, and isobutyllithium obtained in the reaction of the corresponding alkyl chlorides and metals have been recorded. The1H N MR signal for the protons of the CH2Na group is shifted upheld compared with that for the protons of the CH2Li group (doublets at δ -0.88 and δ -0.83, respectively). The composition of the products of reaction of 2-ethylhexyl chloride with sodium depends on the form of the metal reagent employed. The use of sodium balls with diameter up to 2 mm results in the formation of products containing ionic chlorine (30–50 % with respect to Na); the reaction with the dispersion proceeds faster and the reaction product is chlorine-free. The23Na NMR spectra of these substances are also different, which is explained by the formation of 2-ethylhexylsodium complexes with NaCl in the former case.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 901-910 
    ISSN: 1573-9171
    Keywords: carbofunctional silacyclobutanes ; alcohols ; trimethylsilyl ethers ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A four-step synthesis of 1-(ω-ydroxyalkyl)- and 1-(4-hydroxyphenyl)silacyclobutanes was carried out. The influence of the structure of the initial compounds and the reaction conditions on the ratio of the reaction products formed was studied. The stability of the silacyclobutane alcohols and the hydrolysis of their trimethylsilyl ethers were investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 911-913 
    ISSN: 1573-9171
    Keywords: carbofunctional silacyclobutanes ; alcohols ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Speier rearrangement was used for the synthesis of l-(ω-hydroxyalkyl)- and l-(4-hydroxyphenyl)silacyclobutanes.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    ISSN: 1573-9171
    Keywords: 2-nitroethanol ; sodium salt ; 2-oxo-3-hydroxypropionic acid oxime ; sodium salt ; 2-bromo-2-nitropropane-1,3-diol ; 2,2-dinitropropane-1,3-diol ; synthesis ; X-ray analysis ; molecular structure, stereochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel reaction of the sodium salt of 2-nitroethanol in aqueous ammonia resulted in the sodium salt of 2-oxo-3-hydroxypropionic acid oxime (1) has been found. Bromination of1 affords 2-bromo-2-nitropropane-1,3-diol (2) with a previously unknown molecular conformation. The formation mechanisms of compounds1 and2 were suggested. X-ray analysis of products1,2 and that of the model compound, 2,2-dinitropropane-1,3-diol, was performed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    ISSN: 1573-9171
    Keywords: metallofullerenes ; synthesis ; chirality ; platinum ; cluster ; electronic absorption spectra ; 31P NMR spectra ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel optically active exo-metallofullerene derivative, η2-C60Pt[(+)-DIOP] (1) (DIOP is 2,3-o,o'-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphinobutane)), is formed as a result of the cleavage of the chelate metallocycle in Pt[(+)-DIOP]2 and the substitution of the bidentate (+)-DIOP ligand with C60. Cluster 1 was also obtained by replacement of the phosphine ligands in η2-C60Pt(PPh3)2 by (+)-DIOP. Compound 1 was identified by its electronic absorption spectra,31P NMR spectra, and the elemental analysis data. A singlecrystal X-ray study of the 1 cyclooctene solvate, η2-C60Pt[(+)-DIOP] C8H14 was performed. Packing of the fullerene cores in a crystal of 1 · C8H 14 corresponds to the diamond structure subjected to the significant orthorhombic distortions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 1232-1234 
    ISSN: 1573-9171
    Keywords: sterically hindered 2-propargyl-1,3-diketones ; aminomethylation ; synthesis ; copper(1) ; catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract 2-Propargyl-substituted methoxy-1,3-diketones react with alkoxymethylamines or paraform and secondary amines in the presence of CuCl at the acetylene group to afford Mannich bases.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 1490-1491 
    ISSN: 1573-9171
    Keywords: carborane-containing ketones and enols ; synthesis ; isoncrization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A carborane-containing stable simple enol — 1-2-isopropyl-o-carboran-I-yl)-1-phenyl2-mesityl-2-lrydroxyctlrylcne — has been synthesized. This enol does not isomerize to the starting ketone or keto-enol mixture even after prolonged heating in benzene in the presence of CF3COOH.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    ISSN: 1573-9171
    Keywords: arenecyclopentadienyl complexes of ruthenium ; synthesis ; electrochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of are necyc lope ntadienyl complexes,i. e., [Ru(η5-c5R5)(η6- are ne)]+ (1, R= H, arene = C6H6; 2, R = Me, arme = C6H6; 3, R = H, arctic = C6H3Me3; 4, R = Me, arene = C6H3Me3; 5, R = H, arene = C6Me6; 6, R = Me, arene = C6Me6) was studied by cyclic voltammetry. These compounds are capable of both oxidation and reduction. The reduction potential values depend on the number of methyl groups in the complex. Reduction of benzene complexes I and 2 by sodium amalgam in THF leads to the formation of decomplexation products, the addition of hydrogen to benzene, and dimerization of the benzene ligands. Both chemical and electrochemical reductions of mesitylene complexes3 and4 result in dimeric products [(η5-C5R5)Ru(μ-η5;η5-Me3H3C6H3Me3)Ru(η5-C5R5)] (14, R = H; 15, R = Me). The action of sodium amalgam on compound5 gives products of hydrogen addition to both hexamethylbenzene (17) and cyclopentadienyl (18) ligands along with the major product, the dimer [η5-C5H5)Ru(μ-η5; η5-Me6C6C6Me6)Ru(η5-C5H5)] (16). In contrast to5, its permcthylated analog 6 is only capable of adding hydrogen to the hexamethylbenzene ligand.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 1952-1954 
    ISSN: 1573-9171
    Keywords: reactivity ; synthesis ; (N,N-difluoroamino)dinitroacetonitrile ; 5-[(N,N-difluoroamino)dinitromethylltetrazole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High reactivity of the nitrite group in (NN-difluoroamino)dinitroacetonitrile was demonstrated. Based on its reaction with HN3, a new preparative method for the synthesis of 5-[(N,N-difluoroamino)dinitromethylltetrazole was developed; some derivatives of the latter compound have been obtained.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    ISSN: 1573-9171
