Preparation and electron microscopy of intermediate phases in the interval Ce7O12Ce11O20

Crystals of CeO₂, grown from a flux of sodium tetraborate, were reduced in dry hydrogen to compositions in the interval CeO_1.714CeO_1.818. Selected compositions were studied using a high-resolution electron microscope. The phase CeO_1.714(Ce₇O₁₂) was confirmed to have the same unit cell as does Pr₇O₁₂ and Tb₇O₁₂. CeO_1.818(Ce₁₁O₂₀) was found to be isostructural with Tb₁₁O₂₀. Two new phases in the interval were established unequivocally. One of them, probably Ce₁₉O₃₄, is triclinic with a = 6.627, b = 11.478, c = 10.123, α = 100.9, β = 90.0, and γ = 95.5, has not previously been observed in any rare earth oxide system. Another, Ce₆₂O₁₁₂, appears to be isomorphous with Tb₆₂O₁₁₂. The two intermediate phases previously reported in this interval, Ce₉O₁₆ and Ce₁₀O₁₈, were not observed, nor was Ce₁₂O₂₂. Diffraction evidence also points to three additional phases in the interval not previously seen.     

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4‐Chloro‐N‐(4‐cyano‐2‐nitro­phenyl)‐3‐nitro­benz­amide

The structure of the title compound, C₁₄H₇ClN₄O₅, comprises two nearly coplanar phenyl rings connected via an amido moiety.     

Complexation of uranyl ion by three polyacrylamide type polymers: Electrochemical preparation and leaching tests investigations

We describe an original process for the treatment of low level activity radioactive liquid wastes. It deals with the electrochemical preparation of three polyacrylate polymers: polyacrylamide (PAam), polyacrylamidoglycolic acid (PAAG), polyacrylamidomethylpropanesulfonic acid (PAMPS) which are capable of complexing uranyl ions. We have demonstrated the complexation of uranyl by FT-IR and UV-Visible spectroscopy. All these complexes are soluble in water and we insolubilize in turn the complexes by crosslinking or by neutralization of positively charged complexes by the addition of polyanions to the medium. We have then done dynamic and static leaching tests on these insoluble complexes.     

Solvent Extraction of Selenate and Chromate Using a Diaminocalix[4]arene

The extraction of Se(VI) and Cr(VI) using a diammoniumcalix[4]arene was investigated. A study of parameters such as ligand concentration, pH or diluent was carried out and allowed to specify the stoichiometry of the extracted species. It was shown that Se(VI) is extracted into CHCl₃ as (LH₂ ²⁺, Cl^-, HSeO₄ ^-) and ((LH₂ ²⁺)₂, 2Cl^-, SeO₄ ^2-)species at pH 2.6. An increase of pH or an addition of 5% or 10% decanol in CHCl₃ favors the extraction of SeO₄ ^2- over HSeO₄ ^- but leads to a drastic decrease of seleniumextraction. Cr(VI) was shown to be extracted as(LH₂ ²⁺, Cl^-, HCrO₄ ^-) at pH 2.6 and probably as (LH⁺, HCrO₄ ^-) for higher pH.     

Ligand‐Directed Template Assembly for the Construction of Gigantic Molybdenum Blue Wheels

Template‐mediated synthesis is a powerful approach to build a variety of functional materials and complex supramolecular systems. However, the systematic study of how templates structurally evolve from basic building blocks, and then affect the templated self‐assembly, is critical to understanding and utilizing the underlying mechanism, to work towards designed assembly. Here we describe the templated self‐assembly of a series of gigantic Mo Blue (MB) clusters 1 – 4 using l ‐ornithine as a structure‐directing ligand. We show that by using l ‐ornithine as a structure director, we can form new template?host assemblies. Based on the structural relationship between encapsulated templates of {Mo₈} ( 1 ), {Mo₁₇} ( 2 ) and {Mo₃₆} ( 4 ), a pathway of the structural evolution of templates is proposed. This provides insight into how gigantic Mo Blue cluster rings form and could lead to full control over the designed assembly of gigantic Mo‐blue rings.     

Emergence of Function and Selection from Recursively Programmed Polymerisation Reactions in Mineral Environments

Living systems are characterised by an ability to sustain chemical reaction networks far‐from‐equilibrium. It is likely that life first arose through a process of continual disruption of equilibrium states in recursive reaction networks, driven by periodic environmental changes. Herein, we report the emergence of proto‐enzymatic function from recursive polymerisation reactions using amino acids and glycolic acid. Reactions were kept out of equilibrium by diluting products 9:1 in fresh starting solution at the end of each recursive cycle, and the development of complex high molecular weight species is explored using a new metric, the Mass Index, which allows the complexity of the system to be explored as a function of cycle. This process was carried out on a range of different mineral environments. We explored the hypothesis that disrupting equilibrium via recursive cycling imposes a selection pressure and subsequent boundary conditions on products. After just four reaction cycles, product mixtures from recursive reactions exhibit greater catalytic activity and truncation of product space towards higher‐molecular‐weight species compared to non‐recursive controls.