Materials Literature
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Trivacant polyoxotungstates such as α-A-[PW9O34]9− ions react with tBuSiCl3 to afford the anion 1. This can react further with other trichlorosilanes to give α-A-[PW9O34(tBuSiO)3(RSi)]3− ions (R = H, Me, Et, CHCH2, CH2CH2CH2Cl). Similar arsenic compounds are also reported.
Many liquids with vastly different properties can form glasses upon cooling. Although this phenomenon has been known since ancient times, no complete general understanding of the glass transition is available. In his Perspective, Sokolov reviews recent theoretical and experimental progress in unraveling the mysteries…
Fine tuning of the magnetic properties can be achieved in [Ni(tren)]3[Fe(CN)6]2·6 H2O (1, section of structure shown on the right; tren = tris(2-aminoethyl)amine), the first example of a three-dimensional bimetallic network of a Prussian blue analogue containing organic groups. The compound orders as a bulk ferrimagn…
Broad-band dielectric spectroscopy (10 −2 Hz–10 7 Hz) is employed to study the molecular dynamics of three low-molecular-weight glass-forming H-bonded liquids being confined in (dielectrically inactive) porous glasses with pore sizes of 2.5 nm, 5.0 nm and 7.5 nm. From the relaxation time distribution of the dielectric…
Zinc porphyrin/pyridine coordination interactions have been used to assemble complexes containing two different chromophore arrays. These undergo photoinduced electron transfer (see picture) and energy transfer reactions, which mimic some of the primary events in photosynthesis.
In the framework of a recently reported linear-scaling method for density-functional-pseudopotential calculations, we investigate the use of localized basis functions for such work. We propose a basis set in which each local orbital is represented in terms of an array of `blip functions'' on the points of a grid. We a…
Between 2 and 44 gL−1 of the diamide 1 are necessary to obtain stable gels with a wide variety of organic solvents. The circular dichroism of the gels can be attributed to the formation of chiral aggregates from 1, which are held together by hydrogen bonds and van der Waals interactions.
Poly(styrene) was grafted onto silk fibers in an aqueous medium, using ammonium persulphate initiator. Add-ons of up to 100% were achieved. The add-on increased linearly with the monomer concentration of the grafting system, all other factors remaining constant. The yield of the reaction attained about 80% and the ext…
Water-soluble chitosan with a 50% deacetylation degree was prepared according to the literature. The mixtures of water-soluble chitosan and poly(acrylic acid) (PAA) in water was studied by various experimental techniques, such as viscometry, potentiometry, and transmittance measurements. The results showed that water-…
Damping properties of epoxy resin/polyurethane (EP/PU) semi-interpenetrating polymer networks (IPNs) were studied by the dynamic mechanical analysis (DMA) method. It shows that the semi-IPNs have excellent damping properties at ordinary temperature. The maximum value of tan δ is about 1 when the weight composition of…
This study reports the use of texture profile analysis (TPA) to mechanically characterize polymeric, pharmaceutical semisolids containing at least one bioadhesive polymer and to determine interactions between formulation components. The hardness, adhesiveness, force per unit time required for compression (compressibil…
In this paper we apply variational energy band theory to a form of the Holstein Hamiltonian in which the influence of lattice vibrations (optical phonons) on both local site energies (local coupling) and transfers of electronic excitations between neighboring sites (nonlocal coupling) is taken into account. A flexible…
The complexes [PtR(dppm- P,P )(dppm- P )]PF 6 (R = Me, Et, Ph) react with [AuCl(SMe 2 )] to generate the dppm-bridged platinum−gold complexes trans -[PtClR(μ-dppm) 2 Au]PF 6 ( 1 ). Addition of [PtR(dppm- P,P )(dppm- P )]Cl to a solution of silver(I) acetate, followed by acetyl chloride, yields the neutral platinum-sil…
Molecular dynamics simulations of the oligonucleotide duplex d(CGCGCG)2 in aqueous solution are used to investigate the glass transition phenomenon. The simulations were performed at temperatures in the 20 K to 340 K range. The mean square atomic fluctuations showed that the behavior of the oligonucleotide duplex was…
We present a theoretical study of the 1 H NMR chemical shifts in low-valent transition metal hydrides based on density functional theory and gauge-including atomic orbitals (DFT-GIAO). Calculations have been carried out on the representative hydrides HM(CO) 5 (M = Mn, Tc, Re), H 2 Fe(CO) 4, HCo(CO) 4, [HCr(CO) 5 ] -,…
Surface modification and functionalization of polyaniline (PAN) and polypyrrole (PPY) films were achieved by Ar plasma treatment, near-UV-induced graft copolymerization with acrylic acid (AAc) and covalent immobilization of an enzyme (trypsin). The compositions and structures of the modified and functionalized polymer…
Copper 2p3/2 x-ray photoemission spectroscopy (XPS) measurements and near-edge x-ray absorption spectroscopy (NEXAFS) studies of copper-doped ZnO thin films were carried out in order to understand the role of the dopants in increasing the film resistivity. c-Axis-oriented ZnO films (thickness 120 nm) were deposited by…
Magneto-oscillatory behavior of the organic metal $\ensuremath{\kappa}$- $(\mathrm{BEDT}$- $\mathrm{TTF}{)}_{2}\mathrm{Cu}(\mathrm{NCS}{)}_{2}$ has been studied at temperatures above 2 K at which the thermodynamic quantum oscillations are highly suppressed due to the temperature smearing of the Fermi level. Under this…
Real time spectroscopic ellipsometry has been applied to characterize the substrate temperature (T) dependence of the deposition rates for nanocrystalline diamond thin films prepared by microwave plasma-enhanced chemical vapor deposition on seeded Si substrates. With the real time capability, it is possible to determi…
Surface preparation of aluminium alloy adherends is designed to minimize the influence of organic contaminant on the durability of epoxy adhesive bonds. The organic contaminant molecules have the potential to inhibit the bonding of the adhesive with the surface oxide on the adherend. X-ray photoelectron spectroscopy (…