Synthesis and comparison of extraction properties of p-tert-butylcalix[n]arene nitrile derivatives for selected metals and dichromate anions

The article describes the syntheses and extraction properties of two p-tert-butylcalix[6]arene nitrile derivatives (3 and 4). The trinitrile derivative 3 has been synthesized from 5,11,17,23,29,35-hexa-tert-butyl-37,38,39,40,41,42-hexahydroxy-calix[6]arene 1. The compound 1 was directly converted to its hexanitrile derivative (4). In these syntheses, it was considered to explore the role of nitrile sites in the extraction of various metal cations and HCr2O7-/Cr2O72- anions. The liquid-liquid extraction properties of 3 and 4 towards selected alkali/transition metal cations and HCr2O7-/Cr2O72- anions are reported. It has been observed that receptor 3 does not extract alkali/transition metal cations effectively, but shows affinity towards HCr2O7-/Cr2O72- anions at low pH. The compound 4 is an effective form for transferring Ni2+ selectively, while it shows poor transferring ability for HCr2O7-/Cr2O72- anions from an aqueous into a dichloromethane layer. It was observed that the cavity size of the calix[n]arenes and the cooperativity of the functionalities play important roles in two phase extraction systems.