Preparation and characterization of two new 2-D double helical networks based on 1,3-bis(4-pyridyl)propane

Two new coordination polymers, [Zn(p-CH3C6H5SO3)(2)(bpp)(2)](n) (1) and [Cu-2(SCN)(2)(NO3)(2)(bpp)(4)](n) (2) (bpp = 1,3-bis(4-pyridyl) propane), have been synthesized and characterized. Single crystal X-ray diffraction analysis reveals that 1 and 2 exhibit 2-D layer networks composed of alternate left-handed and right-handed bpp-containing helical chains by sharing Zn(II) in 1 and Cu(II) in 2. Compound 1 exhibits a 2-D undulated double-helical network, while 2 shows a two-fold interpenetrated 2-D double-helical network. p-Toluene sulfonates select Zn2+ rather than Cu2+ to coordinate, while both SCN- and NO3- select Cu2+ rather than Zn2+, indicating that the specific organic ligand shows preference/selectivity when different types of metal ions are concurrently present. As a consequence, anionic ligands of different structures impose remarkable influence on the structures of the resultant compounds. Compound 1 shows a broad peak at 415 nm in its emission spectrum, indicating an efficient energy transfer.