title: Synthesis of a tweezer-like bis(arylthiaalkoxy)calix[4]arene as a cation sensor for ion-selective electrodes: an investigation of the influence of neighboring halogen atoms on cation selectivity.
abstract: Two novel tweezer-like 25,27-dihydroxy-26,28-bis(phenylthiaethoxy)calix[4]arenes 6 and 7 were synthesized by the reaction of 25,27-dihydroxy-26,28-bis(bromoethoxy)calix[4]arenes 3 and 4 for the evaluation of their ion-selectivity in ion-selective electrodes (ISEs). X-ray structural analysis indicated that calix[4]arene 7 is in an interesting infinite linear aggregate via self-inclusion. For investigation of the influences of substitutes on the behavior of the ISEs, the halogen substituted aryl analogues of 25,27-dihydroxy-26,28-bis(arylthiaethoxy)calix[4]arenes 8-12 were also synthesized and their ISE performances were evaluated under the same conditions. ISEs based on 6-12 as neutral ionophores were prepared, and their selectivity coefficients for Ag+ (log KAg,M(pot)) were investigated against other alkali metal, alkaline-earth metal, lead, ammonium ions and some transition metal ions using the fixed interference method (FIM). These ISEs showed excellent Ag+ selectivity over most of the interfering cations examined, except for Hg2+ having relative smaller interference (log KAg,Hg(pot) < or = 2.1). The 19F NMR spectra of 9 and 9.AgClO4 were recorded for investigation the fluorine environments in the complex. The 19F NMR spectra strongly suggested that the fluorine atoms on ionophore 9 participated in ligation with silver cation.
authors.affiliation: State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Xianshun
authors.initials: X
authors.lastname: Zeng
authors.forename: Hao
authors.initials: H
authors.lastname: Sun
authors.forename: Langxing
authors.initials: L
authors.lastname: Chen
authors.forename: Xuebing
authors.initials: X
authors.lastname: Leng
authors.forename: Fengbo
authors.initials: F
authors.lastname: Xu
authors.forename: Qinshan
authors.initials: Q
authors.lastname: Li
authors.forename: Xiwen
authors.initials: X
authors.lastname: He
authors.forename: Wenqin
authors.initials: W
authors.lastname: Zhang
authors.forename: Zheng-Zhi
authors.initials: ZZ
authors.lastname: Zhang