Synthesis of Heteropolyoxometalate-Pillared Mg/Al, Mg/Ga, and Zn/Al Layered Double Hydroxides via LDH-Hydroxide Precursors.

We report the synthesis of acidic (Zn/Al-POM) and basic (Mg/Al-POM and Mg/Ga-POM) materials by a general route previously demonstrated only for basic LDH materials. In each case, H(2)W(12)O(40)(6)(-) or PW(11)O(39)(7)(-) pillared materials with significant BET surface areas were obtained. Stringent control over the M(2+):M(3+) ratio in the layers of the POM-pillared products was not possible, and loss of M(2+) was found to be the most severe for the Mg/Ga and Zn/Al materials. Infrared analysis indicated that complete exchange of adipate anions in the precursor material by POM anions was achieved except for the Zn/Al analogues. Removal of the residual adipate anions after washing the product with a dilute base solution was possible, but a concomitant decrease in surface area could not be avoided.