Advanced Materials

Cover image for Advanced Materials

September, 1998

Volume 10, Issue 13

Pages 979–1053

    1. Borate Materials in Nonlinear Optics (pages 979–992)

      Petra Becker

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<979::AID-ADMA979>3.0.CO;2-N

      What properties determine an effective nonlinear optical (NLO) material? These are reviewed and summarized for recently described borate compounds—materials that have proven to be superior to other commonly used NLO materials for UV applications. The Figure shows the arrangement of [B2O5] and [NbO6] groups within the unit cell of CsNbOB2O5.

    2. Colorfast Blue-Light-Emitting Random Copolymers Derived from Di-n-hexylfluorene and Anthracene (pages 993–997)

      Gerrit Klärner, Mark H. Davey, Wei-D. Chen, J. Campbell Scott and Robert D. Miller

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<993::AID-ADMA993>3.0.CO;2-2

      Strong colorfast blue photo- and electroluminescence is reported for random high molecular weight poly(fluorene-co-anthracene)s, prepared via the nickel-mediated copolymerization of the corresponding aryl dibromides. The incorporation of anthracene into the main chain is demonstrated to completely suppress excimer formation—a major drawback of many planar π-systems. Poly(fluorene)s are attractive as active components of organic light-emitting diodes (LEDs) because of their thermal and chemical stability and exceptionally high fluorescence quantum yields.

    3. Nanostructured Polymer Films by Electron-Beam Irradiation and Selective Metallization (pages 997–1001)

      Ingo Lieberwirth, Frank Katzenberg and Jürgen Petermann

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<997::AID-ADMA997>3.0.CO;2-N

      Selective metallization of polymer substrates with tellurium is shown to be effected by electron-beam irradiation. Different behavior is reported, depending on the type of substrate, radiation dose, and substrate temperature. For example, the irradiation of high density polyethylene (HDPE) at <100 C/m2 and subsequent

    4. Kinetic Control of “Unnatural” Chiral Induction in Poly(isocyanide)s (pages 1001–1005)

      David B. Amabilino, Elena Ramos, José-Luis Serrano and Jaume Veciana

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1001::AID-ADMA1001>3.0.CO;2-Y

      Generation of an “unnatural” helical polymer, i.e., a poly-(isocyanide) with side chains of identical absolute configuration to the “natural” one but with a helical secondary structure of opposite handedness, is reported. It is demonstrated that the natural tendency of promesogenic monomer to form poly(isocyanide)s of predominantly one helical sense is not a cooperative process. Rather their secondary structure is trapped during formation through long-range chiral induction. Using a kinetic trick the growth of these “natural” helices can be blocked, allowing the “unnatural” poly(isocyanide) to form in preference.

    5. Ultrathin Cellulose-Based Layers for Detection of Single Antigen Molecules (pages 1005–1009)

      Frank Löscher, Thomas Ruckstuhl and Stefan Seeger

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1005::AID-ADMA1005>3.0.CO;2-A

      The covalent immobilization of antibodies using non-amphiphilic alkylated cellulose films is described—the Figure shows the antibodies attached to the film via imino bonds. Rapid detection of a specific antibody–antigen reaction is demonstrated as is single-molecule detection. Thus biochemical surfaces prepared in this way have great potential as ultrasensitive bio- and immunosensors.

    6. Pattern Recognition by Antibodies for Two-Dimensional Arrays of Molecules (pages 1009–1013)

      David Izhaky and Lia Addadi

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1009::AID-ADMA1009>3.0.CO;2-N

      Direct antibody recognition of supramolecular arrays of small molecules, rather than of an individual molecule, is demonstrated. Monoclonal antibodies, raised and selected against crystals of cholesterol monohydrate are shown by ELISA (enzyme-linked immunosorbent assay) and immunofluorescence imaging to specifically interact with monolayers of cholesterol at the air–water interface. This raises the possibility of producing antibodies against solid antigens and using them to tag geometrical arrays of molecules in, for example, membranes, which cannot be presented as such to the immune system.

    7. Synthesis, Electrochemical Properties, and Molecular Computations of New Tris(thienyl)methyl Cations (pages 1013–1018)

      Frederic Cherioux, Laurent Guyard and Pierre Audebert

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1013::AID-ADMA1013>3.0.CO;2-K

      New octupolar bithiophenic methyl cations belonging to the Crystal Violet family are described (see Figure). The synthesis and electrochemical properties of these cations, which should combine the second-order nonlinear optical properties of Crystal Violet with the electrochemical properties of heterocycles, are reported along with the findings from molecular computations.

    8. Evaporated Crystalline Film of Platinum Dimethylglyoxime with Short One-Dimensional Metal Chains (pages 1018–1022)

      Kaoru Yamamoto, Toshihide Kamata, Yuji Yoshida, Kiyoshi Yase, Fujio Mizukami and Toshiaki Ohta

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1018::AID-ADMA1018>3.0.CO;2-R

      The self-organization of a third-order nonlinear optical metal complex, bis(dimethylglyoximato)platinum(II), Pt(dmg)2, into one-dimensional chains is investigated. It is found that, upon vacuum evaporation on a KBr substrate, epitaxial crystallization of the metal complex takes place and plate-like islands are formed. Within the islands, the metal complex is organized into oriented chains of controllable length. The growth process and structure are discussed from optoelectronic and structural points of view.

