Structure diversities of ten entangled coordination polymers assembled from reactions of Co(II) or Ni(II) salts with 5-(pyridin-4-yl)isophthalic acid in the absence or presence of auxiliary N-donor ligands

The self-assembly of transition metal salts with 5-(pyridin-4-yl) isophthalate ligand and N-donor ligands affords a series of entangled coordination frameworks based on different metal cluster cores, namely, [Co(L)(H2O)(2)]center dot H2O (1), [Ni(L)(H2O)]center dot H2O (2), [Co-4(L)(2)(SO4)(H2O)(5)(OH)(2)]center dot 15.5H(2)O(3), [Co-2(L)(2)(2,2'-bpy)(2)](2)center dot H2O (4), [Co-2(L)(2)(phen)(2)] (5), [Ni(L) (en)(H2O)(2)](2)center dot 2H(2)O(6), [Ni(L)(dap)]center dot 3H(2)O (7), [Co(L)(bph)(H2O)(2)]center dot H2O (8), [Co(L)(bbm)(0.5)]center dot 4H(2)O (9), [Co(L)(bimb)(0.5)](4)center dot 13H(2)O (10) [L = 5-(pyridin-4-yl) isophthalic acid; 2,2'-bpy = 2,2'-bipyridine; phen = 1,10-phenanthroline; en = ethane-1,2diamine; dap = propane-1,2-diamine; bph = (1E, 2E)-1,2-bis(pyridin-4-ylmethylene) hydrazine; bbm = 1,4-di(1H-imidazol1- yl) benzene; bimb = 4,4'-di(1H-imidazol-1-yl)-1,1'-biphenyl]. Their structures were characterized by elemental analysis, IR spectra and TG analyses and further determined by single-crystal X-ray diffraction analysis. The auxiliary ligands play important roles in the formation of various entangled networks. 1-2 show a 2D layer network and its layers are held together by pi-pi stacking interactions and other unconventional interactions. Complex 3 displays an unusual Co-4 cluster core which is linked by , eta(1), eta(1), eta(1) , mu(3)-SO(4)(2-)and mu(3)-OH ions. Upon adding chelating ligands, 4-5 show 2D -> 2D entangled polymers with polycatenated and polyrotaxane features based on 4,4-sql layers. 6-7 still exhibit layer strutures, although they have chelating ligands, which may be due to the absence of pi-pi stacking interactions. 8-10 present pillar-layer structures which are supported by different lengths of pillars. Three-fold interpenetration with polycatenated features are observed in 8-9. 10 exhibits a 4-fold interpenetrating 3D structure with large channel running through its net.