Advanced Materials

Cover image for Advanced Materials

October 1996

Volume 8, Issue 10

Pages fmi–fmi, 787–868

  1. Masthead

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. Masthead (page fmi)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081001

  2. Essay

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. The journal of molecular modeling: Electronic chemistry publishing (pages 787–788)

      Dr. Tim Clark

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081002

      The experience of publishing the first fully electronic chemistry journal has exploded many of the myths and legends of the Internet. Tim Clark, editor of the Journal of Molecular Modeling, describes the aims and ideas behind the journal and considers its acceptance among computational chemists at universities and in industry. He briefly outlines how typically “electronic” features can be more fully exploited and concludes that we are at the beginning of an exciting new phase of scientific publishing.

  3. Materials Forum

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. Materials Forum (page 789)

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081003

  4. Review

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. Organic molecular beam deposition of metallophthalocyanines for opto-electronics applications (pages 791–799)

      Dr. Akira Yamashita and Dr. Takayoshi Hayashi

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081004

      Organic molecular beam deposition (OMBD) enables the deposition of various materials under optimum conditions. This review is restricted to films of metallophthalocyanines (see Figure) and related compounds, which are of interest for opto-electronic applications. Following a description of typical apparatus and conditions, epitaxially grown pseudomorphic films, films with bulk structure, and multilayers are reviewed.

  5. Communications

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. The first radical salt of the polyoxometalate cluster [P2W18O62]6⊖ with bis(ethylenedithio)tetrathiafulvalene (ET): ET11[P2W18O62] · 3H2O (pages 801–803)

      Prof. Eugenio Coronado, José Ramón Galán-Mascarós, Carlos Giménez-Saiz, Carlos J. Gómez-Garcĺa and Dr. Vladimir N. Laukhin

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081005

      The study of organic donor-inorganic cluster hybrids has been extended to polyoxometalates with higher nuclearities and different shapes using the heteropolyanion [P2W18O62]6⊖ combined with bis(ethylenedithio)tetrathiafulvalene. The resulting hybrid material is unique in several respects: the new radical salt has an unprecedented stoichiometry and β-type packing; it is the first well-characterized radical salt of a polymetalate to exhibit metallic behavior. Further possibilities for investigation are briefly outlined.

    2. Extended bis-fused tetrathiafulvalenes incorporating a heteroaromatic π-electron spacer (pages 804–807)

      Dr. Yohji Misaki, Toshihiro Sasaki, Takehiro Ohta, Hideki Fujiwara and Prof. Tokio Yamabe

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081006

      New π-electron donors are being sought for the preparation of organic conductors. The first synthesis of bis-fused π-electron donors incorporating a heteroaromatic π-electron spacer (see Figure) is reported. The electrochemical properties of 3a–c and 4a–c and the crystal structure of 3c are presented, the results for the TCNQ complexes 3a and 4a confirming that the fusion of two donor units is a suitable strategy for the development of highly conducting molecular complexes.

    3. Synthesis and crystal structure of a new unsymmetrical oxygen containing TTF (pages 807–808)

      Dr. Mikael Moge, Dr. Jonas Hellberg, Dr. Karl Wilhelm Törnroos and Dr. Jost-Ulrich von Schütz

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081007

      Many chalcogen-substituted derivatives of tetrathiafulvalene (TTF) are able to form metallic or even superconducting cation radical salts. The particular properties of bis(ethylenedithio)TTF (ET) prompted the synthesis of new oxygen-containing analogues of ET. One such new molecule, ETOX, is presented, which, besides being a new π-donor, is the first mono-oxa derivative of ET. It is shown to be a promising donor for molecular metals and superconductors that gives cation radical salts with a variety of stoichiometries.

    4. Rapid switching solid state electrochromic devices based on complementary conducting polymer films (pages 808–811)

      Shawn A. Sapp, Gregory A. Sotzing, Jerry L. Reddinger and Prof. John R. Reynolds

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081008

      New electrochromic materials (ECMs) must exhibit rapid response times, long-term stability, and a large difference in percentage transmittance between the bleached and colored states. The design, fabrication, and characterization of fast, solid-state, dual conducting polymer EC devices that utilize PEDOT (see Figure) as the cathodically coloring material are described, following background information on ECMs.

    5. λ-Type BETS salts containing a mixed halide gallium anion, GaXx Y4−x [X, Y = F, Cl, Br; BETS = Bis(ethylenedithio)tetraselenafulvalene] (pages 812–815)

      Hisashi Tanaka, Akiko Kobayashi, Taro Saito, Koichi Kawano, Dr. Toshio Naito and F. Hayao Kobayashi

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081009

      A new series of organic superconductors is reported: λ-type salts of bis(ethylenedithio)tetraselenafulvalene (BETS) with mixed halide gallium anions. Their preparation and properties are described, with particular emphasis on the electrical resistivity. A strong correlation is observed between the superconducting transition temperature Tc and the unit cell volume, which should enable the superconducting transition to be investigated systematically and facilitate the design of new organic superconductors with enhanced Tc.

