A two‐dimensional cadmium(II) coordination polymer based on 5‐(pyridin‐4‐yl)isophthalic acid: poly[[tetraaquabis[μ3‐5‐(pyridin‐4‐yl)isophthalato]dicadmium(II)] pentahydrate]

The title Cd^II compound, {[Cd₂(C₁₃H₇NO₄)₂(H₂O)₄]·5H₂O}_n, was synthesized by the hydrothermal reaction of Cd(NO₃)₂·4H₂O and 5‐(pyridin‐4‐yl)isophthalic acid (H₂L). The asymmetric unit contains two crystallographically independent Cd^II cations, two deprotonated L²⁻ ligands, four coordinated water molecules and five isolated water molecules. One of the Cd^II cations adopts a six‐coordinate octahedral coordination geometry involving three O atoms from one bidentate chelating and one monodentate carboxylate group of two different L²⁻ ligands, one N atom of another L²⁻ ligand and two coordinated water molecules. The second Cd^II cation adopts a seven‐coordinate pentagonal–bipyramidal coordination geometry involving four O atoms from two bidentate chelating carboxylate groups of two different L²⁻ ligands, one N atom of another L²⁻ ligand and two coordinated water molecules. Each L²⁻ ligand bridges three Cd^II cations and, likewise, each Cd^II cation connects to three L²⁻ ligands, giving rise to a two‐dimensional graphite‐like 6³ layer structure. These two‐dimensional layers are further linked by O—H...O hydrogen‐bonding interactions to form a three‐dimensional supramolecular architecture. The photoluminescence properties of the title compound were also investigated.     

A novel two‐dimensional cadmium(II) complex: poly[diaquatris(μ4‐cyclohexane‐1,4‐dicarboxylato)bis[2‐(pyridin‐4‐yl)‐1H‐benzimidazole]tricadmium(II)

The title compound, [Cd₃(C₈H₁₀O₄)₃(C₁₂H₉N₃)₂(H₂O)₂]_n or [Cd₃(chdc)₃(4‐PyBIm)₂(H₂O)₂]_n, was synthesized hydrothermally from the reaction of Cd(CH₃COO)₂·2H₂O with 2‐(pyridin‐4‐yl)‐1H‐benzimidazole (4‐PyBIm) and cyclohexane‐1,4‐dicarboxylic acid (1,4‐chdcH₂). The asymmetric unit consists of one and a half Cd^II cations, one 4‐PyBIm ligand, one and a half 1,4‐chdc²⁻ ligands and one coordinated water molecule. The central Cd^II cation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4‐chdc²⁻ ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric Cd^II cations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4‐PyBIm, five O atoms from three 1,4‐chdc²⁻ ligands and one O atom from an aqua ligand. The 1,4‐chdc²⁻ ligands possess two conformations, i.e.e,e‐trans‐chdc²⁻ and e,a‐cis‐chdc²⁻. The cis‐1,4‐chdc²⁻ ligands bridge the Cd^II cations to form a trinuclear {Cd₃}‐based chain along the b axis, while the trans‐1,4‐chdc²⁻ ligands further link adjacent one‐dimensional chains to construct an interesting two‐dimensional network.     

Poly[[(μ2‐biphenyl‐2,4′‐dicarboxylato)[μ2‐1,4‐bis(imidazol‐1‐ylmethyl)benzene]cadmium(II)] 0.15‐hydrate]

The asymmetric unit of the title two‐dimensional coordination polymer, {[Cd(C₁₄H₈O₄)(C₁₄H₁₄N₄)]·0.15H₂O}_n, is composed of one Cd^II cation, one biphenyl‐2,4′‐dicarboxylate (bpdc) anion, one 1,4‐bis(imidazol‐1‐ylmethyl)benzene (bix) ligand and 0.15 solvent water molecules. The coordination environment of the Cd^II cation is defined by four carboxylate O atoms from two different bpdc anions in a chelating mode and two N atoms from two distinct bix ligands, constructing a distorted trigonal prism polyhedron. Two inversion‐related Cd^II cations are bridged together by two positionally disordered bpdc anions, forming a 22‐membered ring with a Cd...Cd distance of 9.1966 (9) Å. These rings are then further linked by two bix ligands, extending into a two‐dimensional layer along (102) with 6³ topology.     

