A family of Pt(II) complexes bearing
monoanionic C^N^N ligands
as luminophoric units as well as a set of monodentate ligands derived
from allenylidene and carbene species were synthesized and characterized
in terms of structure and photophysical properties. In addition, we
present the extraordinary molecular structure of a phosphorescent
complex carrying an allenylidene ligand. Depending on the co-ligand,
an effect can be observed in the photoluminescence lifetimes and quantum
yields as well as in the radiative and radiation less deactivation
rate constants. Their correlation with the substitution pattern was
analyzed by comparing the photoluminescence in fluid solution at room
temperature and in frozen glassy matrices at 77 K. Moreover, in order
to gain a deeper understanding of the electronic states responsible
for the optical properties, density functional theory calculations
were performed. Finally, the cytotoxicity of the complexes was evaluated in vitro, showing that the cationic complexes exhibit strong
effects at low micromolar concentrations. The calculated half-maximum
effective concentrations (EC50 values) were 4 times lower
in comparison to the established antitumor agent oxaliplatin. In contrast,
the neutral species are less toxic, rendering them as potential bioimaging
agents.
Phosphorescent Pt(II) complexes, composed of a tridentate N^N^C donor ligand and a monodentate ancillary ligand, were covalently attached to DNA oligonucleotides. Three modes of attachment were investigated: positioning the tridentate...
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