Two new 3-D photoluminescence metal–organic frameworks based on cubane Cu4I4 clusters as tetrahedral nodes

Two kinds of new organic bridging-type ligands 1,4-diazacycloheptane (dach) and 1,3-bis(4-piperidyl)propane (bpp) were used respectively to react with a mixture of CuI and KI under the solvothermal conditions, generating two new 3-D metal–organic frameworks [Cu4I4(dach)2] 1 and [Cu4I4(bpp)2] 2. Both are based on the cubane Cu4I4 clusters as the nodes, but are extended by the different bridging-type ligands into the different topologies. Compound 1 shows a 2-fold interpenetrated quartz-64.82 topology, whereas compound 2 shows a 5-fold interpenetrated diamond-66 topology. The solid-state emission spectra indicate that both contain the photoluminescence properties with maximum emission peaks at 581 nm for 1 and at 616 nm for 2 upon excitation, respectively.