Advanced Materials

Cover image for Advanced Materials

January 1996

Volume 8, Issue 1

Pages fmi–fmi, 9–97

  1. Masthead

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    1. Masthead (page fmi)

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080101

  2. Essay

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    1. Versailles project on advanced materials and standards (VAMAS) (pages 9–12)

      Dr. James G. Early and Dr. Harry L. Rook

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080102

      Pre-standards research—also called pre-normative research—is necessary in the case of advanced materials because traditional tests are simply not suitable for these materials. The pace at which they enter the market place requires the rapid development of novel approaches to measurement and performance evaluation. VAMAS exists to remove barriers to trade in new technologies by addressing this need for research on which to base international standards. VAMAS's aims and organization are described, and a case study is outlined.

  3. Reviews

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    1. Self-Assembling Frameworks: Beyond microporous oxides (pages 13–28)

      Carol L. Bowes and Prof. Geoffrey A. Ozin

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080103

      The self-assembly of inorganic open framework structures has blossomed during the 1990s. Following a short historical summary of the field, the main features of the major classes of microporous materials—cyanide open-frameworks, chalcogenides, polychalcogenides and thio-pnictates—are described. The Review concludes with a brief discussion of microporous structures of the main group (e.g. K8Sn25, see figure) and organic tecton frameworks.

    2. Polymer Layered Silicate Nanocomposites (pages 29–35)

      Prof. Emmanuel P. Giannelis

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080104

      Polymer nanocomposites with layered silicates as the inorganic (reinforcement) phase exhibit properties that are of interest for commercial applications. In particular, it is shown that nanocomposites produced by polymer melt intercalation, a new, versatile and environmentally benign synthetic approach, exhibit significantly improved stiffness, strength and thermal properties compared to their more conventional counterparts. Miscibility issues and the kinetics of polymer intercalation are also considered.

  4. Communications

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    1. Hydrogen-bonded pseudopolyrotaxanes (pages 37–41)

      Dr. Masumi Asakawa, Peter R. Ashton, Wayne Hayes, Prof. J. Fraser Stoddart, Dr. George R. Brown, Dr. Stephan Menzer, Dr. Andrew J. P. White and Dr. David J. Williams

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080105

      That supramolecular order on the nanometer scale in the crystalline state can be created by using both π–π stacking and hydrogen bonding interactions marks a significant development in the fields of crystal engineering and supramolecular chemistry. The design and construction of pseudorotaxane monomers (see figure) via self-assembly is described, which are then further assembled to form linear pseudopolyrotaxane columns.

    2. Highly ordered materials with ultra-low surface energies: Polyelectrolyte–surfactant, complexes with fluorinated surfactants (pages 41–45)

      Prof. Markus Antonietti, Dr. Susanne Henke and Dr. Andreas Thünemann

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080106

      Are non-stick surfaces “the chemical analogue of the perpetual motion machine”, i.e., unattainable? Cheap and simple-to-produce systems with ultra-low surface energy—and so on the way towards this ideal—are polyelectrolyte–surfactant complexes. Polarization micrographs of such systems involving fluorinated surfactants are presented (see also the cover picture) that reveal highly ordered microphases with high optical anisotropy that can be easily oriented. X-ray and AFM data are also reported.

    3. A novel thermoset polymer optical fiber (pages 45–48)

      Theo A. C. Flipsen, Rob Steendam, Prof. Albert J. Pennings and Prof. Georges Hadziioannou

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080107

      Polymer optical fibers are being investigated with a view to overcoming some of the disadvantages of glass optical fibers in communications applications. Dense cross-linked polymers, such as the polyisocyanurate discussed here (see figure), have been found to be superior in some respects to the thermoplastic polymers used today. Details are given of the fabrication of a polyisocyanurate network using a rare-earth complex as a catalyst.

