Materials Literature
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Treatment of benzocarbaporphyrin 2 with refluxing FeCl3 in CHCl3–alcohol mixtures leads to a remarkably selective oxidation at the interior carbon atom to produce dialkoxy products 5; these species show potentially valuable long wavelength absorptions in their UV–VIS spectra.
Phenyl-modified porous silicas have been synthesized at room temperature by the co-condensation of a siloxane and an organosiloxane in the presence of a surfactant. Mesitylene was employed as a pore swelling agent to produce a mesostructured material. The product has been characterized by powder XRD, nitrogen sorption…
We report on light-induced linear and second- and third-order nonlinear optical effects in high-glass-transition-temperature (Tg) photosensitive nonlinear optical azo polyimides. We present evidence of light-induced orientation of azo chromophores at room temperature in very high-Tg polyimides (Tg up to 350 °C) even t…
Double-mesopore silica with a characteristic N2 adsorption isotherm and narrow bimodal mesopore distribution is synthesized rapidly at room temperature by using aqueous ammonia as the catalyst.
This paper describes experiments performed on laboratory aged 12 kV and service aged 24 kV XLPE cable samples. Results from measurements of residual AC breakdown strength, degree of water treeing and dissipation factors are presented. The dissipation factor at low frequencies was determined by both time and frequency…
The reaction of (c-C6H11)8Si8O12 1 with triflic acid (TfOH) can produce two different ditriflates with the formula (c-C6H11)8Si8O11(OTf)2, which can be hydrolyzed selectively to four different incompletely condensed silsesquioxane frameworks with the formula (c-C6H11)8Si8O11(OH)2 (2, 4, 7 and 8).
A variety of synthetic procedures have been employed that allow access to three new tetranuclear [M4(µ3-O)2]8+ (M = MnIII or FeIII) complexes. The complex [Fe4O2Cl2(O2CMe)6(bpy)2] displays an unusual structural asymmetry in its core that can be described as a hybrid of the bent (butterfly) and planar dispositions of f…
The heteropolyacid H 5 PMo 10 V 2 O 40 ·34H 2 O was found to be an efficient oxygen activating agent in palladium-catalyzed reactions. Aerobic 1,4-oxidations of conjugated dienes were carried out by employing a triple catalytic system consisting of palladium−quinone−heteropolyacid. With this system a mild electron tra…
A novel process is described for synthesizing high aspect ratio, controlled diameter mesoscale poly(phenolformaldehyde) fibres using the well defined channels of mesoporous silica as a mold and their extraction with the structure intact.
The equilibrium volumes and cohesive energies of Ti, Zr and Hf have been calculated using a full-potential (FP) linear-muffin-tin-orbitals (LMTO) method and the generalized-gradient approximation of Perdew and Wang. A structural phase stability analysis between hcp, ω and bcc structures shows a similar crystal structu…
1. INTRODUCTION The prediction of polymer crystallization behavior at a reasonable semiquantitative level of accuracy is important in assessing processability and performance. For example, in both polypropylene (PP) [1–3] and poly(ethylene terephthalate) (PET), the interplay of the effects of rheology and crystallizat…
A comparative study of the spectral-luminescent properties (at 293 K and 77 K) of meso-tetrakis(o-tolyl)porphyrin (o-TTP) and meso-tetraphenylporphyrin (TPP), and also meso-tetrakis(n-propyl)porphyrin (TPrP) in nonaqueous acid media has been carried out with the aim to reveal effects associated with the influence of m…
Electron-transfer reactions in an H-bonded assembly composed of a diacylaminopyridine bearing zinc porphyrin and 1,8:4,5-naphthalenetetracarboxylic diimide (Ka = 2.8 × 102 dm3 mol–1) in benzene occur with kCS = 4.1 × 1010 s–1 and kCR = 3.7 × 109 s–1, while the corresponding covalently linked model with a comparable di…
Nanometric particles of InP are readily prepared by the decomposition of the complex In(PBut2)3 at 167 °C in 4-ethylpyridine; the resulting materials show marked quantum confinement effects, and was investigated using optical absorption and photoluminescence spectroscopies, and transmission electron microscopy.
Ordering kinetics after quenching a block copolymer melt from the disordered state to the ordered state were studied by time-resolved, depolarized light scattering. A theoretical framework for relating the scattering patterns to the granular organization within the sample was developed. In some cases we found that ord…
A series of rhenium(I), zinc(II) and mercury(II) complexes of π-donor-substituted vinyl bipyridines [donor=4-R2N–C6H4–; 4-RO–C6H4–; (C5H5)Fe(C5H4–); (C5H5)Ru(C5H4–)] has been prepared and characterized by 1H NMR and UV-visible spectroscopy. The second-order nonlinear optical properties of bipyridyl ligands and of thei…
Benzyl 4-iodoperfluorobutanoate was synthesized by partial pyrolysis of perfluoroglutaryl chloride in the presence of potassium iodide followed by esterification. This compound gives access to mesogenic molecules with alkyl chain, perfluoroalkyl central bridge, and biphenyl moieties. Segregation of these chemical frag…
QCM showed that SiO2/poly(diallyldimethylammonium chloride) (PDDA) film assembly could be achieved in 2 s for 45 nm silica nanoparticle monolayers and 20 s for PDDA monolayers, with film integrity demonstrated by SEM and spectroscopic ellipsometry.
By using a surfactant-based synthesis strategy, we have earlier demonstrated that the polymerization and growth of silicate micellar assemblies at the air–water interface, under quiescent and dilute acidic aqueous conditions, yields free-standing sub-micron thickness hexagonal mesoporous silica films in which the chan…
A B S T R ACT : Infrared (IR) spectra of well-ordered kaolinites generally show four OH-stretching frequencies, near 3697, 3670, 3652 and 3620 cm i. Raman spectra of the same kaolinites mostly show an additional band near 3686 cm -~, which, in the coarsely crystalline Keokuk kaolinite, largely replaces the 3695 cm -I…