Binding interaction of [Re(H2O)3(CO)3]+ with the DNA fragment d(CpGpG)

Insights into the interaction of the [Re(H2O)(3)(CO)(3)](+) complex (1) with the DNA fragment d(CpGpG) have been obtained by one-(1D) and two-dimensional (2D) NMR spectroscopy. The H8 resonances of the single major [Re(H2O)d(CpGpG)(CO)(3)](-) adduct (2) exhibit pH-independent chemical shift changes attributable to metal N7 binding. The structure of this adduct has been characterized by molecular modeling studies based on 1D and 2D NMR data. In solution, 2 shows the presence of two N7-coordinated guanine moieties in a head-to-head (HH) orientation as evidenced by G2H8/G3H8 cross-peaks in the H-1-H-1 NOESY NMR spectrum. The presence of the 5'-bridging phosphodiester appears to stabilize the HH1 L conformer, as was previously described for related Pt and Rh complexes.