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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 2 -trans-1,2-bis(pyridin-3-yl)ethylene-κ 2 N:N']bis(μ 4 -4,4'-oxydibenzoato-κ 6 O:O,O':O'':O'',O''')dicadmium(II)], [Cd 2 (C 14 H 8 O 5 ) 2 (C 12 H 10 N 2 )] n or [Cd 2 (4,4'-OBB) 2 (3,3'-BPE)] n , has been synthesized by the the self-assembly of Cd(NO 3 ) 2 ·4H 2 O, 4,4'-oxydibenzoic acid (4,4'-H 2 OBB) 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 II centre is coordinated by six carboxylate O atoms from four different 4,4'-OBB 2- ligands and by one pyridyl N atom form a 3,3'-BPE ligand. Adjacent crystallographically equivalent Cd II ions are bridged by 4,4'-OBB 2- ligands, affording a two-dimensional [Cd(4,4'-OBB)] n net extending in the ac plane. Neighbouring [Cd(4,4'-OBB)] n nets are interlinked by 3,3'-BPE along the b axis to form a three-dimensional (3D) [Cd 2 (4,4'-OBB) 2 (3,3'-BPE)] n coordination network. In the network, each Cd II centre is linked by four different 4,4'-OBB 2- ligands and one 3,3'-BPE ligand. Meanwhile, each 4,4'-OBB 2- ligand connects four separate Cd II ions. Therefore, if the 4,4'-OBB 2- ligands and Cd II 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 (4 4 6 2 )(4 4 6 6 ) TCS topology (Pearson, 1985; Blake et al., 2011). The thermal stability and photoluminescence properties of the title compound have also been investigated.

In recent years, coordination polymers constructed from multidentate carboxylate and pyridyl ligands have attracted much attention because these ligands can adopt a rich variety of coordination modes and thus lead to the formation of crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[μ 2 -1,6-bis(pyridin-3-yl)-1,3,5-hexatriene-κ 2 N:N'](μ 3 -naphthalene-1,4-dicarboxylato-κ 4 O 1 ,O 1' :O 4 :O 4' )zinc(II)], [Zn(C 12 H 6 O 4 )(C 16 H 14 N 2 )] n , has been prepared by the self-assembly of Zn(NO 3 ) 2 ·6H 2 O, naphthalene-1,4-dicarboxylic acid (1,4-H 2 ndc) and 1,6-bis(pyridin-3-yl)-1,3,5-hexatriene (3,3'-bphte) under hydrothermal conditions. The title compound has been structurally characterized by IR spectroscopy, elemental analysis, powder X-ray diffraction and single-crystal X-ray diffraction analysis. Each Zn II ion is six-coordinated by four O atoms from three 1,4-ndc 2- ligands and by two N atoms from two 3,3'-bphte ligands, forming a distorted octahedral ZnO 4 N 2 coordination geometry. Pairs of Zn II ions are linked by 1,4-ndc 2- ligands, leading to the formation of a two-dimensional square lattice (sql) layer extending in the ab plane. In the crystal, adjacent layers are further connected by 3,3'-bphte bridges, generating a three-dimensional architecture. From a topological viewpoint, if each dinuclear zinc unit is considered as a 6-connected node and the 1,4-ndc 2- and 3,3'-bphte ligands are regarded as linkers, the structure can be simplified as a unique three-dimensional 6-connected framework with the point symbol 4 4 6 10 8. The thermal stability and solid-state photoluminescence properties have also been investigated.

In recent years, the design and construction of crystalline coordination complexes by the assembly of metal ions with multitopic ligands have attracted considerable attention because of the unique architectures and potential applications of these compounds. Two new coordination polymers, namely poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ 2 N:N'](μ 3 -5-methylisophthalato-κ 4 O 1 ,O 1' :O 3 :O 3' )cadmium(II)], [Cd(C 9 H 6 O 4 )(C 12 H 11 N 3 )] n or [Cd(5-Me-ip)(2-NH 2 -3,4-bpe)] n , (I), and poly[[μ-trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene-κ 2 N:N'](μ 2 -5-hydroxyisophthalato-κ 4 O 1 ,O 1' :O 3 :O 5 )cadmium(II)], [Cd(C 8 H 4 O 5 )(C 12 H 11 N 3 )] n or [Cd(5-HO-ip)(2-NH 2 -3,4-bpe)] n , (II), have been prepared hydrothermally by the self-assembly of Cd(NO 3 ) 2 ·4H 2 O and trans-1-(2-aminopyridin-3-yl)-2-(pyridin-4-yl)ethene (2-NH 2 -3,4-bpe) with two similar dicarboxylic acids, i.e. 5-methylisophthalic acid (5-Me-H 2 ip) and 5-hydroxyisophthalic acid (5-HO-H 2 ip). The coordination network of (I) is a two-dimensional sql net parallel to (101). Adjacent sql nets are further linked to form a three-dimensional supramolecular framework via hydrogen-bonding interactions. Compound (II) is a two-dimensional (3,5)-connected coordination network parallel to (010) with the point symbol (6 3 )(5 5 6 4 7). As the other reactants and reaction conditions are the same, the structural differences between (I) and (II) are undoubtedly determined by the different substituent groups in the 5-position of isophthalic acid. Both (I) and (II) exhibit good thermal stabilities and photoluminescence properties.

The Cd II three-dimensional coordination poly[[[μ 4 -1,4-bis(1,2,4-triazol-1-yl)but-2-ene]bis(μ 3 -5-carboxybenzene-1,3-dicarboxylato)dicadmium(II)] dihydrate], {[Cd 2 (C 9 H 4 O 6 ) 2 (C 8 H 10 N 6 )]·2H 2 O} n , (I), has been synthesized by the hydrothermal reaction of Cd(NO 3 ) 2 ·4H 2 O, benzene-1,3,5-tricarboxylic acid (1,3,5-H 3 BTC) and 1,4-bis(1,2,4-triazol-1-yl)but-2-ene (1,4-btbe). The IR spectrum suggests the presence of protonated carboxylic acid, deprotonated carboxylate and triazolyl groups. The purity of the bulk sample was confirmed by elemental analysis and X-ray powder diffraction. Single-crystal X-ray diffraction analysis reveals that the Cd II ions adopt a five-coordinated distorted trigonal-bipyramidal geometry, coordinated by three O atoms from three different 1,3,5-HBTC 2- ligands and two N atoms from two different 1,4-btbe ligands; the latter are situated on centres of inversion. The Cd II centres are bridged by 1,3,5-HBTC 2- and 1,4-btbe ligands into an overall three-dimensional framework. When the Cd II centres and the tetradentate 1,4-btbe ligands are regarded as nodes, the three-dimensional topology can be simplified as a binodal 4,6-connected network. Thermogravimetric analysis confirms the presence of lattice water in (I). Photoluminescence studies imply that the emission of (I) may be ascribed to intraligand fluorescence.