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.     

Effects of two benzenedicarboxylic acids on the construction of CdII coordination polymers incorporating a flexible N‐donor ligand

Compared with the monomorphic type of ligand, combining mixed ligands in one coordination polymer offers greater tunability of the structural framework. Employment of N‐heterocyclic ligands and aromatic polycarboxylates is an effective approach for the construction of metal–organic frameworks (MOFs). Two new coordination polymers incorporating both 2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole (imb) and benzenedicarboxylic acid isomers, namely, catena‐poly[[[di‐μ‐chlorido‐bis[(2‐carboxybenzoato‐κ²O¹,O^1′)cadmium(II)]]‐bis{μ‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole‐κ²N:N′}] dihydrate], {[Cd(C₈H₅O₄)Cl(C₁₁H₁₀N₄)]·H₂O}_n, (I), and poly[[aqua(μ₂‐benzene‐1,3‐dicarboxylato‐κ³O¹,O^1′:O³){μ₂‐2‐[(1H‐imidazol‐1‐yl)methyl]‐1H‐benzimidazole‐κ²N:N′}cadmium(II)] dihydrate], {[Cd(C₈H₄O₄)(C₁₁H₁₀N₄)(H₂O)]·2H₂O}_n, (II), have been prepared and structurally characterized by single‐crystal X‐ray diffraction. In polymer (I), imb ligands bridge Cd^II ions, forming a one‐dimensional chain, and 2‐carboxybenzoate anions coordinate to the Cd^II ions in a terminal fashion. Polymer (II) exhibits a two‐dimensional network structure in which imb ligands and the benzene‐1,3‐dicarboxylate anions join Cd^II ions co‐operatively. This indicates that changing of the aromatic dicarboxylic acids can result in polymers with different compositions and architectures. Moreover, their IR spectra, PXRD (powder X‐ray diffraction) patterns, thermogravimetric analyses and fluorescence properties were also investigated.     

Two new CdII and ZnII coordination polymers incorporating 1‐aminobenzene‐3,4,5‐tricarboxylic acid: synthesis,crystal structure and characterization

Aminobenzoic acid derivatives are widely used in the preparation of new coordination polymers since they contain O‐atom donors, as well as N‐atom donors, and have a rich variety of coordination modes which can lead to polymers with intriguing structures and interesting properties. Two new coordination polymers incorporating 1‐aminobenzene‐3,4,5‐tricarboxylic acid (H₃abtc), namely, poly[(μ₃‐1‐amino‐5‐carboxybenzene‐3,4‐dicarboxylato)diaquacadmium(II)], [Cd(C₉H₅NO₆)(H₂O)₂]_n, (I), and poly[[bis(μ₅‐1‐aminobenzene‐3,4,5‐tricarboxylato)triaquatrizinc(II)] dihydrate], {[Zn₃(C₉H₄NO₆)₂(H₂O)₃]·2H₂O}_n, (II), have been prepared and structurally characterized by single‐crystal X‐ray diffraction. In polymer (I), each tridentate 1‐amino‐5‐carboxybenzene‐3,4‐dicarboxylate (Habtc^2?) ligand coordinates to three Cd^II ions to form a two‐dimensional network structure, in which all of the Cd^II ions and Habtc^2? ligands are equivalent, respectively. Polymer (II) also exhibits a two‐dimensional network structure, in which three crystallographically independent Zn^II ions are bridged by two crystallographically independent pentadentate 1‐aminobenzene‐3,4,5‐tricarboxylate (abtc^3?) ligands. This indicates that changing the metal ion can influence the coordination mode of the H₃abtc‐derived ligand and further influence the detailed architecture of the polymer. Moreover, the IR spectra, thermogravimetric analyses and fluorescence properties were investigated.     

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 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 one‐dimensional CdII coordination polymer constructed from 4‐(dimethylamino)pyridinium‐1‐acetate ligands and thiocyanate coordination bridges

