Functionalized calix[4]arene as an ionophore: Synthesis,crystal structures and complexation study with Na and K ions |
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Authors: | Subrata Patra Eringathodi SureshParimal Paul |
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Institution: | Analytical Science Division, Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar 364 002, India |
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Abstract: | Calix4]arenes with substituents at three of the four OH groups of the lower rim have been synthesized to investigate their properties as ionophores for Na+ and K+ metal ions. Crystal structures of these trisubstituted compounds revealed that the calixarene moiety has adopted a partial cone conformation, however the precise shape of the molecule, and intra- and intermolecular interactions, are significantly different due to variations of the substituents. Compound L2 encapsulated an acetonitrile molecule in the cavity of the calix moiety, held by C–H?π interactions. In the case of L3, the 2-(2-chloroethoxy)-ethanol substituent is involved in strong intramolecular C–H?π interactions with the centroid of the phenyl rings of the calix, bringing the 2-(2-chloroethoxy)-ethanol moiety inward the calix cone, which prevented the entry of any solvent molecule into the cavity. The complexation properties of L2–L4 with Na+ and K+ ions have been investigated in chloroform–methanol mixture by 1H NMR and an attempt has been made to isolate these complexes in the solid state. Complexation studies reveal that only L3 forms a complex selectively with K+, involving 2-(2-chloroethoxy)-ethanol as a coordinating moiety. The association constant (1.4 × 105 M−1) of the complex has also been determined. |
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Keywords: | Calixarenes Ionophores Complexation with Na+ and K+ Crystal structures |
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