Analytica Chin& Acta 294 (1994) 207-213 Silver-selective membrane electrodes using acyclic dithia benzene derivative neutral carriers. Comparison with related macrocyclic compounds Jaume Casab6 a~*, Teresa Flor ‘, Maria I. Romero a, Francesc Teixidor b, Consuelo Perez-JimCnez b a zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Departamentdc Quhica, Uniuersitat Authma k zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIH Barcel~~, 08193 BeUaterra, Barcelona, Spain b Institut de Cihcia dek Materials (C.S.I.C.), 08193 Beilaterra, Barcelona, Spain Received 19th November 1993; revised manuscript received 4th March 1994 Abstract Four new acyclic dithia benzene derivativ 3 have been synthesized: 1,3-bis[(ethylthioknethyl]benzene; 1,3-b& [(pentylthio)metbyljbenzene; 1,3-bis[(octylthio ethylbenzene, and 1,3-bis[(dodecyltbio)thylfbenzene. All com- pounds have been tested as silver@ ion sensors in membrane-based ion-selective electrodes, exhibiting good sensitivity, detection limits, reproducibility and selectivity. The chemical recognition of silver(I) by these receptors is compared to the behaviour presented by closely related macrocyclic and acyclic polythia compounds. K&y words: Sensors; Acyclic dithia benzene derivatives; Silver-selective membrane electrodes; Macrocyclic com- pounds zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 1. Introduction The chemical recognition of metal ions is a very difficult task due to their ability to show several coordination numbers and their affinity towards different coordination centres. All these features make them suitable to coordinate with a wide range of ligands, even to force ligand rear- rangements in order to fit their coordination preferences. As a result it is very difficult to design a specific receptor for one particular metal ion. * Corresponding author. The alkali and alkali earth elements, except lithium, beryllium and magnesium, are remark- able exceptions. The coordination of these ele- ments is predominantly ionic. They generally dis- play high coordination numbers and exhibit affin- ity towards hard coordination centres like oxygen and nitrogen atoms. These characteristics explain the remarkable selectivity and chemical recogni- tion shown by some macrocyclic polyethers to- wards these metal ions [l-7]. The d” transition metal ions, Ag+ and Hg*+, display singular coordination characteristics. Both have a preference for a coordination number of two. Furthermore they display great affinity for soft coordination centres like sulphur, as well as 0003-2670/94/$07.00 0 1994 Elsevier Science B.V. All rights reserved SSDIOOO3-2670(94)00135-9