A new cadmium–thiocyanate complex, namely catena‐poly[1‐carboxymethyl‐4‐(dimethylamino)pyridinium [cadmium(II)‐tri‐μ‐thiocyanato‐κ⁴N:S;κ²S:N] [[[4‐(dimethylamino)pyridinium‐1‐acetate‐κ²O,O′]cadmium(II)]‐di‐μ‐thiocyanato‐κ²N:S;κ²S:N]], {(C₉H₁₃N₂O₂)[Cd(NCS)₃][Cd(NCS)₂(C₉H₁₂N₂O₂)]}_n, was synthesized by the reaction of 4‐(dimethylamino)pyridinium‐1‐acetate, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, two types of Cd^II atoms are observed in distorted octahedral coordination environments. One type of Cd^II atom is coordinated by two O atoms from the carboxylate group of the 4‐(dimethylamino)pyridinium‐1‐acetate ligand and by two N atoms and two S atoms from four different thiocyanate ligands, while the second type of Cd^II atom is coordinated by three N atoms and three S atoms from six different thiocyanate ligands. Neighbouring Cd^II atoms are linked by thiocyanate bridges to form a one‐dimensional zigzag chain and a one‐dimensional coordination polymer. Hydrogen‐bond interactions are involved in the formation of the supramolecular network.     

A 4′‐(4‐carboxyphenyl)‐3,2′:6′,3′′‐terpyridine‐based luminescent cadmium(II) coordination polymer for the detection of 2,4,6‐trinitrophenol

The title coordination polymer, poly[bis[μ3‐4‐(3,2′:6′,3′′‐terpyridin‐4′‐yl)benzoato]cadmium(II)], [Cd(C₂₂H₁₄N₃O₂)₂]_n or [Cd(3‐cptpy)₂]_n, (I), has been synthesized solvothermally and characterized by IR spectroscopy, thermogravimetric analysis, and single‐crystal and powder X‐ray diffraction. The structure is composed of 3‐cptpy^? ligands bridging Cd atoms, with each Cd atom coordinated by six ligands and each ligand coordinating to three Cd atoms. Each Cd atom is in a slightly distorted trans‐N₂O₄ octahedral environment, forming a two‐dimensional layer structure with a (3,6)‐connected topology. Layers are linked to each other by π–π stacking, resulting in a three‐dimensional supramolecular framework. The strong luminescence and good thermal stability of (I) indicate that it can potentially be used as a luminescence sensor. The compound also shows a highly selective and sensitive response to 2,4,6‐trinitrophenol through the luminescence quenching effect.     

One‐ and two‐dimensional CdII coordination polymers incorporating organophosphinate ligands

Reaction of cadmium nitrate with diphenylphosphinic acid in dimethylformamide solvent yielded the one‐dimensional coordination polymer catena‐poly[[bis(dimethylformamide‐κO)cadmium(II)]‐bis(μ‐diphenylphosphinato‐κ²O:O′)], [Cd(C₁₂H₁₀O₂P)₂(C₃H₇NO)₂]_n, (I). Addition of 4,4′‐bipyridine to the synthesis afforded a two‐dimensional extended structure, poly[[(μ‐4,4′‐bipyridine‐κ²N:N′)bis(μ‐diphenylphosphinato‐κ²O:O′)cadmium(II)] dimethylformamide monosolvate], {[Cd(C₁₂H₁₀O₂P)₂(C₁₀H₈N₂)]·C₃H₇NO}_n, (II). In (II), the 4,4′‐bipyridine molecules link the Cd^II centers in the crystallographic a direction, while the phosphinate ligands link the Cd^II centers in the crystallographic b direction to complete a two‐dimensional sheet structure. Consideration of additional π–π interactions of the phenyl rings in (II) produces a three‐dimensional structure with channels that encapsulate dimethylformamide molecules as solvent of crystallization. Both compounds were characterized by single‐crystal X‐ray diffraction and FT–IR analysis.     

Novel one‐ and two‐dimensional ZnII coordination polymers based on a versatile 3,6‐bis(pyridin‐4‐yl)phenanthrene‐9,10‐dione ligand

