Crystal growth and hydration effects in morpholinium 4-hydroxybenzoate (M4HB)

The growth of a large single crystal of the new non-linear optical salt mor pholinium 4-hydroxybenzoate (M4HB) is reported. Growth of crystals from dry ethanol, or 2-propanol, yields the non-centrosymmetric form belonging to s pace group Cc (No. 9). This is the desirable structure since it exhibits se cond harmonic generation (SHG). Attempts to improve solubility by using a w ater:ethanol co-solvent result in the total loss of SHG activity due to the formation of morpholinium 4-hydroxybenzoate dihydrate in the centrosymmetr ic space group P2(1)/c(No. 14). Crown Copyright (C) 2001 Published by Elsev ier Science B.V. All rights reserved.