Distinct Hydrogen-bonded M~II(H_2O)_8 Clusters as Second Building Units for 1-D,2-D and 3-D Supramolecular Architectures(M=Cobalt and Nickel)

Two mononuclear metal-organic complexes,[Co(Hmpdc)2(H2O)4]·4H2O 1 and [Ni(Hfmpdc)2(H2O)4]·6H2O 2,were prepared from 2,6-dimethylpyridine-3,5-dicarboxylic acid(H2mpdc) and 4-furyl-2,6-dimethylpyridine-3,5-dicarboxylic acid(H2fmpdc) with M(NO3)2 salts,respectively,and characterized by single-crystal X-ray diffraction,elemental analyses,IR spectroscopy,and photoluminescent measurement.Complex 1 crystallizes in triclinic,space group P1 with a = 7.634(5),b = 8.695(5),c = 10.757(6) ,α = 69.647(7),β = 69.957(8),γ = 83.733(7)o,V = 628.9(7) 3,Dc = 1.561 g/cm3,μ(MoKα) = 0.763 mm-1,F(000) = 309,Z = 1,the final R = 0.0553 and wR = 0.1469 for 1909 observed reflections(I 2σ(I)).Complex 2 crystallizes in monoclinic,space group P21/n with a = 9.5934(16),b = 12.422(2),c = 14.826(3) ,β = 105.201(2)o,V = 1705.0(5) 3,Dc = 1.479 g/cm3,μ(MoKα) = 0.655 mm-1,F(000) = 796,Z = 2,the final R = 0.0351 and wR = 0.0889 for 2387 observed reflections(I 2σ(I)).In the crystal structures of 1 and 2,diverse supramolecular motifs from 1-D chains/ladders to 3-D networks are constructed from corresponding distinct [MII(H2O)8] ion clusters as the second building units,respectively.The solid state compounds of 1 and 2 show similar photoluminescent spectra with emission maximum at ca.466 nm at room temperature.