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  • Chemistry  (827)
  • Polymer and Materials Science  (462)
  • 1995-1999  (862)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 1-12 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die elektrochemische Polymerisation von Pyrrol-2-aldehyd-azin, 2,2′-[1,4-Phenylenbis(nitrilomethylidyn)]dipyrrol und 2,2′-[1,4-Biphenylylenbis(nitrilomethylidyn)]dipyrrol läuft als anodische Fällungspolymerisation ab. Monomere und Polymere wurden voltammetrisch unter Verwendung von Platin- und “Paste-carbon”-Elektroden untersucht. Die Ergebnisse stimmen mit MO-Berechnungen überein, wobei die Reaktivität der Monomeren nach Hückel abgeschätzt wurde.
    Notes: The electrochemical polymerization of some Schiff's base-type monomers like pyrrole-2-aldehyde azine, N,N′-di(2-pyrrolylmethylene)-1,4-diaminobenzeneSystematic name: 2,2′-[1,4-phenylenebis(nitrilomethylidyne)]dipyrrole., and N,N′-di(2-pyrrolylmethylene)-4,4′-diaminobiphenylSystematic name: 2,2′-[4,4′-biphenylylenebis(nitrilomethylidyne)]dipyrrole. proceeds as a precipitating polymerization to the anodic compartment. The voltammetric study of monomers and polymers using Pt electrodes and paste-carbon electrodes were carried out. The results are in agreement with the MO calculations using the Hückel approximation for evaluating of the reactivity of the monomers.
    Additional Material: 7 Ill.
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  • 2
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Block copolymers of unsubstituted poly(p-xylylene)(PPX) and Ge- or Sn-organic bridged PPX (GePPX and SnPPX) were prepared by pyrolysis of specially synthesized organometallic p-cyclophane precursors followed by deposition and polymerization of the thus produced p-xylylene monomers. The copolymer structure and thermal behavior were investigated depending on deposition temperature (10 and -196°C). The copolymer PPX-GePPX obtained from solid monomers deposited at -196°C (2a) consists of long quasi-independent PPX and GePPX blocks and has paracrystalline structure. Thermal treatment of 2a near 160°C yields crystalline regions of PPX along with paracrystalline aggregates of GePPX. Pyrolysis of this system near 300°C in an inert atmosphere results in the formation of Ge crystals in PPX matrix. In contrast, the copolymer PPX-GePPX produced by simultaneous deposition and polymerization at 10°C (2a′) contains shorter blocks of PPX and GePPX than the copolymer deposited at -196°C. Copolymer 2a′ turns to the amorphous state during thermal treatment, and its pyrolysis does not lead to Ge-crystal formation; hence the supramolecular structure of the polymer plays an important role in inorganic phase formation. The copolymer PPX-SnPPX (2b) is formed only at a deposition temperature of -196°C; deposition at 10°C yields oligomeric resins. The structure of 2b is nearly the same as that of 2a; pyrolysis of 2b in air results in SnO2-crystal formation in a PPX matrix.
    Additional Material: 3 Ill.
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  • 3
    ISSN: 0948-1907
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Additional Material: 3 Ill.
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  • 4
    ISSN: 1057-9257
    Keywords: tetrathiafulvalenes ; cation radical inner salts (betaines) ; intermolecular hydrogen bonds ; uracil derivatives ; guanine analogues ; DC electrical conductivity ; organic semiconductors ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Dimethyl[2,4-dioxo(1 H,3 H)pyrimido]tetrathiafulvalene (1) and dimethyl-[2-amino-4-oxo(3 H)pyrimido]tetrathiafulvalene (4) form unusual inner salts by oxidation in the presence of bases. The insoluble black-green betaines 2 and 5 react with acids to form cation radical salts. Betaine 2 in the presence of acid and bis-(ethylenedithio)tetrathiafulvalene forms the unexpected double salt 8. In order to synthesise the cation radical salts of 1 and 4, it is necessary to use the ultrasonic method owing to the insolubility of the starting compounds. Electrical measurements of the betaines and cation radical salts in pressed samples show an unexpectedly low resistivity with semiconducting character: for betaine 2 ρ(RT) = 840 Ο cm, for betaine 5 ρ(RT) = 10 Ο cm, for salt 7 ρ(RT) = 40 Ο cm, but for double salt 8 ρ(RT) = 50 Ο cm. In the case of salt 8, very low values of activation energy of electrical conductivity of the order of kT were observed. The synthesis and purification of tetrathiafulvalene 4 from 5-amino-7-oxo(6 H)-1,3-dithiolo[4,5-d]pyrimidineselone-2 are described. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 1 Ill.
