Materials Literature
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Green fields of nanowires: Germanium, a Group IV semiconductor, can act as an efficient catalyst for high-rate (up to 400 μm h−1) growth of very long (up to 200 μm), extremely straight, and quasi-aligned arrays of single-crystalline ZnO nanowires (see picture). The diameter of the Ge particles (0.5–4 μm) is about 5–15…
A general method for entrapment of hydrophobically coated nanocrystals in micrometer and submicrometer composite silica spheres, nano@micro, was developed. The method employs two starting solutions hydrophobic solvent containing the sol−gel precursor, a polymer, and the nanocrystals, and an emulsifying hydrophilic pha…
Softly, softly: VS2 nanotubes (see electron micrograph, layer separation 1.6 nm) are prepared from vanadium oxide nanotubes by a “chimie douce” process. The VS2 nanotubes are remarkably stable; the corresponding bulk compound is unstable unless it is intercalated with alkali-metal atoms. The nanotubes reversibly inter…
Bioinspiration: Polar assembly (a feature of many natural protein-based fibrous structures, such as actin, microtubules, intermediate filaments, and collagens) is demonstrated in a straightforward, synthetic, peptide-based fiber system of de novo design (see false-color confocal-microscope image of fibers). This findi…
The high-nuclearity bismuth oxo cluster [Bi22O26(OSiMe2tBu)14] (see structure) was obtained by partial hydrolysis of Bi(OSiMe2tBu)3. A hydrophobic layer of silanolate groups covers the bismuth oxo core, the structure of which is closely related to that of β-Bi2O3. Both the bismuth oxo cluster and the bismuth silanolat…
Any old ion? Two bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) radical salts with ion channels of stacked [18]crown-6 and Cat/H2O molecules (Cat=H3O+ or NH4+) are described. The structures contain alternating BEDT-TTF layers, [(Cat)M(C2O4)3]2− (M=Ga, Cr) layers, and the [18]crown-6 ion channels (see picture). The s…
We describe the synthesis of two cyclobutadiene(cyclopentadienyl)cobalt-containing poly(p-phenylene ethynylene)s (PPEs) and their use as precursors for stable ceramic surface coatings. Organometallic PPEs were shaped into hexagonally ordered assemblies by using the breath-figure method. Such breath figures can be wash…
We examine the static and dynamic properties of polymer chains in a melt in the presence of a solid surface. A molecular dynamics simulation is carried out using a coarse-grained bead−spring model of polymer chains. Both attractive and repulsive interactions between surface and monomers are examined. Static conformati…
Shape sorting: The incorporation of a flexible coil of variable length into a rigid wedge-shaped building block leads to the spontaneous formation of a rich variety of supramolecular structures. These include a bilayer lamellar structure with in-plane hexagonally ordered perforations (see picture, R=(CH2)13CH3).
The unusual magnetic behavior of [Ru2(μ-O2CMe)(μ-DPhF)3(H2O)]BF4⋅0.5 CH2Cl2 (1; DPhF=N,N′-diphenylformamidinate), which is intermediate between that of compounds with spin states S=1/2 and S=3/2, is attributed to a quantum mechanical spin admixture. This phenomenon results from a multiple bond between the metal atoms…
A series of red and blue highly fluorescent core-substituted naphthalene bisimide dyes has been synthesized and they have been investigated as supramolecular building blocks. NMR and UV-Vis titration experiments of these dyes with complementary melamines revealed the formation of triple hydrogen bonds (DAD-ADA arrays)…
Only C and N atoms are present in the high-nitrogen compound 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine (TAAT), which is thus an ideal precursor for carbon nitrides. Controlled pyrolysis of TAAT afforded novel nitrogen-rich carbon nitrides in the form of nanolayers (C2N3), nanoclusters (C3N5), and nanodendrites (C3N5, s…
Conformation-dependent tuning of color: Starting from aryloxy-substituted perylene bisimides two isomeric diagonally (A) and laterally (B) bridged macrocycles were synthesized (see picture) for three different bridge lengths. These isomers comprise different conformational features and can, therefore, be used as molec…
Functional and externally controllable electroactive nanostructures are obtained by an ionic self-assembly process. 2D rectangular columnar structures (see picture) comprising oligoanilines were prepared by complexation with double-tail phosphate surfactants. Upon heating, tetraaniline complexes show an order–disorder…
Titanium oxide clusters are generated in a supersonic expansion by laser ablation of the metal and reaction with oxygen (0.1-6%) in He expansion gas. Mass spectra of the titanium oxide clusters are observed by photoionization with lasers of three different wavelengths: 118, 193, and 355 nm. Only the 118 nm (10.5 eV) l…
We report the synthesis and characterization of crystal-like structurally well-ordered ethylene-containing hybrid mesoporous organoaluminosilicate materials, which exhibit molecular-level periodicity in the pore walls and enhanced hydrothermal stability. Distilled 1,2-bis(triethoxysilyl)ethylene (BTEE) was used as the…
An exceptionally high capacity for the elimination of volatile organic compounds (VOCs) is displayed by a three-dimensional mesoporous chromium oxide (see picture). Under ambient conditions the material acts as a selective sorbent for VOCs (e.g., toluene), whereas at higher temperatures it is an effective and selectiv…
We report experimental results from a de novo designed oligopeptide that intermolecularly self-assembles into rigid hydrogel networks after an intramolecular folding event. Microscopy and neutron scattering reveal a fibril local structure that is approximately 3 nm in diameter and over several hundred nanometers in le…
A strong blue emission is observed for hybrid Ce3+/Ce4+ cerium phosphate nanotubes, whereas Ce3+ phosphate nanowires exhibit a characteristic double-peak UV luminescence (see picture). These cerium phosphate systems were obtained by annealing novel cerium(IV) phosphate nanotubes at different temperatures.
Local magnetoelectric interactions are revealed as origins of a recently reported coupling between ferroelectric and antiferromagnetic orders in multiferroic $\mathrm{Ho}\mathrm{Mn}{\mathrm{O}}_{3}$. Temperature and field-dependent topography of the antiferromagnetic domain structure evidences massive formation of ``s…