    Keywords: tetraphenylantimony hydrogen phthalate ; synthesis ; X-ray structural study ; molecular structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Tetraphenylantimony hydrogen phthalate, Ph4SbOC(O)C6H4000H-o, was prepared by the reaction of pentaphenylantimony with phthalic acid. According to the data of X-ray structural analysis, the resulting compound is a trigonal-bipyramidal complex of antimony with three phenyl groups in equatorial positions; the fourth phenyl group and the carboxyl fragment are in axial positions. The CSbO angle is 177.5(1)° the Sb-C(Ph)eq and Sb-C(Ph)ax distances are 2.099(4)-2.177(4) A and 2.129(4) A, respectively. The H atom of the free carboxyl group and the carbonyl O atom of another carboxylate group form an intramolecular hydrogen bond.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    ISSN: 1573-9171
    Keywords: trinuclear iron carboxylate complexes ; synthesis ; X-ray structural analysis ; spectroscopy ; cyclic voltammetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reactions of iron(m) salts with a new bidentate ligand, which is potentially capable of forming binuclear iron complexes upon complexation, were studied. Under various conditions, we succeeded in isolating only the trinuclear cationic complex (FeIII 3(O2CR)6(μ3-)17+ (1), where RCO2 is 2-(pyrid-2-ylmethoxy)benzoic acid protonated at the pyridyl moiety. The structure of 1 was established by spectral, magnetic, and X-ray structural studies. Cyclic voltammetry in McCN in the temperature range from -35 to 20 °C demonstrated that 1 undergoes successive FeIII→FeII reduction in three one-electron stages, which is indicative of the electronic interaction between iron atoms in the complex.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 2018-2019 
    ISSN: 1573-9171
    Keywords: trimethylarsine ; trimethylaluminum ; synthesis ; ecological safety
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A convenient, highly efficient, and environmentally safe procedure for the preparation of trimethylarsine was proposed. A quantitative yield of this compound in the reaction of As2O3 with AIMe3 was attained for the first time by using mechanochemical activation of the process.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1903-1906 
    ISSN: 1573-9171
    Keywords: (+)-4α-(1-trimethylsilyloxyethen-1-yl)-2-carene ; (+)-4α-acetyl-2-carene ; synthesis ; ozonization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract (+)-4α-(1-Trimethylsilyloxyethen-1-yl)-2-carene was synthesized, and the products of its ozonization were identified.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1952-1954 
    ISSN: 1573-9171
    Keywords: synthesis ; hypercoordinated organogold(I) compound ; secondary bonds ; diphenylmethane ; X-ray diffraction analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cyclic organogold $$| \overline {Au(o - C_6 H_4 )CH_2 (C_6 H_4 - o)Au(\mu - PPh_2 CH_2 CH_2 } \mathop P\limits^| Ph_2 )$$ complex, containing an Au...Au bond, was prepared by reaction of Ph3PAu(o-C6H4)CH2(C6H4-o)AuPPh3 with dppe. The length of the carbon bridge of the diphosphine ligand, optimal for formation of the Au...Au bond, was preliminarily determined using molecular simulation. The structure of the complex obtained was determined by X-ray diffraction analysis and by MS,1H NMR, and31P NMR.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1970-1970 
    ISSN: 1573-9171
    Keywords: tantalocene ; hydride ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Modified method for preparation of Cp2TaH3 by reaction between TaCl5, CpNa, and LiAlH4 in dimethoxyethane is described: The yield of Cp2TaH3 is 25 %.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 305-309 
    ISSN: 1573-9171
    Keywords: Key words ; (+)-3-carene ; dimethyl ester of (-)-(1R)-cis-homocaronic acid ; dimethyl ester of (+)-(1S)-cis-homocaronic acid ; synthesis ; ozonolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The syntheses of the dimethyl ester of (-)-(1R)-cis-homocaronic acid (7 steps, overall yield 43 %) and its antipode, the dimethyl ester of (+)-(1S)-cis-homocaronic acid (5 steps, overall yield 27 %), were performed starting from (+)-3-carene and its derivatives, (+)-4α-acetyl-2-carene and (+)-4α-acetoxymethyl-2-carene. Oxidative cleavage in the key stages was carried out by ozonization.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 1084-1086 
    ISSN: 1573-9171
    Keywords: pseudocyanines ; N-acryloyloxyethyl andN-alkyl derivatives ; quinolinium salts ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new method for synthesis of 1-[(2-acryloyloxyethyl)- and 1-[(2-propenyl)-2-(2-(1H)-quinolidene)-methyl]-1-ethylquinolinium iodides was proposed. The structures of the dyes obtained were studied by1H NMR spectroscopy.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    ISSN: 1573-9171
    Keywords: hydrosilanes ; amines ; N-siloxycarbonylation ; carbon dioxide ; O-silylurethanes ; synthesis ; hexamethyldisilazane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of hydrosilanes with carbon dioxide and secondary amines or silylamines was studied for the first time. The dependence of the composition and the structure of the products obtained on the nature of the reagents and on the reaction conditions was found. The hydrosilane-carbon dioxide system, unknown previously, can be used as anN-siloxycarbonylating reagent in the synthesis ofO-silylurethanes. A scheme for the formation ofO-silylurethanes was proposed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 2196-2198 
    ISSN: 1573-9171
    Keywords: 4,4′-thiodiphenol ; diamide of phenylphosphonous acid ; crown ethers ; synthesis ; oligothioarylenecyclophosphonites ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new representative of phospho(scIII)crown ethers was obtained based on 4,4′-thiodiphenol and tetraethyldiamide of phenylphosphonous acid. Thiaphospho(III)crown ethers can be prepared by different methods depending on the ratio of the initial reactants and the reaction conditions. The structures of the compounds obtained were confirmed by spectroscopic data and X-ray structural analysis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    Electronic Resource
    Electronic Resource
    Springer
    Glycoconjugate journal 16 (1999), S. 197-203 
    ISSN: 1573-4986
