A new method for fast intercalation of bulk crown ether guest into LDH

Fast intercalation of macrocyclic tetraazacrown ether carboxylic acid derivative (TECA) into the interlayer of Mg/Al-layered double hydroxide (Mg/Al-LDH) via a "one-step" reaction in formamide was carried out. Compared with swelling/restoration and ion-exchange reactions, this method can markedly decrease the reaction time (even shorter than 10 min), thus give high yield of the products and well-retain the hexagonal morphology of the starting LDH. The investigation of the reaction process demonstrated that the preceding combination of TECA and formamide accelerated the swelling of LDH, and the quasi-homogeneous colloidal system promoted the facile incorporation of TECA with the LDH sheets to cause their quick restoration. The obtained staging structure may originate from the flexibility of crown ether guest and LDH host layer, and the structural transformation from homogeneous to second-staging suggests the Daumas-Hérold model rarely observed in LDH system. The simple and fast one-step method can conveniently fabricate new multifunctional hybrid materials with combined advantages of the organic/inorganic intercalates plus those of LDH host.