Two new Zn^II coordination polymers, namely, catena‐poly[[dibromidozinc(II)]‐μ‐[3,6‐bis(pyridin‐4‐yl)phenanthrene‐9,10‐dione‐κ²N:N′]], [ZnBr₂(C₂₄H₁₄N₂O₂)]_n, (1), and poly[[bromido[μ₃‐10‐hydroxy‐3,6‐bis(pyridin‐4‐yl)phenanthren‐9‐olato‐κ³N:N′:O⁹]zinc(II)] hemihydrate], {[ZnBr(C₂₄H₁₅N₂O₂)]·0.5H₂O}_n, (2), have been synthesized through hydrothermal reaction of ZnBr₂ and a 60° angular phenanthrenedione‐based linker, i.e. 3,6‐bis(pyridin‐4‐yl)phenanthrene‐9,10‐dione, in different solvent systems. Single‐crystal analysis reveals that polymer (1) features one‐dimensional zigzag chains connected by weak C—H...π and π–π interactions to form a two‐dimensional network. The two‐dimensional networks are further stacked in an ABAB fashion along the a axis through C—H...O hydrogen bonds. Layers A and B comprise left‐ and right‐handed helical chains, respectively. Coordination polymer (2) displays a wave‐like two‐dimensional layered structure with helical chains. In this compound, there are two opposite helical –Zn–HL– chains [HL is 10‐hydroxy‐3,6‐bis(pyridin‐4‐yl)phenanthren‐9‐olate] in adjacent layers. The layers are packed in an ABAB sequence and are further connected through O—H...Br and O—H...O hydrogen‐bond interactions to form a three‐dimensional framework. In (1) and (2), the mutidentate L and HL ligands exhibits different coordination modes.     

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.     

Crystallographic report: Coordination polymers containing Cd(NO3)2 and Cd(H2O)22+ units bridged by btp ligands (btp = 2,6‐bis(N′‐1,2,4‐triazolyl)pyridine)

There are two kinds of coordination polymers in the title compound: one contains Cd(NO₃)₂ units bridged by 2,6‐bis(N′‐1,2,4‐triazolyl)pyridine (btp) ligands and the other contains Cd(H₂O)₂²⁺ bridged by btp ligands. The two coordination polymers are connected through hydrogen bonds. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

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.     

One‐dimensional copper(II) coordination polymers based on 1,3‐bis(pyridin‐4‐yl)propane and diimine ligands

Two one‐dimensional (1D) coordination polymers (CPs), namely catena‐poly[[[aqua(2,2′‐bipyridine‐κ²N,N′)(nitrato‐κO)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₀H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 1 ), and catena‐poly[[[aqua(nitrato‐κO)(1,10‐phenanthroline‐κ²N,N′)copper(II)]‐μ‐1,3‐bis(pyridin‐4‐yl)propane‐κ²N:N′] nitrate], {[Cu(NO₃)(C₁₂H₈N₂)(C₁₃H₁₄N₂)(H₂O)]·NO₃}_n ( 2 ), have been synthesized using [Cu(NO₃)(NN)(H₂O)₂]NO₃, where NN = 2,2′‐bipyridine (bpy) or 1,10‐phenanthroline (phen), as a linker in a 1:1 molar ratio. The CPs were characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and single‐crystal X‐ray structure determination. The 1,3‐bis(pyridin‐4‐yl)propane (dpp) ligand acts as a bridging ligand, leading to the formation of a 1D polymer. The octahedral coordination sphere around copper consists of two N atoms from bpy for 1 or phen for 2 , two N atoms from dpp, one O atom from water and one O atom from a coordinated nitrate anion. Each structure contains two crystallographically independent chains in the asymmetric unit and the chains are linked via hydrogen bonds into a three‐dimensional network.     

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.     

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.     

Two new cadmium(II) coordination polymers based on bis(1,2,4‐triazol‐1‐yl)alkane ligands and pyrazine‐2,3‐dicarboxylic acid

Assemblies of pyrazine‐2,3‐dicarboxylic acid and Cd^II in the presence of bis(1,2,4‐triazol‐1‐yl)butane or bis(1,2,4‐triazol‐1‐yl)ethane under ambient conditions yielded two new coordination polymers, namely poly[[tetraaqua[μ₂‐1,4‐bis(1,2,4‐triazol‐1‐yl)butane‐κ²N⁴:N^4′]bis(μ₂‐pyrazine‐2,3‐dicarboxylato‐κ³N¹,O²:O³)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₈H₁₂N₆)(H₂O)₄]·2H₂O}_n, (I), and poly[[diaqua[μ₂‐1,2‐bis(1,2,4‐triazol‐1‐yl)ethane‐κ²N⁴:N^4′]bis(μ₃‐pyrazine‐2,3‐dicarboxylato‐κ⁴N¹,O²:O³:O^3′)dicadmium(II)] dihydrate], {[Cd₂(C₆H₂N₂O₄)₂(C₆H₈N₆)(H₂O)₂]·2H₂O}_n, (II). Complex (I) displays an interesting two‐dimensional wave‐like structure and forms a distinct extended three‐dimensional supramolecular structure with the help of O—H...N and O—H...O hydrogen bonds. Complex (II) has a three‐dimensional framework structure in which hydrogen bonds of the O—H...N and O—H...O types are found.     

