Advanced Materials

Cover image for Advanced Materials

November 1994

Volume 6, Issue 11

Pages fmi–fmi, 817–889

  1. Masthead

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

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061101

  2. Essay

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Planning for the future: The role of the ESF (pages 817–818)

      Sir Dai Rees

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061102

      The European Science Foundation is a federation of research councils and academies, from various European countries, that have significant responsibility for the funding of science and scholarship. The changing role of the ESF in recent years is examined, particularly in the face of tighter research budgets in all countries and the increasing part played by the European Union in encouraging collaboration of researchers throughout Europe. Future aims of the ESF are presented.

  3. Reviews

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Conducting Stacked Metallophthalocyanines and Related Compounds (pages 819–833)

      Prof. Michael Hanack and Manuela Lang

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061103

      Phthalocyanine-related compounds have many interesting materials properties. This review concentrates on the conductive properties of phthalo- and naphthalocyaninatometal compounds on the (e.g., see Figure). Syntheses are presented and the relationship between the morphology of the macrocycles and the electrical properties is discussed. Particular attention is paid to the bridged transition metal complexes.

  4. Communications

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Supramolecular orientation of conjugated porphyrin oligomers in stretched polymers (pages 834–836)

      Dr. Harry L. Anderson

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061104

      Conjugated porphyrin oligomers show strong optical dichroism when oriented in a stretched polymer matrix. It is shown that the zinc porphyrin polymer (∼10 repeat units) aligns, as expected, with its backbone in the stretch direction, whereas the dimer orients with its molecular plane perpendicular to the stretch. This anomalous behavior is explained as being due to the formation of supramolecular stacks that orient as single units.

    2. Iron(II) octaethyltetraazaporphyrin, FeOETAP, a canted ferromagnet with Tc = 5.6 K (pages 836–838)

      Brenda J. Conklin, Scott P. Sellers, Dr. Jeffrey P. Fitzgerald and Prof. Gordon T. Yee

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061105

      A four-coordinate azaporphyrin, FeOETAP (see Figure), is reported that has temperature- and field-dependent properties different from those of other fourcoordinate iron(II) porphyrins and related macrocycles, displaying an apparent canted ferromagnetic state. This behavior is compared to that of M2⊕(OETAP), where M = Mn, Co, Ni, Cu, and Zn.

    3. Reversible charge transfer complexes between molecular oxygen and poly(3-alkylthiophene)s (pages 838–841)

      Dr. Mohamed S. A. Abdou, Dr. Frank P. Orfino, Dr. Zi W. Xie, Prof. M. Jamal Deen and Prof. Steven Holdcroft

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061106

      The interaction of poly(3-hexylthiophene), P3HT, with oxygen has been investigated. Evidencein the form of UV–vis absorption, electron paramagnetic resonance data, and a field effect conductivity analysis of a polymer-based field effect transistor–is presented for the existence of a reversible charge transfer complex between P3HT and oxygen. Oxygen-sensor applications can be foreseen for thin film transistors incorporating P3HT.

    4. Effects of structure on the optical and redox properties of the oligothiophene— Tetrathiafulvalene hybrid system (pages 841–845)

      Dr. Jean Roncali, Dr. Lennart Rasmussen, Dr. Christine Thobie-Gautier, Dr. Pierre Frère, Dr. Hugues Brisset, Dr. Marc Sallé, Prof. Jan Becher, Dr. Ole Simonsen, Dr. Thomas K. Hansen, Dr. Amina Benahmed-Gasmi, Dr. Jesus Orduna, Dr. Javier Garin, Prof. Michel Jubault and Prof. Alain Gorgues

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061107

      The optical properties of the oligothiophene–tetrathiafulvalene system are greatly affected by structural factors. An understanding of these, as presented here, is a first step towards reducing the band gap in thiophene oligomers and thus optimizing them for device applications. The effect of spacer length and the role of planarity and rigidity, for example of the syn conformation shown in the Figure, are investigated.

