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

Abstract

We report here seven metal–organic complexes, {[Zn(L)(H₂O)₃]·H₂O}_n (1), {[Zn(L)]·H₂O}_n (2), {[Zn(L)(4,4′-bpy)_0.5]·2H₂O}_n (3), {[Cd(L)]·H₂O}_n (4), {[Cd(L)(1,4-bbi)(H₂O)]·H₂O}_n (5), {[Cu(L)(4,4′-bpy)(H₂O)]·5H₂O}_n (6), and {[Cu(L)(bpe)]·6H₂O}_n (7), prepared by a hydrothermal method (H₃L⁺Cl⁻ = 4-carboxy-1-(3,5-dicarboxy-benzyl)-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.