Solvent- and temperature-driven synthesis of three Cd(II) coordination polymers based on 3,3′-azodibenzoic acid ligand: Crystal structures and luminescent properties

Solvothermal reactions of Cd(OAc)(2)center dot 2H(2)O with 3,3'-azodibenzoic acid (H2L) in N,N'-dimethylformamide (DMF) or DMF/MeOH at 100 degrees C or 120 degrees C gave rise to three cadmium(II) coordination polymers {[CdL(DMF)(2)]center dot 0.5DMF}(n) (1), [CdL(DMF)(MeOH)](n) (2) and {[Cd3L3(DMF)(4)]center dot 0.5DMF}(n) (3). Complexes 1-3 were characterized by elemental analysis, IR, powder X-ray diffraction and single-crystal X-ray diffraction. In 1-3, dinuclear [Cd2L4(DMF)(4)] (1) or [Cd2L4(DMF)(2)(MeOH)(2)] (2) unit and trinuclear [Cd3L6(DMF)(4)] (3) unit acts as a four-connecting node to link its equivalent ones via sharing L ligands to form 2D layers, which are further connected through the C-H center dot center dot center dot pi (1) or hydrogen-bonding interactions (2-3) to afford 3D networks with the 4(12)6(3) topology. The network of 1 allows other one to be penetrated for the formation of twofold interpenetrating pcu net. The formation of 1-3 provided an interesting insight into solvent and temperature effects on the construction of coordination polymers under solvothermal conditions. In addition, the photoluminescent properties of 1-3 in solid state at ambient temperature were also investigated. (C) 2012 Elsevier B. V. All rights reserved.