Sixteen lipophilic N-(X)sulfonyl carbamoyl lariat ethers with polyether ring sizes of 12-crown-4, 14-crown-4, 15-crown-5, and 18-crown-6 are utilized for competitive alkali metal cation extractions from aqueous solutions into chloroform. Variation of the electron-withdrawing properties of X in the series of methyl, phenyl, 4-nitrophenyl, and trifluoromethyl allows the influence of the acidity o...

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...

The asymmetric unit of the title compound, H(3)O(+)·ClO(4) (-)·C(20)H(24)O(6), contains two mol-ecules/ions of each species. Both dibenzo-18-crown-6 mol-ecules have a complexed hydro-nium ion inside their cavity with O-H⋯O and O-H⋯(O,O) links between the two species. The associated perchlorate anions also accept O-H⋯O hydrogen bonds from the hydro-nium ion. Both crown ether mol-ecules are prese...

Rotaxanes can have topological isomers because of their mechanically interlocked axle and wheel components. Directional are formed when the rotaxanes constructed using an asymmetric a three-dimensional non-symmetrical wheel. In this work, directional [2]rotaxanes were synthesised lariat dibenzo-24-crown-8 ether as component sec-ammonium salt axle. Control over isomer ratio was achieved, demonst...

Extraction of microamounts of strontium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B-) in the presence of dibenzo-30-crown-10 (DB30C10, L) has been investigated. The equilibrium data have been explained assuming that the species HL+, SrL2+, SrHL3+ and SrHL3+2 are extracted into the organic phase. The values of extraction and stability constants of the cationic complexes in n...

Semi-empirical (AM1) electronic structure calculations are reported on a pH-switchable [2] rotaxane whose synthesis was reported in [Angew. Chem. Int. Ed., 36 (1997) 1904]. The [2] rotaxane possesses two cationic binding sites, with different affinities toward dibenzo [24] crown-8 (the ring component of the [2] rotaxane) depending upon the pH of the system. The computational results capture thi...