A nuclear magnetic relaxation study of bound water in solutions of disodium cromoglycate.

The amount of water bound to disodium cromoglycate (DSCG) in frozen aqueous solutions was determined from the amplitude of the n.m.r. free induction decay. The hydration number was found to be 15 molecules H2O/molecule DSCG of which 6 H2O molecules were less strongly bound than the rest. Proton T1 and T2 relaxation times in non-frozen solutions implied a values of 10(-8) s for the correlation time of the bound water at 291 K. This is consistent with the mobility of DSCG molecules in a smectic mesophase.