The ability of crown ethers [1—4] and cryptands [5—7] to selectively complex ions and neutral molecules has been the subject of extensive studies over the past two decades. One of the most impor­ tant problems under investigation was the transport of ionic species through membranes in biological sys­ tems [8 ]. Of several transport mechanisms proposed and demonstrated in natural and artificial ...

The extraction of cesium, strontium, and a number stable components simulated high-level waste solutions from nitric acid media with crown ether derivatives in new fluorinated diluents was studied. Based on the data solubility extractants into aqueous phase physicochemical properties used, most promising systems were chosen: ethers 4,4‘(5’)-di-tert-butyldibenzo-18-crown-6 (L1) 4,4‘(5’)-di-tert-...

The extraction-separation of lanthanum and europium ions with bis(2-ethylhexyl) phosphoric acid (DEHPA) in cyclohexane was improved by adding 12-crown-4 (12C4) to the aqueous phase as a masking agent. In the presence of this crown ether the extraction curve of lanthanum ions versus pH shifts to the higher pH region, while the curve is not influenced for the europium ions. Consequently the separ...

the interaction between benzo-15-crown-5 (b15c5), dibenzo-18-crown-6 (db18c6), dibenzyl-daza-18crown-6 (dbzda18c6), n-phenyl-aza-15-crown-5 (npha15c5) and dibenzopyridine-18-crown-6 (dbpy18c6) with π-acceptor 2,3-dichloro-5,6-dicyanobenzoquinone (ddq) in chloroform solution was studied spectrophotometrically. the interaction of b15c5-ddq and db18c6-ddq caused the formation of 1:1 charge transfe...

The synthesis of novel magnesium, copper, and metal-free porphyrazines, peripherally substituted with dithia-7-crown-2 (MPz(7)), dithia-15-crown-5 (MPz(15)), and dithia-18-crown-6 (MPz(18)) macrocycles is reported. These compounds are prepared starting from dicyanoethylene containing crown ethers 3, 2(1), and 2(2), respectively, which contain sulfur as well as oxygen heteroatoms. The "crowned" ...

Single crystals formed from hydrogen-bonding supramolecular cations of o-aminoanilinium (HOPD)­crown ethers, (HOPD)([12]crown-4), (HOPD)([15]crown-5), and (HOPD)([18]crown-6), and one-electron-reduced [PMo12O40] Keggin-type clusters were synthesized. The crystal structures and dielectric responses of the three new compounds (HOPD)4([12]crown-4)4[PMo12O40]¢4CH3CN (1), (HOPD)4([15]crown-5)4[PMo12...