catena‐Poly­[[di­aqua­cadmium(II)]‐μ‐5‐carboxyimidazole‐4‐carboxylato‐κ4N1,O5:O4,N3]

A new cadmium coordination polymer, [Cd(C₅H₂N₂O₄)(H₂O)₂]_n, possesses a one‐dimensional zigzag chain structure built from Cd^II centers bridged sequentially by pairs of O and N atoms of the 5‐carboxyimidazole‐4‐carboxylate ligand. The Cd^II center is in a distorted octahedral geometry, being coordinated by two O atoms from two coordinated water mol­ecules [Cd—O = 2.322 (7) and 2.364 (7) Å], and by two N atoms [Cd—N = 2.222 (6) and 2.232 (6) Å] and two carboxyl O atoms [Cd—O = 2.383 (6) and 2.414 (6) Å] from two 5‐carboxyimidazole‐4‐carboxylate ligands.     

A one‐dimensional coordination polymer based on Cd2O2 clusters: poly[aqua(μ3‐4,4′‐sulfonyldibenzoato)(3,4,7,8‐tetramethyl‐1,10‐phenanthroline‐κ2N,N′)cadmium(II)]

In the title mixed‐ligand metal–organic polymeric complex [Cd(C₁₄H₈O₆S)(C₁₆H₁₆N₂)(H₂O)]_n, the asymmetric unit contains a crystallographically unique Cd^II atom, one doubly deprotonated 4,4′‐sulfonyldibenzoic acid ligand (H₂SDBA), one 3,4,7,8‐tetramethyl‐1,10‐phenanthroline (TMPHEN) molecule and one water molecule. Each Cd^II centre is coordinated by two N atoms from the chelating TMPHEN ligand, three O atoms from monodentate carboxylate groups of three different SDBA²⁻ ligands and one O atom from a coordinated water molecule, giving a distorted CdN₂O₄ octahedral geometry. Single‐crystal X‐ray diffraction analysis reveals that the compound is a one‐dimensional double‐chain polymer containing 28‐membered rings based on Cd₂O₂ clusters, with a Cd...Cd separation of 3.6889 (4) Å. These chains are linked by O—H...O and C—H...O hydrogen bonds to form a three‐dimensional supramolecular framework. The framework is reinforced by π–π and C—O...π interactions.     

catena‐Poly[[aqua(11‐chloropyrido[2′,3′:2,3]pyrimidino[5,6‐f][1,10]phenanthroline‐κ2N4,N5)cadmium(II)]‐μ‐benzene‐1,4‐dicarboxylato‐κ3O1,O1′:O4]: an inclined interpenetrating (6,3) network

The asymmetric unit of the title compound, [Cd(C₈H₄O₄)(C₁₇H₈ClN₅)(H₂O)]_n, contains one Cd^II atom, two half benzene‐1,4‐dicarboxylate (1,4‐bdc) anions, one 11‐chloropyrido[2′,3′:2,3]pyrimidino[5,6‐f][1,10]phenanthroline (L) ligand and one coordination water molecule. The 1,4‐bdc ligands are on inversion centers at the centroids of the arene rings. The Cd^II atom is six‐coordinated by two N atoms from one L ligand, three carboxylate O atoms from two different 1,4‐bdc ligands and one water O atom in a distorted octahedral coordination sphere. Each Cd^II center is bridged by the 1,4‐bdc dianions to give a one‐dimensional chain. π–π stacking interactions between L ligands of neighboring chains extend adjacent chains into a two‐dimensional supramolecular (6,3) network. Neighboring (6,3) networks are interpenetrated in an unusual inclined mode, resulting in a three‐dimensional framework. Additionally, the water–carboxylate O—H...O hydrogen bonds observed in the network consolidate the interpenetrating nets.     

