Sadik Elshani

Macrocyclic Ligands with Partially Fluorinated Sidearms: Synthesis and Metal Ion Complexation

Abstract Derivatives of aza-12-crown-4, aza-15-crown-5, aza-18-crown-6, 1,10-diaza-18-crown-6 and 1,4,8,12-tetraazacyclopentadecane with partially fluorinated substituents attached to nitrogen are prepared. Their efficiencies and selectivities in alkali metal and silver picrate extractions from aqueous solutions into chloroform are determined and compared with those of appropriate model compounds. Ionophores with longer spacers of –CH 2 OCH 2 CH 2 – and –CH 2 CH 2 OCH 2 CH 2 – between the nitrogen atom(s) of the macroring and the perfluoroalkyl group(s) exhibit greater extraction efficiencies than do analogues with shorter spacers consisting of one or two methylene groups.

Lariat Ether Carboxylic Acids, O-Benzylhydroxamates and Hydroxamic Acids with Fluorinated Substituents: Synthesis, Metal Ion Complexation and Solubility in Supercritical Carbon Dioxide

Abstract A series of lariat ether carboxylic acids, O-benzylhydroxamates, and hydroxamic acids with fluorine-containing substituents is prepared. In general, the presence of fluorine-containing substituents is found to increase the solubility of the lariat ethers in supercritical carbon dioxide. Efficiencies of the fluorine-containing lariat ether carboxylic and hydroxamic acids are compared with those for non-fluorinated analogs in solvent extraction of lanthanide ions from aqueous solutions into chloroform. Responses of the fluorine-containing lariat ether O-benzylhydroxamates towards alkali metal cations in solvent polymeric membrane electrodes are compared with those analogous non-fluorinated compounds.

Synthesis of new lipophilic acyclic di-ionizable polyethers, bis(crown ethers) and macrocyclic diamides

Abstract A series of new lipophilic acyclic polyethers containing two carboxylic or hydroxamic acid groups have been prepared. From lipophilic acyclic polyether dicarboxylic acids 2, 9 and 13, the bis(crown ethers) 20–25 were synthesized. From lipophilic acyclic polyether dicarboxylic acids 10–12 and 14, the new macrocyclic diamides 26–32 were prepared in high yields without the use of high dilution techniques or template effects.

Lead Ion Selective Signal Amplification by a Supramolecular Podand Fluoroionophore/Surfactant Complex Sensor in Water

Below the critical micelle concentration (cmc) of Triton X-100, a PD-18C6/Triton X-100 complex was found to exhibit an amplified fluorescence response for Pb2 +  in water. No such signal amplification was noted above the cmc. Dynamic light scattering and dark-field microscope analyses revealed that the PD-18C6/Triton X-100 complex formed micron-size aggregates (1.24±0.39 μm) triggered by selective Pb2 +  binding, resulting in the enhancement of fluorescence intensity with a distinct blue shift of the fluorescence emission at pH 5.70. This is a novel supramolecular function of a PD-18C6/Triton X-100 complex sensor for selective Pb2 +  recognition in water.

Competitive Solvent Extraction of Ra(II) and Ba(II) from Aqueous Solutions with Lipophilic, Acyclic, Di‐ionizable Polyethers

Abstract Twelve lipophilic, acyclic polyethers, each with two terminal N‐(X)sulfonyl carboxamate groups, are found to efficiently extract Ra(II) and Ba(II) at radiotracer levels from aqueous solution into chloroform. With the presence of Ba(II) carrier in the aqueous feed solution, very appreciable Ra(II)/Ba(II) selectivity is observed in single‐stage, liquid‐liquid extraction for the polyether that combines the largest polyether pseudo‐cavity and the most acidic ionizable group.