    5. An efficient strategy towards small bandgap polymers: The rigidification of the π-conjugated system (pages 846–848)

      Dr. Jean Roncali and Dr. Christine Thobie-Gautier

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061108

      The design of narrow bandgap polymers remains a major challenge in the field of organic conductors. An alternative scheme is proposed for reducing the bandgap, namely the construction of a one-dimensional graphitelike chain. Terthienyl frozen in a fully planar syn conformation is used as a simplified model compound for rigidified polythiophene. Its synthesis, cyclic voltammetry results, and electropolymerization are reported, which suggest that even smaller bandgaps could be produced in polythiophenes using this strategy.

    6. The influence of alkoxy side chains on the conformational flexibility of oligo- and polythiophenes (pages 848–851)

      Dr. Stefano V. Meille, Dr. Alessandra Farina, Dr. Federica Bezziccheri and Prof. Maria C. Gallazzi

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061109

      Alkoxy-substituted thiophenes have been shown to yield polymers with a reduced bandgap. An X-ray investigation of two symmetrical pentoxy-substituted 2,2′-bithienyls is reported, and their structure and packing described. It is suggested that the extra rigidity and packing stability of the alkoxythiophene oligomers and polymers accounts for their lower solubility and higher melting points compared to their alkyl-substituted analogues.

    7. First hyperpolarizability of organotin compounds with Td symmetry (pages 851–853)

      Dr. Minh Lequan, Dr. Catherine Branger, Prof. Jacques Simon, Dr. Thierry Thami, Dr. Eve Chauchard and Prof. André Persoons

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061110

      A new class of nonlinear optical materials, tetrahedral tin complexes in which the metal ion can act as a polarizable group linked to donor dimethylamino moieties, is described. An example is shown in the Figure. The quadratic hyperpolarizability coefficients determined by hyper-Raman scattering are reported and the important characteristics of the molecules discussed.

    8. Molecular recognition effects in an L-tartaric acid—Silica composite prepared using the sol-gel method (pages 854–855)

      Dr. Fujio Mizukami, Hiroyuki Izutsu and Tetsuya Osaka

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061111

      Molecular recognition ability is one of the properties exhibited by a composite presented here consisting of an optically active organic compound (L-tartaric acid) and silica. It is reported that the composite formed by the sol-gel method can distinguish the chirality of the complex tris(2,4-pentanedionato) cobalt(III). The reasons for the differing properties of the composites formed by impregnation and the sol-gel method are discussed and circular dichroism spectra presented.

    9. The formation of rings of platinum dots and the control of the size of platinum particles on silica surfaces using organic—Inorganic composites (pages 856–858)

      Dr. Fujio Mizukami, Fumi Taniguchi, Yoshimichi Kiyozumi, Aya Kobayashi, Hiroyuki Izutsu and Kazuyuki Maeda

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061112

      Organic-inorganic composites can be used to tailor the properties of inorganic materials. A method of controlling the distribution and dispersion of platinum in platinum-loaded silica using organic-inorganic compounds prepared in two different ways is described, and an explanation for the unexpected formation of rings of platinum dots on the silica surface (see Figure) is proposed.

    10. A novel method for the preparation of magnetic nanoparticles in a polypyrrole powder (pages 858–860)

      Dr. My T. Nguyen and Dr. Arthur F. Diaz

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061113

      A magnetic polymer composite containing γ-Fe2O3 nanoparticles and prepared from poly(pyrrole-N-propylsulfonate) by a simple reaction with aqueous NH4OH is described. The results of physical characterization by X-ray powder diffraction and an investigation of the magnetic properties are presented. Such composites incorporating particles of metal oxides are of interest for electromagnetic interference shielding and microwave absorbing applications.