A one‐dimensional coordination polymer with a three‐dimensional supramolecular framework: catena‐poly[[[(3,4,7,8‐tetramethyl‐1,10‐phenanthroline)cadmium(II)]‐μ3‐4,4′‐sulfonyldibenzoato] trihydrate]

In the title mixed‐ligand metal–organic polymeric compound, {[Cd(C₁₄H₈O₆S)(C₁₆H₁₆N₂)]·3H₂O}_n, the asymmetric unit contains a crystallographically unique Cd^II atom, one doubly deprotonated 4,4′‐sulfonyldibenzoic acid (H₂SDBA) ligand, one 3,4,7,8‐tetramethyl‐1,10‐phenanthroline (TMPHEN) molecule and three solvent water molecules. Each Cd^II centre is six‐coordinated by two O atoms from a chelating carboxylate group of a SDBA²⁻ ligand, two O atoms from monodentate carboxylate groups of two different SDBA²⁻ ligands and two N atoms from a chelating TMPHEN ligand. There are two coordination patterns for the carboxylate groups of the SDBA²⁻ ligand, with one in a μ₁‐η¹:η¹ chelating mode and the other in a μ₂‐η¹:η¹ bis‐monodentate mode. Single‐crystal X‐ray diffraction analysis revealed that the title compound is a one‐dimensional double‐chain polymer containing 28‐membered rings based on the [Cd₂(CO₂)₂] rhomboid subunit. More interestingly, a chair‐shaped water hexamer cluster is observed in the compound.     

A one‐dimensional CdII coordination polymer: catena‐poly[cadmium(II)‐bis(μ‐6‐methylpicolinato)]

In the title compound, [Cd(C₇H₆NO₂)₂]_n, the Cd^II ion has a distorted octahedral geometry. The 6‐methylpyridine‐2‐carboxylate anions are perpendicular to one another and act as bidentate and bridging ligands. Two carboxylate O atoms bridge the Cd^II ions, forming centrosymmetric dinuclear units. These units are further connected via carboxylate O atoms into a one‐dimensional polymeric chain which extends in the [100] direction.     

A new one‐dimensional cadmium(II) coordination polymer incorporating 4‐[4‐(1H‐imidazol‐1‐yl)phenyl]pyridine and 5‐hydroxybenzene‐1,3‐dicarboxylate ligands

The design and synthesis of new organic lgands is important to the rapid development of coordination polymers (CPs). However, CPs based on asymmetric ligands are still rare, mainly because such ligands are usually expensive and more difficult to synthesize. The new asymmetric ligand 4‐[4‐(1H‐imidazol‐1‐yl)phenyl]pyridine (IPP) has been used to construct the title one‐dimensional coordination polymer, catena‐poly[[[aqua{4‐[4‐(1H‐imidazol‐1‐yl‐κN³)phenyl]pyridine}cadmium(II)]‐μ‐5‐hydroxybenzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³] monohydrate], {[Cd(C₈H₄O₅)(C₁₄H₁₁N₃)₂(H₂O)]·H₂O}_n, under hydrothermal reaction of IPP with Cd^II in the presence of 5‐hydroxyisophthalic acid (5‐OH‐H₂bdc). The Cd^II cation is coordinated by two N atoms from two distinct IPP ligands, three carboxylate O atoms from two different 5‐OH‐bdc²⁻ dianionic ligands and one water O atom in a distorted octahedral geometry. The cationic [Cd(IPP)₂]²⁺ nodes are linked by 5‐OH‐bdc²⁻ ligands to generate a one‐dimensional chain. These chains are extended into a two‐dimensional layer structure via O—H…O and O—H…N hydrogen bonds and π–π interactions.     

