A new one‐dimensional CdII coordination polymer with a two‐dimensional layered structure incorporating 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate ligands

The N‐heterocyclic ligand 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) has a rich variety of coordination modes and can lead to polymers with intriguing structures and interesting properties. In the coordination polymer catena‐poly[[cadmium(II)‐bis[μ‐benzene‐1,2‐dicarboxylato‐κ⁴O¹,O^1′:O²,O^2′]‐cadmium(II)‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole}‐κ²N²:N³;κ²N³:N²] dimethylformamide disolvate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)]·C₃H₇NO}_n, (I), each Cd^II ion exhibits an irregular octahedral CdO₄N₂ coordination geometry and is coordinated by four O atoms from two symmetry‐related benzene‐1,2‐dicarboxylate (1,2‐bdic²⁻) ligands and two N atoms from two symmetry‐related imb ligands. Two Cd^II ions are connected by two benzene‐1,2‐dicarboxylate ligands to generate a binuclear [Cd₂(1,2‐bdic)₂] unit. The binuclear units are further connected into a one‐dimensional chain by pairs of bridging imb ligands. These one‐dimensional chains are further connected through N—H…O hydrogen bonds and π–π interactions, leading to a two‐dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairs via weak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.     

A new three‐dimensional zinc(II) coordination polymer involving 2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐1H‐benzimidazole and benzene‐1,4‐dicarboxylate ligands

Metal–organic frameworks (MOFs) based on multidentate N‐heterocyclic ligands involving imidazole, triazole, tetrazole, benzimidazole, benzotriazole or pyridine present intriguing molecular topologies and have potential applications in ion exchange, magnetism, gas sorption and storage, catalysis, optics and biomedicine. The 2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl]‐1H‐benzimidazole (tmb) ligand has four potential N‐atom donors and can act in monodentate, chelating, bridging and tridentate coordination modes in the construction of complexes, and can also act as both a hydrogen‐bond donor and acceptor. In addition, the tmb ligand can adopt different coordination conformations, resulting in complexes with helical structures due to the presence of the flexible methylene spacer. A new three‐dimensional coordination polymer, poly[[bis(μ₂‐benzene‐1,4‐dicarboxylato)‐κ⁴O¹,O^1′:O⁴,O^4′;κ²O¹:O⁴‐bis{μ₂‐2‐[(1H‐1,2,4‐triazol‐1‐yl)methyl‐κN⁴]‐1H‐benzimidazole‐κN³}dizinc(II)] trihydrate], {[Zn(C₈H₄O₄)(C₁₀H₉N₅)]·1.5H₂O}_n, has been synthesized by the reaction of ZnCl₂ with tmb and benzene‐1,4‐dicarboxylic acid (H₂bdic) under solvothermal conditions. There are two crystallographically distinct bdic²⁻ ligands [bdic²⁻(A) and bdic²⁻(B)] in the structure which adopt different coordination modes. The Zn^II ions are bridged by tmb ligands, leading to one‐dimensional helical chains with different handedness, and adjacent helices are linked by bdic²⁻(A) ligands, forming a two‐dimensional network structure. The two‐dimensional layers are further connected by bdic²⁻(B) ligands, resulting in a three‐dimensional framework with the topological notation 6⁶. The IR spectra and thermogravimetric curves are consistent with the results of the X‐ray crystal structure analysis and the title polymer exhibits good fluorescence in the solid state at room temperature.     

A new two‐dimensional CdII coordination polymer based on 2‐(1H‐imidazol‐1‐ylmethyl)‐6‐methyl‐1H‐benzimidazole and benzene‐1,2‐dicarboxylate: synthesis,crystal structure and characterization

