Acetonitrile vapour inclusion in single-crystal adsorbents [MII2(bza)4(pyz)]n (MII = Rh, Cu)

Abstract

We studied acetonitrile vapour inclusion behaviour for flexible single-crystal hosts [M2(bza)4(pyz)]n (M = Rh2+ (1), Cu2+ (2); bza = benzoate, pyz = pyrazine) by adsorption experiments and single-crystal X-ray analysis of the inclusion state. Independent of metal ions, the flexible single-crystal hosts smoothly and reversibly adsorbed acetonitrile molecules up to ca. 2 molecules per M2 unit through an adsorption leap, which indicated the change of crystal phase transformations. The results showed that the acetonitrile inclusion crystals were isostructural with including acetonitrile molecules aligned in a head-to-tail fashion in a 1D channel. The acetonitrile molecules were densely included in the channel compared with those in an acetonitrile crystal, indicating that the flexible hosts provide a suitable field for observing the acetonitrile inclusion structure. While the inclusion crystal structure was independent of metal ions, the adsorption behaviour has a difference in the critical pressure and amount of the adsorption leap, depending on the metal ions in the host skeletons.