CdII and CoII coordination polymers constructed from benzene‐1,4‐dicarboxylic acid and 2‐(pyridin‐3‐yl)‐1H‐benzimidazole ligands

In poly[aqua(μ₃‐benzene‐1,4‐dicarboxylato‐κ⁵O¹,O^1′:O¹:O⁴,O^4′)[2‐(pyridin‐3‐yl‐κN)‐1H‐benzimidazole]cadmium(II)], [Cd(C₈H₄O₄)(C₁₂H₉N₃)(H₂O)]_n, (I), each Cd^II ion is seven‐coordinated by the pyridine N atom from a 2‐(pyridin‐3‐yl)benzimidazole (3‐PyBIm) ligand, five O atoms from three benzene‐1,4‐dicarboxylate (1,4‐bdc) ligands and one O atom from a coordinated water molecule. The complex forms an extended two‐dimensional carboxylate layer structure, which is further extended into a three‐dimensional network by hydrogen‐bonding interactions. In catena‐poly[[diaquabis[2‐(pyridin‐3‐yl‐κN)‐1H‐benzimidazole]cobalt(II)]‐μ₂‐benzene‐1,4‐dicarboxylato‐κ²O¹:O⁴], [Co(C₈H₄O₄)(C₁₂H₉N₃)₂(H₂O)₂]_n, (II), each Co^II ion is six‐coordinated by two pyridine N atoms from two 3‐PyBIm ligands, two O atoms from two 1,4‐bdc ligands and two O atoms from two coordinated water molecules. The complex forms a one‐dimensional chain‐like coordination polymer and is further assembled by hydrogen‐bonding interactions to form a three‐dimensional network.     

One‐dimensional CuII coordination polymers containing C2h‐symmetric 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate linkers

Two new one‐dimensional Cu^II coordination polymers (CPs) containing the C_2h‐symmetric terphenyl‐based dicarboxylate linker 1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylate (3,3′‐TPDC), namely catena‐poly[[bis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ⁴O,O′:O′′:O′′′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂]·H₂O}_n, (I), and catena‐poly[[aquabis(dimethylamine‐κN)copper(II)]‐μ‐1,1′:4′,1′′‐terphenyl‐3,3′‐dicarboxylato‐κ²O³:O^3′] monohydrate], {[Cu(C₂₀H₁₂O₄)(C₂H₇N)₂(H₂O)]·H₂O}_n, (II), were both obtained from two different methods of preparation: one reaction was performed in the presence of 1,4‐diazabicyclo[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar. Both reactions afforded crystals of different colours, i.e. violet plates for (I) and blue needles for (II), both of which were analysed by X‐ray crystallography. The 3,3′‐TPDC bridging ligands coordinate the Cu^II ions in asymmetric chelating modes in (I) and in monodenate binding modes in (II), forming one‐dimensional chains in each case. Both coordination polymers contain two coordinated dimethylamine ligands in mutually trans positions, and there is an additional aqua ligand in (II). The solvent water molecules are involved in hydrogen bonds between the one‐dimensional coordination polymer chains, forming a two‐dimensional network in (I) and a three‐dimensional network in (II).     

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.     

Synthesis,structure and properties of a new three‐dimensional interpenetrated metal–organic framework with 3,3′‐azodibenzoic acid (H2azdc) and 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb): {[Cd(azdc)(bimb)2]·H2O}n

A new three‐dimensional interpenetrated Cd^II–organic framework based on 3,3′‐azodibenzoic acid [3,3′‐(diazenediyl)dibenzoic acid, H₂azdc] and the auxiliary flexible ligand 1,4‐bis(1H‐imidazol‐1‐yl)butane (bimb), namely poly[[bis[μ₂‐1,4‐bis(1H‐imidazol‐1‐yl)butane‐κ²N³:N^3′][μ₂‐3,3′‐(diazenediyl)dibenzoato‐κ²O:O′]cadmium(II)] monohydrate], {[Cd(C₁₄H₈N₂O₄)(C₁₀H₁₄N₂)₂]·H₂O}_n, (1), was obtained by a typical solution reaction in mixed solvents (water and N,N′‐dimethylformamide). Each Cd^II centre is six‐coordinated by two O atoms of bis‐monodentate bridging carboxylate groups from two azdc²⁻ ligands and by four N atoms from four bimb ligands, forming an octahedral coordination environment. The Cd^II ions are connected by the bimb ligands, resulting in two‐dimensional (4,4) layers, which are further pillared by the azdc²⁻ ligands, affording a threefold interpenetrated three‐dimensional α‐Po topological framework with the Schläfli symbol 4¹²6³. The thermal stability and solid‐state fluorescence properties of (1) have been investigated.     

