Synthesis and characterization of (H2dab)2Cu8Ge4S14·2H2O: An expanded framework based on icosahedral Cu8S12 cluster

A new three-dimensional framework copper-thiogermanate, (H2dab)2Cu8Ge4S14·2H2O (1), was prepared under solvothermal condition and characterized by elemental analysis, single-crystal and powder X-ray diffraction, thermogravimetric analysis and UV–vis diffuse reflectance spectroscopy. Compound 1 crystallizes in the monoclinic space group P2(1)/c, a=11.444(4) Å, b=12.984(4) Å, c=12.455(6) Å, β=91.527(1)°, V=1850.2(3) Å3, Z=2. It contains a new three-dimensional Cu–Ge–S framework constructed from icosahedral [Cu8S12]16− clusters linked by [GeS4]4− and dimeric [Ge2S6]4− units, with diprotonated 1,4-dab (1,4-diaminobutane) and H2O molecules located in the intersecting channels. UV–vis reflectance spectroscopy reveals the band gap of compound 1 is 2.5 eV.