Effect of pressure on slit channels in guaninine sodium salt hydrate: a link to nucleobase intermolecular interactions
The crystal structure of a hydrate of the sodium salt of guanine (2Na+∙C5H3N5O2-∙7H2O) was studied using single-crystal X-ray diffraction and Raman spectroscopy up to ~2.5 GPa, after what the structure distorted and the diffraction pattern from single crystal fragments disappeared along with appearance of powder ring fragments. On increasing pressure the distances between the double walls of the slit channels formed by the guaninine moieties became more equal, the longer one shortening and the shorter one expanding. The topology of the Na+ - water intra-channel infinite clusters was preserved, although these clusters got distorted on compression. Among several types of the OH…O and OH…N hydrogen bonds, only two practically did not change with increasing pressure, namely the bonds connecting the guaninine walls with the intra-channel water molecules. Possible relation to the interactions in the ion channels with the walls formed by the guaninine species in biological systems is discussed.