A family of lanthanide-containing molecular open frameworks with high porosity: [Ln(abdc)(Habdc), nH_2O]_∞ with Ln = La-Eu and 8 ≤ n ≤ 11

摘要

Reactions in water between the di-sodium salt of amino terepthalic acid (C_8H_3NO_4Na_2) and a lanthanide chloride lead to a family of 3D-coordination polymers with general chemical formula [Ln(C_8H_3NO_4)(C_8H _4NO_4), O]∞ where Ln = La-Eu (except Pm) and 8 ≤ n ≤ 11. All these compounds are isostructural. High quality single crystals of [Ln(C_8H_3NO_4)(C_8H _4NO_4), nH_2O]∞ with Ln = La-Sm (except Pm) and 8 ≤ n ≤ 11 have been obtained by slow diffusion in agar-agar gels. The crystal structure has been solved for the Nd-containing compound. This compound crystallizes in the cubic system, space group Ia-3 (no. 206) with a = 26.8056(5) ?. The crystal structure can be described as the juxtaposition of large channels with square cross-section. The channels are filled by highly disordered crystallization water molecules. The dehydration of the compounds by freeze-drying is possible and most of the crystallization water molecules can be removed without destruction of the molecular skeleton. The partially dehydrated compounds have general chemical formula [Ln(abdc)(Habdc), _2H_2O]∞ with Ln = La-Eu except Pm. The porosity of the Nd-containing compound has been estimated by computational methods to 2170 m~2 g~(-1). This dehydrated compound reversibly binds water when exposed to wet atmosphere restoring the initial hydrated phase.