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    Polymer supported calix[4]arene Schiff bases: A novel chelating resin for Hg2+ and dichromate anions
    (TAYLOR & FRANCIS INC, 2005) Karakucuk, A; Kocabas, E; Sirit, A; Memon, S; Yilmaz, M; Roundhill, DM
    This article describes the synthesis and characterization of two new calix[4] arene Schiff bases and their polymeric resins. The extraction properties of these "proton switchable extractants" with alkali, transition, post transition metal cations and for dichromate anions are reported. The two new calix[4] arene based Schiff bases (5 and 6) have been synthesized from 5,17-diformyl-25,27-dipropoxy-26,28-dihydroxycalix[4]arene (4) by treatment with 3-amino-methylpyridine and 1,8-diaminooctane in two separate reaction flasks following the same procedure. Compounds 5 and 6 have been appended to a polymeric resin by treatment with Merrifield resin through a nucleophilic substitution reaction. The receptor compounds (3 and 5-8) do not extract alkali metal cations, but show some selectivity toward transition metal cations, and a particularly high selectivity to Hg2+ and Pb2+. The protonated forms of all of the calixarene-based receptors are good extractants for transferring Cr2O72-/HCr2O7- anions from an aqueous into a dichloromethane layer.
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    Synthesis and characterization of a novel chiral chromogenic calix[41(azoxa)crown-7
    (PERGAMON-ELSEVIER SCIENCE LTD, 2004) Sirit, A; Karakucuk, A; Memon, S; Kocabas, E; Yilmaz, M
    Two new chromogenic compounds, 5 and 6, and a novel chiral chromogenic calix[4](azoxa)crown-7 8 have been synthesized using a calix[4]arene platform. The starting reagents chiral diamine e and calix[4]arene diacid chloride derivative 7 were prepared conveniently according to recent approaches. The H-1 and C-13 NMR, data showed that these compounds exist in a cone conformation. Compounds 5 and 8 have shown broad absorption bands in UV-vis spectra suggesting their utility in different fields, for example, as sensors for ions as well as for chiral molecules. (C) 2004 Elsevier Ltd. All rights reserved.
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    Synthesis and metal ion recognition properties of a novel chiral calix[4](azoxa)crown-7
    (TAYLOR & FRANCIS LTD, 2005) Sirit, A; Kocabas, E; Memon, S; Karakucuk, A; Yilmaz, M
    A novel chiral calix[4](azoxa)crown-7 (9) has been synthesized and its metal ion recognition properties investigated. The starting reagents, chiral diamine 5 and calix[4]arene diacid chloride derivative 8, were prepared according to literature methods. H-1 and C-13 NMR data show that 9 exists in a cone conformation. In liquid-liquid extraction experiments, 9 exhibits selectivity for Li+ among the other alkali metals and a good extraction ability for transition metal cations, suggesting its potential use in different fields, such as a sensor for ions as well as for chiral molecules.
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    Synthesis of two calix[4]arene diamide derivatives for extraction of chromium(VI)
    (PERGAMON-ELSEVIER SCIENCE LTD, 2005) Bozkurt, S; Karakucuk, A; Sirit, A; Yilmaz, M
    The synthesis of four diamide derivatives of the p-tert-butylcalix[4]arenes from the reaction of 5,11,17,23-tetra-tert-butyl-25,27diethoxycarbonylmethoxy-26,28-dihydroxycalix[4]arene 2 with various primary amines were reported. The H-1 and C-13 NMR, data showed that the synthesized compounds exist in the cone conformation. The complexing properties of these compounds toward Cr2O72-/HCr2O7- anions are also studied. It has been observed that receptors 5 and 6 are better extractant than the compounds 3 and 4. The protonated alkyl ammonium form of 5 and 6 is an effective extractant for transferring HCr2O7-/Cr2O72- anions from an aqueous phase into a dichloromethane layer. (c) 2005 Elsevier Ltd. All rights reserved.