Selective amine intercalation behavior of [Cd(1,5-nds)(H2O)2]

Abstract

[Cd(1,5-nds)(H₂O)₂] (1,5-nds = 1,5-naphthalenedisulfonate) is a layered metal sulfonate. It can selectively intercalate ammonia and amines quantitatively without dehydration and form stable adducts, via solid–vapor reaction at room temperature. The resulting adducts were characterized by elemental analyses, IR, TGA-IR and PXRD. The results show that the title compound can absorb up to 4 molar amounts of C₂H₅NH₂ and C₃H₇NH₂. TGA–IR analyses show that amines were intercalated via interactions of different nature. Of these, 2 molar amounts of amine molecules were intercalated via coordinative bonds by replacing the coordinated water molecules, while the extra molar amounts of amines were anchored by weak but steady intermolecular interactions, which is unprecedented in metal phosphate or sulfonate analogs. Guest-driven solid-to-solid phase transformations were also observed. The intercalation process is reversible, selective and preferential, indicating that the title compound could be designed as an amine-sensitive material.