In the construction of coordination polymers, many factors can influence the formation of the final architectures, such as the nature of the metal centres, the organic ligands and the counter‐anions. In the coordination polymer poly[aqua(μ‐benzene‐1,2‐dicarboxylato‐κ⁴O ¹,O ^1′:O ²,O ^2′)[μ‐2‐(1H‐imidazol‐1‐ylmethyl)‐6‐methyl‐1H‐benzimidazole‐κ²N ²:N ³]cadmium(II)], [Cd(C₁₂H₁₂N₄)(C₈H₄O₄)(H₂O)]_n or [Cd(immb)(1,2‐bdic)(H₂O)]_n , each Cd^II ion is seven‐coordinated by two N atoms from two symmetry‐related 2‐(1H‐imidazol‐1‐ylmethyl)‐6‐methyl‐1H‐benzimidazole (immb) ligands, by four O atoms from two symmetry‐related benzene‐1,2‐dicarboxylate (1,2‐bdic²⁻) ligands and by one water molecule, leading to a CdN₂O₅ distorted pentagonal bipyramidal coordination environment. The immb and 1,2‐bdic²⁻ ligands bridge Cd^II ions and form a two‐dimensional network structure. O—H…O and N—H…O hydrogen bonds stabilize the structure. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviour and fluorescence properties of the title polymer have been investigated.     

Syntheses,structures and characterization of isomorphous CoII and NiII coordination polymers based on 2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole and benzene‐1,4‐dicarboxylate

Careful choice of the organic ligands is one of the most important parameters in the rational design and synthesis of coordination polymers. Aromatic polycarboxylates have been widely used in the preparation of metal–organic polymers since they can utilize various coordination modes to form diverse structures and can act as hydrogen‐bond acceptors and donors in the assembly of supramolecular structures. Nitrogen‐heterocyclic organic compounds have also been used extensively as ligands for the construction of polymers with interesting structures. In the polymers catena‐poly[[[diaquabis{2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole‐κN ³}cobalt(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O ¹:O ⁴] dihydrate], {[Co(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n , (I), and catena‐poly[[[diaquabis{2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole‐κN ³}nickel(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O ¹:O ⁴] dihydrate], {[Ni(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n , (II), the Co^II or Ni^II ion lies on an inversion centre and exhibits a slightly distorted octahedral coordination geometry, coordinated by two N atoms from two imidazole rings and four O atoms from two monodentate carboxylate groups and two water molecules. The dicarboxylate ligands bridge metal ions forming a polymeric chain. The 2‐[(1H‐imidazol‐1‐yl)methyl]‐6‐methyl‐1H‐benzimidazole ligands coordinate to the Co^II or Ni^II centres in monodentate modes through an imidazole N atom and are pendant on opposite sides of the main chain. The two structures are isomorphous. In the crystal, the one‐dimensional chains are further connected through O—H…O, O—H…N and N—H…O hydrogen bonds, leading to a three‐dimensional supramolecular architecture. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviours and fluorescence properties of both polymers have been investigated.     

A new one‐dimensional CuII complex with a three‐dimensional supramolecular architecture incorporating benzene‐1,3‐dicarboxylate and 1‐[(1H‐benzotriazol‐1‐yl)methyl]‐1H‐imidazole

Subtle modifications of N‐donor ligands can result in complexes with very different compositions and architectures. In the complex catena‐poly[[bis{1‐[(1H‐benzotriazol‐1‐yl)methyl]‐1H‐imidazole‐κN ³}copper(II)]‐μ‐benzene‐1,3‐dicarboxylato‐κ³O ¹,O ^1′:O ³], {[Cu(C₈H₄O₄)(C₁₀H₉N₅)₂(H₂O)]·2H₂O}_n , each Cu^II ion is six‐coordinated by two N atoms from two crystallographically independent 1‐[(1H‐benzotriazol‐1‐yl)methyl]‐1H‐imidazole (bmi) ligands, by three O atoms from two symmetry‐related benzene‐1,3‐dicarboxylate (bdic²⁻) ligands and by one water molecule, leading to a distorted CuN₂O₄ octahedral coordination environment. The Cu^II ions are connected by bridging bdic²⁻ anions to generate a one‐dimensional chain. The bmi ligands coordinate to the Cu^II ions in monodentate modes and are pendant on opposite sides of the main chain. In the crystal, the chains are linked by O—H…O and O—H…N hydrogen bonds, as well as by π–π interactions, into a three‐dimensional network. A thermogravimetric analysis was carried out and the fluorescence behaviour of the complex was also investigated.     

