Zinc(II) nitrite coordination polymers based on rigid and flexible organic nitrogen donor ligands

Six zinc(II)-organic coordination polymers, [Zn(mu-4,4'-bipy)(NO2)(2)] (n) (1), [Zn(mu-bpa)(NO2)(2)](n) (2), [Zn(mu-bpe)(NO2)(2)](n) (3), [Zn(mu-bpp)(NO2)(2)](n) (4), [Zn(mu-4-bpdb)(NO2)(2)](n) (5) and {[Zn-2(mu-3-bpdb)(2)(NO2)(4)]center dot H2O}(n) (6) {4,4'-bipy = 4,4'-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethene and bpp = 1,3-di(4-pyridyl)propane, 4-bpdb = 1,4-bis(4-pyridyl)2,3-diaza-1,3-butadiene and 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene}, were prepared from reactions of zinc(II) nitrite with six rigid and flexible organic nitrogen donor-based ligands. All these compounds were structurally characterized by X-ray single-crystal diffraction and the structural studies of compounds 1-6 show the compounds are 1-D polymers with distorted octahedral ZnN2O4 coordination environments. The thermal stabilities of compounds 1-6 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Solution state luminescent spectra of compounds 1, 2 and 4 indicate intense fluorescent emissions at ca. 347, 360 and 370 nm, respectively.