Synthesis and characterization of novel calix[4]arene piperazine derivative for the extraction of transition metals and dichromate ions

This article displays the synthesis of N-(2-tosylato)ethylpiperazine (ii) and 5,11,17,23-tetra-tert-butyl-25,27-bis-(2-piprazinoethyl)-26,28-dihydroxycalix4]arene (3). Compounds (ii) and 3 were characterized through elemental analysis, FT-IR, ¹H NMR and/or ¹³C NMR studies. The transition metal cations (Hg²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Cd²⁺) and dichromate anion were studied by liquid–liquid extraction experiment. The results showed that compound 3 has moderate but selective extraction ability for Hg²⁺ and dichromate anion. Comparison between extraction properties of compound 3 with previously reported 5,11,17,23-tetra-tert-butyl-25,27-bis(isoniazidylcarbonylmethoxy)-26,28-dihydroxy-calix4]arene (4) and protonated pyridinium form of 4 (5) is also described.