    Keywords: gangliosides ; synthesis ; GM3 ; GD3 ; lactones ; Ganglioside ; glycosphingolipid nomenclature ; LacCer, β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GM3, II3-α-Neu5AcLacCer, α-Neu5Ac-(2-3)-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GD3, II3(-α-Neu5Ac)3LacCer, α-Neu5Ac-(2-8)-α-Neu5Ac-(2-3)-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GM2, II3-α-Neu5AcGg3Cer, β-GalNAc-(1-4)-[α-Neu5Ac-(2-3)]-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; Gg4Cer, β-Gal-(1-3)-β-GalNAc-(1-4)-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GM1, II3-α-Neu5AcGg4Cer, β-Gal-(1-3)-β-GalNAc-(1-4)-[α-Neu5Ac-(2-3)]-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GM1-lactone, β-Gal-(1,3)-β-GalNAc-(1-4)-[α-Neu5Ac-(2-3,1-2)]-β-Gal-(1-4)-β-Glc-(1-1)-Cer ; GD1b, II3(-α-Neu5Ac)2 Gg4Cer, β-Gal-(1-3)-β-GalNAc-(1-4)-[α-Neu5Ac-(2-8)-α-Neu5Ac-(2-3)]-β-Gal-(1-4)-β-Glc-(1-1)Cer ; GD1b-dilactone, β-Gal-(1-3)-β-GalNAc-(1-4)-[α-Neu5Ac-(2-8, 1-9)-α-Neu5Ac-(2-3, 1-2)]-β-Gal-(1-4)-β-Glc-(1-1)-Cer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple procedure is described for preparing GM3 ganglioside, from a few milligrams to grams, from GM1-lactone (Sonnino et al., (1985) Glycoconjugate J 2: 343–54) [1]. The synthesis was carried out under the following optimal conditions: 30 mM GM1-lactone in 0.25 M H2SO4 in DMSO, 30 min, 70°C, nitrogen atmosphere, strong stirring. The yield of GM3 was 55%. The procedure applied to milligram amounts of GD1b-dilactone gave GD3 ganglioside.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    ISSN: 1573-4986
    Keywords: glycosaminoglycan ; pentasaccharide serine ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel pentaosyl serine; GalNAcα(1–4)GlcAβ(1–3)Galβ(1–3)Galβ(1–4)Xylβ(1–3)Ser (2), a putative intermediate of chondroitin sulfate and/or heparan sulfate biosynthesis, was synthesized.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 1573-4986
    Keywords: Glycoside ; synthesis ; cancer ; hexamethylmelamine ; methylol ; formaldehyde ; modelling ; deacetylation ; triazine ; N-hydroxymethyl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of analogues of the anti-tumour drug 2-[N-(hydroxymethyl)methylamino]-4,6-bis (dimethylamino)-1,3,5-triazine (HMPMM) in which the OH or a dimethylamino group is replaced by a carbohydrate has been explored. Triazinyl β-glycosides were readily prepared by reaction of sugars with trimethyl-triazinylammonium salts. These were made with one or two methylamino groups on the triazine for reaction with formaldehyde to give the cytotoxic NMeCH2OH group. However, reaction of the triazinyl glycosides with formaldehyde gave complex intractable mixtures. When the carbohydrate portion was changed to the fully protected 2,3,4,6-tetra-O-acetyl glucose a good yield of the 2-[N-(hydroxymethyl)methylamino]-4-(dimethylamino)-1,3,5-triazin-2-yl tetra-O-acetyl β-glucoside was obtained. However, de-acetylation using sodium methoxide also removed the N–CH2OH group. We are investigating protection of the base-sensitive N–CH2OH group as trialkylsilyl and benzyl ethers and are looking at de-acetylation methods that are more selective. We have prepared glycosides in which the sugar is joined through the oxygen of the NMeCH2OH group. Coupling of acetobromoglucose with HMPMM catalysed by silver salts was not successful. Although methyl and cyclohexyl derivatives of HMPMM may be produced in high yields by reaction of HMPMM with methyl and cyclohexyl alcohols under acidic catalysis, production of glycosides in this way gave poor yields. MNDO calculations on reactions of HMPMM helped us devise improved reaction conditions for the condensation of 2,3,4,6-tetra-O-acetyl glucose with HMPMM and its derivatives. The best procedure to generate one of the target glycosides is to react 2,3,4,6-tetra-O-acetyl glucose and formaldehyde with 2-methylamino- 4,6-bis(dimethylamino)-1,3,5-triazine. The β-glycoside product was de-acetylated using potassium carbonate in dry methanol. Abbreviations: HMM, hexamethylmelamine (2) or 2,4,6-tris(dimethylamino)-1,3,5-triazine; HMPMM, hydroxymethylpentamethylmelamine or 2-[N-(hydroxymethyl)-methylamino]-4,6-bis(dimethylamino)-1,3,5-triazine; PMM, Pentamethylmelamine or 2-methylamino-4,6-bis(dimethylamino)-1,3,5-triazine; TBMS, t-Butyldimethylsilyl; p-TSA, p-Toluenesulphonic acid
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    ISSN: 1573-4854
    Keywords: mesoporous silica ; hexagonal phase ; synthesis ; room temperature ; inorganic silicate sources ; acidic medium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The room-temperature synthesis of mesoporous silica was investigated by using cationic surfactants and inorganic Si sources, like sodium silicate and colloidal silica. Mesoporous silica analogous to the hexagonal MCM-41 could be obtained over a wide range of pH below ca. 11 within short synthesis time (3 h), when the Q4-state Si was absent in the Si source solution prior to mixing with an aqueous solution of cationic surfactants. It was suggested that the strongly acidic conditions (pH 〈 1) were favorable to give mesoporous silica materials with higher surface area and larger mesopore volume.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    ISSN: 1573-4986
    Keywords: E-selectin ; P-selectin ; sialyl dimeric Lex ; glycolipid ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The first total synthesis of glycononaosyl ceramide with a sialyl dimeric Lex sequence 1 is described. Regio- and stereo-selective glycosylations of sialyl donors 6,7,8 with the suitably protected Lex trisaccharide acceptors 9,10β were performed to give the expected tetrasaccharides 15 and 21, which were converted into the corresponding donors 20 and 22. Boron trifluoride etherate-promoted glycosylation of 20 with pentasaccharide acceptor 11 afforded regioselectively the expected nonasaccharide 23. After replacing benzyl groups of 23 by acetyl groups, the anomeric acetate was transformed into the α-trichloroacetimidate 27. The crucial coupling between 27 and (2S, 3R, 4E-3-O-benzoyl-2-N-tetracosanoylsphingenine 3 was executed to afford completely protected β-glycoside 28. Finally, selective cleavage of the methyl ester and N,O-deprotection of 28 gave the target ganglioside 1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    ISSN: 1573-4986
    Keywords: glycopeptide ; synthesis ; T cell ; immune response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The 2-bromoethyl β-glycosides of the disaccharide galabiose [Gal(α1-4)Gal] and the trisaccharides globotriose [Gal(α1-4)Gal(β1-4)Glc] and 3′-sialyllactose [Neu5Ac(α2-3)Gal(β1-4)Glc] have been prepared by improved routes. The 2-bromoethyl glycosides were then used in cesium carbonate promoted alkylations of the sulfhydryl groups of cysteine and homocysteine residues in T cell stimulating peptides. This convergent and general approach was used to prepare 16 neoglycopeptides which were obtained in 52–95% yields after purification by HPLC. 1H NMR spectroscopy revealed that β-elimination and epimerization of neoglycopeptide stereocentres did not occur during the synthesis.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    ISSN: 1573-4986
