The synthesis and structure determinations of lanthanum, samarium, ytt
erbium, and lutetium complexes of is((diethylcarbamoyl)methoxy)-26,28-
dihydroxycalix [4] arene (L) are described. The four structures displa
y similar characteristics with the trivalent lanthanide cation being e
ncapsulated in an eight-coordinate oxygen environment, consisting of s
ix oxygens from the calixarene, a water molecule, and unidentate picra
te for lanthanum [La(L-2H)(picrate)(H2O)]; and bidentate chelating pic
rate for the other lanthanides [Ln(L-2H)(picrate)]Ln = Sm, Yb, Lu. Und
er optimised experimental conditions solvent extraction investigations
showed the calix[4]arene ligand L exhibited generally very high perce
ntage extractabilities of lanthanide cations into dichloromethane, pre
sumably on account of the ligand's unique lower rim oxygen containing
coordination sphere and its lipophilic exterior.