Ln(iii) complexes with triptycene based tripodal ligands: speciation and equilibria

Abstract

Triaminotriptycene was used as a rigid anchoring platform for preparing several organic ligands for Ln(III) complexation. In this work we present detailed speciation studies with a tripodal ligand L6 possessing terminal carboxamide coordinating moieties. The solution speciation for different [Ln]/[L] ratios is investigated using NMR and mass spectrometry and compared with those of closely related ligands L7 and L8. A special interest is devoted to chemical equilibria in metal excess, whereby different complex species are generated through slow transformations. The effect of the ionic radius along the lanthanide series is discussed for tetranuclear and trinuclear complexes.