    9. Self-Dispersion: Spontaneous Formation of Colloidal Dyes in Water (pages 1022–1024)

      Heinz Langhals, Wolfgang Jona, Florian Einsiedl and Stefan Wohnlich

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1022::AID-ADMA1022>3.0.CO;2-O

      Spontaneous formation of colloidal dyes in water is investigated by scanning electron microscopy. The authors report that crown ether–substituted perylene dyes spontaneously form solid particles (see Figure) upon contact with water. The colloidal dispersion exhibits a ruby-like color and is very stable. Thus, the dye can be applied as a tracer for the investigation of the movement of water to answer geochemical questions.

    10. Multilayered Ferromagnets Based on Hybrid Organic–Inorganic Derivatives (pages 1024–1028)

      Valerie Laget, Claudie Hornick, Pierre Rabu, Marc Drillon, Philippe Turek and Raymond Ziessel

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1024::AID-ADMA1024>3.0.CO;2-C

      Supramolecular multilayered ferromagnets in which metal layers are interleaved with iminonitroxide benzoate radical anions have been synthesized and characterized by the authors. The structure of these novel compounds (see cover) consists of stacks of alternating organic–inorganic layers. Long-range ferromagnetism is evidenced by magnetic and electroparamagnetic resonance (EPR) measurements, and shows clear interaction between the two sub-networks. In this respect, this new class of hybrid magnets differs markedly from classical intercalated layer compounds.

    11. Crystallization of Mesoscale Particles over Large Areas (pages 1028–1032)

      Sang Hyun Park, Dong Qin and Younan Xia

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1028::AID-ADMA1028>3.0.CO;2-P

      Crystallization of mesoscale particles by a simple and general methodology is reported here. The versatility of this method is demonstrated by the production of monolayers, bilayers, and multilayers of polystyrene beads (see the scanning electron micrograph shown in the Figure). The method is useful, for example, for the fabrication of new sensor types or photonic bandgap structures.

    12. Monodisperse Ferromagnetic Particles for Microwave Applications (pages 1032–1035)

      Philippe Toneguzzo, Guillaume Viau, Olivier Acher, Françoise Fiévet-Vincent and Fernand Fiévet

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1032::AID-ADMA1032>3.0.CO;2-M

      Ferromagnetic metal-based materials display interesting properties for microwave applications. Here the authors report obtaining ferromagnetic monodisperse particles in the nanometer size range by the polyol process. By accurate control of the particle size the influence of the particle upon the microwave permeability could be studied. Three different behaviors are detected in a size range varying by over two orders of magnitude, in which the change from a polydomain to a monodomain configuration occurs.

    13. A Novel Pathway for Synthesis of Submicrometer-Size Solid Core/Mesoporous Shell Silica Spheres (pages 1036–1038)

      Gunter Büchel, Klaus K. Unger, Akihiko Matsumoto and Kazuo Tsutsumi

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1036::AID-ADMA1036>3.0.CO;2-Z

      The synthesis of tailored nanoparticles—non-porous and porous—is a major challenge in advanced materials science. The authors here report the synthesis of submicrometer-size silica particles with a solid core and a thin porous shell (see Figure). The thermal stability and the high specific surface area make these silica beads suitable as adsorbents for various applications in chromatography.

    14. Evidence for Physisorption of Aluminum on the Surface of Electroluminescent Sexiphenyl (pages 1038–1043)

      Norbert Koch, Li-M. Yu, Vincent Parenté, Roberto Lazzaroni, Robert L. Johnson, Günther Leising, Jean-J. Pireaux and Jean-Luc Brédas

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1038::AID-ADMA1038>3.0.CO;2-N

      The interface between aluminum and electroluminescent sexiphenyl (6P) is investigated by means of photoelectron spectroscopy together with quantum mechanical calculations. X-ray and ultraviolet photoelectron spectroscopy are used to reveal that the interaction of aluminum—often used as the electron-injecting electrode in light-emitting diodes—on a 6P surface is of the van der Waals type, i.e., the metal atoms physisorb on the organic compound. In addition, it is calculated that bond formation between Al atoms and phenylene oligomers is not energetically favored.

    15. Macroporous Membranes with Highly Ordered and Three-Dimensionally Interconnected Spherical Pores (pages 1045–1048)

      Sang Hyun Park and Younan Xia

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1045::AID-ADMA1045>3.0.CO;2-2

      Highly ordered three-dimensional macroporous membranes can be useful as photonic bandgap structures or as supports for new diffractive optical sensors. As discussed here, these membrane films (see Figure) can be produced with monodispersed nanoparticles as templates. The membranes consist of organic polymers and show a uniform pore size distribution.

    16. Templating Nanoporosity in Thin-Film Dielectric Insulators (pages 1049–1053)

      James L. Hedrick, Robert D. Miller, Craig J. Hawker, Kenneth R. Carter, Willi Volksen, Do Y. Yoon and Mikael Trollsås

      Article first published online: 26 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199809)10:13<1049::AID-ADMA1049>3.0.CO;2-F

      Porous thin-film dielectric insulators with significantly lower dielectric constants are expected to have great impact on the fabrication of ever smaller semiconductor devices and chips with higher packaging densities. Here two routes to the preparation of such nanoporous thin films are presented. A method has been developed that generates polyimide foams with nanopores from a block copolymer in which the dispersed phase undergoes thermolysis. The other approach described uses branched, highly functional macromolecules as molecular templates during vitrification of a silesquioxane.