Separation of phenylenediamine isomers by using decamethylcucurbit[5]uril

Using multiple techniques, this work studied the binding behaviors of decamethylcucurbit[5]uril (Me10Q[5]) with o-, m- and p-phenylenediamine (PDA) isomers both in the solid state and in aqueous solution. Experimental data indicate that Me10Q[5] forms exclusion complexes with the three PDA isomers, but their binding affinities are significantly different. Their different binding interactions provided an effective method to separate the three PDA isomers by using Me10Q[5]: when p-phenylenediamine interacts with Me10Q[5] in acidic medium (3.0 mol L−1 HCl), they precipitated immediately and quantitatively; m-phenylenediamine can continuously form microcrystals with Me10Q[5] after a period of time; however, o-phenylenediamine cannot form solid substances with Me10Q[5] under the same conditions.