4f and 3d-4f heterobimetallic Schiff base complexes involving nitrogen
ligands: X-ray structures, photoluminescence, stability and DNA/RNA
cleavage ability
Anna M. Kaczmarek,a P. Alvarez-Porebski,c Tineke Mortierb, F. Lynen,c Rik Van Deun,a
Kristof Van Heckeb
a) L3- Luminescent Lanthanide Lab, Department of Inorganic and Physical Chemistry, Ghent
University, Krijgslaan 281-S3, B-9000 Ghent, Belgium
b) XStruct, Department of Inorganic and Physical Chemistry Ghent University, Krijgslaan 281S3, B-9000 Ghent, Belgium
c) Separation Science Group, Department of Organic and Macromolecular Chemistry, Ghent
University, Krijgslaan 281-S4, B-9000 Ghent, Belgium
e-mail: anna.kaczmarek@ugent.be
The interest in the chelation of metal ions by Schiff base macrocyclic and acyclic
ligands originates from the role that these complexes play in bioinorganic and medicinal
inorganic chemistry.1-3 The key Schiff base condensation reaction involves a reaction
between amine and carbonyl precursors to eliminate (condense) water and yield an
imine. Often these syntheses are carried out in the presence of the appropriate metal ions
which act as templates in directing the steric course of the reaction.
In our work we present two series of lanthanide (Ln) and lanthanide-copper (CuLn) complexes synthesized in the presence of two different nitrogen Schiff base ligands
prepared either from 2,6-diacetylpyridine and dietylenetriamine or ortho-vanillin and
ethylenediamine. Their crystal structures have been determined using single crystal Xray diffraction techniques. Additionally their photoluminescence and stability in
solution were investigated. Several of the Ln and Cu-Ln complexes yield strong visible
or near-infrared luminescence of the lanthanide when excited into the chelating ligand
band.
As it is known that lanthanide ions are remarkably effective catalysts for the
hydrolytic cleavage of phosphate ester bonds of RNA and DNA,4 therefore the newly
synthesized Ln Schiff base complexes are considered as artificial RNA/DNA nucleases.
References
1) Vigato, P. A.; Tamburini, S., Coord. Chem. Rev. 2004, 248, 1717-2128.
2) Riley, D. P., Chem. Rev. 1999, 99, 2573-2587.
3) Radecka-Paryzek, W. ; Patroniak, V.; Lisowski, J., Coord. Chem. Rev. 2005, 249, 2156-2175.
4) Morrow, J. R. ; Buttrey, L. A. ; Shelton, V. M. ; Berback, K. A., J. Am. Chem. Soc. 1992, 114, 19031905.
Acknowledgement: RVD thanks the Hercules Foundation (project AUGE/09/024 “Advanced Luminescence Setup”)
for funding. KVH thanks the Hercules Foundation (project AUGE/11/029 "3D-SPACE: 3D Structural Platform
Aiming for Chemical Excellence") and the Research Fund – Flanders (FWO) for funding.