A one‐dimensional lead(II) coordination polymer with terminal and bridging 5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylate ligands

In the coordination polymer catena‐poly[[[diaqua[5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ²N³,O⁴]lead(II)]‐μ‐5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ³N³,O⁴:N²] dihydrate], {[Pb(C₁₀H₆N₃O₄)(H₂O)₂]·2H₂O}_n, the two 5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylate ligands have different coordination modes, one being terminal and the other bridging. The bridging ligand links Pb^II cations into one‐dimensional coordination polymer chains. The structure is also stabilized by intra‐ and interchain π–π stacking interactions between the pyridine rings, resulting in the formation of a two‐dimensional network. Extensive hydrogen‐bonding interactions lead to the formation of a three‐dimensional supramolecular network.     

Synthesis and characterization of two one‐dimensional CdII coordination polymers (CPs) with 5‐amino‐2,4,6‐tribromoisophthalic acid and flexible N‐donor bipyridyl ligands

The bromo‐substituted aromatic dicarboxylic acid 5‐amino‐2,4,6‐tribromoisophthalic acid (H₂ATBIP) was used to assemble with Cd^II ions in the presence of the N‐donor flexible bipyridyl ligands 3,3′‐(diazene‐1,2‐diyl)dipyridine (mzpy) and 1,3‐bis(pyridin‐3‐ylmethyl)urea (3bpmu), leading to the formation of two chain coordination polymers by adopting solution methods, namely, catena‐poly[[[triaqua(5‐amino‐2,4,6‐tribromoisophthalato‐κO)cadmium(II)]‐μ‐3,3′‐(diazene‐1,2‐diyl)dipyridine‐κ²N¹:N^1′] dihydrate], {[Cd(C₈H₂Br₃NO₄)(C₁₀H₈N₄)(H₂O)₃]·2H₂O}_n or {[Cd(ATBIP)(mzpy)(H₂O)₃]·2H₂O}_n, ( 1 ), and catena‐poly[[[tetraaquacadmium(II)]‐μ‐1,3‐bis(pyridin‐3‐ylmethyl)urea‐κ²N¹:N^1′‐[diaquabis(5‐amino‐2,4,6‐tribromoisophthalato‐κO)cadmium(II)]‐μ‐1,3‐bis(pyridin‐3‐ylmethyl)urea‐κ²N¹:N^1′] octahydrate], {[Cd(C₈H₂Br₃NO₄)(C₁₂H₁₂N₄O)(H₂O)₃]·4H₂O}_n or {[Cd(ATBIP)(3bpmu)(H₂O)₃]·4H₂O}_n, ( 2 ). Both complexes were characterized by FT–IR spectroscopic analysis, thermogravimetric analysis (TGA), solid‐state diffuse reflectance UV–Vis spectroscopic analysis, and single‐crystal and powder X‐ray diffraction analysis (PXRD). The mzpy and 3bpmu ligands bridge the Cd^II metal centres in ( 1 ) and ( 2 ) into one‐dimensional chains, and the ATBIP²⁻ ligands show a monodentate coordination to the Cd^II centres in both coordination polymers. A discrete water tetramer exists in ( 1 ). Within the chains of ( 1 ) and ( 2 ), there are halogen bonds between adjacent ATBIP²⁻ and mzpy or 3bpmu ligands, as well as hydrogen bonds between the ATBIP²⁻ ligands and the coordinated water molecules. With the aid of weak interactions, the structures of ( 1 ) and ( 2 ) are further extended into three‐dimensional supramolecular networks. An analysis of the solid‐state diffuse reflectance UV–Vis spectra of ( 1 ) and ( 2 ) indicates that a wide indirect band gap exists in both complexes. Complexes ( 1 ) and ( 2 ) exhibit irreversible and reversible dehydration–rehydration behaviours, respectively, and the solid‐state fluorescence properties of both complexes have been studied.     