Two‐dimensional ZnII and one‐dimensional CoII coordination polymers based on benzene‐1,4‐dicarboxylate and pyridine ligands

Coordination polymers constructed from metal ions and organic ligands have attracted considerable attention owing to their diverse structural topologies and potential applications. Ligands containing carboxylate groups are among the most extensively studied because of their versatile coordination modes. Reactions of benzene‐1,4‐dicarboxylic acid (H₂BDC) and pyridine (py) with Zn^II or Co^II yielded two new coordination polymers, namely, poly[(μ₄‐benzene‐1,4‐dicarboxylato‐κ⁴O:O′:O′′:O′′′)(pyridine‐κN)zinc(II)], [Zn(C₈H₄O₂)(C₅H₅N)]_n, (I), and catena‐poly[aqua(μ₃‐benzene‐1,4‐dicarboxylato‐κ³O:O′:O′′)bis(pyridine‐κN)cobalt(II)], [Co(C₈H₄O₂)(C₅H₅N)₂(H₂O)]_n, (II). In compound (I), the Zn^II cation is five‐coordinated by four carboxylate O atoms from four BDC²⁻ ligands and one pyridine N atom in a distorted square‐pyramidal coordination geometry. Four carboxylate groups bridge two Zn^II ions to form centrosymmetric paddle‐wheel‐like Zn₂(μ₂‐COO)₄ units, which are linked by the benzene rings of the BDC²⁻ ligands to generate a two‐dimensional layered structure. The two‐dimensional layer is extended into a three‐dimensional supramolecular structure with the help of π–π stacking interactions between the aromatic rings. Compound (II) has a one‐dimensional double‐chain structure based on Co₂(μ₂‐COO)₂ units. The Co^II cations are bridged by BDC²⁻ ligands and are octahedrally coordinated by three carboxylate O atoms from three BDC²⁻ ligands, one water O atom and two pyridine N atoms. Interchain O—H…O hydrogen‐bonding interactions link these chains to form a three‐dimensional supramolecular architecture.     

A one‐dimensional zinc(II) coordination polymer with a three‐dimensional supramolecular architecture incorporating 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole and adipate

The synthesis of coordination polymers or metal–organic frameworks (MOFs) has attracted considerable interest owing to the interesting structures and potential applications of these compounds. It is still a challenge to predict the exact structures and compositions of the final products. A new one‐dimensional coordination polymer, catena‐poly[[[bis{1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole‐κN³}zinc(II)]‐μ‐hexane‐1,6‐dicarboxylato‐κ⁴O¹,O^1′:O⁶,O^6′] monohydrate], {[Zn(C₆H₈O₄)(C₉H₈N₆)₂]·H₂O}_n, has been synthesized by the reaction of Zn(Ac)₂ (Ac is acetate) with 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐tetrazole (bimt) and adipic acid (H₂adi) at room temperature. In the polymer, each Zn^II ion exhibits an irregular octahedral ZnN₂O₄ coordination geometry and is coordinated by two N atoms from two symmetry‐related bimt ligands and four O atoms from two symmetry‐related dianionic adipate ligands. Zn^II ions are connected by adipate ligands into a one‐dimensional chain which runs parallel to the c axis. The bimt ligands coordinate to the Zn^II ions in a monodentate mode on both sides of the main chain. In the crystal, the one‐dimensional chains are further connected through N—H…O hydrogen bonds, leading to a three‐dimensional supramolecular architecture. In addition, the title polymer exhibits fluorescence, with emissions at 334 and 350 nm in the solid state at room temperature.     