    Keywords: heparin biosynthesis ; carbohydrates ; sulfated disaccharides ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of the disaccharides methyl 4-O-(2′/3′-O-sulfo-β-d-glucopyranosyluronic acid)-2-amino-2-deoxy-α-d-glucopyranoside3 and4 as, disodium salts is described. Allyl 4,6-O-benzylidene-α-d-glucopyranoside6 was converted to trichloroacetimidate20 Glycosylation of20 with5 promoted by BF3·OEt2 gave disaccharide21. Deacetylation of21 followed by monoacetylation of the resultant diol22 afforded the two monoacetylated disaccharides23 and24. Sulfation and deprotection of each disaccharide gave the desired sulfated compounds3 and4.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    ISSN: 1573-4986
    Keywords: CMP-Neu5Ac analogues ; synthesis ; sialyltransferase inhibitors ; sialyltransferase assay ; α(2-6)-sialyltransferase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Quinic acid (4) was transformed into phosphitamides 6, 14, and 15, which could be readily linked to 5′-O-unprotected cytidine derivative 7; ensuing oxidation of the obtained phosphite triesters with tert-butylhydroperoxide furnished the corresponding phosphate triesters 8, 16, and 17, respectively. Hydrogenolytic debenzylation of the phosphate moiety, base catalysed removal of acetyl protective groups, and basic hydrolysis of the methylester of the quinic acid moiety furnished CMP-Neu5Ac analogues 1-3. In order to measure their inhibition of sialyltransferases, a nonradioactive sialyltransferase assay [employed for α(2-6)-sialyltransferase from rat liver (EC 2.4.99.1)] based on reversed-phase HPLC separation of UV-abelled acceptor 20 (p-nitrophenyl glycoside of N-acetyllactosamine) from the UV-labelled product 21 (p-nitrophenyl glycoside of sialyl α(2-6′)-N-acetyllactosamine) and p-nitrophenylalanine as internal standard was developed. The assay reproduced the reported KM values for CMP-Neu5Ac and N-acetyllactosamine and the Ki values for CDP. 1 and 2 turned out to be potent sialyltransferase inhibitors. © 1998 Rapid Science Ltd
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    ISSN: 1573-4986
    Keywords: enzymic sialylation ; glycosphingolipid ; GM3 ; GM3 analog ; lyso-GM3 ; lyso-GM3 analog ; modified polyacrylamide ; photolysis ; polymer support ; sialyltransferase ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two water-soluble polymers, carrying 0.24 meq g−1 of lactosyl-β(1-1)-sphingosine (7) and 0.13 meq g−1 of lactosyl-β(1-3)-sphingosine (8) were prepared. The polymers served as acceptors in the α-(2-3)-sialyltransferase reaction (up to 55.3 and 38.5% transfer yields, respectively). Subsequent photolysis, released compounds 11 (lyso-GM3) and 12 (lyso-GM3 analog), respectively; acylation and chromatography afforded (5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2-3)-β-D-galactopyranosyl-(1-4)-β-D-glucopyranosyl-(1-1)-(2S, 3R, 4E)-2-octadecanoylamino-4-octadecene-1,3-diol (13, GM3) and (5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2-3)-β-D-galactopyranosyl-(1-4)-β-D-glucopyranosyl-(1-3)-(2S, 3R, 4E)-2-octadecanoylamino-4-octadecene-1,3-diol (14, GM3 analogue), respectively, thus presenting a route to glycosphingolipids possessing the unusual glycosyl-β(1-3)-spingosine linkage.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 1573-1561
    Keywords: Eriocrania semipurpurella ; Eriocrania sangii ; Eriocraniidae ; Lepidoptera ; sex pheromone ; GC-EAD ; chiral gas chromatography ; mass spectrometry ; synthesis ; field trapping ; nonan-2-one ; (Z)-6-nonen-2-one ; (2S,6Z)-nonen-2-ol ; (2R,6Z)-nonen-2-ol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The fifth abdominal segment of femaleEriocrania semipurpurella (Stephens) andE. sangii (Wood) contains a pair of exocrine glands. Hexane extracts of this segment were prepared from both species and analyzed by gas chromatography with simultaneous flame ionization and electroantennographic detection (EAD). For both species, the EAD active peaks were identified as nonan-2-one, (Z)-6-nonen-2-one, and (Z)-6-nonen-2-ol by means of mass spectrometry and comparison of retention indices with those of synthetic standards. Enantiomeric separation of chiral alcohols from the female extracts was achieved by gas chromatographic analysis on a cyclodextrin column. InE. semipurpurella, a mixture of (2S,6Z)-nonen-2-ol and (2R,6Z)-nonen-2-ol (2: I) was found, whereas inE. sangii (2S,6Z)-nonen-2-ol was the predominant enantiomer and only traces of theR enantiomer were indicated by the antennal response. In field tests, a blend of the three compounds was not attractive to conspecific males. A subtractive assay showed that the alcohol in various enantiomeric mixtures was the only attractive compound, whereas addition of (Z)-6-nonen-2-one to the alcohol completely inhibited the attraction of both species. A trapping experiment including a wide range of ratios between theR andS enantiomers showed that baits containing 95–100% of theS enantiomer were attractive to maleE. sangii, whereas males ofE. semipurpurella were attracted to all tested ratios of the enantiomers. However, the response profiles of maleE. semipurpurella differed between populations from southern Sweden, south Finland, and the Kola Peninsula in Russia. In south Sweden males were maximally attracted to a racemic mixture of the alcohols. At the Kola PeninsulaE. semipurpurella was attracted to baits containing 95–100% of theR enantiomer. In south Finland all tested ratios between 0 and 100%R enantiomer trappedE. semipurpurella, but the trap catches appeared to be bimodally distributed with peaks around 15 and 70%R enantiomer. The trapping results suggest the existence of pheromone races or sibling species among the specimens identified asE. semipurpurella.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 33 (1999), S. 459-467 
    ISSN: 1573-1111
