Materials Literature
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[structure-see text]A series of fluorene-dithia[3.3]paracyclophane copolymers was synthesized by Suzuki coupling reactions of suitable precursors. Transannular pi-pi interactions altered the electronic and optical properties of the polymer backbone significantly. A large red shift in the emission spectrum of the unsub…
Neutral double-stranded helicates and molecular triangles and squares are formed through the self-assembly of spacer-bridged bis(pyrrol-2-ylmethyleneamine) ligands and ZnII ions (see scheme). The steric requirements of the Zn centers and the size and relative flexibility of the ligands dictate the degree of associatio…
Abstract Polyethylene (PE)/montmorillonite (MMT) nanocomposites were prepared by in situ coordination polymerization using a MMT/MgCl 2 /TiCl 4 catalyst activated by Al(Et) 3 . The catalyst was prepared by first diffusing MgCl 2 into the swollen MMT layers, followed by loading TiCl 4 on the inner/outer layer surfaces…
Ru(III) and Ni(II) ammine complexes were grafted onto the pore surface of MCM-41 by ion exchange from basic aqueous solution. Covalent anchoring of the type M−O−Si (M = Ru or Ni) is obtained by this method. The structure of the grafted complexes was studied by UV−vis, FT-IR, and X-ray absorption spectroscopy. [Ru(NH 3…
The phase diagram of the dense ices VII, VIII (molecular phases), and X (nonmolecular phase) was investigated over a $P\ensuremath{-}T$ region of 12-298 K and 2-100 GPa by infrared absorption measurements. The ice VII-VIII and VIII-X phase boundaries determined in this study agree with those provided by previous Raman…
CeO 2 -based binary oxides catalyzed the cyclization of 1,6-hexanediol into cyclopentanone at temperatures of 400–475 °C. CeO 2 -based solid solution with Mn content of 20 mol% shows the highest catalytic activity, both conversion and selectivity, while both pure CeO 2 and Mn 2 O 3 have the cyclization ability of 1,6-…
Stacking faults are found to play a crucial role in the evolution of the structural and magnetic properties of cobalt subjected to ball milling. This has been evidenced by using complementary techniques, i.e., magnetometry and torque measurements, nuclear magnetic resonance (NMR) and x-ray diffraction (XRD). After sho…
Presented are density functional calculations on various Mn(salen) systems that are active catalysts in the epoxidation of olefins. Correlation of various structural properties such as Mn=O bond strengths, atomic charges, and C-O distances of evolving bonds in transition state geometries with modified Hammett constant…
Abstract Four dry corn starches with different amylose content were blended at 185°C with poly(lactic acid) (PLA) at various starch:PLA ratios using a lab‐scale twin‐screw extruder. Starch with 30% moisture content also was blended with PLA at a 1:1 ratio. Each extrudate was ground and dried. The powder was mixed with…
We investigate the equilibrium geometries and the systematics of bonding in various isomers of a 24-atom boron cluster using Born-Oppenheimer molecular dynamics within the framework of density functional theory. The isomers studied are the rings, convex and quasiplanar structures, the tubes, and closed structures. A s…
Small gold (5 nm) and zirconia (2−3 nm) particles inside the mesopores of SBA-15 were visualized with bright-field electron tomography. Due to the ordered nature of the mesopores and the related diffraction contrast present in the tilt series, the 3D-reconstruction is difficult to interpret. Unequivocal information ha…
It is difficult for outdoor apparel manufacturers to interpret the technical information provided by fabric suppliers concerning fabric ‘breathability’ properties because different methods and test conditions are used. In addition, fabrics with hydrophilic components change their properties under different humidity co…
For single-walled carbon nanotubes (SWCNTs), given the known product of the Young's modulus Y and the wall (bond) thickness t ( Yt ≅ 0.3685 TPa·nm) and the known temperature of tip-end melting ( T m = 1593 K), as well as their functional dependence on atomic coordination and bonding energy, the dimension and strength…
The Suzuki cross-coupling reactions between aryl halides (or triflates) and boronic acid derivatives are one of the most important palladium-catalyzed reactions. This paper discusses the examination of the Pd(0) nanoparticles by TEM. It also details the calculation of the turnover numbers (TONs) and the turnover frequ…
Step by step: Bis(merocyanine) dyes 1 self-assemble in a stepwise manner with increasing concentration to afford supramolecular polymers, organogels, and liquid-crystalline phases. The close contacts between the chromophores within these superstructures enables strong D- and H-type excitonic coupling to be observed.
Abstract Polypropylene/montmorillonite nanocomposites (PPCN) were prepared by melt intercalation with maleic anhydride modified low isotactic polypropylene as the compatibilizer. The linear and nonlinear rheological properties of polypropylene/montmorillonite nanocomposites were studied. The deviation from linear beha…
As shown by Overhauser and others, the pair-distribution function $g(r)$ of a many-electron system may be found by solving a two-electron scattering problem with an effective screened electron-electron repulsion $V(r)$. We propose a simple physical picture in which this screened repulsion is the ``dressed-dressed'' in…
We investigate the occurrence of Hund's rule magnetism in C60(n+-) molecular ions, by computing the ground-state spin for all charge states n from -3 to +5. The two competing interactions, electron-vibration (e-v, including Jahn Teller, favoring low spin) and electron-electron (e-e, including Hund-rule exchange, favor…
A recent Letter reports photoemission data for the free C60 molecule, showing an interesting three-peak structure, presented as evidence of dynamic Jahn-Teller (DJT) effect in the C60+ ion. Those data constitute, along with earlier spectra by the Uppsala group, the best available piece of experimental evidence about t…
The short and intermediate range order of an amorphous Ge$_{30}$Se$_{70}$ alloy produced by Mechanical Alloying were studied by Reverse Monte Carlo simulations of its x-ray total structure factor, Raman scattering and differential scanning calorimetry. The simulations were used to compute the $G^{\text{RMC}}_{\text{Ge…