OLIGODEOXYGUANYLATES - A CASE OF SELF-ASSEMBLY LEADING TO LYOTROPIC LIQUID-CRYSTALS

The guanosine derivatives d(Gp)1-5G, dissolved in water, give rise to cholesteric and hexagonal mesophases. The results of X-ray Diffraction, Optical Microscopy, Circular Dichroism and Small Angle Neutron Scattering measurements indicate that the building block of the liquid-crystalline phases is a chiral rod, composed of a stacked array of Hoogsteen-bonded guanosine tetramers. The concentration at which the cholesteric,phase appears increases with the oligomerisation degree, a pattern that seems to be related to the change of the ratio of negative charge/guanine units along the series.