Materials Literature
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Quenching of the luminescent excited state of Eu 3+ ions by C−H high-vibrational modes was studied by deuteration of the encapsulating ligand and the solvent. Novel polydentate hemispherands providing nine donor atoms, which form overall neutral complexes with rare earth ions, were synthesized in nine steps, allowing…
The thermotropic phase behaviour and self-assembling features of some non-ionic tetraphenylporphyrins and phthalocyanines containing oligo(ethylene oxide) alkoxy or alkyl units have been investigated. From DSC measurements and polarization microscopy it was concluded that none of the tetraphenylporphyrins was mesomorp…
Biodegradable polymers have attracted much attention as implantable drug delivery systems. Uncertainty in extrapolating in vitro results to in vivo systems due to the difficulties of appropriate characterization in vivo, however, is a significant issue in the development of these systems. To circumvent this limitation…
Iron loss measurements of Mn-Zn ferrite cores up to the megahertz range are reported. Taking the dc magnetic hysteresis, the eddy, and displacement currents into account, magnetic and electric field distributions in the cores are computed with the cylindrical coordinates and Bessel functions. The computed iron loss du…
Citrate synthase forms citrate by deprotonation of acetyl-CoA followed by nucleophilic attack of this substrate on oxaloacetate, and subsequent hydrolysis. The rapid reaction rate is puzzling because of the instability of the postulated nucleophilic intermediate, the enolate of acetyl-CoA. As alternatives, the enol of…
Heterogeneous mesoporous stable basic catalysts have been prepared by wet or solid-state impregnation of MCM-41 with caesium acetate and lanthanum nitrate followed by thermal decomposition. 133 Cs MAS NMR data of CsLa/MCM-41 show an increase in the Cs–O bond length in the CsLa mixed oxides compared with that in Cs oxi…
Thermally stable mesoporous hexagonal aluminophosphates (UHM-1) and silicoaluminophosphates (UHM-3) are synthesized based on ion-pair interactions of aluminophosphate species in the presence of tetramethylammonium hydroxide with a cationic surfactant [C 16 H 33 NMe 3 Cl].
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Carbon nitride films (CNx) have been deposited by sputtering a graphite target with nitrogen ions. Films were grown both with and without the presence of an assisting focused N2 ion beam. The sputter beam voltage was varied between 150 and 1500 V and the applied assisting beam voltage from 80 to 500 V. The substrate w…
Zirconium-doped mesoporous silicas of mole ratio Si/Zr from 50 to 5 are Lewis-acid catalysts, with a linear correlation between the zirconium content and total acidity.
The understanding of space charge effects depends largely on how concurrent phenomena, such as thermal and electrical aging are understood. A model describing thermal and environmental aging of dielectric polymers is discussed. The model essentially is based on the rate theory associated with the name of Eyring. One b…
A docosanuclear metal complex of nanometric size and dendritic shape made of an osmium(ii)-based core and containing 21 ruthenium(ii)-based units in the branches has been prepared. The key building blocks are the [Os(2,3-dpp) 3 ] 2+ ‘complex ligand’, and the [Ru(2,3-Medpp) 2 Cl 2 ] 2+ and [{Ru(bpy) 2 (µ-2,3-dpp)} 2 Ru…
Highly functionalized silsesquioxanes and spherosilicates of the formulae [(RCHCH) 8 Si 8 O 12 ] and [(RCHCHSiMe 2 -O) 8 Si 8 O 12 ] can be prepared by cross-metathesisreactions of alkenes with readily available vinyl-substituted silsesquioxane and spherosilicate frameworks, [(vinyl) 8 Si 8 O 12 ] 1 and [(vinylSiMe 2…
The synthesis and single-crystal X-ray structure analysis of the unusual Mo/V polyoxometalate compound Na 0.5 K 6.5 [Mo VI 8 V IV 4 O 36 (V V O 4 )(V IV O) 2 ]·12.5H 2 O which contains capped α-Keggin fragments linked to a chain is reported; this chain is an interesting object for magnetochemists and can be considered…
Synchrotron X-ray diffraction patterns for highly crystalline MCM-41 a mesoporous silicate molecular sieve are presented. The form factor observed in seven orders of diffraction is used to show the existence of a two-layer wall structure, with a narrower mesopore than previously assumed, and much void space in the wal…
Self-assembly and non-covalent interactions are employed for the preparation of a new family of cationic artificial supramolecular multiporphyrin aggregates incorporating Pd II and Pt II bisphosphane complexes as auxiliaries.
It has recently been demonstrated that hexagonal mesoporous silica films can be grown at mica/water interfaces. In this report it is established that the films can also be synthesized on cleaved pyrolytic graphite. Diffraction and microscopy studies of the growth, structure and form of the films indicate that the chan…
The application of combinatorial methods to the synthesis and characterization of novel materials is described for the case of solution‐phase synthesis of phosphors based on rare‐earth‐activated refractory metal oxides. A scanning multiinkjet system is shown to be suitable for the fabrication of a liberry such as (La…
The ionic and n‐type conductivities of ceria‐based electrolytes doped with gadolinium (10 and 20 cation %) or gadolinium and praseodymium (2% Pr and 18% Gd) were studied by impedance spectroscopy in air, between 573 and 1273 K, and by constant frequency (10 kHz) conductivity measurements as a function of the oxygen pa…
Active catalysts for the epoxidation of alkenes by tert-butyl hydroperoxide are provided by silasesquioxane titanium(IV) derivatives; a non-leaching catalyst, not prone to irreversible protic cleavage of its siloxy functions by the oxidizing agent, contains a terdentate silasesquioxane ligand.