    11. Nanoporous tin(IV) sulfides: Mode of formation (pages 860–865)

      Tong Jiang, Prof. Geoffrey A. Ozin and Dr. Robert L. Bedard

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061114

      Nanoporous R-SnS-n materials e.g. (Et4N)2Sn3S7, have been sythesized and characterized. The crystal structures of two molecular tin(IV) sulfide species that are thought to be important in the formation of these materials are reported. Both contain the dimer (Sn2S6)4⊖, which can be combined (see Fingure) to form the Sn4S4 broken-cube clusters that constitute the open framework of R-SnS-1.

    12. Rapid chemography of porous silicon undergoing hydrolysis (pages 865–868)

      Dr. Leigh T. Canham, Dr. Steven J. Saunders, Dr. Paul B. Heeley, Dr. Andrew M. Keir and Dr. Timothy I. Cox

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061115

      Highly porous silicon reacts with water vapor in the air to create images on photographic plates within seconds. It is demonstrated that this process, known as chemography, can be used diagnostically to reveal inhomogeneity in porous silicon layers that is not always detectable by optical or electron microscopy. It is suggested that many dried highly porous semiconductors may constitute a significant health hazard owing to the liberation of high concentrations of toxic hydrides through hydrolysis.

  5. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Langmuir monolayer assemblies on chemical oscillators (pages 869–871)

      Dr. Mitsuru Yoneyama, Dr. Akiteru Fujii and Dr. Shuichi Maeda

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061116

      Oscillatory chemical reactions are exemplified by the Belousov- Zhabotinskii (BZ) reaction. A new type of structurally ordered chemical oscillator is reported: the BZ reactor-Langmuir monolayer coupled system (see Figure), where the monolayer contains Ru(bpy)32⊕ (bpy is bipyridyl), which luminesces. The preparation and spatio-temporal properties of this system are described.

  6. Materials Forum

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Materials Forum (page 871)

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061117

  7. Research News

    1. Top of page
    2. Masthead
    3. Essay
    4. Reviews
    5. Communications
    6. Research News
    7. Materials Forum
    8. Research News
    1. Perforated monolayers (pages 872–874)

      Dr. Mark D. Conner and Prof. Steven L. Regen

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061118

      The synthesis of polymeric membranes that exhibit high permeation selectivity and high flux is a major challenge that has important technological implications. The concept of perforated monolayers (i.e., two-dimensional arrays of porous surfactants) has been introduced in an attempt to rationally design such materials. The presented results indicate that these ultrathin materials have potential as novel membranes for separation.

    2. Molecular sieve encapsulated organic dyes and metal chelates (pages 875–880)

      Prof. Dieter Wöhrle and Prof. Günter Schulz-ekloff

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061119

      Inorganic molecular sieves have a well-defined internal structure of uniform cages, cavities, or channels–see the Figure for an example–making them suitable for many applications. Recently the inclusion of dyes and metal chelates as guests has been studied. The results are reviewed briefly, including the preparation and characterization of the host/guest system and the chemical reactivity.

    3. Thin-film fabrication by laser ablation of addition polymers (pages 881–887)

      Dr. Graciela B. Blanchet and Dr. Curtis R. Fincher Jr.

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061120

      Laser ablation can be used to deposit polymer thin films, in addition to its widespread application for the deposition of inorganic materials. The production of polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA) films by evaporation of the solid polymer target with a pulsed UV laser is described. The composition and morphology of the films, the lasertarget interaction, and the film characterization are discussed. Finally, possible routes are considered for how the ablation proceeds.

    4. Observation of phase-separated polymeric LB films using scanning probe microscopy (pages 888–889)

      Dr. Tomoyuki Yuba, Dr. Shiyoshi Yokoyama, Prof. Masa-Aki Kakimoto and Dr. Yoshio Imai

      Article first published online: 15 SEP 2004 | DOI: 10.1002/adma.19940061121

      Formation of polyimide films by the Langmuir-Blodgett (LB) method is described. The preparation and possible applications of the films are detailed. In a mixed LB film of two different polyimides, friction force microscopy reveals hexagonal islands (see Figure), which is the first observation of two-dimensional phase separation in a polymer mixture.

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