On heating the hydrated complexes 18-Crown[6].M[H(2)PO(4)].xH(2)O (x= 2 for M = K, Rb; x= 1.5 for M = Cs), quantitatively prepared by mechanical mixing of crystalline 18-Crown[6] and M[H(2)PO(4)], to ca. 60 degrees C, water loss takes place, accompanied by the extrusion of the crown ether from the crystalline complex and followed by reconstruction of the inorganic phase M[H(2)PO(4)](M = K, Rb, ...

Ab initio QMCF-MD simulations of aqueous 18-crown-6 (18C6) and strontium(II)-18-crown-6 (18C6-Sr) were performed to gather insight into their hydration properties. Strongly different characteristics were found for the two solutes in terms of structure and dynamics such as H-bonding. They, however, have in common that their backbone shows high flexibility in aqueous medium, adopting structures s...

BACKGROUND Dibenzo-18-crown-6 (DB18C6) exhibits the binding selectivity for alkali metal cations in solution phase. In this study, we investigate the main forces that determine the binding selectivity of DB18C6 for the metal cations in aqueous solution using the density functional theory (DFT) and the conductor-like polarizable continuum model (CPCM). RESULTS The bond dissociation free energi...

The enthalpies of solution of the cyclic ethers 1,4-dioxane, 12-crown-4 and 18-crown-6 in mixtures of ethanol and water have been measured within the whole mole fraction range at T = 298.15 K. The enthalpy of solvation has been calculated. In pure ethanol and pure water, the solvation enthalpy of the investigated cyclic ethers depends linearity on the number of -CH2CH2- groups in the cyclic eth...

The title compound, C(18)H(26)N(2)O(5)P(2), was obtained accidently from the reaction between N,N-dimethyl-phospho-ramido-chloridic acid 4-methyl phenyl ester, NaNO(2) and 18-crown-6 in acetonitrile under reflux conditions. The asymmetric unit contains one half-mol-ecule, the complete mol-ecule being generated by crystallographic twofold symmetry, with the bridging O atom lying on the rotation ...

Sandwich-type hydrogen-bonded supramolecular dications (DAAz(2+))([18]crown-6)(2) and (DAAz(2+))(dicyclohexane[18]crown-6)(2) (DAAz(2+) = 4,4'-(phenylazophenyl)diammonium) were introduced into [Ni(dmit)(2)](-) anions via a diffusion method to form novel single crystals (DAAz(2+))([18]crown-6)(2)[Ni(dmit)(2)](2) (1) and (DAAz(2+))(dicyclohexane[18]crown-6)(2)[Ni(dmit)(2)](2) (2), respectively, w...

We describe a facile synthesis of the cyapho-cyanamide salt [Na(18-crown-6)][N(CN)(CP)] from reaction [Na(18-crown-6)][PH2] (18-crown-6=1,4,7,10,13,16-hexaoxacyclooctadecane) with dimethyl N-cyanocarbonimidate, (MeO)2C=N(CN). The proceeds elimination two equivalents methanol. Careful tuning conditions allowed for isolation and characterization N-cyano(carboximidate)phosphide intermediate [HP{C(...

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 were determined by monitorin...

Deltahedral nine-atom clusters of silicon, Si(9)(2-), were synthesized by mild oxidation of a liquid ammonia solution of K(12)Si(17) with Ph(3)GeCl in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) or 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane). The clusters were structurally characterized in [K(18-crown-6)](2)Si(9).C(5)H(5)N (yellow; orthorhombi...

A novel synergistic extraction system was investigated for the possible selective separation of light lanthanoids using an ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, as an extraction solvent and 2-thenoyltrifluoroacetone and 18-crown-6 as extractants. Trivalent lanthanum was efficiently extracted as a cationic ternary complex by the cation-exchange process, wh...