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A Ce 2 Zr 2 O 8 mixed oxide was prepared, and the influence of redox treatments on its reduction behavior was systematically analyzed. The temperature of reduction was found to change on application of redox cycles under severe conditions, with the final appearance of temperature-programmed reduction profiles dictated by the exact conditions employed in the redox cycle (temperature of treatment and concentration of H 2 ). In addition, the conditions necessary in the reducing and oxidizing parts of the redox cycle showed interdependence. The reduction was found to vary from a single high-temperature peak to a single lowtemperature peak, via double-peak profiles with various relative intensities. Structural analysis of the sample after application of analogous treatments indicated that the reduction behavior follows a pathway, with t′ and κ phases at the two extremes (high-and low-temperature single-peak profiles). The latter phase contains pyrochlore-type cation ordering. However, bulk ordering is not necessary to promote low-temperature reduction. The evidence suggests that the two-peak profiles are observed when cation ordering is very limited, and a single low-temperature peak is observed when domains of the κ phase coexist with larger amounts of the t′ phase. Thus, even the presence of partial ordering at the surface is sufficient to produce an effect.

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The novel title macrocycles, based on methylene-bridged 1,5-naphthalene units, have been obtained by template effect in a thermodynamically controlled synthesis. In detail, the prism[5]arene 1 or the prism[6]arene 3 was selectively removed from the equilibrium mixture by using the complementary ammonium-templating agent. When only the solvent 1,2-DCE was used, the 1,4-confused derivative 2 was obtained. The prism[5]arene here described shows a deep π-electron-rich aromatic cavity that exhibits a great affinity for the quaternary ammonium guests, originating from favorable cation···π and + NC–H···π interactions. This recognition motif is the basis of the templated synthesis of the prism[ n ]arenes here reported.

Evidence is presented that the well-established phenomenon of promotion of Ce0.5Zr0.5O2 reduction by suitable treatment procedures may be controlled by adjusting the conditions; and that such reduction leads to the formation of the pyrochlore structure at extremely low temperature

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Ethyl- and propyl-prism[6]arenes are obtained in high yields and in short reaction times independent of the nature and size of the solvent in the cyclization of 2,6-dialkoxynaphthalene by paraformaldehyde. PrS[6]Et...