Synthesis,structural characterization and thermal properties of a new copper(II) one‐dimensional coordination polymer based on bridging N,N′‐bis(2‐hydroxybenzylidene)‐2,2‐dimethylpropane‐1,3‐diamine and dicyanamide ligands

The design and synthesis of polymeric coordination compounds of 3d transition metals are of great interest in the search for functional materials. The coordination chemistry of the copper(II) ion is of interest currently due to potential applications in the areas of molecular biology and magnetochemistry. A novel coordination polymer of Cu^II with bridging N,N′‐bis(2‐hydroxyphenyl)‐2,2‐dimethylpropane‐1,3‐diamine (H₂L‐DM) and dicyanamide (dca) ligands, catena‐poly[[[μ₂‐2,2‐dimethyl‐N,N′‐bis(2‐oxidobenzylidene)propane‐1,3‐diamine‐1:2κ⁶O,N,N′,O′:O,O′]dicopper(II)]‐di‐μ‐dicyanamido‐1:2′κ²N¹:N⁵;2:1′κ²N¹:N⁵], [Cu₂(C₁₉H₂₀N₂O₂)(C₂N₃)₂]_n, has been synthesized and characterized by CHN elemental analysis, IR spectroscopy, thermal analysis and X‐ray single‐crystal diffraction analysis. Structural studies show that the Cu^II centres in the dimeric asymmetric unit adopt distorted square‐pyramidal geometries, as confirmed by the Addison parameter (τ) values. The chelating characteristics of the L‐DM²⁻ ligand results in the formation of a Cu^II dimer with a double phenolate bridge in the asymmetric unit. In the crystal, the dimeric units are further linked to adjacent dimeric units through μ_1,5‐dca bridges to produce one‐dimensional polymeric chains.     

A self‐penetrated three‐dimensional zinc(II) coordination framework based on 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid and 1,3‐bis[(imidazol‐1‐yl)methyl]benzene ligands: synthesis,structure and properties

With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H₃TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel Zn^II‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ₃‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn₃(C₂₄H₁₂N₃O₆)₂(C₁₄H₁₄N₄)₃]·2C₃H₇NO·3H₂O}_n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent Zn^II centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB^3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each Zn^II centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The Zn^II centres are connected by TATB^3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link Zn^II centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 6⁵·7·8¹³·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr⁴⁺ and Cu²⁺ ions.     

Synthesis,structure, thermostability and luminescence properties of ZnII and CdII coordination polymers based on dimethysuccinate and flexible 1,4‐bis(imidazol‐1‐ylmethyl)benzene ligands

The design and synthesis of functional coordination polymers is motivated not only by their structural beauty but also by their potential applications. Zn^II and Cd^II coordination polymers are promising candidates for producing photoactive materials because these d¹⁰ metal ions not only possess a variety of coordination numbers and geometries, but also exhibit luminescence properties when bound to functional ligands. It is difficult to predict the final structure of such polymers because the assembly process is influenced by many subtle factors. Bis(imidazol‐1‐yl)‐substituted alkane/benzene molecules are good bridging ligands because their flexibility allows them to bend and rotate when they coordinate to metal centres. Two new Zn^II and Cd^II coordination polymers based on mixed ligands, namely, poly[[μ₂‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ²N³:N^3′]bis(μ₃‐2,2‐dimethylbutanoato‐κ³O¹:O⁴:O^4′)dizinc(II)], [Zn₂(C₆H₈O₄)₂(C₁₄H₁₄N₄)]_n, and poly[[μ₂‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ²N³:N^3′]bis(μ₃‐2,2‐dimethylbutanoato‐κ⁵O¹,O^1′:O⁴,O^4′:O⁴)dicadmium(II)], [Cd₂(C₆H₈O₄)₂(C₁₄H₁₄N₄)]_n, have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric analysis. Both complexes crystallize in the monoclinic space group C2/c with similar unit‐cell parameters and feature two‐dimensional structures formed by the interconnection of S‐shaped Zn(Cd)–2,2‐dimethylsuccinate chains with 1,4‐bis(imidazol‐1‐ylmethyl)benzene bridges. However, the Cd^II and Zn^II centres have different coordination numbers and the 2,2‐dimethylsuccinate ligands display different coordination modes. Both complexes exhibit a blue photoluminescence in the solid state at room temperature.