A new one‐dimensional CdII coordination polymer incorporating 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylate)

Imidazole‐4,5‐dicarboxylic acid (H₃IDC) and its derivatives are widely used in the preparation of new coordination polymers owing to their versatile bridging coordination modes and potential hydrogen‐bonding donors and acceptors. A new one‐dimensional coordination polymer, namely catena‐poly[[diaquacadmium(II)]‐μ₃‐2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylato)], [Cd(C₁₆H₆N₄O₈)_0.5(H₂O)₂]_n or [Cd(H₂Phbidc)_1/2(H₂O)₂]_n, has been synthesized by the reaction of Cd(OAc)₂·2H₂O (OAc is acetate) with 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylic acid) (H₆Phbidc) under solvothermal conditions. In the polymer, one type of Cd ion (Cd1) is six‐coordinated by two N atoms and two O atoms from one H₂Phbidc⁴⁻ ligand and by two O atoms from two water molecules, forming a significantly distorted octahedral CdN₂O₄ coordination geometry. In contrast, the other type of Cd ion (Cd2) is six‐coordinated by two N atoms and two O atoms from two symmetry‐related H₂Phbidc⁴⁻ ligands and by two O atoms from two symmetry‐related water molecules, leading to a more regular octahedral coordination geometry. The Cd1 and Cd2 ions are linked by H₂Phbidc⁴⁻ ligands into a one‐dimensional chain which runs parallel to the b axis. In the crystal, the one‐dimensional chains are connected through hydrogen bonds, generating a two‐dimensional layered structure parallel to the ab plane. Adjacent layers are further linked by hydrogen bonds, forming a three‐dimensional structure in the solid state.     

A new two‐dimensional ZnII coordination polymer based on 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene and 5‐nitrobenzene‐1,3‐dicarboxylic acid: synthesis,crystal structure and physical properties

A novel two‐dimensional (2D) Zn^II coordination framework, poly[[μ‐1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene](μ‐5‐nitrobenzene‐1,3‐dicarboxylato)zinc(II)], [Zn(C₈H₃NO₆)(C₁₄H₁₄N₄)]_n or [Zn(NO₂‐BDC)(1,3‐BMIB)]_n [1,3‐BMIB is 1,3‐bis(2‐methyl‐1H‐imidazol‐1‐yl)benzene and NO₂‐H₂BDC is 5‐nitrobenzene‐1,3‐dicarboxylic acid], has been prepared and characterized by IR, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. Single‐crystal X‐ray diffraction analysis revealed that the compound is a new 2D polymer with a 6³ topology parallel to the (10) crystal planes based on left‐handed helices, right‐handed helical NO₂‐BDC–Zn chains and [Zn₂(1,3‐BMIB)₂]_n clusters. In the crystal, adjacent layers are further connected by C—H…O hydrogen bonds, C—H…π interactions, C—O…π interactions and N—O…π interactions to form a three‐dimensional structure in the solid state. In addition, the compound exhibits strong fluorescence emissions in the solid state at room temperature.     

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.     

A new two‐dimensional CoII coordination polymer based on bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether and biphenyl‐4,4′‐diyldicarboxylic acid: synthesis,crystal structure and photocatalytic degradation activity

A novel two‐dimensional Co^II coordination framework, namely poly[(μ₂‐biphenyl‐4,4′‐diyldicarboxylato‐κ²O⁴:O^4′){μ₂‐bis[4‐(2‐methyl‐1H‐imidazol‐1‐yl)phenyl] ether‐κ²N³:N^3′}cobalt(II)], [Co(C₁₄H₈O₄)(C₂₀H₁₈N₄O)]_n, has been prepared and characterized by IR, elemental analysis, thermal analysis and single‐crystal X‐ray diffraction. The crystal structure reveals that the compound has an achiral two‐dimensional layered structure based on opposite‐handed helical chains. In addition, it exhibits significant photocatalytic degradation activity for the degradation of methylene blue.     

