Absorptive ionophores for Fe3+ cation by parent calix[n]arenes

The absorption of Fe3+ ion from the aqueous phase to the solid phase was carried out by using p-tert-butyl calix[6]arene (L-1), calix[6]arene (L-2), p-tert-butyl calix[8]arene (L-3), and calix[8]arene (L-4). The effect of varying pH upon the absorption capability of parent calixarenes was examined. It was found that the compounds (L-1, L-2, L-3, and L-4) showed the highest extractability toward Fe3+ ion at 4.5-5.4. The calixarene L-2 shows a strong binding ability to Fe3+ ion. Based on the continuous variation method, calixarene L-2 formed 1:1 complex with Fe3+ ion.