Materials Literature
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Unusual morphological features of boron nitride nanotubes produced via metal–oxide-promoted high-temperature syntheses from carbon nanotubes, boron oxide, and nitrogen were observed using high-resolution transmission electron microscopy. The tubes normally displayed open ends and preferentially two or four tubular lay…
The architecture of windmill hexameric zinc(II) -porphyrin array 1 is attractive as a light-harvesting functional unit in view of its three-dimensionally extended geometry that is favorable for a large cross-section of incident light as well as for a suitable energy gradient from the peripheral porphyrins to the meso-…
We report the results of an investigation carried on Methyl Red-doped nematic liquid crystals with the aim of studying the basic mechanism of the extraordinarily large nonlinear response recently reported. We show that the experimental data can be explained as due to light-induced modifications of the anchoring condit…
The field strength of the axial ligands determines the spin state of saddled iron(III) porphyrin complexes. Strong axial ligands (L), such as imidazole and 4-dimethylaminopyridine, lead to the formation of complexes with a pure S=1/2 state, while weak ligands, such as THF, give complexes with a pure S=3/2 state. Inter…
Hydrogen-bonding interactions between a benzotri(imidazole) derivative and a polymerizable alkoxybenzoic acid result in the formation of a supramolecular hexagonal columnar liquid crystal. Light-induced polymerization followed by removal of the benzotri(imidazole) core produces a porous polymer with hexagonal channels.
Extreme reaction conditions lead to the synthesis of γ-P3N5. Its crystal structure (see picture), unlike that of the normal pressure modification α-P3N5, is not exclusively built from PN4 tetrahedra, but from both PN4 tetrahedra (blue) and tetragonal PN5 pyramids (red). A tetragonal PN5 pyramid structure element has n…
A series of hydrosoluble dendrimers has been synthesized by capping phosphorus-containing dendrimers with hydrophilic end groups. These dendrimers form aqueous rigid gels at very low concentration (ca. 1.5 % per weight; see picture), which allows, for example, confinement of acids or metals. The structure of the gels…
Wenn ich erklären soll, welche Bedeutung die Entdeckung leitfähiger Polymere hatte, so habe ich zwei einfache Antworten: Erstens gab es sie nicht (und konnte es sie nicht geben!) und zweitens verfügen sie über eine einzigartige Kombination von Eigenschaften, wie man sie bei keinem anderen bekannten Material findet. Di…
Increased hydrophobicity of well-defined polyoxometalate clusters is possible through complexation with cationic surfactants in a one-pot reaction. The clusters, of toroid and spherical shape and colloidal dimensions, then organized into ordered, supramolecular assemblies, as shown schematically, are similar to classi…
An oxide single crystalline whisker has been prepared which displays superior thermoelectric properties at high temperature in air. The whisker has an average composition of (Bi, Pb)2.2(Sr, Ca)2.8Co2Oy (abbreviated to BC-232 whisker) and a layered structure in which two different sublattices, CoO2 and rocksalt (Bi, Pb…
Seit der Entdeckung im Jahre 1977, dass Polyacetylen (CH)x, heute im Allgemeinen als Prototyp für leitfähige Polymere bekannt, durch chemische oder elektrochemische p- oder n-Dotierung in den metallischen Zustand gebracht werden kann, hat sich die Entwicklung auf dem Gebiet leitfähiger Polymere auf unerwartet rasante…
In this paper the problem of the theory of a quasicrystal structures - the determination of coordinates of each atom of quasicrystal in analytical form - is solved. Within the framework of the proposed model a periodic crystal can be presented as a particular case of a quasicrystal. The simple and explicit analytical…
The segmental ligand 2-[6-(N,N-diethylcarbamoyl)pyridin-2-yl]-1,1'-dimethyl-5,5'-methylene-2'-(6-methylpyridine-2-yl)bis[1H-benzimidazole] (L3) reacts with a stoichiometric mixture of LnIII (Ln = La, Eu, Gd) and M(II) (M = Zn, Fe) in acetonitrile to produce selectively the heterodimetallic triple-stranded helicates (H…
Addition of a coligand in reactions of phosphonates with salts of late 3d metals can lead to more soluble and tractable materials, such as the {Co13} cage shown (Co: green; P: purple). The structure contains two central PhPO32− ligands, surrounded by a hexanuclear cobalt helix, capped by seven further cobalt sites.
We model a cubic-to-tetragonal martensitic transition by a Ginzburg-Landau free energy in the symmetric strain tensor. We show in three dimensions (3D) that solving the St. Venant compatibility relations for strain, treated as independent field equations, generates three anisotropic long-range potentials between the t…
Transparent conducting indium tin oxide (ITO) thin films were grown by pulsed laser deposition (PLD) on flexible polyethylene terephthalate (PET) substrates. The structural, electrical, and optical properties of these films were investigated as a function of substrate deposition temperature and background gas pressure…
Strong piezoelectricity in perovskite-type PbZn1−xTixO3 (PZT) and Pb(Zn1/3Nb2/3)O3–PbTiO3 (PZN–PT) systems is generally associated with the existence of a morphotropic phase boundary (MPB) separating regions with rhombohedral and tetragonal symmetry. An x-ray study of PZN–9% PT has revealed the presence of an orthorho…
A metal-free approach to the living ring-opening polymerization (ROP, shown schematically) of lactide has been developed using strongly basic amines such as 4-(dimethylamino)pyridine as transesterification catalysts. These organic catalysts must be used in combination with a nucleophile such as an alcohol, which is th…
This lecture is not directly related to our discovery and development of conducting polymers to which the Nobel Prize in Chemistry 2000 was awarded. However, I would like to present my previous work that I had carried out just before we reached the discovery of chemical doping. I hope that this will be of use and deep…
When asked to explain the importance of the discovery of conducting polymers, I offer two basic answers: first they did not (could not?) exist, and second, that they offer a unique combination of properties not available from any other known materials. The first expresses an intellectual challenge; the second expresse…