    Keywords: cyclodextrin derivatives ; cyclodextrin glycerol ethers ; synthesis ; complexation ; solubilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Epichlorohydrin was reacted with cyclodextrins to form the non-cyclic and cyclic glycerol ethers of β- and γ-cyclodextrin (abbreviated as glyc-CD). Cyclic substitution extends the cyclodextrin cavity in a way that is as rigid and non-polar as the cavity of the parent cyclodextrin. Derivatives with extended cavities should better accommodate large or odd shaped molecules. The binding of drugs to the new cyclodextrin derivatives was investigated, through degradation rate studies and solubilization studies, and compared to that of β-cyclodextrin, γ-cyclodextrin and hydroxypropyl-β-cyclodextrin. The inclusion binding of small molecules such as acetazolamide, ethoxyzolamide and chlorambucil, in the glyc-CDs was either increased or decreased compared to the other cyclodextrins. However, larger molecules, such as indomethacin and hydrocortisone, always bound better to the glyc-CDs with up to 180% increase in the stability constant. The degradation rate within the cyclodextrin cavity was not affected by the above derivation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 21 (1995), S. 1745-1762 
    ISSN: 1573-1561
    Keywords: beaver ; Castor canadensis ; castoreum ; neutral compounds ; monoterpenes ; co-injection ; fractionation ; identification ; synthesis ; territory marking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract North American beavers (Castor canadensis) mark their territories with castoreum, the strong-smelling paste in their castor sacs. In their own territories, beavers respond with scent marking to experimental scent marks that consist of strange castoreum (or selected components). In part, the unique odor of castoreum is due to large amounts of phenolic compounds and neutral compounds. Purified neutral compounds were analyzed by GC. GC-MS, and NMR; identities of the neutral compounds were confirmed by comparing the properties of authentic compounds with those of the isolated compounds. We identified 13 neutral compounds that had not been reported before for castoreum. Most of these are oxygen-containing monoterpenes. Of the nine neutral compounds reported by Lederer (1949), only three are confirmed in our analysis; the other six neutral compounds are either absent or are not volatile enough to be detected by our methods. Eight compounds—6-methyl-l-heptanol, 4,6-dimethyl-l-heptanol, isopinocamphone, pinocamphone, two linalool oxides, and their acetates—were synthesized for structure identification and bioassays.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 1435-1536
    Keywords: Key words Conducting polymer ; polypyrrole ; silica ; nanocomposite ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The effect of varying the oxidant, monomer and silica sol concentrations, silica sol diameter, polymerization temperature, stirring rate and oxidant type, on the particle size, polypyrrole content and conductivity of the resulting polypyrrole– silica colloidal nanocomposites has been studied. Surprisingly, nanocomposite formation appears to be relatively insensitive to most of the above synthesis parameters. One synthesis parameter which does have a significant and reproducible effect is the stirring rate: smaller, more monodisperse nanocomposite particles are obtained from rapidly stirred reaction solutions. However, this effect is only observed for the (NH4)2S2O8 oxidant. An alternative oxidant, H2O2/Fe3+, was found to give nanocomposites of similar particle size, polypyrrole content and conductivity to those obtained using the (NH4)2S2O8 oxidant. The colloid stability of these polypyrrole–silica nanocomposite particles depends on their silica content. The colloid stability of a silica-rich nanocomposite prepared using the (NH4)2S2O8 oxidant in the presence of electrolyte was comparable to that of a silica sol, whereas a polypyrrole-rich nanocomposite prepared using FeCl3 had markedly poorer colloid stability under these conditions. These observations are consistent with a charge stabilization mechanism for these nanocomposite particles.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 276 (1998), S. 662-668 
    ISSN: 1435-1536
    Keywords: Key words Liquid crystal polymers ; ionogenic polymers ; synthesis ; hydrogen bond ; order parameter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  A series of new ionogenic liquid crystalline (LC) copolymers (A4CB-AA) was prepared by radical copolymerization of 4-(4-cyanobiphenyl-4′-yloxy) butyl acrylate (A4CB) and acrylic acid (AA). The presence of the AA units do not prevent the development of the nematic phase, which is typical of the initial cyanobiphenyl homopolymer. At a content of AA of 42–52 mol%, the copolymers produce the S Ad type of mesophase, and this phenomenon is explained by an increased rigidity of the main chain due to the development of intramolecular hydrogen bonds. By increasing the concentration of AA units higher than 55 mol%, the development of mesophase is prevented, and the as-received copolymers are amorphous. A crucial role of intramolecular hydrogen bonds for the development of the S A phase in the copolymers is proved by synthesizing and studying the copolymers, in which the same type of the mesogenic group A4CB is preserved but the second component is provided by methyl ether of acrylic acid; such copolymers are able to produce only a nematic phase. Studying orientation of LC A4CB-AA copolymers in the magnetic field by the method of wide-line 1H NMR spectroscopy allows one to calculate the temperature dependences of order parameter S and to advance a correct interpretation of experimental data.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    ISSN: 1572-9001
    Keywords: Azoxyfurazan ; ballistic modifier ; diaminofurazan ; energetic material ; explosive ; synthesis ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of the energetic compound 4-[(4-nitro-1,2,5-oxadiazol-3-yl)-NNO-azoxyl]-1,2,5-oxadiazol-3-amine (3) was achieved in two steps from diaminofurazan (1). Compound 3 was characterized by X-ray diffraction. From the X-ray structure a bifurcated intramolecular H bond between O(2)-H(2)-N(4) was observed. In addition, intramolecular H bonding was observed between H(1) and N(7)′ of an adjacent molecule. One molecule of ethanol and one-half molecule of water per molecule of3 was observed in the crystal lattice. However, no H bonding was observed between the solvent molecules and3 in the crystal lattice. Despite the presence of solvent in the crystal lattice,3 was found to have a high crystal density (d=1.856 g/cm3).