A three‐dimensional ZnII coordination polymer constructed from 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands exhibiting photoluminescence

Ligands based on polycarboxylic acids are excellent building blocks for the construction of coordination polymers; they may bind to a variety of metal ions and form clusters, as well as extended chain or network structures. Among these building blocks, biphenyltetracarboxylic acids (H₄bpta) with C ₂ symmetry have recently attracted attention because of their variable bridging and multidentate chelating modes. The new luminescent three‐dimensional coordination polymer poly[(μ₅‐1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylato)bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]dizinc(II)], [Zn₂(C₁₆H₆O₈)(C₁₂H₁₀N₄)]_n , was synthesized solvothermally and characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The crystal structure contains two crystallographically independent Zn^II cations. Both metal cations are located on twofold axes and display distorted tetrahedral coordination geometries. Neighbouring Zn^II centres are bridged by carboxylate groups in the syn –anti mode to form one‐dimensional chains. Adjacent chains are linked through 1,1′‐biphenyl‐2,2′,4,4′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands to form a three‐dimensional network. In the solid state, the compound exhibits blue photoluminescence and represents a promising candidate for a thermally stable and solvent‐resistant blue fluorescent material.     

A three‐dimensional ZnII coordination network based on 5,5′‐methylenebis(2,4,6‐trimethylisophthalic acid) and 2,7‐bis(1H‐imidazol‐1‐yl)fluorene: synthesis,structure and luminescence properties

In recent years, coordination polymers constructed from multidentate carboxylate ligands and N‐containing ligands have attracted much attention since these ligands can adopt a rich variety of coordination modes which can lead to crystalline products with intriguing structures and interesting properties. A new coordination polymer, namely poly[[diaqua[μ‐2,7‐bis(1H‐imidazol‐1‐yl)fluorene‐κ²N³:N^3′][μ‐5,5′‐methylenebis(3‐carboxy‐2,4,6‐trimethylbenzoato)‐κ²O¹:O^1′]zinc(II)] hemihydrate], {[Zn(C₂₃H₂₂O₈)(C₁₉H₁₄N₄)(H₂O)₂]·0.5H₂O}_n, 1 , was prepared by the self‐assembly of Zn(NO₃)₂·6H₂O with 5,5′‐methylenebis(2,4,6‐trimethylisophthalic acid) (H₄BTMIPA) and 2,7‐bis(1H‐imidazol‐1‐yl)fluorene (BIF) under solvothermal conditions. The structure of 1 was determined by elemental analysis, single‐crystal X‐ray crystallography, powder X‐ray diffraction, IR spectroscopy and thermogravimetric analysis. Each Zn^II ion is six‐coordinated by two O atoms from two H₂BTMIPA^2? ligands, by two N atoms from two BIF ligands and by two water molecules, forming a distorted octahedral ZnN₂O₄ coordination geometry. Adjacent Zn^II ions are linked by H₂BTMIPA^2? ligands and BIF ligands, leading to the formation of a two‐dimensional (2D) (4,4)‐ sql network, and intermolecular hydrogen‐bonding interactions connect the 2D layer structure into the three‐dimensional (3D) supramolecular structure. Each 2D layer contains two kinds of helices with the same direction, which are opposite in adjacent layers. The luminescence properties of complex 1 in the solid state have also been investigated.     

The crystal structure,luminescence and nitrobenzene‐sensing properties of a two‐dimensional MnII coordination polymer based on 2,6‐bis(imidazol‐1‐yl)pyridine

A two‐dimensional Mn^II coordination polymer (CP), poly[bis[μ₂‐2,6‐bis(imidazol‐1‐yl)pyridine‐κ²N³:N^3′]bis(thiocyanato‐κN)manganese] [Mn(NCS)₂(C₁₁H₉N₅)₂]_n, (I), has been obtained by the self‐assembly reaction of Mn(ClO₄)₂·6H₂O, NH₄SCN and bent 2,6‐bis(imidazol‐1‐yl)pyridine (2,6‐bip). CP (I) was characterized by FT–IR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. The crystal structure features a unique two‐dimensional (4,4) network with one‐dimensional channels. The luminescence and nitrobenzene‐sensing properties were explored in a DMF suspension, revealing that CP (I) shows a strong luminescence emission and is highly sensitive for nitrobenzene detection.     

