THE GALLOPHOSPHATE MOLECULAR-SIEVE CLOVERITE AS A HOST FOR LIQUID-CRYSTALS

The gallophosphate cloverite has been investigated because of its appl icability to act as a host for larger molecules. 4-n-pentyl-4'-cyanobi phenyl (5CB) and 4-n-octyl-4'-cyanobiphenyl (8CB) liquid crystals were used as guest molecules. The results show that the adsorption of liqu id crystals from the gas phase proceeds without destruction of the clo verite structure. The typical phase properties of the liquid crystals remain unchanged after adsorption on cloverite: however, they appear w ith lower intensity in the DSC curve. A new smectic phase seems to be formed inside the cloverite pore system. FTIR measurements show the in teraction of 5CB with the Lewis and Bronsted acid sites of cloverite. Desorption of liquid crystals out of the pore system proceeds slowly u nder liberation of the POH groups of the lattice. In summary, the resu lts show that the gallophosphate cloverite is a suitable host for larg e molecules. (C) 1998 Elsevier Science B.V. All rights reserved.