    6. Transient photoconductivity in a discotic hexagonal plastic crystal (pages 815–819)

      Dr. Jürgen Simmerer, Birgit Glüsen, Dr Wolfgang Paulus, Andreas Kettner, Peter Schuhmacher, Dieter Adam, Karl-Heinz Etzbach, Karl Siemensmeyer, Prof. Joachim H. Wendorff, Prof Helmut Ringsdorf and Prof. Dietrich Haarer

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081010

      Charge-carrier transport in organic materials is the fundamental physical process behind devices such as laser printers. Charge-carrier mobility data are presented for hexabutyloxytriphenylene (H4T), which exhibits an unusually high charge-carrier mobility, which can be traced to the formation of a plastic discotic phase. The Figure shows the normal discotic hexagonal texture with six-fold symmetry observed for H4T at 144°C; this symmetry disappears at lower temperatures (see also the cover).

    7. Poly(2,2′-spaced-dipyrroles): Bandgap contraction by additive and charge-transfer mechanisms (pages 819–823)

      Prof Giorgio Pagani, Dr. Anna Berlin, Dr. Augusto Canavesi, Dr. Gilberto Schiavon, Dr. Sandro Zecchin and Gianni Zotti

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081011

      A strategy to decrease the bandgap of polypyrrole in modified pyrrole-based polymers is the alternation of acceptor (A) and donor (D) groups in the chain. The synthesis of appropriate monomers, their electropolymerization to polyconjugated conducting polymers, and evidence for the narrow bandgap properties of the corresponding neutral systems are described. It is demonstrated that in the presence of specific charge-transfer interactions between the A and D groups the decrease in the bandgap is strongly enhanced.

    8. The mobility of charge carriers in all four phases of the columnar discotic material hexakis(hexylthio)triphenylene: Combined TOF and PR-TRMC results (pages 823–826)

      Anick M. van de Craats, John M. Warman, Dr. Matthijs P. de Haas, Dr. Dieter Adam, Dr. Jürgen Simmerer, Prof Dietrich Haarer and Dr. Peter Schuhmacher

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081012

      Peripherally alkyl-substituted aromatic molecules are of interest because they are predicted to promote the rapid vectorial conduction of electronic charge. It is shown—using the example of HHTT, see Figure—that the results obtained by flash-photolysis time-of-flight conductivity and pulse-radiolysis time-resolved microwave conductivity measurements are complementary, allowing the charge-carrier mobility to be determined in all four phases of HHTT.

    9. Ferromagnetic order in a novel imino nitroxide (IT)Py(C [TRIPLE BOND] CH) radical derived from 2-ethynyl-pyridine (pages 826–829)

      Francisco M. Romero, Dr. Raymond Ziessel, Dr. Marc Drillon, Dr. Jean-Louis Tholence, Dr. Carley Paulsen, Dr. Nathalie Kyritsakas and Prof. Jean Fisher

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081013

      Purely organic ferromagnets are rare, the main problem being the relative orientation of the spins in a three-dimensional network. The first example of ferromagnetic ordering in an imino-nitroxide radical is reported. A detailed analysis of the structure reveals that CCH[BOND]O hydrogen bonds are responsible for both the crystal packing and the ferromagnetic spin interactions within an infinite chain of ordered molecules. This radical is unique: its structure is the first demonstration of the use of terminal acetylenes to generate supramolecular networks.

    10. AFM studies of the initial stages of spin-coated prepolymer film growth on silicon wafers (pages 829–833)

      Thomas Gesang, Dr. Ralf Höper, Prof. Wulf Possart, Prof. Jürgen Petermann and Prof. Otto-Diedrich Hennemann

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081014

      Polymeric film growth on inorganic substrates plays an important role in the technology of sensors and microelectronics. A study of the film growth of a prepolymer of the dicyanate of bisphenol A (DCBA) spin-coated onto silicon substrates is presented in which layer-by-layer growth is demonstrated. This mode of growth is thought to be related to an enrichment of the trimer (see Figure) including a triazine ring.

