The supramolecular helical architecture of 8-oxoinosine and 8-oxoguanosine derivatives.

The 8-oxoguanosine derivative 1 and the 8-oxoinosine derivative 2b, with appropriate substituents on their ribose moieties, form hexagonal lyotropic mesophases in hydrocarbon solvents. Small-angle X-ray scattering analysis of a film of 1 and of the meso-phase of 2b, and NMR and CD spectra of isotropic solutions of 2b, indicate that in both cases the supramolecular structures adopted are continuous helices formed by a hydrogen-bond network between the heterocyclic bases. Notably, while derivative 2b, which bears large substituents on its ribose moiety, undergoes self-assembly and mesophase formation, oxoinosine 2a, with only decanoyl groups on its ribose moiety, does not. This may be ascribed to the reduced amphiphilic properties of the latter and the absence of aromatic groups.