Lanthanide-daunomycin interactions. Predominance of ML2 at low metal to ligand ratios

Spectroscopic investigations have been undertaken on the effects of lanthanide ions on the spectrum of the anticancer agent, daunomycin. The visible spectral perturbations due to the metal ions resulted in hypochromic effects in the 480 nm region and in shifts towards longer wavelength. The different metal ions investigated did not give any significant difference in the, spectral character. Data analysis according to the methods of molar ratio, continuous variation and graphical approaches based on simplex matrix theory indicated the presence of predominantly a ML₂ species at metal to ligand ratios, less than one. Data also suggested the presence of ML and ML₃ as well.