Synthesis and Theoretical Study of Gadolinium(III) Complex of Heptadentate (N4O3) Tripodal Schiff Base Ligand

Abstract

A new potentially heptadentate (N₄O₃) Schiff base ligand
{N[(CH₂)₂N = CH(2-OH-5-BrC₆H₃)]₂[(CH₂)₃N = CH(2-OH-
5-BrC₆H₃)]} (H₃L) was synthesized and characterized by
elemental analysis and various spectroscopic methods. This
ligand was derived from the condensation reaction of a tripodal
tetraamine ligand, bis(2-aminoethyl)(3-aminopropyl)
amine (pee) with 3 equiv. of 5-bromosalicylaldehyde. The
neutral gadolinium(III) complex of this bulky ligand was also
synthesized. The complex was characterized by microanalysis
and IR spectra. The capability of H₃L as well as its
unsubstituted analogs to encapsulate a lanthanide ion, herein
La(III), has been theoretically studied by ab initio restricted
Hartree-Fock (RHF) and density functional B3LYP methods.