    4. The metal-on-polymer interface in polymer light emitting diodes (pages 48–52)

      Prof. William R. Salaneck and Prof. Jean-Luc Brédas

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080108

      The oxidation of calcium electrodes on polymer light emitting diodes (LEDs) can influence the lifetime of the LEDs by an order of magnitude. This finding illustrates how important the metal–polymer interface can be for LEDs. This aspect, which so far has usually been neglected, is investigated experimentally and interpreted in terms of quantum chemical modeling. It is shown that for all the metals considered (A1, K, Rb, Na, Ca) an interfacial region is formed between the metal and the polymer which behaves differently from the bulk.

    5. Field-effect transistor made with a sexithiophene single crystal (pages 52–54)

      Dr. Gilles Horowitz, Dr. Francis Garnier, Dr. Abderrahim Yassar, Dr. Riadh Hajlaoui and Dr. Fayçal Kouki

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080109

      For the fabrication of organic transistors sexithiophene (6T) is one of the most promising materials. Since high purity improves the transistor performance of 6T, the FET described here was built on an ultrapure sexithiophene single crystal, shown in the figure as a gray block. The characteristics of this transistor—better than those of FETs based on evaporated polycrystalline sexithiophene—are presented.

    6. Heterocyclic heptamers containing thiophene and pyrrole units: Synthesis and properties (pages 54–59)

      Dr. James P. Parakka, Dr. Judith A. Jeevarajan, Dr. Antony S. Jeevarajan, Dr. Lowell D. Kispert and Prof. Michael P. Cava

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080110

      Studies on septithiophenes are relatively rare compared to the available detailed investigations of sexithiophenes. The balance is redressed here by a report of the synthesis, electrochemistry and spectroscopic properties of a new α,ω-disubstituted septithiophene and two pyrrole-containing septithiophene and two pyrrole-containing septithiophene analogues. Two different routes are described by which it was attempted to impart solubility in organic solvents to septithiophenes–one unsuccessful and one successful. Evidence of an unusual three-electron transfer process is also presented.

    7. Synthesis, crystal structure, and magnetic properties of 5-methyl-l,2,4-triazole-nitronyl nitroxide: A one-dimensional compound with unusually large ferromagnetic intermolecular interactions (pages 60–62)

      Prof. Olivier Kahn, Dr. Andreas Lang, Dr. Yu Pei and Dr. Lahcène Ouahab

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080111

      Triazole nitronyl nitroxide radicals and their derivatives are open-shell molecules with potential applications as building blocks for the synthesis of multi-property molecular materials. The title compound (see figure) exhibits exceptionally strong ferromagnetic interactions. Its synthesis, crystallographic data and magnetic properties are described. Possible mechanisms for the origin of these properties are suggested.

    8. Synthesis and aggregation of a phthalocyanine symmetrically-functionalized with eight tetrathiafulvalene units (pages 63–65)

      Dr. Mark A. Blower, Prof. Martin R. Bryce and Wayne Devonport

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080112

      The first phthalocyanine derivative decorated with peripheral tetrathiafulvalene (TTF) units has been synthesized. The synthetic design strategy and the derivative's spectroscopic and electrochemical characterization are described. It is noted that the tendency of phthalocyanine units to assemble in solution is not prevented and also that the redox behavior of the appended TTF units is not hindered. The potential of TTF–phthalocyanines for molecular electronics is pointed out.

    9. Chromophore-zeotype composites: Direct synthesis of an array of strictly aligned metal-organic complex chromophores in a crystalline silica matrix (pages 65–69)

      Prof. Peter Behrens, Dr. Gianpietro van de Goor, Frank Marlow, Dr. Katrin Hoffmann, Stefan Kallus and Prof. Ferdi Schüth

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080113

      Chromophores embedded in zeolite-type hosts have potential applications in optical devices. However, the conventional preparation results in an inhomogeneous distribution of the chromophores. It is demonstrated that direct synthesis can result in chromophore-zeolite composites with well-defined stoichiometry and uniform chromophore distribution, as illustrated for [Cocpmath imageF]-NON in the figure.

