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Structures of platinum and chromium supported on zeolite beta were investigated by XAFS, XPS, UV–vis, NH3-TPD, XRD, CO chemisorption, and molecular dynamics simulation. Both platinum and chromium were uniformly dispersed in the micropore of zeolite beta. Loading of chromium helped platinum to disperse highly and stabilized in the micropore of beta. Major species of platinum on PtCr/beta after calcination at 773 K was Pt2+ forming a Pt–O bond. The Pt–O bond disappeared, and a Pt–Pt bond did not appear by reducing PtCr/beta in hydrogen, accompanying formation of Pt0. Chromium was loaded as chromate anion in the micropore of zeolite. Results of molecular dynamics simulation showed that Pt2+ associated with CrO4 2– in the micropore of zeolite beta was more stable than those in the absence of chromium species. We concluded that CrO4 2– electrostatically stabilizes Pt2+ and inhibits migration and aggregation of platinum.

Metallacrowns composed of three Ru(alkylbenzene) units bridged by 2,3-pyridinediolate (pyO 2 2À) are known to act as Li + -selective ionophores. In this study, we synthesized analogues with anisole and 3,5-dimethylanisole as the arene ligands, i.e., [{Ru(anisole)(pyO 2 )} 3 ] and [{Ru(3,Their extraction properties for lithium and sodium picrates were investigated in a dichloromethane-water system at 25 1C. Compared to [{Ru(alkylbenzene)(pyO 2 )} 3 ], the new metallacrowns allow faster and greater extraction of Li + with much higher Li + /Na + selectivity. [{Ru(3,5-dimethylanisole)(pyO 2 )} 3 ] is superior to [{Ru(anisole)(pyO 2 )} 3 ] in the Li + /Na + selectivity. The extraction equilibrium constants and separation factors were determined for each system. The separation factor between Li + and Na + reaches 7.1 Â 10 4 with [{Ru(3,5-dimethylanisole)(pyO 2 )} 3 ]. The highly Li + -selective metallacrown was applied to the extraction separation of Li + from seawater.

A neutral macrocyclic ligand, p-methyloxacalix [3]arene methyl ether (MOC3A-Me), was synthesized and its extraction properties for alkali metal picrates was investigated in a dichloromethane/water system at 25ºC. The alkali metal ions were extracted by MOC3A-Me with a selectivity sequence Li + < Na + < K + ≤