    11. New conjugated polymer/sol-gel glass composites: Luminescence and optical waveguides (pages 833–837)

      Erez Z. Faraggi, Yoram Sorek, Ofer Levi, Prof. Yair Avny, Prof. Dan Davidov, Dr. Ronny Neumann and Prof. Renata Reisfeld

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081015

      Composites of a sol-gel glass and a conjugated polymer have the potential to combine their unique properties: the high stability and ease of preparation of the sol-gel host and the optical fluorescence of the polymers. Two methods of preparation of such new composites are described, one of which successfully leads to composites with photoluminescence similar to that of homogeneous films of conjugated polymers. This result opens up new vistas in the fabrication of devices based on thin films of conjugated polymers using composite materials.

    12. Fabrication of three-dimensional micro-structures: Microtransfer molding (pages 837–840)

      Xiao-Mei Zhao, Younan Xia and George M. Whitesides

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081016

      Microtransfer molding is a new technique for rapidly fabricating micrometer-scale structures over large areas (3.5 cm × 0.8 cm). This new technique, which involves the solidification of a liquid precursor in an elastomeric mold, can generate microstructures of organic polymers and ceramics such as that shown in the Figure on both planar and contoured surfaces and is able to make three-dimensional structures layer by layer.

    13. Microemulsion polymerization: New surfactant systems by counterion variation (pages 840–844)

      Prof. Markus Antonietti and Hans-Peter Hentze

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081017

      Novel surfactant systems that allow the formation of polymerizable microemulsions are required for the synthesis of ultrafine polymer latices. The work reported here extends the ability to formulate new microemulsion “recipes” by means of a new approach: the geometry and polarity of a given surfactant can be adjusted by electrostatic coupling with an appropriate organic counterion, e.g., the generation of a very bulky hydrophobic head group. It is demonstrated that counterion variation of classical surfactants leads to a significant improvement of classical microemulsions.

    14. The first crystalline hexagonal Si3N4 microtubes (pages 844–847)

      Hubert Huppertz, Norbert Stock and Prof. Wolfgang Schnick

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081018

      Hollow, regularly shaped hexagonal Si3N4 microtubes (see Figure) have been synthesized by reaction of cobalt metal with silicon diimide. Some are partially and some completely filled with metallic inclusions, which were identified as Co2Si. The formation of crystalline transparent filaments with non-transparent spherical or polyhedral particles at the tip is also reported.

    15. The effects of DC electric currents on the in-vitro calcification of bioactive silicon wafers (pages 847–849)

      Dr. Leigh T. Canham, Jon P. Newey, Chris L. Reeves, Mike R. Houlton, Dr. Armando Loni, Dr. Andrew J. Simons and Dr. Timothy I. Cox

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081019

      That silicon could become an important tissue-compatible biomaterial is suggested by recent results. First observations are reported here of the significant effects that electrical bias has on the calcification process under simulated a cellular physiological conditions. Cathodic current flow through porous silicon is shown to accelerate the kinetics of calcium phosphate deposition. Reasons why formation is restricted to the cathodically biased region and why calcium phosphate is not formed within the silicon layer are discussed.

    16. Bioactive polycrystalline silicon (pages 850–852)

      Dr. Leigh T. Canham, Chris L. Reeves, David O. King, Paul J. Branfield, Jim G. Crabb and Dr. Michael C. L. Ward

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081020

      The bioactivity of a range of microstructured silicon materials should be assessed since it has been demonstrated that low porosity microporous silicon is “bioactive”. Work reported here shows that certain types of polycrystalline silicon are also bioactive, being corroded and exhibiting surface deposits of calcium phosphate (see Figure) when kept in simulated body fluids (SBF).

  6. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews
    1. Molecular orbital energy level engineering in organic transistors (pages 853–855)

      Dr. Ananth Dodabalapur, Dr. Howard E. Katz and Dr. Luisa Torsi

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081021

      The application of heterostructure concepts to organic field effects transistors (FETs) is briefly reviewed. In particular, the physics of operation of α-sexithiophene- and C60-based FETs—which can act as p- or n-channel transistors depending on the sign and magnitude of the gate bias—and of isotype heterostructure FETs is outlined. In the latter, both active materials, e.g., an aromatic diamine and α-sexithiophene, transport the same (majority) carrier type.

    2. Semiconductor nanotube formation by a two-step template process (pages 857–859)

      Dr. Patrick Hoyer

      Version of Record online: 29 OCT 2004 | DOI: 10.1002/adma.19960081022

      Multistep template synthesis offers an easy and general route to complicated nanostructures. A two-step replication procedure is described that can be used to prepare nanotubes of titanium dioxide (see Figure) or other semiconducting materials. The requirements placed on the starting material, the synthesis route, and the TiO2 deposition mechanism are considered and filling of the tubes is briefly discussed.

  7. Book Reviews

    1. Top of page
    2. Masthead
    3. Essay
    4. Materials Forum
    5. Review
    6. Communications
    7. Research News
    8. Book Reviews

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