Synthesis, structure and photoluminescence properties of a three-dimensional cadmium(II) (4,5)-connected coordination network.

The assembly of coordination polymers from metal ions and organic moieties is currently attracting considerable attention in crystal engineering due to their intriguing architectures and potential applications as functional materials. A new coordination polymer, namely poly[[μ-trans-1,2-bis(pyridin-3-yl)ethylene-κN:N']bis(μ-4,4'-oxydibenzoato-κO:O,O':O'':O'',O''')dicadmium(II)], [Cd(CHO)(CHN)] or [Cd(4,4'-OBB)(3,3'-BPE)], has been synthesized by the the self-assembly of Cd(NO)·4HO, 4,4'-oxydibenzoic acid (4,4'-HOBB) and trans-1,2-bis(pyridin-3-yl)ethene (3,3'-BPE) under hydrothermal conditions. The title compound was structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each Cd centre is coordinated by six carboxylate O atoms from four different 4,4'-OBB ligands and by one pyridyl N atom form a 3,3'-BPE ligand. Adjacent crystallographically equivalent Cd ions are bridged by 4,4'-OBB ligands, affording a two-dimensional [Cd(4,4'-OBB)] net extending in the ac plane. Neighbouring [Cd(4,4'-OBB)] nets are interlinked by 3,3'-BPE along the b axis to form a three-dimensional (3D) [Cd(4,4'-OBB)(3,3'-BPE)] coordination network. In the network, each Cd centre is linked by four different 4,4'-OBB ligands and one 3,3'-BPE ligand. Meanwhile, each 4,4'-OBB ligand connects four separate Cd ions. Therefore, if the 4,4'-OBB ligands and Cd ions are considered as 4- and 5-connecting nodes, the structure of the title compound can be simplified as a 3D (4,5)-connected binodal framework with the rare (46)(46) TCS topology (Pearson, 1985; Blake et al., 2011). The thermal stability and photoluminescence properties of the title compound have also been investigated.