Structural Ion Selectivity of Thia Crown Ether Compounds with a Bulky Block Subunit and Their Application as an Ion-Sensing Component for an Ion-Selective Electrode

Coated-wire silver ion-selective electrode based on silver complex of cyclam

A coated-wire ion-selective electrode (ISE) based on cyclam (1,4,8,11-tetraazacyclotetradecane) as a neutral carrier in a polyvinyl chloride (PVC) matrix was fabricated for the determination of Ag(I) ions. The coated-wire ISE exhibited a linear Nernstian response over the range 1 x 10(-1) to 1 x 10(-7) M with a slope of 59 +/- 2 mV per decade change and a detection limit of 5 x 10(-8) M. The ISE shows a greater preference for Ag over other cations with good precision. The electrode was selective towards Ag(I) ions in the presence of 13 different metal ions tested. The selectivity coefficients (K(ij)) were determined for Na(I), K(I), Mg(II), Ca(II), Ba(II), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Pb(II) and Hg(II). The selectivity coefficients of these cations are in the range of 10(-4) to 10(-2). This ISE was used for the determination of free silver and total silver in electroplating bath solutions, additives and brighteners.

PVC-based 1,3,5-trithiane sensor for cerium(III) ions

A PVC membrane sensor for cerium(III) ions based on 1,3,5-trithiane as membrane carrier was prepared. The sensor has a linear dynamic range of 1.0 x 10(-1)-5.0 x 10(-5) M, with a Nernstian slope of 19.4+/-0.4 mV decade(-1), and a detection limit 3.0 x 10(-5) M. It has a fast response time of < 15 s and can be used for at least 5 months without any considerable divergence in potentials. The proposed sensor revealed comparatively good selectivities with respect to alkali, alkaline earth, and some transition and heavy metal ions and could be used in a pH range of 5.0-8.0. It was used as an indicator electrode in potentiometric titration of oxalate and fluoride ions and in determination of F- ion in some mouth wash preparations.

Molecular design of crown ethers. 19.(1) synthesis of novel disulfide- and diselenide-bridged Bis(benzo-12-crown-4)s and their Ag(+)-selective electrode properties

Two novel heteroatom-bridged bis(benzo-12-crown-4 ether)s, i.e., bis(2-nitro-4,5-(1,4,7,10-tetraoxadecamethylene)phenyl) disulfide (4) and diselenide (5), have been synthesized and characterized by elemental analysis and mass, IR, UV, and (1)H NMR spectroscopy. An X-ray crystallographic structure was obtained for 4. Ion-selective electrodes (ISE) for Ag(+), containing 4 and 5 in PVC membrane as neutral carriers, were prepared, and their selectivity coefficients for Ag(+) () were determined against other heavy metal ions, alkali and alkaline-earth metal ions, and ammonium ion using the matched potential method. These ISEs showed excellent Ag(+) selectivities, log </= -4.0, against most of the interfering cations examined, except for Hg(+) (log >/= -1.2). These values are comparable to those reported for the representative Ag(+)-selective thioethers 6 and 7, revealing that both disulfide and diselenide functionalities in 4 and 5 are equally effective Ag(+)-selective binding sites as the 1,7-dithia-4-oxa functionality in 6 and 7, irrespective of the different atom type and relative position of the sulfur/selenium donors in the ligands. Also discussed are the steric and electronic effects of the nitro groups in 4 and 5 on the Nernstian slopes obtained with the 4- and 5-based ISEs.