Advanced Materials

Cover image for Advanced Materials

December, 1998

Volume 10, Issue 18

Pages 1505–1562

    1. Organic Vapor Phase Deposition (pages 1505–1514)

      Marc Baldo, Miriam Deutsch, Paul Burrows, Herman Gossenberger, Michael Gerstenberg, Vladimir Ban and Stephen Forrest

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1505::AID-ADMA1505>3.0.CO;2-G

      Organic vapor phase deposition (OVPD) opens new opportunities in the control of composition and structure of organic thin films. The use of this recently developed process is examined for the growth of four archetypal organic systems: a crystalline organic salt (the optically nonlinear charge transfer salt DAST, see Figure), amorphous and polymeric organic films, and an optically pumped organic laser (Alq3 doped with Rhodamine 6G).

    2. Engineering the Microfabrication of Layer-by-Layer Thin Films (pages 1515–1519)

      Sarah L. Clark and Paula T. Hammond

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1515::AID-ADMA1515>3.0.CO;2-E

      Layer-by-layer assembly is a simple, yet elegant method for creating a variety of thin-film architectures on surfaces. Many proposed applications for layer-by-layer thin films, such as electro-optical devices or sensors, require the films to be patterned to form micrometer-scale features, and mechanization of this process is a prerequisite. Here the use of a modified commercial slide stainer for the layer-by-layer adsorption process is discussed. Reproducible, uniform patterns over square-centimeter-range surface areas are achieved and the number of layers that may be selectively adsorbed is extended using this approach.

    3. Optical Switching and Fluorescence Modulation in Photochromic Metal Complexes (pages 1519–1522)

      Alvaro Fernández-Acebes and Jean-Marie Lehn

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1519::AID-ADMA1519>3.0.CO;2-R

      Among organic photochromic compounds (attractive for optical data storage) diarylethenes are of special interest as switching units. They undergo a reversible electrocyclic interconversion between a colorless, non-conjugated open state (see Figure) and a colored, conjugated closed state. The design and synthesis of dithienylethene-tungsten complexes and the photoswitching of their luminescence properties is reported.

    4. An All-Plastic and Flexible Electrochromic Device Based on Elastomeric Blends (pages 1522–1525)

      Wilson A. Gazotti, Giuseppe Casalbore-Miceli, Alessandro Geri, Anna Berlin and Marco A. de Paoli

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1522::AID-ADMA1522>3.0.CO;2-U

      All-plastic and flexible electrochromic devices will facilitate new technological applications, such as information display and storage, in the automotive industry (rear-view mirrors) and in architecture (smart windows). Here the authors describe an all-plastic and flexible solid-state electrochromic device using two optically complementary conductive polymer blends deposited on ITO-PET (indium tin oxide–poly(ethyleneterephthalate)), and a polymeric electrolyte. The device was constructed under atmospheric conditions and showed good optical characteristics.

    5. Poly[4-(2-heteroaryl)benzenamines]: Novel Electrically Conducting Alternating Copolymers of Aniline and Chalcophenes (pages 1525–1529)

      Siu-Choon Ng and Lingge Xu

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1525::AID-ADMA1525>3.0.CO;2-C

      Polyaniline (PAN)—an electrically conductive conjugated polymer—was always of major interest due to its unique properties. However, the insolubility of PAN in common organic solvents hampered commercial exploitation. The synthesis of new copolymers of aniline and chalcophenes is reported. The Figure shows a scanning electron micrograph of a poly[4-(2-furyl)benzenamine] film cast from tetrahydrofuran.

    6. Does the Self-Assembled Coating of Magnetic Nanoparticles Cover Individual Particles or Agglomerates? (pages 1529–1532)

      Tanya Prozorov, Ruslan Prozorov and Aharon Gedanken

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1529::AID-ADMA1529>3.0.CO;2-P

      Monolayer coatings on magnetic nanoparticles are of special interest because of their important technological applications in electronics, magnetic recording, magnetic fluids, etc. The surfactant coating acts as a stabilizer and is believed to prevent agglomeration. In this study the authors show that the self-assembly of the monolayer coating takes place on the surface of agglomerates, rather than on the surface of separate nanoparticles. This result is confirmed by elemental analysis and surface area and magnetic measurements of samples with different chain lengths of the surfactant molecule.