Construction and photocatalytic properties of two metal‐mediated coordination polymers based on benzene‐1,3,5‐tricarboxylic acid and trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene

With the rapid development of modern industry, water pollution has become an intractable environmental issue facing humans worldwide. In particular, the organic dyes discharged into natural water from dyestuffs, dyeing and the textile industry are the main sources of pollution in wastewater. To eliminate these types of pollutants, degradation of organic contaminants through a photocatalytic technique is an effective methodology. To exploit more crystalline photocatalysts for the degradation of organic dyes, two coordination polymers, namely catena‐poly[[(3,5‐dicarboxybenzene‐1‐carboxylato‐κO ¹)silver(I)]‐μ‐trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ²N :N ′], [Ag(C₉H₅O₆)(C₁₂H₁₀N₂)]_n or [Ag(H₂BTC)(3,4′‐bpe)]_n , (I), and poly[[(μ₃‐5‐carboxybenzene‐1,3‐dicarboxylato‐κ⁴O ¹,O ^1′:O ³:O ³)[μ‐trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ²N :N′ ]cadmium(II)] monohydrate], {[Cd(C₉H₄O₆)(C₁₂H₁₀N₂)]·H₂O}_n or {[Cd(HBTC)(3,4′‐bpe)]·H₂O}_n , (II), have been prepared by the hydrothermal reactions of benzene‐1,3,5‐tricarboxylic acid (H₃BTC) and trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene (3,4′‐bpe) in the presence of AgNO₃ or Cd(NO₃)₂·4H₂O, respectively. These two title compounds have been structurally characterized by IR spectroscopy, elemental analysis, single‐crystal X‐ray diffraction and powder X‐ray diffraction. In (I), the Ag^I ions and organic ligands form a one‐dimensional coordination chain, and adjacent coordination chains are connected by Ag…O interactions to give rise to a two‐dimensional supramolecular network. Each two‐dimensional network is entangled with other equivalent networks to generate an infrequent interlocked 2D→3D (2D and 3D are two‐ and three‐dimensional, respectively) supramolecular framework. In (II), the Cd^II ions are bridged by the HBTC²⁻ and 3,4′‐bpe ligands, which lie across centres of inversion, to give a two‐dimensional coordination network. The thermal stabilities and photocatalytic properties of the title compounds have also been studied.     

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 new two‐dimensional managnese(II) coordination polymer constructed by 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylate)

In recent years, N‐heterocyclic carboxylate ligands have attracted much interest in the preparation of new coordination polymers since they contain N‐atom donors, as well as O‐atom donors, and have a rich variety of coordination modes which can lead to polymers with intriguing structures and interesting properties. A new two‐dimensional coordination polymer, namely poly[[μ₃‐2,2′‐(1,2‐phenylene)bis(4‐carboxy‐1H‐imidazole‐5‐carboxylato)‐κ⁶O⁴,N³,N^3′,O^4′:O⁵:O^5′]manganese(II)], [Mn(C₁₆H₈N₄O₈)]_n or [Mn(H₄Phbidc)]_n, has been synthesized by the reaction of Mn(OAc)₂·4H₂O (OAc is acetate) with 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylic acid) (H₆Phbidc) under solvothermal conditions. In the polymer, each Mn^II ion is six‐coordinated by two N atoms from one H₄Phbidc²⁻ ligand and by four O atoms from three H₄Phbidc²⁻ ligands, forming a significantly distorted octahedral MnN₂O₄ coordination geometry. The Mn^II ions are linked by hexadentate H₄Phbidc²⁻ ligands, leading to a two‐dimensional structure parallel to the ac plane. In the crystal, adjacent layers are further connected by N—H…O hydrogen bonds, forming a three‐dimensional structure in the solid state.     

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 three‐dimensional cadmium(II) coordination polymer: poly[[[μ‐4,4′‐(propane‐1,3‐diyl)dipyridine‐κ2N:N](μ‐3,3′‐thiodipropionato‐κ3O,O′:O)cadmium(II)] monohydrate]

In the title coordination polymer, {[Cd(C₆H₈O₄S)(C₁₃H₁₄N₂)]·H₂O}_n, the Cd^II atom displays a distorted octahedral coordination, formed by three carboxylate O atoms and one S atom from three different 3,3′‐thiodipropionate ligands, and two N atoms from two different 4,4′‐(propane‐1,3‐diyl)dipyridine ligands. The Cd^II centres are bridged through carboxylate O atoms of 3,3′‐thiodipropionate ligands and through N atoms of 4,4′‐(propane‐1,3‐diyl)dipyridine ligands to form two different one‐dimensional chains, which intersect to form a two‐dimensional layer. These two‐dimensional layers are linked by S atoms of 3,3′‐thiodipropionate ligands from adjacent layers to form a three‐dimensional network.     

