(2,2′-bipy)[In2(OH)2(H2O)](SO4)2: The first indium sulfate with a layer structure

The first indium sulfate coordination complex, (2,2′-bipy)[In2(OH)2(H2O)](SO4)2 (2,2′-bipy=2,2′-bipyridyl) was hydrothermally synthesized and characterized by single-crystal X-ray diffraction (XRD), the powder XRD, elemental analysis, inductively coupled plasma (ICP) analysis, thermogravimetric analysis (TGA), IR spectroscopy and fluorescent spectroscopy. It is noteworthy that this compound exhibits a novel two-dimensional layer structure, which is built up from two distinct motifs, a butlerite-type chain and a single 4-ring (S4R) unit. The adjacent layers are stably packed together and extended into three-dimensional supramolecular arrays via π–π stacking interactions of the 2,2′-bipy ligands. Additionally, this compound shows strong fluorescent property at room temperature, which may be assigned to ligand-centered π*–π transitions.