Syntheses, crystal structures and properties of two unusual pillared-layer 3d–4f Ln–Cu heterometallic coordination polymers

Two unusual pillared-layer 3d–4f Ln–Cu heterometallic coordination polymers, {[Ln2Cu5Br4(IN)7(H2O)6]·H2O}n (Ln=Eu (1) and Gd (2), HIN=isonicotinic acid), have been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. The structure determination reveals that 1 and 2 are isostructural and feature a novel three-dimensional pillared-layer hetrometallic structure built upon the linkages of one-dimensional (1D) linear Ln–carboxylate chains, zero-dimensional (0D) Ln–carboxylate Ln2(IN)8 dimers, rare 1D zigzag [Cu5Br4]n inorganic chains and IN− pillars. In both 3D structures, there are Ln–carboxylate layers resulted from the connections of 1D Ln–carboxylate chains and 0D Ln2(IN)8 dimers through O–H⋯O hydrogen bondings. The luminescent properties of 1 have been investigated. The magnetic properties of 1 and 2 have also been studied.