Synthesis and characterization of new heterodinuclear (4f, 4f′) lanthanide complexes

Abstract

A tripodal compartmental Schiff base ligand resulting from reaction of 3-ethoxysalicylaldehyde and tris(2-aminoethyl)amine can yield heterodinuclear lanthanide complexes in which the Ln ions are coordinated in the inner N 4O 3 and the outer O 3O 3 sites. The key compound in this synthetic route is the neutral mononuclear complex in which the lanthanide ion is chelated in the inner N 4O 3 coordination site. Introduction of the second lanthanide ion as a trifluoroacetate salt yields heterodinuclear entities which are soluble enough to be characterized by electrospray mass spectrometry techniques. With the help of the lanthanide induced shifts observed in the 1 H NMR spectra of different heterodinuclear complexes, we have been able to confirm that the equivalent chloride species are not subject to scrambling in methanol solution.