Synthesis and chiral separation of ruthenium bipyridyl 1,5-dihydroxyanthraquinone

The variables influencing the synthesis of (cis-Ru(II)(bipyridyl)$\sb2$-1,5-Dihydroxyanthraquinone)$\sp+\rm(PF\sb6)\sp-\ (RUC\sb{34}H\sb{23}N\sb4O\sb4PF\sb6,$ MW:796.8) were investigated so suitable quantities of highly purified, well characterized metal complex could be synthesized for physical-chemical measurements including nuclear magnetic resonance structural studies, and complex/DNA binding experiments. Both thin-layer chromatography and column chromatography with magnesium carbonate absorbent were useful techniques for sample purification. A significant part of the research was the chiral resolution of delta and lambda stereoisomers of the rigid chiral metal complexes with octahedral coordination of Ru(II). A $\gamma$-Cyclodextrin-bonded HPLC column proved suitable for the separation (R$\rm\sb s$ = 0.8-1.0). Empirical determination of the most appropriate solvents and other chromatographic variables led to the following conditions for the relatively large, aromatic, complex cation: buffer: 0.01 M CH$\sb3$COONH$\sb4$/0.1% triethylamine = 1:1; pH = 3.5; mobile phase: acetonitrile/buffer = 15/85; temperature 25-26 $\sp\circ$C; flow rate: 0.3-1.0 ml/min. The propeller-type metal-complex cation (ML$\rm\sb2X)\sp+$ was designed to have two bipyridyl blades and a third with 1,5-dihydroxyanthraquinone. Since many antibiotic, anticancer/antitumor drugs have a quinoidal component, the ruthenium coordination compounds are useful both for DNA/drug molecular recognition studies and promising in the design of new, more sequence-specific, potentially less toxic drugs.