Chromogenic sensing of Cu(II) by imino linked thiacalix[4]arene in mixed aqueous environment

Thiacalix[4]arene based imino receptors 4–5 carrying azophenol appendage have been synthesized and studied for their binding abilities towards different metal ions (Li+, Na+, K+, Cd2+, Ni2+, Cu2+, Zn2+, Ag+, Pb2+ and Hg2+). Receptor 4 showed selective chromogenic sensing for Cu2+ ions in mixed aqueous conditions (THF:H2O, 9:1 v/v).