Synthesis, structure, and characterization of three series of 3d-4f metal-organic frameworks based on rod-shaped and (6,3)-sheet metal carboxylate substructures

Three series of porous lanthanide metal-organic coordination polymers, namely [Cu(bpy)Ln(3)(ip)(5)-(Hip)(H2O)] [Ln = Er (1a), Y (1b), Eu (1c); bpy = 2,2'-bipyridine, H(2)ip = isophthalic acid], [Cu-3(bpy)(2)Ln(2)(ip)(6)-(H2O)(5)] [Ln = Yb (2a), Gd (2b), Tb (2c)], and [Cu,Ln,(ip),] [Ln = Eu (3a), Gd (3b)] have been synthesized hydrothermally by the reaction of the combination of 3d-4f metal centers and N-/O-donor ligands. X-ray diffraction analyses reveal that polymers 1a-c and 2a-c, as well as 3a,b are isomorphous in structure. Polymers 1a-c consist of 3D alpha-Po networks based on a inorganic rod-shaped secondary building units (SBUs) of {Er6Cu2(bipy)(2)(O-2)(11)} which are 27.03 angstrom in length. Polymers 2a-c also contain 3D alpha-Po networks, constructed from shorter (14.79 angstrom) but similarly rod-shaped SBUs of {Yb2Cu3-(bpy)(2)(O2C)(12)}. The structure also contains hydrogen-bonded (H2O)(6) chains which can be reversibly dehydrated/rehydrated. Polymers 3a,b contain metal carboxylate substructures which have 2D (6,3) topologies; these layers are bridged by the ip(2-) ligands to give an overall 3D network which contains two sorts of cavities. This series of Ln-Cu coordination polymers are further characterized by antiferromagnetic behavior.