A unique 3-D 3d–4f heterometallic coordination polymer with double betaine ligand: Crystal structure and magnetic properties

A unique 3d–4f heterometallic coordination polymer with double betaine ligand, [GdCu2(L1)4(H2O)2](ClO4)7 · 6H2O 1 (L1 = 1,3-bis(pyridinio-4-carboxylato)-propane), has been synthesized by the self-assembly of Cu(ClO4)2 and Gd(ClO4)3 with flexible double betaine ligand L1, and structurally characterized by single-crystal X-ray diffraction. The structure of 1 can be regarded as being constructed by the cross-linkage of the vertex-sharing double-paddle-wheel-like trinuclear [Cu(COO)4Gd(COO)4Cu] units and L1 ligands to produce an interesting cationic NaCl-like framework with a 41263 topology, which is counter-balanced by the perchlorate ions located in the interspaces of the framework. Variable-temperature magnetic susceptibilities of 1 show there is no magnetic interaction between the Cu(II) and Gd(III) ions.