A three‐dimensional supramolecular framework based on the interlinkage of an interpenetrating diamondoid coordination network

In the development of coordination‐driven crystalline materials, O‐ and N‐atom donors from carboxylate and pyridyl‐based ligands are widely used classes of multidentate bridging ligands composed of several terminal coordinating groups linked by either rigid or flexible spacers. The rigidity of the ligands can play a vital role in the determination of the structures formed. A new Cd^II supramolecular compound, namely poly[μ‐adipato‐κ²O ¹:O⁴‐μ‐adipato‐κ⁴O ¹,O ^1′:O ⁴,O^4′‐diaquabis[μ‐1,4‐bis(pyridin‐4‐yl)‐1,3‐butadiene‐κ²N :N ′]dicadmium(II)], [Cd₂(C₆H₈O₄)₂(C₁₄H₁₂N₂)₂(H₂O)₂]_n , (I), has been synthesized by the self‐assembly of Cd(NO₃)₂·4H₂O, adipic acid (hexane‐1,6‐dioic acid; H₂adp) and the dipyridyl ligand 1,4‐bis(pyridin‐4‐yl)buta‐1,3‐diene (1,4‐bpbd) under hydrothermal conditions. Single‐crystal X‐ray diffraction analysis reveals that each Cd^II centre is located in a distorted octahedral coordination environment, coordinated by one water O atom, three carboxylate O atoms from two different adp²⁻ ligands and two N atoms from two different 1,4‐bpbd ligands. The Cd(H₂O) units are interconnected by the μ₂,κ²‐adp²⁻, μ₂,κ⁴‐adp²⁻ and 1,4‐bpbd ligands, which lie across centres of inversion, to give a 6⁶‐ dia network. Large cavities within a single diamondoid network permit the mutual threefold interpenetration of crystallographically equivalent frameworks. Hydrogen‐bonding interactions between the coordinated water molecules and adp²⁻ carboxylate O atoms anchor the interpenetrating networks into a unique three‐dimensional supramolecular structure. Topologically, taking the coordinated water molecules and Cd^II centres as nodes, the whole architecture can be simplified as a binodal (3,7)‐connected supramolecular framework. The identity of (I) was further characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis and powder X‐ray diffraction. The solid‐state photoluminescence properties of (I) were also investigated.     

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 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.     

A two‐dimensional mixed‐valence CuII/CuI coordination polymer constructed from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate

Coordination polymers are a thriving class of functional solid‐state materials and there have been noticeable efforts and progress toward designing periodic functional structures with desired geometrical attributes and chemical properties for targeted applications. Self‐assembly of metal ions and organic ligands is one of the most efficient and widely utilized methods for the construction of CPs under hydro(solvo)thermal conditions. 2‐(Pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylate (HPIDC²⁻) has been proven to be an excellent multidentate ligand due to its multiple deprotonation and coordination modes. Crystals of poly[aquabis[μ₃‐5‐carboxy‐2‐(pyridin‐3‐yl)‐1H‐imidazole‐4‐carboxylato‐κ⁵N¹,O⁵:N³,O⁴:N²]copper(II)dicopper(I)], [Cu^IICu^I₂(C₁₀H₅N₃O₄)₂(H₂O)]_n, (I), were obtained from 2‐(pyridin‐3‐yl)‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PIDC) and copper(II) chloride under hydrothermal conditions. The asymmetric unit consists of one independent Cu^II ion, two Cu^I ions, two HPIDC²⁻ ligands and one coordinated water molecule. The Cu^II centre displays a square‐pyramidal geometry (CuN₂O₃), with two N,O‐chelating HPIDC²⁻ ligands occupying the basal plane in a trans geometry and one O atom from a coordinated water molecule in the axial position. The Cu^I atoms adopt three‐coordinated Y‐shaped coordinations. In each [CuN₂O] unit, deprotonated HPIDC²⁻ acts as an N,O‐chelating ligand, and a symmetry‐equivalent HPIDC²⁻ ligand acts as an N‐atom donor via the pyridine group. The HPIDC²⁻ ligands in the polymer serve as T‐shaped 3‐connectors and adopt a μ₃‐κ²N,O:κ²N′,O′:κN′′‐coordination mode, linking one Cu^II and two Cu^I cations. The Cu cations are arranged in one‐dimensional –Cu1–Cu2–Cu3– chains along the [001] direction. Further crosslinking of these chains by HPIDC²⁻ ligands along the b axis in a –Cu2–HPIDC²⁻–Cu3–HPIDC²⁻–Cu1– sequence results in a two‐dimensional polymer in the (100) plane. The resulting (2,3)‐connected net has a (12³)₂(12)₃ topology. Powder X‐ray diffraction confirmed the phase purity for (I), and susceptibilty measurements indicated a very weak ferromagnetic behaviour. A thermogravimetric analysis shows the loss of the apical aqua ligand before decomposition of the title compound.     

