Selective Anion-Exchange Properties of Second-Stage Layered Double Hydroxide Heterostructures

The anion-exchange properties of second-stage [Zn 2 Cr(OH) 6 ]Cl 0.5 (succinate) 0.25 · n H 2 O (Zn 2 Cr-Succ/Cl) and [Zn 2 Cr(OH) 6 ]Cl 0.5 (tartrate) 0.25 · n H 2 O (Zn 2 Cr-Tart/Cl) materials were investigated by means of time-resolved in situ energy-dispersive X-ray diffraction (EDXRD). Selective anion-exchange reactions were observed that were a result of the segregation between organic and inorganic anions. Indeed, the reaction of Zn 2 Cr-Succ/Cl and Zn 2 Cr-Tart/Cl second-stage compounds with either fluoride or adipate anions initially occurs with preferential replacement of the hydrophilic Cl ion with F or replacement of the hydrophobic succinate or tartrate anions with adipate; this leads to the formation of new second-stage intermediates Zn 2 Cr-Succ/F and Zn 2 Cr-Tart/F or Zn 2 Cr-Adip/Cl. The formation of such heterostructures offers new perspectives for LDH intercalation chemistry, particularly in the direction of multifunctional materials.