Reversible Water Ad-/Desorption Behavior of a 3D Polycatenation Network, [Zn(bpp)(BDC)]·1.5(H₂O), Constructed by 2D Undulated Layered MOF

Abstract

A three-dimensional (3D) polycatenation supramolecular network with chemical formulas, [Zn(bpp)(BDC)]·1.5H2O (1), (bpp = 1,3-bis(4-pyridyl)propane, BDC2− = dianion of terephthalic acid), was synthesized and structurally determined. In compound 1, the coordination geometry of Zn(II) ion is distorted tetrahedral, where its 2D undulated layered framework is constructed via the bridges of Zn(II) ions with bpp and BDC2− ligands. Adjacent 2D layers are arranged in a combined parallel and interpenetrated manner to complete its 3D polycatenation supramolecular architecture. Compound 1 shows a one-step dehydration process with the weight losses of 6.1%, approximately equal to the weight percentage of losing 1.5 guest water molecules. The cyclic thermogravimetric analysis reveals that compound 1 shows reversible, sponge-like water de-/adsorption behavior during de-/rehydration processes. Compound 1 also exhibits significant water vapor hysteresis isotherm.

Keywords

• supramolecular compound
• metal–organic framework
• H bonding interaction
• π-π stacking interaction