Three Novel Polymeric CoII/CuII Complexes Assembled from 5-Nitro-1,2,3-benzenetricarboxylate and 4,4'-Bipyridine: Syntheses, Crystal Structures, and Magnetic Properties

Abstract

To investigate the coordination behaviour of tricarboxylate ligands that always induced the formation of intriguing metal organic frameworks, three CoII/CuII complexes constructed with bi-/tri-nuclear secondary building units (SBUs), namely CoII3(O2N-btc)2(4,4′-bpy)3(H2O)2 (1), [CuII3(O2N-btc)2(4,4′-bpy)2(H2O)2]·2H2O(2) and [CuII5(O2N-btc)2(O2N-btcH)2(4,4′-bpy)2(μ2 -OH2)2(H2O)8]·4H2O(3) (O2N-btcH3 = 5-nitro-1,2,3-benzenetricarboxylate, 4,4′-bpy = 4,4-bipyridyl), were hydrothermally synthesized using O2N-btcH3 and 4,4′-bpy as ligands. Complexes 1 and 2 exhibit the 3D framework constructed from a binuclear [M2(COO)2] (M = CuII and CoII) unit and a mononuclear MII unit, displaying (4·6·8)2(64·82) (42·68·83·102) and (4·6·8)2(62·84) (42·62·810·12) topology, respectively. Complex 3 displays an interesting 2D ladder-layered network constructed from a trinuclear [Cu3(μ2-OH2)2] unit and a mononuclear CuII unit as the linking nodes, showing (42.6)2(46.66.83) nets. These compounds are well characterized by elemental analysis, FTIR, thermogravimetric analysis and powder X–ray diffraction. The direct current magnetic susceptibility measurements were carried out to study their magnetic properties.