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 novel three‐dimensional zinc(II) coordination polymer based on 3,3′‐{[1,3‐phenylenebis(methylene)]bis(oxy)}dibenzoic acid and 1,4‐bis(pyridin‐4‐yl)benzene: synthesis,crystal structure and photocatalytic properties

A novel three‐dimensional (3D) Zn^II coordination polymer, namely, poly[[[1,4‐bis(pyridin‐4‐yl)benzene](μ₃‐3,3′‐{[1,3‐phenylenebis(methylene)]bis(oxy)}dibenzoato)zinc(II)] 1,4‐bis(pyridin‐4‐yl)benzene], {[Zn(C₂₂H₁₆O₆)(C₁₆H₁₂N₂)]·C₁₆H₁₂N₂}_n or {[Zn(PMBD)(DPB)]·DPB}_n, 1 , where H₂PMBD is 3,3′‐{[1,3‐phenylenebis(methylene)]bis(oxy)}dibenzoic acid and DPB is 1,4‐bis(pyridin‐4‐yl)benzene, has been synthesized by self‐assembly using zinc nitrate, a semi‐rigid dicarboxylic acid and a nitrogen‐containing ligand. The single‐crystal X‐ray structure determination indicates that 1 possesses an intriguing 3D architecture with a 4‐connected uninodal cds topology, which is constructed from dinuclear {Zn₂} clusters and V‐shaped PMBD^2? linkers. Compound 1 exhibits excellent photocatalytic activity on the degradation of the organic dyes Rhodamine B (RhB), Rhodamine 6G (Rh6G) and Methyl Red (MR).     

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.     

Two two‐dimensional MnII and NaI coordination polymers constructed by the flexible benzene‐1,4‐dioxy­acetate ligand

Two new two‐dimensional coordination polymers, poly­[[[aqua(2,2′‐bi­pyridine‐κ²N,N′)manganese(II)]‐μ₃‐p‐phenyl­enebis­(oxy­acet­ato)‐κ³O:O′:O′′] dihydrate], {[Mn(C₁₀H₈O₆)(C₁₀H₈N₂)(H₂O)]·2H₂O}_n, (I), and poly­[[di‐μ‐aqua‐bis­[aqua­sodium(I)]]‐μ₄‐p‐phenyl­enebis­(oxy­acetato)‐κO:O′,O′′:O′′′,O′′′′:O′′′′′], [Na₂(C₁₀H₈O₆)(H₂O)₄]_n, (II), have been synthesized and characterized by X‐ray single‐crystal diffraction. In (I), there are two 1,4‐BDOA²⁻ [p‐phenyl­enebis­(oxy­acetate) or, more commonly, benzene‐1,4‐dioxy­acetate] ligands, each lying about inversion centres, while in (II), there is one such ligand and it also has crystallographically imposed inversion symmetry. In (I), each Mn^II atom displays an octahedral MnN₂O₄ configuration, defined by three carboxyl O atoms of different 1,4‐BDOA²⁻ groups, two N atoms of one 2,2′‐bi­pyridine ligand and one water mol­ecule. In (II), each Na^I atom is octahedrally coordinated by one ether O atom, two carboxyl O atoms of different 1,4‐BDOA²⁻ ligands and three water mol­ecules. The metal ions in complexes (I) and (II) are bridged by 1,4‐BDOA²⁻ groups into two‐dimensional layer structures. Furthermore, three‐dimensional supramolecular networks are constructed via hydrogen bonds in (I) and (II), and by additional π–π stacking interactions in (I).     

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.