Syntheses of fluorescent thiocyanate supramolecular compounds with unusual two-dimensional structures

Three novel thiocyanate supramolecular compounds have been synthesized and characterized by X-ray diffraction and fluorescent spectra. Compound [pipH]2[Co(NCS)4] (pip=piperazine) 1 possesses a two-dimensional layer connected by the combination of N–H⋯N hydrogen bonds and weak S⋯S contacts. Under the same conditions, using nickel salt instead of cobalt salt as a starting material, we obtained a different two-dimensional supramolecular layer [pipH]2[Ni(NCS)4] 2 connected by unusual N–H⋯S hydrogen bonds and weak S⋯S contacts. In order to observe the influence of the dimension of ligand on the self-assembly structure, dabco was used for substituting pip, and compound [dabcoH]2[Ni(NCS)4] (dabco=1,4-Diazabicyclo[2.2.2] octane) 3 was gained, which constructed two-dimensional, highly wavy network with hourglass-shaped cavities only through N–H⋯S hydrogen bonds.