Multiple Regulated Assembly, Crystal Structures and Magnetic Properties of Porous Coordination Polymers with Flexible Ligands

Four novel coordination polymers of Ni II and Co II with flexible ligands, namely [Ni(oba)(bpe)] n · n H 2 O ( 1 ), [Co(oba)(bpe)] n ( 2 ), [Ni 2 (oba) 2 (bpy) 2 (H 2 O) 2 ] n · n bpy ( 3 ), and [Co(oba)(bpy) 1/2 ] n ( 4 ) [H 2 oba = 4,4′‐oxybis(benzoic acid), bpe = 1,2‐bis(4‐pyridyl)ethane, bpy = 4,4′‐bipyridine] were synthesised by hydrothermal reactions and characterised by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The Ni II ions in complex 1 are linked by flexible oba and bpe ligands to form square‐grid‐like corrugated sheets. These sheets are interpenetrated with each other, resulting in the formation of a 3D porous network with lattice water molecules in the channels. The variable temperature X‐ray diffraction analysis shows that the framework is stable up to 300 °C despite the complete removal of the lattice water molecules during the heat treatment. Complex 2 can be regarded as possessing a α‐polonium‐related topology. Triple interpenetration occurs to form a nonporous structure. In complex 3 , the oba and bpy ligands link Ni II ions into 1D train‐like boxes. These boxes are entangled, with the aid of hydrogen bonds, leading to the formation of a 3D porous supramolecular architecture. Free bpy ligands reside in the channels. The Co II ions in complex 4 are linked by oba and bpy ligands to form a complicated 3D coordination polymer. The lattice water molecules in complex 1 and free bpy ligands in complex 3 can be regarded as templates that play an important role in the formation of the porous structures of complexes 1 and 3 . The magnetic properties of complexes 1 , 2 , and 4 have also been investigated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)