    7. Self-Assembling Functional Molecules in Mesoporous Silicate Materials: Optical Properties and Mesophase of Dye-Doped M41S (pages 1532–1536)

      Itaru Honma and Hao S. Zhou

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1532::AID-ADMA1532>3.0.CO;2-S

      A synthetic pathway to functional mesoporous silicate materials of the M41S type by self-assembly between a dye-bound surfactant and sol-gel-derived silica is presented here. Functional molecules are doped and assembled in the center of the mesochannels of these products. Acidic synthesis conditions allowed silicate mesophases to be formed as lamellar films and hexagonal powders (see Figure).

    8. Bioelectronic Glasses: Electrical Addressability of Sol-Gel Immobilized Biomolecules (pages 1536–1540)

      Ying Tang and Bakul C. Dave

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1536::AID-ADMA1536>3.0.CO;2-4

      The unique functional responses of electroactive biomolecules offer untapped opportunities for designing novel materials for molecular bioelectronics. Assembling these biomolecules into a geometric structure that provides rigidity, optical and/or electronic accessibility, and stability is critical for practical applications. The results presented here demonstrate that it is possible to establish electronic communication with a redox-active biomolecule immobilized within the porous structure of a sol-gel. The authors provide a viable approach to utilizing proteins and enzymes for bioelectronic device applications.

    9. Controlled Nanocrystallization of Organic Molecules in Sol-Gel Glasses (pages 1540–1543)

      Alain Ibanez, Serguei Maximov, Antoine Guiu, Catherine Chaillout and Patrice L. Baldeck

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1540::AID-ADMA1540>3.0.CO;2-1

      Quantum size effects can be used to modify material properties on the nanometer scale. This has yet to be extensively studied in organic materials. Here a simple generic preparation of stable organic nanocrystals embedded in sol-gel glasses is reported. The Figure shows a transmission electron bright field image of 4,4-sulfonyldiphenol nanocrystals in a gel-glass splinter.

    10. Statistically Controlled Self-Assembly of Polar Molecular Crystals (pages 1543–1546)

      Stephan W. Roth, Philip J. Langley, Andrea Quintel, Michael Wübbenhorst, Peter Rechsteiner, Peter Rogin, Olaf König and Jürg Hulliger

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1543::AID-ADMA1543>3.0.CO;2-K

      The synthesis of polar molecular materials with designed properties is a fundamental target of materials research. Here a fully rational synthesis of polar materials from a given set of precursors (perhydrotriphenylene and three different guests) is presented. A simulation shows that varying the relative proportions of each guest permits the level of polarity to be tuned with a high degree of control. These results are fundamental to the understanding of how a complex supramolecular system self-assembles into a material with polar properties.

    11. Fluorescent Phasmidic Liquid Crystals (pages 1546–1551)

      Benjamin P. Hoag and Douglas L. Gin

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1546::AID-ADMA1546>3.0.CO;2-2

      Incorporation of emission properties into organic liquid crystals (LCs) is currently an active area of research. The authors present the first example of a functional phasmidic LC with intrinsic luminescence properties. It is shown that organization in the solid state—the Figure indicates the average ordering of hexacatenar LCs in the hexagonal phase (top view)—has a distinct effect on the emission profiles of these materials.

    12. Polymorphic Molecular Materials—The Importance of Tertiary Structures (pages 1553–1557)

      Joel S. Miller

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1553::AID-ADMA1553>3.0.CO;2-I

      Molecule-based materials can exhibit a variety of technologically useful cooperative properties not associated with individual molecules, such as ferromagnetism, superconductivity, and ferroelectricity. Selected examples are used to illustrate the fact that, although in general the molecular structure differs in only minor ways, the qualitative or quantitative differences of the crystal or tertiary structure may lead to substantial differences in the solid-state bulk (magnetic) properties, e.g., presence or lack of ordering, or simply a raising or lowering of the ordering temperature.

    13. Organometallic Nanostructures: Self-Assembly of Poly(ferrocene) Block Copolymers (pages 1559–1562)

      Jason A. Massey, K. Nicole Power, Mitchell A. Winnik and Ian Manners

      Article first published online: 8 JAN 1999 | DOI: 10.1002/(SICI)1521-4095(199812)10:18<1559::AID-ADMA1559>3.0.CO;2-J

      Self-assembly of block copolymers with incompatible segments is known to generate a variety of different morphologies, and provides an attractive, alternative route to nanostructures. The authors describe some of their recent collaborative work on novel organometallic nanostructures made possible by the recent synthetic access to poly(ferrocene) block copolymers (see Figure and also the cover).