Poly[[aqua(4,4′‐diazenediyldibenzoato‐κ4O,O′:O′′,O′′′)cadmium(II)]: a twofold interpenetrated three‐dimensional coordination polymer of PtS topology

In the title coordination compound, [Cd(C₁₄H₈N₂O₄)(H₂O)]_n, the Cd^II cation and the coordinated water molecule lie on a twofold axis, whereas the ligand lies on an inversion center. The Cd^II center is five‐coordinated in a distorted square‐pyramidal geometry by four carboxylate O atoms from four different 4,4′‐diazenediyldibenzoate (ddb) anions and one water O atom. The three‐dimensional frameworks thus formed by the bridging ddb anions interpenetrate to generate a three‐dimensional PtS‐type network. Additionally, the coordination water molecule and the carboxylate O atom form a hydrogen‐bonding interaction, stabilizing the three‐dimensional framework structure.     

Poly[[aqua(μ7‐ethylenediaminetetraacetato)dicadmium(II)] monohydrate]

The title compound, {[Cd₂(C₁₀H₁₂N₂O₈)(H₂O)]·H₂O}_n, consists of two crystallographically independent Cd^II cations, one ethylenediaminetetraacetate (edta) tetraanion, one coordinated water molecule and one solvent water molecule. The coordination of one of the Cd atoms, Cd1, is composed of five O atoms and two N atoms from two tetraanionic edta ligands in a distorted pentagonal–bipyramidal coordination geometry. The other Cd atom, Cd2, is six‐coordinated by five carboxylate O atoms from five edta ligands and one water molecule in a distorted octahedral geometry. Two neighbouring Cd1 atoms are bridged by a pair of carboxylate O atoms to form a centrosymmetric [Cd₂(edta)₂]⁴⁻ unit located on the inversion centre, which is further extended into a two‐dimensional layered structure through Cd2—O bonds. There are hydrogen bonds between the coordinated water molecules and carboxylate O atoms within the layer. The solvent water molecules occupy the space between the layers and interact with the host layers through O—H...O and C—H...O interactions.     

A novel two‐dimensional (4,4) network based on dinuclear cadmium secondary building units: poly[(μ5‐benzene‐1,4‐diacetato)[μ2‐1,4‐bis(1,2,4‐triazol‐1‐yl)butane]cadmium(II)]

In the title mixed‐ligand metal–organic polymeric compound, [Cd(C₁₀H₈O₄)(C₈H₁₂N₆)]_n or [Cd(PBEA)(BTB)]_n [H₂PBEA is benzene‐1,4‐diacetic acid and BTB is 1,4‐bis(1,2,4‐triazol‐1‐yl)butane], the asymmetric unit contains one Cd^II ion, one BTB molecule and one PBEA²⁻ anion. The Cd^II ion is in a slightly distorted pentagonal–bipyramidal geometry, coordinated by five carboxylate O atoms from three distinct PBEA²⁻ anions and by two BTB N atoms. There are two coordination patterns for the carboxylate groups of the PBEA²⁻ ligand, one being a μ₁‐η¹:η¹ chelating mode and the other a μ₂‐η²:η¹ bridging mode, while the BTB molecule shows a trans–trans–trans conformation. The crystal structure is constructed from the secondary building unit (SBU) [Cd₂(CO₂)₄N₂O₂], in which the two metal centres are held together by two PBEA²⁻ linkers. The SBU is connected by BTB and PBEA²⁻ bridges to form a two‐dimensional grid‐like (4,4) layer with meshes of dimensions 14.69 × 11.28 Å.     

