THIACALIXARENE DERIVATIVES INCORPORATED IN OPTICAL-SENSING MEMBRANES FOR METAL ION RECOGNITION

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.