Chemistry Reference
In-Depth Information
11
Groove - Binding Ruthenium( II )
Complexes as Probes of
DNA Recognition
Jayden A. Smith , J. Grant Collins and F. Richard Keene
11.1 Introduction
The application of polypyridyl transition metal complexes to the structural elucida-
tion of biological molecules had its origins in the observations of Dwyer
et al.
in the
1950s.
1
The different biological activity of tris(phenanthroline) complexes of Fe(II),
Ni(II), Ru(II), Os(II), Co(II) and Zn(II) in laboratory mice was reported, with
selectivity of the D (right-handed) in preference to the L (left - handed) enantiomer
noted in the case of inert species. They also noted a curariform activity and signifi -
cant antibacterial characteristics, and a signifi cant enhancement of activity on methyl
substitution on the ligands in the cases of iron and ruthenium species. As such com-
plexes were chemically inert, Dwyer
et al.
reasoned that any effect they had must
be based primarily on their
physical
interactions with biological systems.
Ruthenium has often been the metal of choice when studying the interactions
of polypyridyl transition metal complexes with nucleic acids, owing to the well-
established chemistry and rich photophysical properties of this genre.
2
Polypyridyl-
ruthenium complexes are typically chemically inert, meaning their interactions with
nucleic acids are usually noncovalent and hence reversible, and being octahedral
tris(bidentate) species they possess an inherent chirality which can be exploited in
their interactions with chiral polynucleotides. Furthermore, these complexes exhibit
strong metal - to - ligand charge transfer (MLCT) - induced absorbances in the visible
