Galina G. Talanova

A Calixarene-Based Fluorogenic Reagent for Selective Mercury(II) Recognition.

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-dimethoxycalix[4]arene (2), is reported. In solvent extraction from aqueous acidic solutions (HNO(3)), 2 exhibits excellent selectivity for Hg(II) over a wide range of transition, alkali, and alkaline earth metal cations. Quenching of its fluorescence due to Hg(II) coordination is unaffected by the presence of 100-fold excesses of alkali metal cations, alkaline earth metal cations, Ag(I), Tl(I), Cd(II), Co(II), Cu(II), Ni(II), Pb(II), Pd(II), Zn(II), or Fe(III).

New Fluorogenic Dansyl-Containing Calix[4]arene in the Partial Cone Conformation for Highly Sensitive and Selective Recognition of Lead(II)

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 calix[4]arene 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 conformations adopted by the flexible dansyl-containing prototype upon complexation with lead ion. In acidic MeCN-H2O (1:1 v/v) solutions, the partial cone fluoroionophore allowed for detection of Pb (2+) at the levels as low as 2.5 ppb, which is totally compatible with the regulations of the U.S. Environmental Protection Agency and the World Health Organization on the limiting content of this hazardous pollutant in drinking water.

Novel caesium-selective, 1,3-alternate calix[4]arene-bis(crown-6-ethers) with proton-ionizable groups for enhanced extraction efficiencyElectronic supplementary information (ESI) available: HSQC spectra for Na+ and Cs+ complexes of ionized 7, and graphs for Cs+ extraction. See http://www.rsc.org/suppdata/p2/b1/b109638a/

Synthesis of a series of novel 1,3-alternate calix[4]arene-bis(crown-6-ethers) with a proton-ionizable group (PIG) located in front of one crown ether cavity is reported. Variation of the X group in the N-(X-sulfonyl)carbamoyl substituent on the calixbiscrowns provides variation of acidity of the PIG. NMR spectroscopic studies demonstrate that the position of the PIG within the molecule allows it to participate in cooperative metal ion coordination by the ligand. In solvent extraction of alkali metal cations from aqueous solutions of varying pH into chloroform, the novel ionophores possess enhanced efficiency relative to a non-ionizable analog, while retaining high Cs+ selectivity. The Cs+ extraction constants of the proton-ionizable calixbiscrowns are proportional to their acidities. Under the conditions employed, 1 ∶ 1 complexes of the ionized calixbiscrowns with Cs+ are the dominant species extracted into the organic phase.

New proton-ionizable, cesium-selective calix[4]arene-bis(crown-6-ethers) with markedly enhanced extraction efficiency

The first 1,3-alternate calix[4]arene-bis(crown-6-ethers) with a proton-ionizable group located in front of one crown ether cavity are synthesized. Compared with an analog that has no proton-ionizable group, the two new ligands possess markedly higher Cs+ extraction efficiency.

Extraction Selectivities of Crown Ethers for Alkali Metal Cations: Differences between Single-Species and Competitive Solvent Extractions

Separation factor values for pairs of alkali metal cations determined in competitive solvent extractions of alkali metal picrates from aqueous solutions into chloroform by a variety of benzo- and cyclohexano-group-containing crown ethers vary significantly from extrapolations based upon the results of single-species extraction experiments. For almost all of the crown ether-alkali metal cation combinations examined, the separation factor values are greater for competitive solvent extraction. In view of the unexpected results for sodium picrate extraction by dibenzo-24-crown-8, the solid-state structure of the isolated complex was determined.

Dansyl-containing fluorogenic calixarenes as optical chemosensors of hazardous metal ions: a mini-review

Fluorescent chemosensors serve as an efficient tool for selective detection of toxic metal ions (Hg2+, Cd2+, Pb2+, etc.) in the environment. This review is focused on optical metal ion recognition with employment of calixarene-based sensors containing one or more dansyl fluorophore groups. The effect of structural variations, including the mode of dansyl unit attachment, calixarene scaffold type and conformation, as well as the identity and pattern of upper- and lower-rim substituents on the selectivity and sensitivity of these fluoroionophores towards hazardous metal ions is discussed.

New chelating polymers for heavy metal ion sorption

Twenty-six new chelating polymers containing pyridyl (Py) or bipyridyl (Bipy) units as ligating centers were synthesized by free-radical reactions of 2-vinylpyridine, 4-vinylpyridine, or 4-methyl-4′-vinyl-2,2′-bipyridine with different dimethacrylate crosslinkers and evaluated for heavy metal ion sorption from aqueous solutions. Both the Py- and Bipy-containing polymers are highly selective for Cu(II) over Co(II) and Ni(II) and for Hg(II) over Cd(II). The polymeric materials with Bipy binding sites generally exhibit more efficient metal ion sorption than do the corresponding Py-containing copolymers. The metal ion sorption capacity of the copolymer also depends on the structure of the dimethacrylate crosslinker.

Novel fluorogenic calix[4]arene-bis(crown-6-ether) for selective recognition of thallium(I)

A new fluorogenic, dansyl group-containing derivative of 1,3-alternate calix[4]arene-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.

Calix[4]arenes with hard donor groups as efficient soft cation extractants. Remarkable extraction selectivity of calix[4]arene N-(X)sulfonylcarboxamides for HgII

Calix[4]arene N-(X)sulfonylcarboxamides efficiently extract HgII from acidic aqueous nitrate solutions with excellent selectivity over alkali, alkaline earth and many transition metal ions, including PbII, AgI and PdII.

Calix[4]arenes with a novel proton-ionizable group: synthesis and metal ion separations

New calix[4]arenes with two N-(X)sulfonyl carboxamide groups of ‘tunable’ acidity are synthesized from the corresponding calixarene dicarboxylic acid and exhibit good to excellent extraction selectivity for Pb2+ over most alkali, alkaline earth and transition metal ions.