Bis(2,2′-bipyridine)-bis(μ3-phthalato)-dicopper(II) tetrahydrate as molecular sieve with zero-dimensional structure

Crystal structure of the title compound: [Cu2(bipy)2(pht)2]·4H2O (bipy = 2,2′-bipyridine, pht = dianion of phthalic acid), CuBP·4H2O, consists of dinuclear entities, which are further connected by π–π stacking interactions between bipy ligands. In this way small channels (micropores) oriented parallel to the [0 0 1] direction and containing loosely hydrogen bonded water molecules are formed. The structural changes during dehydration–rehydration have been thoroughly investigated using TG/DSC analysis, FT-IR spectroscopy, X-ray powder diffraction, optical and scanning electron microscopy, and sorption experiments. In addition, dehydration process was analyzed from the aspect of kinetics. A complete reversibility of the dehydration–rehydration CuBP·4H2O(s) ⇌ CuBP(s) + 4H2O(g) process was confirmed by all means. Therefore, CuBP·4H2O can be classified as molecular sieve with quite unexpected zero-dimensional structure.

Copper(II) complex with 2,2′-bipyridine (bipy) and dianion of phthalic acid (pht) consists of binuclear [Cu2(bipy)2(pht)2] units with water molecules located in channels parallel to the [0 0 1] direction. This flexible MOF shows a complete reversibility of dehydration and rehydration. [Cu2(bipy)2(pht)2]·4H2O is the first reported 0D molecular sieve retaining the structure upon dehydration–rehydration cycles.Figure optionsDownload as PowerPoint slide