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  • 5
    ISSN: 1057-9257
    Keywords: tetrathiafulvalenes ; cation radical inner salts (betaines) ; intermolecular hydrogen bonds ; uracil derivatives ; guanine analogues ; DC electrical conductivity ; organic semiconductors ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Dimethyl[2,4-dioxo(1 H,3 H)pyrimido]tetrathiafulvalene (1) and dimethyl-[2-amino-4-oxo(3 H)pyrimido]tetrathiafulvalene (4) form unusual inner salts by oxidation in the presence of bases. The insoluble black-green betaines 2 and 5 react with acids to form cation radical salts. Betaine 2 in the presence of acid and bis-(ethylenedithio)tetrathiafulvalene forms the unexpected double salt 8. In order to synthesise the cation radical salts of 1 and 4, it is necessary to use the ultrasonic method owing to the insolubility of the starting compounds. Electrical measurements of the betaines and cation radical salts in pressed samples show an unexpectedly low resistivity with semiconducting character: for betaine 2 ρ(RT) = 840 Ω cm, for betaine 5 ρ(RT) = 10 Ω cm, for salt 7 ρ(RT) = 40 Ω cm, but for double salt 8 ρ(RT) = 50 Ω cm. In the case of salt 8, very low values of activation energy of electrical conductivity of the order of kT were observed. The synthesis and purification of tetrathiafulvalene 4 from 5-amino-7-oxo(6 H)-1,3-dithiolo[4,5-d]pyrimidineselone-2 are described. © 1997 John Wiley & Sons, Ltd.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 61 (1996), S. 1465-1471 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: New methods of preparing polymer suspensions of narrow particle size distribution with amino and carboxylic groups on the particle surface have been suggested. The effects of various factors on the diameter and size distribution of polymer particles, their stability, and concentration of functional groups on the particle surface were investigated. The application of such polymer suspensions for immunochemical studies was shown. © 1996 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 46 (1998), S. 169-179 
    ISSN: 0006-3525
    Keywords: macromolecular carriers ; drug targeting and delivery ; branched chain synthetic polypeptides ; membrane-synthetic polypeptide interaction ; lipid monolayers/bilayers ; polymer therapeutics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The surface properties at the air/water interface and the interaction of branched chain polymeric polypeptides with a general formula poly[Lys-(DL-Alam-X1)], where X = Π (AK), Ser (SAK), or Glu (EAK), with phospholipids were investigated. Polylysine derivatives with polycationic (SAK, AK) or amphoteric (EAK) were capable to spread and form stable monomolecular layers. The stability of monolayers at the air/water interface was dependent on the side-chain terminal amino acid residue of polymers and can be described by SAK 〈 AK 〈 EAK order. The area per amino acid residue values calculated from compression isotherms were in the same range as compared to those of linear poly-α-amino acids and proteins. Moreover, these polymers interact with phospholipid monomolecular layers composed of dipalmitoyl phosphatidyl choline (DPPC) or DPPC/PG (PG: phosphatidyl glycerol; 95/5, mol/mol). Data obtained from compression isotherms of phospholipids spread on aqueous polymer solutions at different initial surface pressure indicated that insertion into lipid monolayers for SAK or AK is more pronounced than for EAK. The interaction between branched polypeptides and phospholipid membranes was further investigated using lipid bilayers with DPPC/PG and fluorescent probes located either at the polar surface [1-(4-trimethylammonium-phenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) sodium anilino naphthalene sulfonate (ANS)] or within the hydrophobic core (DPH) of the liposome. Changes in fluorescence intensity and in polarization were observed when TMA-DPH or ANS, but not DPH were used. Comparative data also indicate that all three polymers interact only with the outer surface of the bilayer, but even the most marked penetration of polycationic polypeptide (SAK) did not result in alteration of the ordered state of the alkyl chains in the bilayer. Taken together, data obtained from mono- or bilayer experiments suggest that the interaction between branched polymers and phospholipids are highly dependent on the charge properties (Ser vs Glu) and on the identity (Ser vs Ala) of side-chain terminating amino acids. The binding of polymers to the model membranes could be mainly driven by electrostatic forces, but the significant role of hydrophilic properties in case of SAK cannot be excluded. © 1998 John Wiley & Sons, Inc. Biopoly 46: 169-179, 1998
    Additional Material: 8 Ill.
