Hard templating of nanocrystalline titanium dioxide with chiral nematic ordering

Anatase TiO(2) nanocrystals have been organized into high-surface-area (150-230 m(2) g(-1)) mesoporous films with long-range chiral nematic ordering. The chiral structure of the anatase films causes them to selectively reflect circularly polarized light and appear iridescent. These materials show replication of structural features found in the silica template on nanometer to millimeter length scales.     

6 + 6] Schiff-base macrocycles with 12 imines: giant analogues of cyclohexane

Hexagon-shaped [6 + 6] Schiff-base macrocycles with 12 imine bonds are reported. These giant macrocycles possess 6 N2O2 coordination environments and mass spectrometry evidence for hexametallation of one macrocycle is provided. Semi-empirical calculations reveal two stable conformations with boat and chair geometries for the macrocycles metallated with Ni(II), analogous to the conformations observed for cyclohexane.     

Tautomerization in naphthalenediimines: a keto-enamine Schiff base macrocycle

[reaction: see text] A new [3 + 3] Schiff base macrocycle incorporating naphthalene groups has been prepared. By examination of its properties, X-ray crystallography of model compounds, and calculations, it has been determined that the macrocycle exists predominantly as the keto-enamine tautomer. This unexpected tautomerization presents an unusual hexaketo interior in the macrocycle.     

Writing on the wall with a new synthetic quill

A new class of periodic mesoporous organosilicas (PMOs) with organic groups incorporated inside the channel walls of the material is discussed. In particular, the unique properties and chemistry exhibited by periodic mesoporous methylenesilica, an isoelectronic analogue of periodic mesoporous silica, are highlighted. Finally, some of the advances made in our group and others, as well as future directions that we envision in the field are described.     

Electrical resistivity of PdHx: II. Phonon resistivity

The temperature dependent phonon resistivity of the nearly stoechiometric PdH compound has been measured. The results can be explained in terms of two phonon branches, an acoustical one primarily determined by the Pd lattice and an optical one determined by the hydrogen lattice. Some implications concerning the occurence of superconductivity in this system have also been drawn.     

Structural Elucidation of Selective Solvatochromism in a Responsive-at-Metal Cyclometalated Platinum(II) Complex

We report the synthesis, characterization, and spectroscopic investigations of a new responsive-at-metal cyclometalated platinum(II) complex. With mild chemical oxidants and reductants, it was possible to obtain the same complex in three different oxidation states and each of these complexes was structurally characterized by single-crystal X-ray diffraction. We discovered that the platinum(II) complex displays strong solvatochromism in the solid state, which can be attributed to modulation of Pt⋅⋅⋅Pt interactions that results in switching between optical and photoluminescent states. Incorporating responsive-at-metal species as dynamic components in nanostructured materials might facilitate response amplification, sensing, actuation, or self-healing processes.     

Parallel time integration with multigrid

With current trends in computer architectures leading towards systems with more, but not faster, processors, faster time-to-solution must come from greater parallelism. We present a family of truly multilevel approaches to parallel time integration based on multigrid reduction (MGR) principles. The resulting multigrid-reduction-in-time (MGRIT) algorithms are non-intrusive approaches, which directly use an existing time propagator and, thus, can easily exploit substantially more computational resources then standard sequential time-stepping. Furthermore, we demonstrate that MGRIT offers excellent strong and weak parallel scaling up to thousands of processors for solving diffusion equations in two and three space dimensions. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)