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 1573-4846
    Keywords: synthesis ; 1H NMR ; 13C NMR ; gas chromatogram/mass spectrum ; hybridized silicon alkoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using silicon tetrachloride (SiCl4), tert-butanol (t-BuOH), ethanol (EtOH) and NH3, the hybridized silicon ethoxide 3-tert-butoxide (Si(OEt)x(OBut)4-x) was synthesized and the configuration of the material was investigated by FT-IR,1 H and 13C NMR and gas chromatogram/mass spectrum (GC/MS) techniques. The results confirm that both the ethoxy and the tert-butoxy groups have been attached to silicon atoms. Furthermore, the alkoxy group types and their relative amounts in the alkoxide were also determined by 1H and 13C NMR and GC/MS.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    Springer
    Journal of porous materials 1 (1995), S. 185-198 
    ISSN: 1573-4854
    Keywords: zeolite ; synthesis ; colloidal sol ; monodisperse ; dynamic light scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The use of dynamic light scattering as an analysis method within the field of zeolite synthesis has proved to be a powerful and robust tool with which the particle size and the corresponding particle size distribution can be determined. The method has been employed in the evaluation of the crystallization of several types of colloidal zeolite from ‘clear homogeneous’ solutions. Examples of such zeolites are zeolite N-Y, hydroxysodalite, and TPA-silicalite-1. The fact that the particle size can be determined in as-synthesized zeolite sols as a function of synthesis time enables one to follow, for example, the crystallization process in terms of particle size increase, the process of particle size tailoring as well as to obtain information on the growth mechanism in zeolite synthesis. The colloidal nature of sols following redispersion of zeolite powders and colloidal zeolite organosols has been assessed using dynamic light scattering. The advantages as well as problems associated with the use of dynamic light scattering for characterization of colloidal zeolites are discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    ISSN: 1573-4854
    Keywords: molecular sieve ; synthesis ; cobalticinium ion ; template
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The clathrate type molecular sieve SAPO-16 was prepared via a hydrothermal synthesis using bis(cyclopentadienyl)cobalt(III) hydroxide, Cp2CoOH, as a template and characterized by XRD, FT-IR, UV-Vis and SEM. Additionally, the preparation and characterization of possibly new isostructural SAPO-UTD-3 and CoAPO-UTD-3 materials is reported.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    Springer
    Journal of porous materials 5 (1998), S. 121-126 
    ISSN: 1573-4854
    Keywords: TiO2-pillared saponite ; synthesis ; pore size distribution ; UV-Vis reflectivity ; TG-DTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The preparation of TiO2-pillared saponite was carried out in a CH3COOH aqueous solution. Titanium ion species to intercalate into the interlayer of saponite were obtained by an addition of Ti(C3H7O)4 to an aqueous solution of CH3COOH and by subsequent aging of the solution for a prescribed time. Ti4+-intercalated saponite including organic materials was obtained by ion exchange. After the sample was calcined at 500°C in air, TiO2-pillared saponite was obtained. The resulting TiO2-pillared saponite (Ti-Sapo) possessed surface areas in the range 300–400 m2/g and a sharp pore size distribution with the pore radius of 1.2 nm. The basal spacing of the product heated at temperature 〉250°C was about 2.45 nm. The pillar height of TiO2 in the Ti-Sapo was estimated to be 1.5 nm.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    Springer
    Reaction kinetics and catalysis letters 66 (1999), S. 71-77 
    ISSN: 1588-2837
    Keywords: Alumina ; alumina aerogel ; synthesis ; gelation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis of alumina aerogels has been carried out by hydrolysis of aluminium isopropylate as an aerogel precursor dissolved in isopropanol or methanol, followed by gelation of the sols obtained and drying under supercritical conditions and calcination. The influence of two main preparation parameters, precursor concentration and reagents (water to aluminium isopropylate) mole ratio, on the physicochemical properties of aerogels was investigated.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    ISSN: 1573-904X
    Keywords: bisphosphonates ; tetracycline ; calcification ; hydroxyapatite ; bone resorption ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. This work was aimed at synthesizing novel bisphosphonates (BPs) and examining them in comparison to clinically used BPs such as pamidronate and alendronate, and to tetracycline, in order to evaluate their potential as anticalcification and antiresorption agents. The correlation between the various models was examined in order to establish facile experimental models for pre-screening of potential compounds. Methods. Nitrogen-containing heterocyclic, novel BPs such as 2-(3-methylimidazolio) ethylidene-l,l-bisphosphonic acid betaine (VS-5b), 2-(2-dimethylamino-4-pyrazinio)ethylidene-1,1 -bisphosphonic acid betaine (VS-6b), and 2-(2-α-pyridylethylthio) ethylidene-1,1-bisphosphonic acid (ISA-225), were synthesized and evaluated in comparison to clinically used BPs, in various experimental models of resorption and calcification. Results. The physicochemical properties of the novel compounds are slightly different than the BPs in clinical use: the pKa values are lower, the affinity for hydroxyapatite is lower and the solubilities of the calcium salts are higher. The anticalcification potencies of the novel compounds were high and ranked as follows: alendronate = pamidronate 〉 VS-6b = VS-5b = ISA-225 〉 tetracycline. The in vivo antiresorption activity of VS-5b and VS-6b in comparison to that of the clinically employed, pamidronate, was shown to be similar and higher, respectively. Conclusions. The anticalcification activity of the novel compounds as well as that of tetracycline was lower than that of alendronate. The antiresorption activity of VS-6b was similar to that of pamidronate. A good correlation between the different models was found, enabling the facile screening of novel compounds. The activities of tetracycline and EDTA highlight the distinct behavior of BPs as "crystal poison”. In addition, tetracycline was found to be a potent anticalcification agent in the ectopic calcification model.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    ISSN: 1573-1111