3‐(Pyridin‐4‐yl)acetylacetone: CdII and HgII compete for nitrogen coordination

3‐(Pyridin‐4‐yl)acetylacetone (HacacPy) acts as a pyridine‐type ligand towards Cd^II and Hg^II halides. With CdBr₂, the one‐dimensional polymer [Cd(μ‐Br)₂(HacacPy)Cd(μ‐Br)₂(HacacPy)₂]_∞ is obtained in which five‐ and six‐coordinated Cd^II cations alternate in the chain direction. Reaction of HacacPy with HgBr₂ results in [Hg(μ‐Br)Br(HacacPy)]_∞, a polymer in which each Hg^II centre is tetracoordinated. In both compounds, each metal(II) cation is N‐coordinated by at least one HacacPy ligand. Equimolar reaction between these Cd^II and Hg^II derivatives, either conducted in ethanol as solvent or via grinding in the solid state, leads to ligand redistribution and the formation of the well‐ordered bimetallic polymer catena‐poly[[bromidomercury(II)]‐μ‐bromido‐[aquabis[4‐hydroxy‐3‐(pyridin‐4‐yl)pent‐3‐en‐2‐one]cadmium(II)]‐di‐μ‐bromido], [CdHgBr₄(C₁₀H₁₁NO₂)₂(H₂O)]_n or [{HgBr}(μ‐Br){(HacacPy)₂Cd(H₂O)}(μ‐Br)₂]_∞. Hg^II and Cd^II cations alternate in the [100] direction. The HacacPy ligands do not bind to the Hg^II cations, which are tetracoordinated by three bridging and one terminal bromide ligand. The Cd^II centres adopt an only slightly distorted octahedral coordination. Three bromide ligands link them in a (2 + 1) pattern to neighbouring Hg^II atoms; two HacacPy ligands in a cis configuration, acting as N‐atom donors, and a terminal aqua ligand complete the coordination sphere. Classical O—H…Br hydrogen bonds stabilize the polymeric chain. O—H…O hydrogen bonds between aqua H atoms and the uncoordinated carbonyl group of an HacacPy ligand in a neighbouring strand in the c direction link the chains into layers in the (010) plane.     

A two‐dimensional cadmium(II) coordination polymer constructed from 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate and 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate ligands

Crystals of poly[[aqua[μ₃‐4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylato‐κ⁵O¹O^1′:N³,O⁴:O⁵][μ₄‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylato‐κ⁷N³,O⁴:O⁴,O^4′:O¹,O^1′:O¹]cadmium(II)] monohydrate], {[Cd₂(C₁₅H₁₄N₂O₄)(C₁₆H₁₄N₂O₆)(H₂O)]·H₂O}_n or {[Cd₂(Hcpimda)(cpima)(H₂O)]·H₂O}_n, (I), were obtained from 1‐(4‐carboxybenzyl)‐2‐propyl‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃cpimda) and cadmium(II) chloride under hydrothermal conditions. The structure indicates that in‐situ decarboxylation of H₃cpimda occurred during the synthesis process. The asymmetric unit consists of two Cd²⁺ centres, one 4‐carboxy‐1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐5‐carboxylate (Hcpimda²⁻) anion, one 1‐(4‐carboxylatobenzyl)‐2‐propyl‐1H‐imidazole‐4‐carboxylate (cpima²⁻) anion, one coordinated water molecule and one lattice water molecule. One Cd²⁺ centre, i.e. Cd1, is hexacoordinated and displays a slightly distorted octahedral CdN₂O₄ geometry. The other Cd centre, i.e. Cd2, is coordinated by seven O atoms originating from one Hcpimda²⁻ ligand and three cpima²⁻ ligands. This Cd²⁺ centre can be described as having a distorted capped octahedral coordination geometry. Two carboxylate groups of the benzoate moieties of two cpima²⁻ ligands bridge between Cd2 centres to generate [Cd₂O₂] units, which are further linked by two cpima²⁻ ligands to produce one‐dimensional (1D) infinite chains based around large 26‐membered rings. Meanwhile, adjacent Cd1 centres are linked by Hcpimda²⁻ ligands to generate 1D zigzag chains. The two types of chains are linked through a μ₂‐η² bidentate bridging mode from an O atom of an imidazole carboxylate unit of cpima²⁻ to give a two‐dimensional (2D) coordination polymer. The simplified 2D net structure can be described as a 3,6‐coordinated net which has a (4³)₂(4⁶.6⁶.8³) topology. Furthermore, the FT–IR spectroscopic properties, photoluminescence properties, powder X‐ray diffraction (PXRD) pattern and thermogravimetric behaviour of the polymer have been investigated.     

