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    Facilitated Transfer of Alkali and Alkaline-Earth Metal Ions by a Calix[4]arene Derivative Across Water/1,2-Dichloroethane Microinterface: Amperometric Detection of Ca2+
    (Wiley-V C H Verlag Gmbh, 2010) Bingöl, Haluk; Kaykal, Ferhat; Akgemci, Emine Güler; Sırıt, Abdulkadir
    The host-guest complexation reactions between 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dimethoxy calix[4] arene ( BDDC4) and alkali and alkaline-earth metal ions were investigated by facilitated ion transfer processes across water/1,2-dichloroethane microinterface by using steady-state cyclic voltammetry and differential pulse voltammetry. The obtained facilitated transfers for Li+, Na+, K+, Rb+ and Ca2+ were evaluated under the different experimental conditions, at the excess concentrations of metal ions with respect to BDDC4 and vice versa. The association constants having 1 : 1 stoichiometry for Li+, Na+, K+ and Rb+ in 1,2-DCE were determined. Also, we demonstrated that BDDC4 can play an important role for the development of highly selective chemical sensor for Ca2+ among alkaline-metal ions in the concentration range of 0.1-1.0 mM in aqueous solution.
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    Selective sodium ion transfer across a water/1,2-dichloroethane micro-interface by a calix[4]arene derivative
    (ELSEVIER SCIENCE SA, 2011) Kaykal, Ferhat; Kocabaş, Erdal; Bingöl, Haluk; Akgemci, Emine Güler; Coşkun, Ahmet
    The transfer of alkali and alkaline-earth metal ions facilitated by a calix[4]arene derivative, 25,27-di [(2-ethoxy)benzaldehyde]-26,28-dihydroxy-5,11,17,23-tetra(tert-butyl) calix[4]arene (DBC4), across a water/1,2-dichloroethane (1,2-DCE) micro-interface supported at the tip of a micropipette was investigated. The well-defined voltammetric behavior was obtained only for Na+ ion among the used metal ions by using the electrochemical methods. The measurements were performed when the bulk concentration of Na+ ion in the aqueous phase is much higher than that of DBC4 in the organic phase, and vice versa. The diffusion coefficient of DBC4 in the DCE phase was calculated to be equal to (4.2 +/- 0.2) x 10(-6) cm(2) s(-1). The logarithm of the association constant of DBC4-Na+ complex having 1:1 stoichiometry in 1,2-DCE was determined as 3.99. The differential pulse voltammetry was used for amperometric detection of Na+ ion in chloride medium. The results show that DBC4 can be used for many analytical applications such as ion recognition and fabrication of electrochemical sensor for Na+ ion because of its good selectivity. (C) 2011 Elsevier B.V. All rights reserved.
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    Synthesis and electrochemical properties of a novel calix[4]arene derivative for facilitated transfer of alkali metal ions across water/1,2-dichloroethane micro-interface
    (TAYLOR & FRANCIS LTD, 2011) Kaykal, Ferhat; Bingöl, Haluk; Sarıgüney, Ahmet B.; Coşkun, Ahmet; Akgemci, Emine Güler
    The alkali metal ion transfers facilitated by a novel calix[4]arene derivative (OPEC) across the water/1,2-dichloroethane (1,2-DCE) micro-interface supported at the tip of a micropipette were presented. The well-defined voltammetric behaviours except Cs+ was obtained by cyclic voltammetry and differential pulse voltammetry. The bulk concentration of metal ions was much higher than that of OPEC in the performed measurements. The diffusion coefficient of OPEC in the 1,2-DCE phase was calculated as 5.18 +/- 0.70 x 10(-6) cm(2) s(-1). On the basis of the changes of the half-wave transfer potentials, the logarithms of the association constants having 1:1 ionophore-ion complex stoichiometry for Li+, Na+, K+ and Rb+ in 1,2-DCE were determined as 4.80, 4.62, 4.98 and 5.32, respectively. The facilitated ion transfers were also evaluated by the Randles equivalent circuit used for ac-impedance data analysis.