    Keywords: crystalline inclusion compounds ; synthesis ; X-ray analysis ; 13C CPMAS NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The structures of 1,4-bis(pyrazol-1'-yl)-2,3,5,6- tetrakis(3'',5''-dimethylpyrazol-1''-yl) benzene 1, its monohydrate, 1a, four 1 : 2 host : guest complexes, 1b–1e (acetic, propionic, pentanoic, and (±)-2-methyl butyric acids) and a di-picrate salt, 1f, have been determined by X-Ray analysis. In all complexes, in the salt and in the monohydrate compound, the host molecules are hydrogen bonded to two centrosymmetric related guests and to the water molecule which is disordered over two positions to mimic the inclusion complexes. In all compounds, the host exhibits Ci symmetry having the lone pair on the N(2) atom of each pyrazole pointing alternately upwards (u) and downwards (d) from the benzene ring. 1H and 13C NMR spectra of the free host 1 and of the complexes are consistent with the ududud conformation and the stoicheiometry of the inclusion compounds.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    ISSN: 1573-1111
    Keywords: unsymmetrical ditopic calixcrown ; synthesis ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Consecutive base-catalysed reactions of calix[4]arene with the ditosylates of two different polyetherdiols result in the relatively efficient production of an unsymmetrical calix biscrown-6 which, after reduction of an ethoxycarbonyl substituent to an hydroxymethyl group, has been characterised structurally by a room-temperature, single crystal X-ray study of its chloroform solvate. Crystals of ( 4), C53H62O13... ∼0.57CHCl3, are triclinic, P¯1, a 18.95(3), b 12.394(9), c 11.756(7) Å α 106.93(5), β 101.77(8), γ 94.63(8)°, Z = 2; R was 0.088 for 2231 ’observed' (I 〉 3σ(I)) diffractometer data.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 29-43 
    ISSN: 1573-1111
    Keywords: SPV-B24C8 copolymer ; synthesis ; ion-selective electrodes ; potassium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A synthetic procedure has been developed for the preparation of styrene/4'-vinyl-benzo-24-crown-8 copolymer (SPV-B24C8). The resulting copolymer was used as a membrane carrier to construct a K+ ion-selective electrode. The electrode exhibits a Nernstian response for K+ ions over a wide concentration range. The nature of the plasticizer, the additive, the concentration of internal solutions in the electrodes and the composition of the membrane were investigated. The performance of the electrode in terms of electrode reproducibility, response stability and regeneration was also studied. The selectivity coefficients of the electrode for potential interferents including alkali, alkaline earth, some transition and heavy metal ions were found to be in the order of 10-3 or less. The electrode was successfully used for the determination of potassium ion in blood serum.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 26 (1996), S. 253-268 
    ISSN: 1573-1111
    Keywords: 12-Membered crown ethers ; synthesis ; ion-selective membrane electrodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of lipophilic derivatives of benzo-12-crown-4 and naphtho-12-crown-4 has been synthesized. The behavior of the prepared derivatives in membrane ion-selective electrodes has been studied. Selectivity changes dependent on the position and number of substituents have been observed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 29 (1997), S. 175-185 
    ISSN: 1573-1111
    Keywords: p-tert-Butylcalix[5]arene ; synthesis ; complexation ; crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The formation of p-tert-butylcalix[5]arene by the opening ofp-tert-butyldihomooxacalix [4]arene and the addition of a monomer has beenstudied. Various facets, including the effects of bases and the nature ofthe monomer added to the p-tert-butyldihomooxacalix[4]arene, have beeninvestigated. p-tert-Butylcalix[5]arene can be prepared in yields up to30%. The structure of its 1 : 2 complex with DMF has been determinedby X-ray crystallography. Crystals are triclinic, space group P¯1, a =1428.2(3) pm, b = 1837.3(3) pm, c = 1276.1(2) pm, α = 108.98(1)°,β = 105.02(2)°, γ = 95.21(1)°, Z = 2, D c = 1.059 kg m-3,final R value = 0.087. The macrocycle adopts a cone conformation, one guestenclosed inside the cavity, the other one outside.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    ISSN: 1573-1111
    Keywords: P-pivot lariat ethers ; synthesis ; nucleophilic substitution ; metal ion complexation ; molecular receptors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A series of hydrophopic ( 2 and 3) and new hydrophilic ( 4– 7) molecular receptors of the PNP-lariat ether with tetra-substituted cyclotriphosphazene subunits have been prepared by the complete nucleophilic substitution of chlorine atoms in the reactive PNP-crown precursor 1 with the respective sodium cation-paired oxyanions (phenoxy → 2, β-naphthoxy → 3, and methoxytrioxyethylenoxy → 4) and aliphatic amines (n-propylamine → 5 aziridine → 6, and pyrrolidine → 7). Their structures were established by MS and 31P NMR spectroscopy and their metal ion complexing properties tested by a TLC method. Comparison of the complexation behaviour for ligands 1– 7 shows that the affinity for particular cations is strongly substituent-dependent and, in general, is significantly enhanced by cooperation of the side arm donor atoms (O or N) with the parent PNP-crown structure in the binding process. The remarkable affinity of some ligands for selected cations, in particular lithium, cesium, and silver ions, is interpreted in terms of structure-property relationships.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    ISSN: 1573-9171