    10. 13C-CPMAS NMR characterization and molecular dynamics of oligothiophenes in the solid state (pages 69–73)

      Dr. Giovanna Barbarella, Massimo Zambianchi, Laura Favaretto, Sandra Rossini and Dr. Daniele Casarini

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080114

      13C-Cross polarization magic angle spinning (CPMAS) NMR is excellently suited to studying the solid-state structure, conformation and molecular dynamics of oligothiophenes, but to date few data are available. The investigation reported here focuses on a homologous series of unsubstituted oligothiophenes. It is shown that 13C-CPMAS NMR is capable of detecting changes in the symmetry properties of the oligothiophenes and of discriminating between odd- and even-number oligothiophenes.

    11. Spontaneous magnetization in a 2:3 complex formed by 3,4′,5-tris(N-oxy-tert-butylamino)biphenyl and manganese(II)bis(hexafluoroacetylacetonate) (pages 73–76)

      Prof. Hiizu Iwamura and Prof. Katsuya Inoue

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080115

      The basic problem in the design of molecular magnets is how to assemble unpaired electrons and align their spins on the macroscopic scale. One line of investigation involves heterospin systems consisting of transition metal ions and organic free radicals as ligands. Results are reported for such a system (see figure) in which the heterospin system forms a 2-D network, which increases Tc compared to a 1-D network.

    12. Mesomorphic behavior of new double swallow-tailed compounds (pages 76–79)

      Dr. Wolfgang Weissflog, Dr. Iris Letko, Dr. Siegmar Diele and Prof. Gerhard Pelzl

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080116

      Double swallow-tailed compounds are special cases of tetracatenar mesogens (mesogens consisting of a rod-like core and two half-disc shaped moieties), where the branches are not attached directly to the terminal rings. Experiments are reported in which the middle part of the core and the length of the terminal chains were varied. The resulting effects on the transition temperatures and phase behavior are described and trends pointed out.

    13. Regularly interstratified layered silicate heterostructures: Precursors to pillared rectorite-like intercalates (pages 79–83)

      Wouter L. Ijdo, Dr. Ton Lee and Prof. Thomas J. Pinnavaia

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080117

      A fundamental advance in the intercalation chemistry of clays is the formation for the first time of smectite clay heterostructures with regularly stratified organic and inorganic exchange cations, e.g. the fluorohectorite heterostructure with gallery cations Na⊕ and C16H33PBumath image shown in the figure. Their transformation into rectorite-like alumina pillared analogues is also demonstrated.

  5. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    1. Boron-doped molybdenum silicides (pages 85–88)

      Dr. Mitchell Meyer, Dr. Matthew Kramer and Prof. Mufit Akinc

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080118

      Replacement materials for the superalloys currently used in gas turbine engines are needed if the operating temperature—and thus efficiency—is to be increased. Candidates include ceramics (which have problems with low fracture toughness) and intermetallics. The materials discussed here consist of a Mo5Si3 matrix combined with one or two other phases to increase the ductility and oxidation resistance. The oxidation behavior and creep behavior are examined, in particular upon the addition of boron.

    2. Organic two-dimensional templates for the fabrication of inorganic nanostructures: Organic/inorganic superlattices (pages 89–91)

      Dr. Nobuo Kimizuka and Prof. Toyoki Kunitake

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080119

      The self-organization of inorganic precursors in predetermined patterns is the first step towards the ability to synthesize mesoscopic inorganic materials. Several techniques are described, including the immobilization of inorganic precursors by coordination with bilayer ligands (see figure), which led, for example, to a novel Cd4Br12S cluster. Finally, the formation of organic/inorganic superlattices is outlined.

    3. Dye composite layers by physical vapor deposition (pages 93–97)

      Dr. Steffen Jäger and Prof. Horst Böttcher

      Article first published online: 29 OCT 2004 | DOI: 10.1002/adma.19960080120

      The embedding of dyes in metal halides, metal sulfides and metal oxides has become possible with the introduction of multi-source physical vapor deposition (MSPVD). This in turn has led to potential applications such as colored layers, spectral sensitization of semiconductors and systems for controlled release of drugs. The technique of MSPVD is briefly described and the optical properties of the dye composite films are discussed.