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Hybride auf Kieselgelbasis mit lamellaren oder hexagonalen Strukturen entstehen direkt aus neuartigen Alkylsiloxan‐Oligomeren 1. Diese Selbstorganisations‐Strategie öffnet einen Zugang zu geordnetem mikroporösem Kieselgel und mesostrukturierten kieselgelbasierten Hybridmaterialien (siehe Schema: 1. Hydrolyse und Polykondensation, 2. Selbstorganisation).

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We report a "mild anodization" (MA) process using aluminum oxalate (Alox) as an additive to suppress breakdown of porous anodic alumina (PAA) in the electrolyte of phosphoric acid at high potentials and comparatively high temperatures. It is shown for the first time that continuously tunable pore intervals (D(int)) from 410 to 530 nm with ordered hexagonal pore arrangement can be controlled by varying the concentrations of phosphoric acid and Alox at anodization voltages (U(a)) from 180 to 230 V, far beyond the U(a) in the single electrolyte of phosphoric acid or oxalic acid. The fabricated PAA films are uniform without any burning spots, and the anodization temperature can be increased to 10-20 degrees C with a much higher growth rate of PAA films than that at a low temperature. Meanwhile, a typical two-step anodization process could also be performed under our conditions. Our results could not only extend the applications of PAA templates but also facilitate understanding of the effects of anions in the process of anodic oxidation.

Ph ys ika lisc h -Ch e m is c h es Ins titu t de r Un i ve rs itat Zurich, Win terth u rers trass e 190, C H -8057 Zurich, SwitzerlandQuantitative simulations of EPR powder spectra of organic radical cations in zeolites are reported. The anisotropy of the hyperfine interactions and of the g-factor tensors is interpreted in terms of the mobility of the species. The radical cation formed by spontaneous oxidation of tetramethylethene in activated HZSM-5 is shown to rotate about the axis perpendicular to the molecular plane at room temperature, but it is immobile at 100 K. The radical cation derived from 2,5-dimethylhexa-l,5-diene in H-mordenite can execute only librational motion on a timescale of ca. 50 ns.