Materials Literature
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The exciton decay rate at a rough interface in type-II semiconductor superlattices is investigated. It is shown that the possibility of recombination of indirect excitons at a plane interface essentially affects kinetics of the exciton photoluminescence at a rough interface. This happens because of strong correlation…
The excited triplet state deactivation of zinc(II) meso -diaryloctaalkylporphyrins (ZnDAOAP) has been studied over a wide temperature range using transient triplet−triplet absorption spectroscopy together with steady-state and time-resolved phosphorescence techniques. The results from transient absorption measurements…
Our prior designs for molecular-based information storage devices have employed multiple redox-active units organized in weakly coupled, covalently linked arrays. To explore a simpler design, we report here the synthesis of porphyrin arrays where porphyrins with identical oxidation potentials are directly linked to on…
We present the rational design and synthesis of multiporphyrin arrays containing thiol-derivatized linkers for the purpose of multibit molecular information storage. Porphyrin dimers and trimers were synthesized by the Pd-mediated coupling of iodo-substituted and ethynyl-substituted porphyrin building blocks in 5-51%…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTriplet Energy Transfer in Porphyrin Dimers: Comparison between π- and σ-Chromophore Bridged SystemsJoakim Andréasson, Johan Kajanus, Jerker Mårtensson, and Bo AlbinssonView Author Information Departments of Physical Chemistry and Organic Chemistry Chalmers University…
The structure and orientation of heptylxanthate adsorbed on a ZnS surface have been studied by the FTIR-ATR technique. By using polarized light and the dichroic ratio, we found the average tilt angle to be approximately 44 degrees. The adsorbed layer studied was prepared by self-assembly from solution or by spraying t…
The structure of Pd interacted with acid sites of ZSM-5 was studied by using extended X-ray absorption fine structure (EXAFS). Dispersed PdO was generated on ZSM-5 upon the oxidation treatment, where the degree of dispersion was dependent on the acid amount of ZSM-5 support. The reduction of the dispersed PdO with H 2…
The storage of multiple bits of information at the molecular level requires molecules with a large number of distinct oxidation states. Lanthanide triple-decker sandwich molecules employing porphyrins and phthalocyanines afford four cationic states and are very attractive for molecular information storage applications…
Transparent nanocomposite gels have been synthesized by the sol−gel method using hybrid precursors composed of two triethoxysilane groups and a mid polyether chain [poly(ethylene oxide) or poly(propylene oxide)] of various chain lengths. The end silicate groups are linked with the polyether chain through urea bridges…
The giant, nanoporous Keplerate (NH4)42[Mo132O372(CH3COO)30(H2O)72] was incorporated into a permeable ultrathin film using a stepwise self-assembly strategy. Alternating adsorption of the Keplerate anions and PAH results in single layers with an apparent surface coverage of ≈50%. Such permeable composite coatings may…
Detailed EXAFS (extended X-ray absorption fine structure spectroscopy) measurements have been collected for two nanocrystalline forms of zirconia, namely, dense films of yttria-stabilized cubic zirconia (YSZ) and tetragonal phase powders of pure ZrO 2 . Zr and Y K edge EXAFS spectra for the YSZ films with grain sizes…
Attempts were made to prepare completely regioregular poly(3-dodecylthienylenevinylene) (PDDTV) and the completely regiorandom PDDTV. However, attempts to prepare the regioregular PDDTV by a Heck polymerization of 2-bromo-3-dodecyl-5-vinylthiophene leads to a regioirregular PDDTV that also contains cross-conjugated de…
Glycidol as latent branching AB 2 monomer was used in combination with glycidyl ethers as linear AB comonomers for the preparation of hyperbranched random copolymers with controlled degree of polymerization ( DP n = 42−72) and relatively low polydispersity ( M w /M n < 1.7). Extending previous theoretical consideratio…
The elastic-like and viscous-like viscosity components of model, Brownian hard sphere suspensions were determined. The elastic-like component, sometimes called the thermodynamic component, is due to Brownian motion while the viscous-like component, sometimes called the hydrodynamic component, is due to hydrodynamic in…
Optically active photochromic ( S )- and ( R )-1-(2-methyl-5-phenyl-3-thienyl)-2-[2-(3-methyl-1-penten-1-yl)-5-phenyl-3-thienyl]-3,3,4,4,5,5-hexafluorocyclopentenes ( ( S )-1a and ( R )-1a ) were synthesized. X-ray crystallographic measurement showed that ( S )-1a and ( R )-1a single crystals adopted orthorhombic chir…
Latex beads are used as a combined template and porogen in the fabrication of monolithic silica containing a hierarchy of pores. Prefabricated core/shell particles, prepared by the layer-by-layer assembly of zeolite (silicalite) nanoparticles onto spherical latex templates, are assembled into macroscopic close-packed…
Layered hydroxide metal acetates (metal = zinc, cobalt, and nickel) have been prepared by a new route belonging to the chimie douce method. This novel method involves the hydrolysis, in polyol medium, of in situ-formed complexes supposed to be alkoxyacetates. These layered hydroxide metal acetates present poorly order…
An electrochemical procedure, based on the dissolution of a metallic anode in an aprotic solvent, has been used to obtain silver nanoparticles ranging from 2 to 7 nm. By changing the current density, it is possible to obtain different silver particle sizes. The influence of the different electrochemical parameters on…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThe First Example of Ammonium Selenothioates: Isolation and CharacterizationToshiaki Murai, Takeshi Kamoto, and Shinzi KatoView Author Information Department of Chemistry, Faculty of Engineering Gifu University, Yanagido, Gifu 501-1193, Japan Cite this: J. Am. Chem. So…
The synthesis and the spectroscopic and structural characterization of lower-rim-silylated and rare-earth-metalated calix[4]arenes are presented. Hexamethyldisilazane, HN(SiMe3)2, reacted in a selective manner with [p-tert-buttylcalix[4]arene]H4 (1) in refluxing mesitylene to give the 1,3-silylated product [p-tert-but…