A new two‐dimensional ZnII coordination polymer constructed by a multidentate N‐heterocyclic ligand and 5‐carboxybenzene‐1,3‐dicarboxylate

In the coordination polymer, poly[[{μ‐1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐imidazole‐κ²N:N′}(μ‐5‐carboxybenzene‐1,3‐dicarboxylato‐κ²O¹:O³)zinc(II)] dimethylformamide monosolvate pentahydrate], {[Zn(C₉H₄O₆)(C₁₁H₁₀N₄)]·C₃H₇NO·5H₂O}_n, the Zn^II ion is coordinated by two N atoms from two symmetry‐related 1‐[(1H‐benzimidazol‐2‐yl)methyl]‐1H‐imidazole (bmi) ligands and two O atoms from two symmetry‐related 5‐carboxybenzene‐1,3‐dicarboxylate (Hbtc²⁻) ligands in a slightly distorted tetrahedral geometry. The Zn^II ions are bridged by Hbtc²⁻ and bmi ligands, leading to a 4‐connected two‐dimensional network with the topological notation (4⁴.6²). Adjacent layers are further connected by 12 kinds of hydrogen bonds and also by π–π interactions, resulting in a three‐dimensional supramolecular architecture in the solid state.     

A helical zinc(II) coordination polymer assembled from 1,3‐bis[(pyridin‐3‐yl)methoxy]benzene and benzene‐1,4‐dicarboxylic acid

In catena‐poly[[aqua[1,3‐bis(pyridine‐3‐ylmethoxy)benzene‐κN]zinc(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O¹:O⁴], [Zn(C₈H₄O₄)(C₁₈H₁₆N₂O₂)(H₂O)]_n, each Zn^II centre is tetrahedrally coordinated by two O atoms of bridging carboxylate groups from two benzene‐1,4‐dicarboxylate anions (denoted L²⁻), one O atom from a water molecule and one N atom from a 1,3‐bis[(pyridin‐3‐yl)methoxy]benzene ligand (denoted bpmb). (Aqua)O—H...N hydrogen‐bonding interactions induce the formation of one‐dimensional helical [Zn(L)(bpmb)(H₂O)]_n chains which are interlinked through (aqua)O—H...O hydrogen‐bonding interactions, producing two‐dimensional corrugated sheets.     

A three‐dimensional CdII coordination polymer constructed from 1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands

The title coordination polymer, poly[[aqua(μ₅‐1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylato)bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene]dicadmium(II)] dihydrate], {[Cd₂(C₁₆H₆O₈)(C₁₂H₁₀N₄)₂(H₂O)]·2H₂O}_n, was crystallized from a mixture of 1,1′‐biphenyl‐2,2′,5,5′‐tetracarboxylic acid (H₄bpta), 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐bib) and cadmium nitrate in water–dimethylformamide. The crystal structure consists of two crystallographically independent Cd^II cations, with one of the Cd^II cations possessing a slightly distorted pentagonal bipyramidal geometry. The second Cd^II centre is coordinated by carboxylate O atoms and imidazole N atoms from two separate 1,4‐bib ligands, displaying a distorted octahedral CdN₂O₄ geometry. The completely deprotonated bpta⁴⁻ ligand, exhibiting a new coordination mode, bridges five Cd^II cations to form one‐dimensional chains viaμ₃‐η¹:η²:η¹:η² and μ₂‐η¹:η¹:η⁰:η⁰ modes, and these are further linked by 1,4‐bib ligands to form a three‐dimensional framework with a (4².6⁴)(4.6²)(4³.6⁵.7²) topology. The structure of the coordination polymer is reinforced by intermolecular hydrogen bonding between carboxylate O atoms, aqua ligands and crystallization water molecules. The solid‐state photoluminescence properties were investigated and the complex might be a candidate for a thermally stable and solvent‐resistant blue fluorescent material.     