Poly[di‐μ‐aqua‐μ‐1,2‐bis(pyridin‐4‐yl)ethene‐κ2N:N′‐tetrakis(4‐iodobenzoato‐κ2O,O′)dicadmium]

Colourless crystals of the title compound, [Cd₂(C₇H₄IO₂)₄(C₁₂H₁₀N₂)(H₂O)₂]_n, were obtained by the self‐assembly of Cd(NO₃)₂·4H₂O, 1,2‐bis(pyridin‐4‐yl)ethene (bpe) and 4‐iodobenzoic acid (4‐IBA). Each Cd^II atom is seven‐coordinated in a pentagonal–bipyramidal coordination environment by four carboxylate O atoms from two different 4‐IBA ligands, two O atoms from two water molecules and one N atom from a bpe ligand. The Cd^II centres are bridged by the aqua molecules and bpe ligands, which lie across centres of inversion, to give a two‐dimensional net. Topologically, taking the Cd^II atoms as nodes and the μ‐aqua and μ‐bpe ligands as linkers, the two‐dimensional structure can be simplified as a (6,3) network.     

A two‐dimensional CdII coordination polymer with 2,2′‐(disulfanediyl)dibenzoate and 1,10‐phenanthroline ligands

In poly[[μ₃‐2,2′‐(disulfanediyl)dibenzoato‐κ⁵O:O,O′:O′′,O′′′](1,10‐phenanthroline‐κ²N,N′)cadmium(II)], [Cd(C₁₄H₈O₄S₂)(C₁₂H₈N₂)]_n, the asymmetric unit contains one Cd^II cation, one 2,2′‐(disulfanediyl)dibenzoate anion (denoted dtdb²⁻) and one 1,10‐phenanthroline ligand (denoted phen). Each Cd^II centre is seven‐coordinated by five O atoms of bridging/chelating carboxylate groups from three dtdb²⁻ ligands and by two N atoms from one phen ligand, forming a distorted pentagonal–bipyramidal geometry. The Cd^II cations are bridged by dtdb²⁻ anions to give a two‐dimensional (4,4) layer. The layers are stacked to generate a three‐dimensional supramolecular architecture via a combination of aromatic C—H...π and π–π interactions. The thermogravimetric and luminescence properties of this compound were also investigated.     

The two‐dimensional coordination polymer poly[diaqua(μ2‐1H‐imidazo[4,5‐f][1,10]phenanthroline)‐μ4‐sulfato‐μ3‐sulfato‐dicadmium(II)]

In the title coordination polymer, [Cd₂(SO₄)₂(C₁₃H₈N₄)(H₂O)₂]_n, there are two crystallographically independent Cd^II centres with different coordination geometries. The first Cd^II centre is hexacoordinated by four O atoms of four sulfate ligands, one water O atom and one N atom of a 1H‐imidazo[4,5‐f][1,10]phenanthroline (IP) ligand, giving a distorted octahedral coordination environment. The second Cd^II centre is heptacoordinated by four O atoms of three sulfate ligands, one water O atom and two N atoms of one chelating IP ligand, resulting in a distorted monocapped anti‐trigonal prismatic geometry. The symmetry‐independent Cd^II ions are bridged in an alternating fashion by sulfate ligands, forming one‐dimensional ladder‐like chains which are connected through the IP ligands to form two‐dimensional layers. These two‐dimensional layers are linked by interlayer hydrogen bonds, leading to the formation of a three‐dimensional supramolecular network.     

