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  • General Chemistry  (38)
  • Physics  (4)
  • 1995-1999  (31)
  • 1980-1984  (11)
  • 1
    Electronic Resource
    Electronic Resource
    Intermediates and Side-Reactions in the Synthesis of Molecular Diphenolatonickel Compounds Containing Trimethylphosphane Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 2027-2032 
    Details
    ISSN: 1434-1948
    Keywords: Nickel(0) ; Oxidation ; Phenols ; Structure ; Ion pairs ; Hydrogen bonds ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Admission of molecular oxygen to a solution containing Ni(PMe3)4 and substituted phenols (ArOH) affords bisphenolatonickel compounds trans-Ni(OAr)2(PMe3)2 [ArOH = 2-chlorophenol (1), 2-bromophenol (2), 2,4,6-trichlorophenol (3)]. In the absence of dioxygen the phenols reversibly protonate the nickel complex to form ionic compounds [NiH(PMe3)4]+ Y- containing hydrogen-bonded anions Y = [H2(2-Cl-C6H4O)3] (4), [H(2-OH-C6H4COO)2] (5). As a side-reaction, formal insertion of nickel to give 2-hydroxyphenylnickel compounds Ni(Ar′)X(PMe3)3 [Ar′ = 2-OH-C6H4; × = Br (6), I (7)], trans-Ni(Ar′)Cl(PMe3)2 [Ar′ = 2-OH-3,5-Cl2-C6H2 (8)] and trans-Ni(OAr)Cl(PMe3)2 [Ar = 2,4,6-Cl3-C6H2 (9)] is observed. An X-ray crystal structure determination of 1 shows a trans square planar arrangement of donor atoms, that of 6shows a distorted square pyramid, while 4 contains tetrahedral nickel cations with a delocalized hydrogen atom and triphenolate anions H2(ArO)3-.
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  • 2
    Electronic Resource
    Electronic Resource
    Syntheses and Structures of Molecular Diphenolatonickel Compounds Containing Trimethylphosphane Ligands (1998)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 621-627 
    Details
    ISSN: 1434-1948
    Keywords: Nickel ; Oxidation ; Phenols ; Structure ; Dynamic NMR spectroscopy ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of substituted phenols and dioxygen with Ni(PMe3)4 yields the low-spin tetracoordinate diphenolatonickel compounds Ni(OAr)2(PMe3)2 [ArOH = 2-tert-butylphenol (1), 2-tert-butyl-4-methylphenol (2), 2-tert-butyl-6-methylphenol (3), 2,4-di(tert-butyl)phenol (4), 2-tert-butyl-4-methoxophenol (5), 2-chloro-4-tert-butylphenol (6), 2-isopropylphenol (7), 3-tert-butylphenol (8)]. As is revealed by variable temperature 1H- and 13C-NMR spectroscopy the complexes constitute a mixture of two isomers, each of which can be observed separately at lower temperatures when interconversion is slower. An additional 6-carbaldehyde function transforms the phenolate into a chelating ligand, giving rise to a high-spin hexacoordinate compound Ni(OAr)2(PMe3)2 (9). X-ray crystal-structure determinations of 2 and 3 show a trans square-planar structure, and that of 9 shows a trans octahedral arrangement of donor atoms P2O4. Bulky substituents in the 3- or 4-position, or non-demanding substituents in the 2-position, are less effective in stabilizing molecular diphenolatonickel complexes.
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  • 3
    Electronic Resource
    Electronic Resource
    Carbynehydrido- and Vinylidenehydridoosmium Complexes with Os(PCy3)2 as a Molecular Unit (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 951-957 
    Details
    ISSN: 1434-1948
    Keywords: Osmium ; Alkynes ; Carbyne complexes ; Hydrido complexes ; Vinylidene complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of OsCl3·2H2O with PCy3 leads under reducing conditions either to [OsH6(PCy3)2] (1) or [OsH2Cl2(PCy3)2] (2). Treatment of 2 with terminal alkynes HC≡CR (R = Ph, SiMe3) affords the carbynehydrido complexes [OsHCl2(≡CCH2R)(PCy3)2] (4, 5), of which 5 (R = SiMe3) is easily converted with traces of water into [OsHCl2(≡CCH3)(PCy3)2] (6). Compound 4 (R = Ph) reacts with NaOMe to yield the vinylidenehydridoosmium(II) complex [OsHCl(=C=CHPh)(PCy3)2] (7) which upon treatment with HBF4/OEt2 gives the five-coordinate cationic species [OsHCl(≡CCH2Ph)(PCy3)2]-BF4 (8). The reaction of [OsH3Cl(PCy3)2] (9) with HC≡CC(CH3)2Cl affords a mixture of [OsHCl2(≡CCH=CMe2)(PCy3)2] (10) and [OsCl2(H2)(=CHCH=CMe2)(PCy3)2] (11). Compound 11 is quite labile and by elimination of H2 gives 10. The molecular structure of 10 has been determined by X-ray crystallography.
