Transition metals with specific coordination geometries have been employed for the rational design and construction of highly ordered supramolecular structures. [1] We have shown that the simple combination of the square-planar coordination geometry of palladium (908 bond angle) with pyridinebased bridging ligands leads to the quantitative self-assembly of nanometer-sized, discrete organic frameworks [2] such as ªmolecular squaresº [3,4] and an adamantanoid cages.[5] Here we report the efficient self-assembly of nanometer-sized macrotricycles from ten small components. Treatment of [Pd(NO 3 ) 2 (en)] (1) with the tripyridylmethane 2 [6] results in self-assembly to the nanometer-sized macrotricyclic framework 3, in which four ligand molecules are held together by six metal ions (Scheme 1). A similar ten-component self-assemScheme 1. Synthesis of 3.bly process leads to formation of the nanoscale macrotricycle 5 from 1 and the triazine-based ligand 4 (Scheme 2). Recently, there were a few reports of the metal-directed self-assembly of nanometer-sized macrocycles. [7,8] However, their structures Scheme 2. Synthesis of 5.have often been deduced from spectroscopic data. [8] In contrast, the structures of nanometer-sized macrotricycles 3 and 5 were unambiguously determined by X-ray crystallographic analyses.Ligand 2 was suspended in an aqueous solution of 1 (1.5 equiv), and the mixture was heated at 70 8C.[9] After 40 min a colorless clear solution was obtained. Analysis by NMR spectroscopy of the solution obtained by carrying out the reaction in D 2 O showed the quantitative self-assembly of 1 and 2 to form a single product. The addition of aqueous NaClO 4 (1m) resulted in precipitation of 3´12 ClO 4 in 85 % yield. When ethanol/water was employed as the solvent, the product was obtained from the solution directly as a NO À 3 salt by cooling to about 5 8C for several days. The elemental analyses agreed with the empirical formulas of 3´12 ClO 48 H 2 O and 3´12 NO 3´1 2 H 2 O. The NMR spectra of 3 contain only one acetoxyl signal (
Nanometer-sized bowls: six metal centers and four tridentate ligands self-assemble in aqueous solution to give the macrotricycle 1, which has approximate dimensions of 3×2×2 nm. Another macrocycle (not shown), obtained with a different ligand, is of similar size and topology but differs considerably from 1 in its host-guest behavior.
Schüsseln im Nanomaßstab: Sechs Metallzentren und vier dreizähnige Liganden lagern sich in wäßriger Lösung zum Makrotricyclus 1 zusammen, der ca. 3×2×2 nm3 groß ist. Ein weiterer Makrocyclus (nicht gezeigt), bei dem ein anderer Ligand eingesetzt wurde, ist zwar von ähnlicher Größe und Topologie, unterscheidet sich aber von 1 deutlich in seinem Wirt‐Gast‐Verhalten.
We have been following a male case of congenital sodium diarrhea (CNaD), who had a distended abdomen, passed watery stools with high sodium concentration, and showed metabolic acidosis in the first week of life. He also showed hyponatremia, low urine sodium, high serum aldosterone and high renin activity, Other possible causes of secretory diarrhea were ruled out. The initial effective treatment was oral supplements of water and electrolytes lost in the fecal fluid: with this he gained weight, and hyponatremia and metabolic acidosis were corrected. Loperamide hydrochloride was administered to increase intestinal absorption of sodium, as the serum prostaglandin was high. Watery diarrhea then improved, but as he passed stools, we stopped and postponed the treatment for a while; the stools then became watery again. Although diarrhea has persisted, he has not shown any abnormalities in growth or psychomotor development for the first two Years of life.
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