A three‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from biphenyl‐3,4′,5‐tricarboxylate and 1,4‐bis(1H‐imidazol‐1‐yl)benzene ligands

Coordination polymers (CPs) built by coordination bonds between metal ions/clusters and multidentate organic ligands exhibit fascinating structural topologies and potential applications as functional solid materials. The title coordination polymer, poly[diaquabis(μ₄‐biphenyl‐3,4′,5‐tricarboxylato‐κ⁴O³:O^3′:O^4′:O⁵)tris[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)benzene‐κ²N³:N^3′]dicopper(II)dicopper(I)], [Cu^II₂Cu^I₂(C₁₅H₇O₆)₂(C₁₂H₁₀N₄)₃(H₂O)₂]_n, was crystallized from a mixture of biphenyl‐3,4′,5‐tricarboxylic acid (H₃bpt), 1,4‐bis(1H‐imidazol‐1‐yl)benzene (1,4‐bib) and copper(II) chloride in a water–CH₃CN mixture under solvothermal reaction conditions. The asymmetric unit consists of two crystallographically independent Cu atoms, one of which is Cu^II, while the other has been reduced to the Cu^I ion. The Cu^II centre is pentacoordinated by three O atoms from three bpt³⁻ ligands, one N atom from a 1,4‐bib ligand and one O atom from a coordinated water molecule, and the coordination geometry can be described as distorted trigonal bipyramidal. The Cu^I atom exhibits a T‐shaped geometry (CuN₂O) coordinated by one O atom from a bpt³⁻ ligand and two N atoms from two 1,4‐bib ligands. The Cu^II atoms are extended by bpt³⁻ and 1,4‐bib linkers to generate a two‐dimensional network, while the Cu^I atoms are linked by 1,4‐bib ligands, forming one‐dimensional chains along the [20] direction. In addition, the completely deprotonated μ₄‐η¹:η¹:η¹:η¹ bpt³⁻ ligands bridge one Cu^I and three Cu^II cations along the a (or [100]) direction to form a three‐dimensional framework with a (10³)₂(10)₂(4².6.10².12)₂(4².6.8².10)₂(8) topology via a 2,2,3,4,4‐connected net. An investigation of the magnetic properties indicated a very weak ferromagnetic behaviour.     

A two‐dimensional ZnII coordination polymer constructed from benzene‐1,2,3‐tricarboxylic acid and N,N′‐bis[(pyridin‐4‐yl)methylidene]hydrazine

The hydrothermal synthesis of the novel complex poly[aqua(μ₄‐benzene‐1,2,3‐tricarboxylato)[μ₂‐4,4′‐(hydrazine‐1,2‐diylidenedimethanylylidene)dipyridine](μ₃‐hydroxido)dizinc(II)], [Zn(C₉H₃O₆)(OH)(C₁₂H₁₀N₄)(H₂O)]_n, is described. The benzene‐1,2,3‐tricarboxylate ligand connects neighbouring Zn₄(OH)₂ secondary building units (SBUs) producing an infinite one‐dimensional chain. Adjacent one‐dimensional chains are connected by the N,N′‐bis[(pyridin‐4‐yl)methylidene]hydrazine ligand, forming a two‐dimensional layered structure. Adjacent layers are stacked to generate a three‐dimensional supramolecular architecture via O—H...O hydrogen‐bond interactions. The thermal stability of this complex is described and the complex also appears to have potential for application as a luminescent material.     

Two new isostructural mercury(II) complexes involving the N‐heterocyclic 1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole ligand: syntheses,structures and properties

The unsymmetrical N‐heterocyclic ligand 1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole (bmi) has three potential N‐atom donors and can act in monodentate or bridging coordination modes in the construction of complexes. In addition, the bmi ligand can adopt different coordination conformations, resulting in complexes with different structures due to the presence of the flexible methylene spacer. Two new complexes, namely bis{1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole‐κN ³}dibromidomercury(II), [HgBr₂(C₁₀H₉N₅)₂], and bis{1‐[(benzotriazol‐1‐yl)methyl]‐1H‐1,3‐imidazole‐κN ³}diiodidomercury(II), [HgI₂(C₁₀H₉N₅)₂], have been synthesized through the self‐assembly of bmi with HgBr₂ or HgI₂. Single‐crystal X‐ray diffraction shows that both complexes are mononuclear structures, in which the bmi ligands coordinate to the Hg^II ions in monodentate modes. In the solid state, both complexes display three‐dimensional networks formed by a combination of hydrogen bonds and π–π interactions. The IR spectra and PXRD patterns of both complexes have also been recorded.