From discrete molecules to one-dimensional coordination polymers containing Mn(II), Zn(II) or Cd(II) pyridine-2-aldoxime building unit

The syntheses, spectroscopic characterization and crystal structures for eight coordination compounds [Cd(HCO2)(2)(pya)(2)] (1), {[M(bdc)(pya)]center dot 1.5DMF}(n) (M = Mn(II), Zn(II), Cd(II) (2-4), [Zn(SO4)(Pya)(H2O)(3)] (H2O) (5), [(ZnSO4)(2)(pya)(4)] DMF center dot 2H(2)O (6), [Zn(SO4)(pya(H2O)(2)](n) (7), and [Cd(SO4)(pya)(H2O)](n) (8) [pya = pyridine-2-aldoxime, bdc = 1,4-benzenedicarboxylate, DMF = N,N\u27-dimethylformamide] are reported. Compounds 1-4 and 6 contain two, while 5, 7, and 8 contain one neutral pya ligand coordinated in a chelate mode to the metal center through the N-pyridyl and N-oxime atoms. The dicarboxylic bdc anions provide an access to 1D polymeric arrays in 2-4. The hybrid sulfates including discrete mononuclear (5), binuclear (6), and 1D polymeric (7, 8) coordination arrays were obtained due to different binding modes of coordinated sulfate anion. While solid state fluorescence of new polymeric compounds 2-4 is similar to that of the H(2)bdc ligand, a rare dual emission is observed for compounds 7 and 8. According to TD-DFT calculations, emission at 400 and 650 nm originates from n pi* and pi pi* states of the pya ligand respectively. (C) 2013 Elsevier Ltd. All rights reserved