1D helix, 2D brick-wall and herringbone, and 3D interpenetration d10 metal-organic framework structures assembled from pyridine-2,6-dicarboxylic acid N-oxide

Five novel interesting d(10) metal coordination polymers, [Zn(PDCO)(H2O)(2)](n), (PDCO = pyridine-2,6-dicarboxylic acid N-oxide) (1), [Zn-2(PDCO)(2)(4,4'-bpy)(2)(H2O)2 center dot 3H(2)O](n) (bpy = bipyridine) (2), [Zn(PDCO)(bix)](n) (bix = 1,4-bis(imidazol-1 -ylmethyl)benzene) (3), [Zn(PDCO)(bbi)center dot 0.5H(2)O](n) (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (4), and [Cd(PDCO)(bix)1.5 center dot 1.5H(2)O](n) (5), have been synthesized under hydrothermal conditions and structurally characterized. Polymer 1 possesses a one-dimensional (1 D) helical chainlike structure with 41 helices running along the c-axis with a pitch of 10.090 angstrom. Polymer 2 has an infinite chiral two-dimensional (2D) brick-wall-like layer structure in the ac plane built from achiral components, while both 3 and 4 exhibit an infinite 2D herringbone architecture, respectively extended in the ac and ab plane. Polymer 5 features a most remarkable and unique three-dimensional (3D) porous framework with 2-fold interpenetration related by symmetry, which contains channels in the b and c directions, both distributed in a rectangular grid fashion. Compounds 1-5, with systematic variation in dimensionality from 1D to 2D to 3D, are the first examples of d(10) metal coordination polymers into which pyridinedicarboxylic acid N-oxide has been introduced. In addition, polymers 1, 4, and 5 display strong blue fluorescent emissions in the solid state. Polymer 3 exhibits a strong SHG response, estimated to be approximately 0.9 times that of urea.