Synthesis,crystal structure and characterization of a three‐dimensional CdII coordination polymer constructed from 2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalate

Bifunctional organic ligands are very popular for the design of coordination polymers because they allow the formation of a great diversity of structures. In the title coordination polymer, the new bifunctional inversion‐symmetric ligand 2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalic acid (abbreviated as H₂bttpa) links Cd^II cations, giving rise to the three‐dimensional Cd^II coordination polymer catena‐poly[diaqua[μ₄‐2,5‐bis(1H‐1,2,4‐triazol‐1‐yl)terephthalato‐κ⁴O¹:O⁴:N⁴:N^4′]cadmium(II)], [Cd(C₁₂H₆N₆O₄)(H₂O)₂]_n or [Cd(bttpa)(H₂O)₂]_n. The asymmetric unit consists of half a Cd^II cation, half a bttpa²⁻ ligand and one coordinated water molecule. The Cd^II cation is located on a twofold axis and is hexacoordinated in a distorted octahedral environment of four O and two N atoms. Four different bttpa²⁻ ligands contribute to this coordination, with two carboxylate O atoms in trans positions and two triazole N atoms in cis positions. Two aqua ligands in cis positions complete the coordination sphere. The fully deprotonated bttpa²⁻ ligand sits about a crystallographic centre of inversion and links two Cd^II cations to form a chain in a μ₂‐terephthalato‐κ²O¹:O⁴ bridge. This chain extends in the other two directions via the triazole heterocycles, producing a three‐dimensional framework. O—H…O hydrogen bonds and weak C—H…N interactions stabilize the three‐dimensional crystal structure. The FT–IR spectrum, X‐ray powder pattern, thermogravimetric behaviour and solid‐state photoluminescence of the title polymer have been investigated. The photoluminescence is enhanced and red‐shifted with respect to the uncoordinated ligand.     

A rare `mesh of trees' (mot) net: poly[aquahemi[μ4‐1,6‐bis(1,2,4‐triazol‐1‐yl)hexane](μ2‐5‐nitroisophthalato)cadmium(II)]

In the title coordination compound, [Cd(C₈H₃NO₆)(C₅H₈N₃)_0.5(H₂O)]_n, each Cd^II atom is six‐coordinated in a distorted octahedral environment surrounded by three carboxylate O atoms from two different 5‐nitroisophthalate (5‐NIP²⁻) ligands, two N atoms from two distinct 1,6‐bis(1,2,4‐triazol‐1‐yl)hexane (bth) ligands and one water molecule. The Cd^II centres are bridged by the bth ligands, which lie across centres of inversion, to give a honeycomb‐like two‐dimensional layer structure; the layers are further connected by the bridging 5‐NIP²⁻ ligands with a κ²;κ¹‐μ₂ coordination mode to generate the final three‐dimensional structure. Topologically, taking the the Cd^II atoms and the bth ligands as different four‐connected nodes and the 5‐NIP²⁻ ligands as linkers, the three‐dimensional structure can be simplified to a rare `mesh of trees' (mot) net with the Schäfli symbol (6⁶)(6⁴.8²)₂.     

Poly[aqua[μ2‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ2N3:N3′](μ2‐5‐hydroxybenzene‐1,3‐dicarboxylato‐κ4O1,O1′:O3,O3′)cadmium(II)], a twofold interpenetrated CdSO4‐like metal–organic polymer

In the title cadmium(II) complex, [Cd(C₈H₄O₅)(C₁₄H₁₄N₄)(H₂O)]_n, the 5‐hydroxybenzene‐1,3‐dicarboxylate (5‐OH‐1,3‐bdc) and 1,4‐bis(imidazol‐1‐ylmethyl)benzene (1,4,‐bix) ligands bridge water‐coordinated Cd^II atoms to generate a three‐dimensional network. Two carboxylate groups from different ligands function as O,O′‐chelates, while two imidazole N atoms from different ligands coordinate in a monodentate fashion, and one water molecule completes the seven‐coordinate pentagonal bipyramid around the Cd^II atom, in which the N atoms occupy the axial sites and the O atoms occupy the equatorial sites. The overall architecture is a twofold interpenetrated CdSO₄‐type framework. The two crystallographically equivalent frameworks are linked by O—H...O hydrogen bonds between the water, hydroxy and carboxylate groups.