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...

Novel 2-benzothiazole-, 4-pyridine-, and 2- and 4-quinoline-based styryl dyes containing an N-methylbenzoaza-15(18)-crown-5(6)-ether moiety were synthesized. A detailed electronic spectroscopy study revealed high performance of these compounds as optical molecular sensors for alkali and alkaline-earth metal cations. They were shown to considerably surpass analogous chromoionophores based on N-p...

Simple chelating agents have been synthesized using a porphyrin and a covalently linked crown-ether. Depending on the relative spatial arrangement of both motifs, the resulting ligands, either a macrotricycle or bis-macrocycles, differ one from another by their flexibility or their aptitude to chelate bivalent or trivalent cations. The coordination chemistry as well as the structural study of t...

In this study two solid supports, silica and florisil, were impregnated with crown ether (dibenzo-18-crown-6) and Fe(III) ions and their efficiency was compared in the adsorption process of As(V) from aqueous solutions. The solid supports were impregnated with crown ether due to their ability to build complexes with positives ions. Fe(III) was used because of As(V) affinity for it. The impregna...

Complexes of the anion of the secondary amine 2-phenylaminopyridine (LH) with the heavier alkali metals Na-Cs have been prepared in the presence of various macrocyclic polyether crowns [12-crown-4 (12C4), 15-crown-5 (15C5), and 18-crown-6 (18C6)], which coordinate to the metal ions in all cases. Depending on the combination of alkali metal and crown, the products include separated ion pairs [(c...

the complexation reactions between mg2+, ca2+, sr2+ and ba2+ metal cations with 15-crown-5 (15c5) were studied in acetonitrile (an)-methanol (meoh) binary mixtures at different temperatures using conductometric method. 15c54 forms 1:1 complexes with mg2+, ca2+ and sr2+ cations in solutions. the ma2+ cation forms a 2:1 complex (ratio of lighand to cation) in solutions. a linear relation was obse...

The formation of alkali-metal ion complexes with the crown ethers, 18-crown-6(18c6), benzo-18c6 and dibenzo-18c6 has been investigated. Theoretical studies of structural changes on complexation, binding energies and changes in electron distribution have been carried out using ab initio quantum theoretical methods. A complementary study of the NMR chemical shifts and coupling constants has also ...