COMPARATIVE-STUDY OF THE HYDRATION SYSTEMS FORMED DURING INTERACTIONSOF HYDROGEN PHOSPHATE DIANIONS WITH PUTRESCINE, NOR-PUTRESCINE AND MAGNESIUM DICATIONS

A comparative study of hydration systems, formed as a result of the in teraction between hydrogen phosphate dianions and three naturally occu rring cations (putrescine (Put), its nor-homologue (nPut) and magnesiu m), is presented. On the basis of X-ray data and IR, NMR and calorimet ric measurements, we have determined how the structure and physicochem ical properties of the cations influence the system of phosphate resid ue hydration. Our study demonstrates that the stability of the hydrati on systems depends not only on the character of the bonds used by wate r to link with other salt components (coordinate or hydrogen bonds), b ut also on the location of the water molecules in the crystal lattice. In addition, contrary to magnesium salts, the dehydration of diamine (Put and nPut) hydrogen phosphates is reversible. Both dehydration and rehydration processes take place in the solid state. During rehydrati on, the crystalline anhydrous salt absorbs water molecules from the at mosphere, This leads to the reconstruction of the hydrated salt struct ure; this means that the salt which is the product of rehydration is i dentical with that obtained by crystallization from water solution. (C ) 1997 Elsevier Science B.V.