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Journals and Conferences
A fluorogenic derivative of 1,3-alternate calixarenebis(crown-6) (1) containing a dansyl group in the proton-ionizable side arm has been employed in selective sensing of Tl+ and Cs+ at low concentration levels in MeCN-H2O (1:1) mixed solvent. Optical recognition of these two metal cations by 1 occurs in contrasting modes. On the basis of the results of… (More)
The first calixarene-based fluorogenic Hg(II)-selective extractant, 5,11,17,23-tetrakis(1,1-dimethylethyl)-25,27-bis(N-(5-dimethylaminonaphthalene-1-sulfonyl)carbamoylmethoxy)-26,28-dimethoxycalixarene (2), is reported. In solvent extraction from aqueous acidic solutions (HNO(3)), 2 exhibits excellent selectivity for Hg(II) over a wide range of… (More)
A new fluorogenic, dansyl group-containing derivative of 1,3-alternate calixarene-bis(crown-6-ether) provides optical recognition of Tl+ with selectivity over many other metal cations, including Na+, K+, Ca2+, Ag+, Hg2+ and Pb2+, and embodies the first example of a calixarene-based fluorescent Tl+-chemosensor.
The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation-exchange resins from hydrochloric acid media is examined. The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the sorption of certain cations, thereby improving the… (More)
Twelve new proton-ionizable, picrylamino-type chromogenic lariat ethers derived from dibenzo-14-crown-4, dibenzo-16-crown-5 and dibenzo-19-crown-6 demonstrate good selectivity and remarkable color response upon extraction of alkali metal cations from basic aqueous solutions into chloroform.
For an assessment of the outcomes from use of an appropriately "preorganized" calixarene-based ionophore versus its conformationally mobile prototype, solvent extraction propensities of flexible calixarene di-[N-(X-sulfonyl)carboxamides] for alkali, alkaline earth metal cations, Pb2+, Ag+ and Hg2+ are compared with those for seven new rigid analogs fixed… (More)
Metal ion recognition by proton-ionizable calixarenes is often affected by interference from the Na present in many aqueous solutions. To assess the Na-effect on calixarene selectivity towards alkaline earth metal cations (AEMC), competitive solvent extraction of Mg, Ca, Sr, and Ba from aqueous solutions into chloroform by di-ionizable calixarene… (More)
Optical sensing of metal ions using calixarenes with covalently attached chromophores (fluorophores) has attracted considerable attention of researchers. However, the alternative approach involving host-guest complexes of calixarenes with dyes in metal recognition has been scarcely explored. In this work, addition of different metal cations to the aqueous… (More)
The structure of the title complex, [Na(2)(C(80)H(98)N(4)O(10)S(2))(H(2)O)]·4CH(3)CN, obtained after crystallization from aceto-nitrile, contains two formula units in the asymmetric unit (Z' = 2) and an estimated four mol-ecules of acetonitrile per calixarene moiety. It is unusual for two Na(+) ions to occupy the lower rims of the cone calixarene, as in… (More)
A new efficient and highly selective fluorescent chemosensor for determination of Pb (2+) has been obtained by covalent attachment of two pendent proton-ionizable dansylcarboxamide groups to the calixarene preorganized in the partial cone conformation. This geometry of the calixarene moiety was chosen on the basis of the prior (1)H NMR study of… (More)