Phosphine is conformationally stable because of the high inversion energy barrier of the phosphorus atom, which allows the phosphorus atom to become a chiral center. Thus, enantiopure P-stereogenic 12-, 15-, 18-, and 21-membered aliphatic phosphines "diphosphacrowns" were synthesized from secondary P-stereogenic bisphosphine as a chiral building block. Their complexation behaviors with alkali m...

By employing different diimine complexes and a naphthanoimidazolate (L(1)) or benzoimidazolate (L(2)) anion ligand as linker, a series of trimetallo-macrocycles have been synthesized through a directed self-assembly approach that involves spontaneous deprotonation of the ligands in aqueous solution. Some compounds, namely, [M(3)L(3)](NO(3))(3) (M = (18-crown-6-phen)Pt, 1 or 7; (15-crown-5-phen)...

New crown ether Schiff base derivatives were prepared by the condensation of 4'-formylbenzo-15-crown-5 or 4'-formyl-5'-hydroxybenzo-15-crown-5 with 1,2-bis(2-aminophenoxy)ethane. The structures of these new compounds were confirmed on the basis of elemental analysis, IR, (1)H- and (13)C-NMR, UV-Vis and mass spectroscopic data.

crown ethers 12-crown-4 (12c4), benzo-15-crown-5 (b15c5), 18-crown-6 (18c6), nitrobenzo-18-crown-6 (nb18c6) dibenzo-18-crown-6 (db18c6) and dicyclohexyl-18-crown-6 (dc18c6), dissolved in dichloromethane, are able to form oxonium-ion complexes in contact with aqueous sulfuric and hydrochloric acid solutions. this ability allows the transfer of cr(vi) oxanions from the acid media, through an orga...

The title compound, [Sr(C(14)H(20)O(5))(2)](I(3))(2), obtained by slow evaporation of an ethanol/dichloro-methane solution (1:1) of SrCl(2), benzo-15-crown-5 and I(2), is built of sandwich-like [Sr(benzo-15-crown-5)(2)](2+) cations and isolated linear I(3) (-) anions which are arranged in alternating layers parallel to (010). The triiodide anions are located in general positions, whereas the ca...

The complexation reactions between Tl+ and Pb2+ ions and crown ethers 12-crown-4(12C4), 15-crown-5 (15C5), benzo-15-crown-5 (B15C5), 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and aza-18-crown-6 (A18C6) were studied in 90% acetonitrile and 90% ethanol solutions at 25 °C, using an a.c. polarographic technique. The stoichiometry and stability of the complexes we...

Compounds consisting of [M(1,2-disila-[3n]crown-n)]2+ (M = Mg, Ca, Sr, Ba; n = 5, 6) and [Ba(1,2-disila-benzo[18]crown-6)]2+ cations and different anions were obtained by equimolar reaction of the hybrid disila-crown ethers 1,2-disila[15]crown-5 (1), 1,2-disila[18]crown-6 (2) and 1,2-disila-benzo[18]crown-6 (7) with alkaline earth metal salts. Even with strongly coordinating anions such as Br- ...

The title compound {alternative names: 11-methyl-2,3-benzopyrromethenone and 3-[(1-methylpyrrol-2-yl)methylidene]-2,3-dihydro-1H-isoindol-1-one}, C(14)H(12)N(2)O, was prepared by the base-catalysed condensation of phthalimidine with 2-formyl-1-methylpyrrole; yellow orthorhombic crystals, space group Pbca, were obtained from ethanol. The molecule is almost planar, having Z(-)antiperiplanar geome...

Hydrogels containing benzo-18-crown-6 were used to modify microcantilevers for measurements of the concentration of Pb2+ in aqueous solutions. These microcantilevers undergo bending deflection upon exposure to solutions containing various Pb2+ concentrations as the result of a swelling of the hydrogels. It was found that a concentration of 10(-6) M Pb2+ can be detected using this technology. Ot...