    Additional Material: 1 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Synthesis and Diels-Alder Reactions of Some New (Phthalocyanine)nickel Complexes (1999)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1999 (1999), S. 693-703 
    Details
    ISSN: 1434-1948
    Keywords: (Phthalocyanine)nickel complexes ; Unsymmetrical phthalocyanines ; Isobenzofurans ; Diels-Alder reactions ; Ladder-type molecules ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The octasubstituted (phthalocyanine)nickel complexes 4a,b, soluble in common organic solvents, bearing four dienophilic functionalities were synthesized from the corresponding phthalodinitriles 3a,b and nickel(II) acetate. Reaction of 4a with tetracyclone 5 led to the phthalocyanine-tetracyclone adduct 6 which is a precursor for an intermediate phthalocyanine 7 containing four isobenzofuran moieties. The capability of 7 to react as tetrakis(diene) was demonstrated by its reaction with naphthoquinone. Furthermore, the unsymmetrical phthalocyanines 13 and 16a,b,c containing one dienophilic functionality were synthesized using a statistical approach. Their tetracyclone adducts 17, 18a,b,c can be used for the synthesis of ladder-type phthalocyanine dimers. The dimer 22 was synthesized from 18c and p-benzoquinone via the isobenzofuran intermediate 19 and the benzoquinone adduct 21. For dehydration experiments the naphthoquinone monoadduct 23 was synthesized from 18c. Dehydration of 22 and 23 was carried out successfully with p-toluenesulfonic acid. The Diels-Alder reactions are discussed with respect to the occurring exo/endo ratio.
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis of an Oligo(phenylenevinylene)-Bridged Phthalocyanine Dimer (1999)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1999 (1999), S. 1687-1691 
    Details
    ISSN: 1434-193X
    Keywords: Nickel phthalocyanines ; Phthalocyanines ; Diels-Alder reactions ; Polymers ; Wittig reactions ; Cycloadditions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The nickel phthalocyanine 4, which is soluble in common organic solvents, has been synthesized from the corresponding tetracyclone monoadduct 1 and acrolein (3). Reaction of 4 with p-toluenesulfonic acid leads to the modified phthalocyanine monoaldehyde 5. The capability of 5 to undergo a Wittig reaction has been demonstrated with benzyltriphenylphosphonium bromide (6). Furthermore, a dimer 9 has been synthesized by treating 5 with 0.5 equiv. of xylylenebis(triphenylphosphonium bromide) (8). Dimer 9 constitutes a model compound for corresponding PPV polymers containing phthalocyanine subunits.
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  • 6
    Electronic Resource
    Electronic Resource
    Microstructured peptide-functionalised surfaces by electrochemical polymerisationDedicated to Professor Ivar Ugi on the occasion of his 65th birthday (1996)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 2 (1996), S. 667-672 
    Details
    ISSN: 0947-6539
    Keywords: binding assays ; immunosensors ; electrochemical polymerisations ; peptide derivatives ; peptide immobilisation ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: For the first time, antigenic peptides have been immobilised by electrochemical polymerisation after having been modified with a polymerisable functional group. 3-Hydroxyphenylacetic acid was chosen as the novel polymerisable group. The synthetic peptides represent epitopes of the bovine foot and mouth disease virus and of the sodium channel of the cardiac muscle. The polymerisation was performed by applying a constant anodic potential or by cyclic voltammetry. A combination of these two methods was also employed, that is, cyclic voltammetry with a delay at the anodic vertex potential. No additional free phenolic monomer was required for the polymerisation. The layers formed by the polymerisation were recognised by specific antibodies. The specific binding of the antibodies to the polymer film could be demonstrated by ELISA, an enzyme-linked amperometric immunoassay, and electrochemical impedance measurements, as well as by fluorescence-labelled antibodies. A peptide derived from laminine was also immobilised by electrochemical polymerisation. It could be shown that neuroblastoma cells adhere to this layer.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.1460020608
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of ion content in ionomer on the ion conductivity of polymer electrolytes based on the P(MMA-co-LiMA)/PEG/LiCF3SO3 blend (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 991-997 
    Details
    ISSN: 0887-6266
