The ordered layered double hydroxide, [LiAl2(OH)(6)]Cl.2H(2)O exhibits shape-selective ion-exchange intercalation of dicarboxylate anions. Specific isomeric preferences can be controlled by varying the reaction temperatures. The intercalated guests can be quantitatively recovered from the host lattice with concomitant regeneration of the host offering a novel approach in separation science. To illustrate the potential of this new material in separation science, we describe the isolation of pure 1,4-benzenedicarboxylate and 2,6-naphthalenedicarboxylate from mixtures of their isomers. The neutral organic acids are both monomers in the synthesis or a range of important polyesters.