    Keywords: oligodienyl chain ; transition metals ; synthesis ; stability ; π-coordination ; IR spectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The results of investigations performed in the Laboratory of Organometallic Catalysis of the A. V. Topchiev Institute of Petrochemical Synthesis of the RAS are reviewed. The oligodienyl compounds of a series of transition metals, R n olM and R n olMXm (Rol= R′(diene)3–10, where R′ is an alkyl, allyl, alkenyl, or H; (diene)3–10 is an oligodienyl group with 3–10 monomeric diene units; M = Ti3+, Cr2+, Mn2+, Co2+, Ni2+, Nd3+, Pr3+, Sm3+, and Gd3+; X is a halogen or an electronegative group), have been synthesized for the first time and some of their properties have been studied. The stability of oligodienyl compounds is much higher than that of the corresponding π-alkenyl derivatives. The IR spectra of the compounds synthesized allowed us to conclude that their stability and some peculiarities of the reactions of these compounds can be explained by π-coordination of the isolated double bond of the oligodienyl chain to the transition metal.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 410-415 
    ISSN: 1573-9171
    Keywords: bisphthalocyanines ; rare-earth elements ; synthesis ; absorption spectra ; ESR ; X-ray photoelectron spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using electron spectroscopy, X-ray photoelectron spectroscopy, and ESR spectroscopy, the blue forms of bisphthalocyanines of rare-earth elements were found to have structures of sandwich-type complexes with isoelectronic phthalocyanine ligands linked with tetravalent metal ions, [Pc2−Ln4+Pc2−]0. A comparative spectral and electrochemical study of the blue and green forms oftert-butyl-substituted bisphthalocyanines was carried out for almost the whole series of rare-earth metals. Lutetium octa(perfluoro-tert-butyl)- and perchlorobisphthalocyanines were synthesized for the first time.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 44 (1995), S. 689-694 
    ISSN: 1573-9171
    Keywords: acetylenic ketones ; 1,3-diketones ; aminovinylketones ; synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple route for the synthesis of 1,3-diketones by the reaction of acetylenic ketones with amines followed by hydrolysis of the resulting aminovinylketons is suggested.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    ISSN: 1573-9171
    Keywords: synthesis ; molecular complexes ; o-quinones ; bis[tris(trifluoromethyl)germyl]-mercury(n) ; thermolysis ; one-electron oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Stable molecular complexes of bis[tris(trifluoromethyl)germyl]mercury(II) Hg[(CF3)3Ge]2 (1) witho-quinones (3,6-di-tert-butylbenzoquinone-1,2 (2), 3,6-di-tert-butyl-4,5-dimethoxybenzoquinone-1,2 (3), and 1,4,5,7-tetra-tert-butyldibenzo[1,4]dioxin-2,3-dione (4)) have been synthesized and characterized by elemental analysis and IR and electronic absorption spectroscopies. Depending on the ratio between the starting reactants, the reactions ofo-quinones with1 gave complexes of the composition R2Hg · Q (5,7,9) or R2Hg · Q2 (6,8,10), where Q=2 (5,6),3 (7,8),4 (9,10); R=Ge(CF3)3. According to the spectral data, the molecule ofo-quinone in R2Hg · Q acts as a neutral ligand, whereas the second molecule ofo-quinone in R2Hg · Q2 is not coordinated to1. It has been found by ESR that thermolysis of polycrystalline samples of complexes6 and10 involves intermediate formation of radical pairs and finally yields paramagnetico-semiquinone complexes, SQGe(CF3)3, which are typical products of one-electron oxidation of Organometallic compounds byo-quinones.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    ISSN: 1573-9171
    Keywords: quinolinium salts ; 2-dicyanomethyleneindan-1,3-dione ; merocyanines ; synthesis ; X-ray structural analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The reaction of 1-allyl-4-methylquinolinium bromide with 2-dicyanomethyleneindan-1,3-dione in the presence of a two-fold excess of triethylamine affords 1-allyl-4-[2-cyano-2-(indan-1,3-dione-2-ylidene) ethylidene]-1,4-dihydrogtiinoline, a representative of a new class of merocyanines. The structure of this compound has been established by X-ray structural analysis. A substantial intramolecular charge transfer and a hydrogen bond between the vinyl hydrogen atom and the indandione oxygen atom have been found.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    Springer
    Russian chemical bulletin 45 (1996), S. 2547-2550 
    ISSN: 1573-9171
    Keywords: synthesis ; geminal (difluoroamino)nitro compounds ; cation ; solvents and solvent mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel preparative method for the synthesis of geminal (difluoroamino)nitro compounds was developed, The method involves the reaction ofN,N-difluoro-O-fluorosulfonyl- hydroxylamine with the corresponding salts of nitro compounds, Dependences of the yields of (difluoroamino)nitro compounds on the reaction conditions, the nature of the cation in the salts, and the properties of solvents were studied.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    ISSN: 1573-9171
    Keywords: hexacoordinated tin compounds ; synthesis ; X-ray study ; stereochemical nonrigidity ; dynamic and multinuclear NMR spectroscopy ; quantum-chemical calculations ; MNDO ; MNDOJPM3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Previously unknown (0-Sn)-bischelated bis(lactamomethyl)dichlorostannanes have been synthesized by a direct method from metallic tin and N-chloromethyllactams. According to X-ray structural analysis data, in the solid state in these compounds the tin atom is hexacoordinated and has an octahedral configuration with the two carbon atoms in the transposition, and both coordinating oxygen atoms and the two halogen atoms in thecis-position. A comparison to Ge-analogs indicates that the replacement of the central atom of the coordination unit MCl2O2C2 has inconsistent effects on the parameters of the latter. According to1H and1191 Sn NMR data, the hexacoordination of tin and the geometry of the coordination unit are also retained in solution at low temperatures. At higher temperatures a dynamic process takes place resulting in isochronisms of the protons signals of the NCH2Sn groups. Quantum-chemical calculations of isomeric bis(lactamomethyl)dichlorostannanes by MNDO and MNDO/PM3 methods have been discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...