3D cubic Fm3m mesoporous aluminosilicates (AlKIT-5) with very high structural order and unprecedented loadings of Al in the silica framework are reported by Ajayan Vinu and co-workers on p. 640. The specific surface area, specific pore volume, and pore diameter of AlKIT-5 can be increased by increasing Al incorporation in the silica framework while retaining the well-ordered 3D cage-type porous structure. The mechanism of this unusual behavior is discussed in detail. In a catalytic activity study, AlKIT-5(10) is found to be superior over zeolite catalysts including ZSM-5.
Organic Light-Emitting Diodes
A new series of star-shaped bipolar host molecules thatcontain hole-transporting triphenylamine andelectron-transporting benzimidazole moieties are designed,based on calculations using density functional theory, and prepared by Masa-aki Kakimoto and co-workers, as reportedon p. 584. The theoretical calculation of energy levels affords helpful ideas to design molecules with a favorable localization of HOMO/LUMO levels and a predefined enhancement ofthe triplet energy gap. The derivatives are employed as hosts to fabricate phosphorescent organic LEDs by spin-coating and vacuum deposition.
Several nanoscale technological applications rely on the promise of highly anisotropic magnetic materials. Verónica Salgueirin˜o-Maceira, Miguel A. Correa-Duarte, andco-workers report on p. 616 the structure, magnetic properties, and interfacial exchange anisotropy effects of unique wires of Ni/NiO synthesized using carbon nanotubes as substrates.Structural analyses of these nanocomposites in correlation withmagnetic measurements show that the crystalline NiO outershells cause an enhanced exchange bias, providing an extra source of anisotropy that leads to their magnetization stability.
An amphiphilic block copolymer is synthesized by RAFTp olymerization and then assembled into micelles in aqueoussolution. Subsequent crosslinking throughout the shell affordswell-defined nanoparticles. In an attempt to narrow the particlesize distributions, the dodecyl trithiocarbonate chain end of theblock copolymer was replaced by a 2-cyanoisopropyl moiety.The primary advantages of this system include the ability to conduct in situ synthesis of nanoparticles that are crosslinkeddirectly and derivatized easily before, during, or after the crosslinking, as demonstrated by Karen L. Wooley and co-workers on p. 551.