SYNTHESIS AND PROPERTIES OF TEREPHTHALATE AND BENZOATE INTERCALATES OF MG-AL LAYERED DOUBLE HYDROXIDES POSSESSING VARYING LAYER CHARGE

The influence of layer charge on the intercalation of terephthalate an d benzoate anions in MgAl layered double hydroxides has been studied. It is found that, under the synthesis conditions used here, incorporat ion of the anion is dependent upon the Mg:Al ratio of the host sheets. pure terephthalate and benzoate intercalates are formed for a ratio o f 2 or less from both chloride and nitrate solutions. At higher values of layer charge competitive incorporation of the counteranion present in the solution (i.e., chloride or nitrate) occurs with decreased inc orporation of inorganic anions at ratio 3 or higher. Two extreme orien tations are observed for the organize anion within the gallery-either vertical (i.e., perpendicular to the layers) or horizontal. In the cas e of terephthalate a monolayer arrangement exists, whereas for benzoat e the vertical arrangement is a bilayer and the horizontal a monolayer . Whether a vertical or horizontal orientation is adopted depends upon the charge on the layers, the temperature, and the degree of hydratio n of the sample.