Template Synthesis, Crystal Structure and Luminescent Properties of Neutral N 4 O 3 Tripodal Ln III L Complexes (Ln III = La 3+ , Eu 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Tm 3+ or Lu 3+ ; H 3 L = Tris{[3′‐(2′′‐pyridyl)‐5′‐ tert ‐butyl‐2′‐hydroxybenzylidene‐2‐imino]ethyl}amine)

In the presence of Ln 3+ (Ln = La, Eu, Gd, Tb, Dy, Ho, Er, Tm or Lu), tris(2‐aminoethyl)amine condensed with three equivalents of 3‐(2′‐pyridyl)‐5‐ tert ‐butyl‐2‐hydroxybenzaldehyde in methanol to give the neutral Schiff‐base complex Ln III L (Ln = La 1 , Eu 2 , Gd 3 , Tb 4 , Dy 5 , Ho 6 , Er 7 , Tm 8 and Lu 9 ; H 3 L = tris{[3′‐(2′′‐pyridyl)‐5′‐ tert ‐butyl‐2′‐hydroxybenzylidene‐2‐imino]ethyl}amine). The structures of compounds 4 − 7 were determined by X‐ray crystallography. The crystal structure analyses revealed that the Schiff base behaves as a tri‐deprotonated heptadentate ligand encapsulating the lanthanide metal ion within the N 4 O 3 cavity, with all the pyridyl groups being pendant. Solution spectroscopic data suggest that the Ln III L complexes remain intact in methanol and exist as nine‐coordinate non‐electrolytes with the lanthanide metal ions coordinated to the N 4 O 3 cavity of the tripodal Schiff base and two solvent molecules. The solution photoluminescent properties of these lanthanide Schiff‐base complexes were also examined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)