Advanced Functional Materials

Cover image for Vol. 12 Issue 5

May, 2002

Volume 12, Issue 5

Pages 319–394

    1. Contents: Adv. Funct. Mater. 5/2002 (pages 319–321)

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<319::AID-ADFM319>3.0.CO;2-X

    2. Controlled Growth of ZnO Nanowires and Their Optical Properties (pages 323–331)

      P. Yang, H. Yan, S. Mao, R. Russo, J. Johnson, R. Saykally, N. Morris, J. Pham, R. He and H.-J. Choi

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<323::AID-ADFM323>3.0.CO;2-G

      Single-crystalline zinc oxide nanowires can be synthesized in a rational manner using the simple vapor transport and condensation process presented here. The orientation, position, diameter, and morphology of the nanowires can be controlled and lasing action is observed in nanowire arrays without the need for fabricated mirrors. The control that can be achieved over the position and morphology is illustrated on the cover and in the Figure, respectively.

    3. Highly Ordered Fe and Nb Stripe Arrays on Facetted α-Al2O3 (10equation image0) (pages 333–338)

      M. Huth, K.A. Ritley, J. Oster, H. Dosch and H. Adrian

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<333::AID-ADFM333>3.0.CO;2-C

      Polycrystalline and epitaxial nanowires of Fe and Nb can be grown on facetted sapphire via molecular beam epitaxy (MBE). Geometrical shadowing is used in conjunction with partial de-wetting of the epilayer on the facets to produce highly ordered nano- and mesostripes (see Figure). Advantages over other stripe fabrication strategies include epitaxial quality, tunable width, and the ability to grow superconducting and rare earth nanowires.

    4. 2-Pyridones as a New Photochemically Stable Structural Design for the Off-Resonant Optical Kerr Effect (pages 339–346)

      S. Burger, F. Chérioux, K. Monnier-Jobé, B. Laude and H. Maillotte

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<339::AID-ADFM339>3.0.CO;2-P

      2-Pyridones (see Figure) exhibit a stable and off-resonant optical Kerr effect. Several push–pull molecules with this particular non-aromatic heterocycle as a spacer between different donor and acceptor groups have been synthesized, and the good transmitter behavior of the pyridonic ring is demonstrated here. A polymer based on this structural design has also been developed.

    5. A Thermally and Electrochemically Switchable Molecular Array Based on a Manganese Schiff Base Complex (pages 347–351)

      D. Ruiz-Molina, K. Wurst, D.N. Hendrickson, C. Rovira and J. Veciana

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<347::AID-ADFM347>3.0.CO;2-T

      A molecular switch with six electronic states, all of which exhibit different optical and magnetic properties, is reported. The molecule with these unusual properties is a manganese complex with two identical tridentate ligands: it undergoes reversible one-electron oxidation and thermal valence tautomerization, involving Mn oxidation states and radical vs. ionic ligands. The Figure shows one tautomer of the oxidized form.

    6. Orientation of Organic Nanocrystals Grown in Sol–Gel Matrices under a High Magnetic Field (pages 352–358)

      N. Sanz, I. Wang, J. Zaccaro, E. Beaugnon, P.L. Baldeck and A. Ibanez

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<352::AID-ADFM352>3.0.CO;2-8

      Organic chromophores with high quadratic nonlinear optical (NLO) efficiencies have been embedded in sol–gel glasses. The effect of applying a high magnetic field during crystal growth is examined—a weak and inhomogeneous second harmonic generation (SHG) response is observed when no magnetic field is applied, while in the presence of a magnetic field significantly improved SHG is obtained. It is demonstrated that the magnetic field promotes dye aggregation and improves the crystallinity by reducing the orientational freedom of the organic nanocrystals and increasing dipole–dipole interactions.

    7. [Cp*W(dmit)2]: An Organometallic 15-Electron Neutral Radical (d1) with Optical Limiting Properties in Solution and an Antiferromagnetic Ground State in the Solid State (pages 359–366)

      B. Domercq, C. Coulon, P. Feneyrou, V. Dentan, P. Robin and M. Fourmigué

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<359::AID-ADFM359>3.0.CO;2-H

      The paramagnetic dithiolene/cyclopentadienyl tungsten complex d1 [Cp*W(dmit)2] (see Figure) is examined and compared with its Mo counterpart. Density functional theory calculations are employed to analyze its geometry. The complex is found to exhibit positive optical density variations in transitory nanosecond spectroscopy and a weak optical limiting effect. In the solid state, antiferromagnetic interactions lead to an antiferromagnetic ordering below TNéel = 4.5 K.

    8. Chiral Nematic Polymer Mixture Containing Crosslinker and Photosensitive Chiral Dopant: New Type of Materials with Tunable Photo-Optical Properties (pages 367–372)

      A.Yu. Bobrovsky and V.P. Shibaev

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<367::AID-ADFM367>3.0.CO;2-L

      Recording and storage of optical information using a cholesteric mixture of a menthyl-containing copolymer (see Figure), a photosensitive chiral dopant, a mesogenic diacrylate, and a photoinitiating agent has been achieved. Several options are available for reversible and irreversible data storage based on the photopolymerization of the diacrylate and the helix untwisting of the copolymer.

    9. Novel Diffusion-Barrier Materials Against Oxygen for High-Density Dynamic Random Access Memory Capacitors (pages 373–381)

      D.-S. Yoon and J.S. Roh

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<373::AID-ADFM373>3.0.CO;2-X

      Ru-based oxygen diffusion barrier materials that use a new sacrificial design concept are proposed as a means of achieving high-density capacitors. A much lower sheet resistance can be obtained than with alternative barriers as well as a low contact resistance even after annealing at 750 °C. The thermal stability and capacitance characteristics of simple stack-like structures (see Figure) using Ru compounds as the glue layer are found to be very promising.

    10. Replicating the Structure of a Crosslinked Polyferrocenylsilane Inverse Opal in the Form of a Magnetic Ceramic (pages 382–388)

      J. Galloro, M. Ginzburg, H. Míguez, S.M. Yang, N. Coombs, A. Safa-Sefat, J.E. Greedan, I. Manners and G.A. Ozin

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<382::AID-ADFM382>3.0.CO;2-X

      Crosslinked polyferrocenylsilane inverse opals have been prepared by the thermal ring opening polymerization of spirocyclic [1]silaferrocenophanes confined within the interstitial void spaces of silica crystal colloidal templates. These organometallic polymer inverse opals could be converted in high yields to magnetic ceramic replicas through pyrolysis at 900 °C (see Figure).

    11. Solid Polymer Electrolytes Based on Ionic Graft Polymers: Effect of Graft Chain Length on Nano-Structured, Ionic Networks (pages 389–394)

      J. Ding, C. Chuy and S. Holdcroft

      Article first published online: 17 MAY 2002 | DOI: 10.1002/1616-3028(20020517)12:5<389::AID-ADFM389>3.0.CO;2-5

      Highly conductive polystyrene sulfonate films containing a high density of ionic graft chains (see Figure) consist of ionic domains that coalesce into a network of nanochannels. These ionic graft membranes show various degrees of phase separation, whereby the extent of phase separation affects the water sorption and ionic conductivity. The polymers obtained provide fundamental information regarding the design and properties of solid polymer electrolytes.