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  • 8
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 5′-amino-5′-deoxy-2′,3′-O-isopropylideneadenosine (4) was obtained in pure form from 2′,3′-O-isopropylideneadenosine (1), without isolation of intermediates 2 and 3. The 2-(4-nitrophenyl)ethoxycarbonyl group was used for protection of the NH2 functions of 4 (→7). The selective introduction of the palmitoyl (= hexadecanoyl) group into the 5′-N-position of 4 was achieved by its treatment with palmitoyl chloride in MeCN in the presence of Et3N (→5). The 3′-O-silyl derivatives 11 and 14 were isolated by column chromatography after treatment of the 2′,3′-O-deprotected compounds 8 and 9, respectively, with (tert-butyl)dimethylsilyl chloride and 1H-imidazole in pyridine. The corresponding phosphoramidites 16 and 17 were synthesized from nucleosides 11 and 14, respectively, and (cyanoethoxy)bis(diisopropylamino)phosphane in CH2Cl2. The trimeric (2′-5′)-linked adenylates 25 and 26 having the 5′-amino-5′-deoxyadenosine and 5′-deoxy-5′-(palmitoylamino)adenosine residue, respectively, at the 5′-end were prepared by the phosphoramidite method. Similarly, the corresponding 5′-amino derivatives 27 and 28 carrying the 9-[(2-hydroxyethoxy)methyl]adenine residue at the 2′-terminus, were obtained. The newly synthesized compounds were characterized by physical means. The synthesized trimers 25-28 were 3-, 15-, 25-, and 34-fold, respectively, more stable towards phosphodiesterase from Crotalus durissus than the trimer (2′-5′)ApApA.
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  • 9
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some new (2′-5′)oligoadenylate trimers, i.e., 22-28, containing the antiviral nucleoside ribavirin (= 1-(β-D-ribofuranosyl)-1H-1,2,4-triazole-3-carboxamide; 7) and the synthetic cytokine 6-(benzylamino)purine riboside (= N6-benzyladenosine; 1) in different positions of the trimer, have been synthesized by the phosphotriester method. The selectively blocked nucleosides 2-6 and 8-11 and the 2′-phosphodiesters 13 and 14, used for the oligonucleotide syntheses, were synthesized from the corresponding unprotected ribonucleosides 1 and 7, and isolated by silica-gel column chromatography. The fully deblocked trimers 22-28 were purified by ion-exchange chromatography on DEAE-Senacell 23-SS. The newly synthesized compounds were characterized by physical means. The ability of synthesized trimers to inhibit HIV-1 replication and to improve RNase L activation were investigated. Some of the synthesized trimers showed also biological inhibition of HIV-1 reverse transcriptase and HIV-1-induced syncytia formation. It was shown that AdoBn-containing trimers inhibited HIV-1-induced syncytia formation 〉 1500-fold, independently of the position of the AdoBn residue in the oligomer chain.
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  • 10
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some new (2′-5′)triadenylates 13-16, containing at the 2′-terminal end 3′-fluoro-2′,3′-dideoxyadenosine derivatives, have been synthesized by the phosphotriester method. The selectively blocked nucleosides 2, 4, 5, and 7, were synthesized from the corresponding unprotected nucleosides 1, 3, and 6. The synthesized trimers 13, and 14 were 4- and 8-fold, respectively, more stable towards phosphodiesterase from Crotalus durissus than the natural trimer 17. In comparison to trimer 17 the new compounds 13-15 inhibit HIV-1 reverse transcriptase (RT) activity, and 15 and 16 the HIV-1 induced syncytia formation 2-3 fold whereas none of 13-16 can improve R Nase L activity.
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