Materials Literature
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A new series of acceptor-substituted nickel tetraphenylporphyrins were synthesized in order to examine the efficiency of the π-conjugation through the olefinic linkages to the β-carbon of porphyrins. Perturbed absorption spectra were found for the substituted porphyrins and may be attributed to the reduced symmetry of…
Despite similar ring deformations in solution and in the solid state, the chloroiron(III) derivative of 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin ([FeCl(oetpp)], shown schematically) prepared in this study exhibits only a very weak quantum-mechanical admixture of spin S=3/2 (only 4-10 %) with spin…
Modern research is increasingly focusing on structuring matter on a nanometer length scale rather than producing molecularly new species. This article describes a method for synthesizing porous solids from rigid colloidal templates in three steps (see scheme): a) assembly of colloidal particles into a regular array, b…
Pythagoräische Harmonie besteht bei den hier beschriebenen kugelförmigen Polyoxometallat-Clustern (Strukturbeispiel siehe Bild), da es interessante Beziehungen zwischen den sogenannten magischen Zahlen (12, 32, 42, 72, 132; für sphärische Viren relevant) und der Zahl der Baueinheiten der Cluster gibt. Die Größe dieser…
A novel exchange between ligands and/or guest molecules can be accomplished in giant molecular spheres (an example is shown in the picture) which are in equilibrium with the corresponding giant baskets in solution.
Giant polyoxometalates with catalytic, magnetic, and antiviral properties, which are in part attributable to their structures, are currently of great interest. Herein is described the synthesis and characterization of 1, a structurally novel tetrameric complex from Keggin ions (see picture). This complex is stable und…
For practical applications of poled electrooptic polymers, highly efficient and thermally stable nonlinear optical (NLO) chromophores are required. We describe here a concise synthesis and characterization of a series of donor−acceptor chromophores incorporating a bithiophene moiety in the conjugated bridge. They disp…
The quantitative evaluation of the effect of an insulating dendritic shell on the redox properties of an embedded iron porphyrin core has been achieved for the first time using water-soluble dendritic iron porphyrins with tethered axial ligands (shown schematically). Thus, these complexes, whose redox properties have…
Hypericin and stentorin are the most important representatives of the phenanthroperylene quinones. Their tautomerism, dissociation, conformation, and association equilibria make them structurally complex, and they are interesting on the one hand for medical applications (for example, photodynamic therapy) and on the o…
A survey is presented of current investigations of the impact of band structure effects on various aspects of the interaction of charged particles with real solids. The role that interband transitions play in the decay mechanism of bulk plasmons is addressed, and results for plasmon linewidths in Al and Si are discuss…
We study the statistical properties of the scattering matrix S(q|k) for the problem of the scattering of light from a randomly rough one-dimensional surface, defined by the equation $x_3 = \zx$, where the surface profile function $\zx$ constitutes a zero-mean, stationary, Gaussian random process, through the effects o…
Polyansidine organic conductor, was chemically synthesized, via the chemical oxidation of ansidine by persulfate anion in aqueous solution . The prepared polymer was characterized by different methods of analysis such as: thermogravimetric analysis, electric conductivity, infrared and UV—visible absorption spectroscop…
The role of hindered amine light stabilizers (HALS) in the protection of polyolefins continues to expand. HALS are essential components in formulations developed for outdoor use and have been proven to be effective thermo-oxidative stabilizers. The physicochemical properties of hindered amines have a profound effect o…
The influence of convection on the morphology of primary dendrites and on the distribution of germanium in primary crystals of hypoeutectic Ag–Ge alloy was studied. The experiment in microgravity provided conditions for the suppression of melt flow. Both the morphology of the primary dendrites and their chemical compo…
The red luminescence at 686 nm in KTaO3 is investigated in pure as-grown and doped (Al, Ba, Cr, Fe, Er, Li, Mg, Ni, Rh, V, Zr) crystals from different growth laboratories. In contrast to earlier results [1,2] which led to the conclusion that the main center should be an intrinsic defect Ta3+ + O2- vacancy, we found th…
Dark opaque blue to transmissive light blue is the color transition that poly(3,4-propylenedioxythiophene) (PProDOT) and derivatives undergo when switched from their reduced to oxidized state. These polymers are very promising electrochromic materials—they exhibit more rapid switching, lower oxidation potentials, and…
Current voltage (I–V) characteristics have been studied at various temperatures in amorphous thin films of Ge22Se78−xBix and GexSe80−xTe20 where 0≤x≤10. At low electric fields, ohmic behaviour is observed. However, at high electric fields (E≡104 V cm−1) the current becomes superohmic. Analysis of the data shows the ex…
Raman spectroscopy was used to investigate Al selectivity in Si‐doped tetramethylammonium hydroxide (TMAH) solutions whose Si dopant concentration covers both Al passivating and Al nonpassivating instances. Raman spectra of the Si doped solutions suggest different dominant ionic silicate species for passivating and no…
The conversion coefficients from photon fluence to ambient dose equivalent, H* (10) and effective doses were calculated for photons up to 10 GeV. A Monte Carlo code EGS4 was used for these calculations and secondary particle transports were considered. The calculated ambient dose equivalents were compared to the calcu…
Fast and temperature-stable emission band at 5.8 EV has been reveadled in a K2SO4 crystal. This emission can be effectively excited by photons of hv > 15 eV and is interpreted as radiative electron transitions between the subbands of a splitted valence band. The threshold of the formation of electron-hole pairs equals…