Thiacalixarene Derivatives Incorporated in Optical-Sensing Membranes for Metal Ion Recognition

Abstract

This work deals with the evaluation of different thiacalix[4]arene derivatives included in polymeric PVC membranes for the optical sensing of metallic cations. Two ligands have been studied: thiacalix[4]arene (ligand 4) and its p-tert-butyl-derivative (ligand 2). Membranes including ligand 4 were tested for different metals and better results were obtained for Cd²⁺, Ag⁺, and Pb²⁺. In the case of films incorporating the neutral ionophore, ligand 2, a pH sensitive dye (ETH 2439), and an anionic additive were also added. A selective response to Ag⁺ was achieved in acetate buffer at pH 5.

Keywords:

• Bulk optode
• Silver
• Thiacalix[4]arenes
• Toxic heavy metals

Acknowledgments

This study has been financed by the Spanish Ministry of Foreign Affairs through the scientific cooperation project A/5569/06 and by the Spanish National Research Programme project CGL2007-66861-C4.

Notes

*(1) = thiacalixarene 4; (2) = thiacalixarene 2.

*measured with ICP-OES.

**measured with the proposed optical membrane system.