Materials Literature
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An improved and efficient synthetic route to four functionalized bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) derivatives 2-5 is reported. Tetrathiolate 1 was readily prepared from 2,2'-bis(1,3,4,6-tetrathiapentalen-5-one) under carefully controlled conditions. Subsequent reaction of 1 with selected primary alkyl…
Surface plasmon resonance of periodic narrow-grooved metallic thin films were studied with finite-difference time-domain simulations. Two distinguishable modes, surface plasmon polaritons and localized surface plasmons, are associated with different periods. The surface plasmon polaritons have widely extended near-fie…
We report first-principles total-energy electronic-structure calculations that provide energetics and electronic structures of double-walled BN nanotubes, $(n,0)$@(15,0) and $(m,0)$@(20,0). We find that the most favorable double-walled nanotubes studied here are (7,0)@(15,0) and (12,0)@(20,0) in which the interwall di…
Aligned calcite crystals have been grown in an hexagonal arrangement (see Figure) using highly oriented Au (111) films on monocrystalline mica substrates. This alignment is observed over distances larger than the dimensions of monocrystalline Au(111) domains. A change in nucleation face with pH during growth—reflectin…
A spine- or herringbone-like array of molecules characterizes the crystal structure of the organic semiconductor 2,5-bis(4-biphenylyl)thiophene (BP1T). Its bent molecular shape enforces an upright disposition of the molecular long axes against the ab-plane that parallels the crystal faces of the flake-like crystals (s…
Using results of first-principles band structure calculations and a model tight-binding approach, we investigate the local stability of the half-metallic ferrimagnetic (FiM) states in double perovskites ${\mathrm{Sr}}_{2}\mathrm{Fe}M{\mathrm{O}}_{6}$ $(M=\mathrm{Mo},$ Re, and W). In ordered compounds, a generalized do…
Tubular structures of an elementary bile steroid derivative (see Figure and front cover) can be obtained in dilute aqueous suspensions. They exhibit quite monodisperse cross sections (52 nm diameter) with a large inner cylindrical cavity of 49 nm diameter. The tubules can be easily oriented, which is a promising prope…
The conformational behavior of four [Ln(DOTA)(H(2)O)](-) systems (Ln = La, Gd, Ho, and Lu) has been characterized by means of ab initio calculations performed in vacuo and in aqueous solution, the latter by using the polarizable continuum model (PCM). Calculated molecular geometries and conformational energies of the…
The alkyltrimethylammonium templates, cited in the original patent for the preparation of MCM-41, have been replaced by a novel set of templates, 1-alkyl-3-methylimidazolium salts. Systematic studies have revealed subtle differences in the performance of the novel templates, and identify them as viable reagents in the…
Block copolymers were prepared by ring-opening polymerization of epsilon-caprolactone in the presence of monohydroxyl or dihydroxyl poly(ethylene glycol) (PEG), using Zn powder as catalyst. The resulting poly(epsilon-caprolactone) (PCL)-PEG diblock and PCL-PEG-PCL triblock copolymers were characterized by various anal…
We present fully atomistic molecular dynamics simulations for a realistic model of a glass-forming polymer: polyisoprene. The simulations are carried out at 363 K and extend until 20 ns. We calculate the self-part of the Van Hove correlation function G(s)(r,t), the mean-squared displacement <r(2)(t)>, the second-order…
We have evaluated the possible redox chemical methods for precisely determining the oxygen content in complex cobalt oxides that are being studied increasingly for their interesting electric and magnetic properties. For the evaluation, BaNdCo2O5 + δ and Sr2(Ca,Y)Co2O6 + δ phases are selected as reference materials to…
Thermally stable dipolar and octupolar (D2d, D3) NLO-phores are readily accessible by combining one, two, or three 4,4'-bis(dialkylaminostyryl)-[2,2']-bipyridyl ligands with zinc(II) salts. The off-resonant beta0 values point out the superiority of octupoles versus dipoles in terms of nonlinearity/transparency tradeof…
Nanoparticle self-assembly onto polyelectrolyte-coated surfaces is exploited to produce dense nanoparticulate thin films on both planar and spherical substrates (the Figure shows a coated polystyrene sphere). A new type of ligand-stabilized gold nanoparticle is used to produce these films in a single step. An attracti…
Nanometer-sized metallic palladium particles can be synthesized by hydrogen reduction of Pd2+ ions dissolved in the water core of a water-in-CO2 microemulsion. The Pd nanoparticles, stabilized by the micromeulsion and uniformly dispersed in the supercritical fluid phase, are effective catalysts for hydrogenation of ol…
We revisited the problem of the stability of the superconducting state in ${\mathrm{Rb}}_{x}{\mathrm{WO}}_{3}$ and identified the main causes of the contradictory data previously published. We have shown that the ordering of the Rb vacancies in the nonstoichiometric compounds have a major detrimental effect on the sup…
The intrinsic linewidth ${\ensuremath{\Gamma}}_{\mathrm{TA}}$ of the transverse acoustic phonon observed in the relaxor ferroelectric compound $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}{)}_{0.8}{\mathrm{Ti}}_{0.2}{\mathrm{O}}_{3}$ (PMN-20%PT) begins to broaden with decreasing temperature around 650 K, nearly…
We have observed the $S$- and $Q$-branch Raman spectra of ${\mathrm{H}}_{2}$, HD, and ${\mathrm{D}}_{2}$ adsorbed at $85\mathrm{K}$ and pressures up to 8 atm on single-walled, carbon nanotubes (SWNT). Comparative data for ${\mathrm{H}}_{2}$ on graphite and ${\mathrm{C}}_{60}$ were also collected. Frequency-downshifted…
Oxygen-deficient SrFeO 3 - δ (0.02 < δ < 0.26) perovskites were prepared by soft-chemistry procedures, followed by annealing under different conditions, including high oxygen pressure. These materials contain Fe cations in the mixed Fe 3+ −Fe 4+ valence state. The samples were characterized by X-ray and neutron powder…
The metastable lifetime of the square-lattice and simple-cubic-lattice kinetic Ising models are studied in the low-temperature limit. The simulations are performed using Monte Carlo with Absorbing Markov Chain algorithms to simulate extremely long low-temperature lifetimes. The question being addressed is at what temp…