Matthew Goodall, Patricia M. Kelly, David Parker, Karsten Gloe and Holger Stephan
The synthesis is reported of two sets of oxa-amide ionophores based
on 2-phenylglycerol and cis,cis-cyclohexane-1,3,5-triol,
with ligand coordination numbers of four, five and six. Ionophores based on
the hexadentate cyclohexyl triamide 9 show excellent
Na+/K+ selectivity (-log
KpotNa,K = 3.1), and
the pentadentate analogue 10 shows good Li+/Na+
selectivity (-log
K
potLi,Na = 2.2). Solution NMR
and liquid–liquid extraction studies confirmed the formation of
1∶1 complexes and IR studies pinpointed the presence of amide
binding. Ligands based on 2-phenylglycerol exhibited good Ca2+
selectivity which was highest for the hexadentate triamide, 6. Detailed
ESMS studies revealed similar trends in ion-binding, performed under
controlled conditions.