Construction of a series of metal-organic frameworks based on novel flexible ligand 4-carboxy-1-(3,5-dicarboxy-benzyl)-pyridinium chloride and selective d-block metal ions: crystal structures and photoluminescence

We report here seven metal-organic complexes, {[Zn.L)(H2O)(3)]center dot H2O}(n) (1), {[Zn(L)]center dot H2O}(n) (2), {[Zn(L)(4,4'-bpy)(0.5)]center dot 2H(2)O}(n) (3), {[Cd(L)]center dot H2O}(n) (4), {[Cd(L)(1,4-bbi)(H2O)]center dot H2O}(n) (5), {[Cu(L)(4,4'-bpy)(H2O)]center dot 5H(2)O}(n) (6), and {[Cu(L)(bpe)]center dot 6H(2)O}(n) (7), prepared by a hydrothermal method (H3L+Cl- = 4-carboxy-1-(3,5-dicarboxybenzyl)- pyridinium chloride, bpy = 4,4'-bipyridine, bbi = 1,1'-(1,4-butanediyl) bis(imidazole), bpe = 1,2-di(pyridine-4-yl)-ethylene). These complexes show different structures including helical chains, novel pillared layers, 3D 3-fold interpenetrating frameworks, interesting 2D -> 3D interdigitated architectures and Z-shaped double layer structures, and so on. The diversity of the structures of these complexes proves that the newly synthesized ligand H3L+Cl- is an excellent candidate for the construction of MOFs. Additionally, the thermal stabilities and photoluminescence properties are also investigated.