    Keywords: poly(methyl methacrylate-co-lithium methacrylate)(P(MMA-co-LiMA)) ; ionomer ; polymer electrolyte ; ion content ; ion conductivities ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have prepared polymer electrolytes composed of poly(methyl methacrylate-co-lithium methacrylate) ionomer (P(MMA-co-LiMA)), low molecular weight PEG, and LiCF3SO3 salt. The ion groups in P(MMA-co-LiMA) could enhance the miscibility between the MMA units and PEG in the polymer electrolytes. This miscibility enhancement made the pathway of ion transport less tortuous, and consequently led to the increase in ion conductivity. The maximum ambient ion conductivities in these systems were measured to be in the range of 10-4-10-5 S/cm. The polymer electrolytes became transparent at the higher ion content owing to the enhanced miscibility. The mechanical stability of the polymer electrolytes was also improved through the introduction of ion groups into the PMMA. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 991-997, 1998
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  • 8
    Electronic Resource
    Electronic Resource
    Segmental and chain orientational behavior of spandex fibers (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 1821-1832 
    Details
    ISSN: 0887-6266
    Keywords: spandex fiber ; polyurethane ; orientation function ; birefringence ; melt and dry spinning ; hysteresis ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The internal structure and orientation behavior of two series of spandex fibers, which were made with different spinning methods and different soft and hard segment types, were studied by FTIR (Fourier Transform Infrared Spectroscopy), polarizing light microscopy, and Instron. The orientation behavior of hard and soft segments was studied with FTIR and those of polymeric chains with polarizing miscroscopy while the fibers were being stretched by the mechanical stretcher. The orientation behavior of dry-spun fibers was observed to be very different from that of the melt-spun fibers, which may be explained in terms of the internal structural difference such as the degree of phase separation and mechanical stability of the hard domains between the two types of fibers. In general, the dry-spun fibers showed better elastic recovery property than the melt-spun fibers. Since the polymer for the dry-spun fibers was synthesized with ethylene diamine as a chain extender resulting in the urea groups in the hard segments, it forms more stable hard domain due to the high cohesion energy between the urea groups. The change of the birefringence values during the cyclic deformation was studied with the polarizing light microscopy. The birefringence behaviors of the two dry-spun fibers were similar, whereas there was a noticeable difference between the two melt-spun fibers. The difference was explained in terms of the effect of crosslinking agent in one of the melt-spun fibers, which can stabilize the hard domain structure against the external stress. Mechanical hysteresis values measured gave results consistent with those of FTIR and birefringence measurements. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1821-1832, 1997
    Additional Material: 10 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    C3H4Si Species: Generation and Matrix-Spectroscopic Identification of Some Silacyclobutadiene Isomers (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1297-1305 
    Details
    ISSN: 1434-193X
    Keywords: Matrix isolation ; Ab initio calculations ; Photochemistry ; Silylenes ; Silaethenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Flash pyrolyses of four suitable precursors - namely 1,1,1-trimethyl-2-propargyldisilane (32), its allenyl (34) and propynyl isomer (35), as well as 2-ethynyl-1,1,1,2-tetramethyldisilane (31) - lead to the formation of three C3H4Si species (7, 11, and 15). By examination of their photochemistry five additional compounds of the same composition (12, 13, 14, 17, and 18) were identified. Except ethynylsilaethene (18), all compounds observed are silylenes. Their identification is based on the comparison of the experimental and calculated (BLYP-6-31G*) IR spectra. Silacyclobutadiene (4) or silatetrahedrane (25) could not be detected.
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  • 10
    Electronic Resource
    Electronic Resource
    Gas-Phase Reactions of 1,2-Dimethylcyclopentene and of 2,6-Heptanedione with Ozone: Unprecedented Formation of an Ozonide by Ozone Treatment of a Diketone (1998)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 627-629 
    Details
    ISSN: 1434-193X
    Keywords: Gas-phase chemistry ; Ozonolysis ; Ozonide ; Cycloolefin ; Diketone ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas-phase ozonizations of 1,2-dimethylcyclopentene (1) and of 2,6-heptanedione (5) afforded in each case dimethylcyclopentene ozonide (2) in low yields. In the ozonization of 1, diketone 5 was formed as the single major product, along with nine “abnormal” ozonolysis products which were formed by oxidative cleavage of carbon-carbon single bonds.
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