Low‐dimensional coordination polymeric structures in alkali metal complex salts of the herbicide (2,4‐dichlorophenoxy)acetic acid (2,4‐D)

The Li, Rb and Cs complexes with the herbicide (2,4‐dichlorophenoxy)acetic acid (2,4‐D), namely poly[[aqua[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ³O¹:O¹:O^1′]lithium(I)] dihydrate], {[Li(C₈H₅Cl₂O₃)(H₂O)]·2H₂O}_n, (I), poly[μ‐aqua‐bis[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ⁴O¹:O^1′:O^1′,Cl²]dirubidium(I)], [Rb₂(C₈H₅Cl₂O₃)₂(H₂O)]_n, (II), and poly[μ‐aqua‐bis[μ₃‐(2,4‐dichlorophenoxy)acetato‐κ⁵O¹:O^1′:O^1′,O²,Cl²]dicaesium(I)], [Cs₂(C₈H₅Cl₂O₃)₂(H₂O)]_n, (III), respectively, have been determined and their two‐dimensional polymeric structures are described. In (I), the slightly distorted tetrahedral LiO₄ coordination involves three carboxylate O‐atom donors, of which two are bridging, and a monodentate aqua ligand, together with two water molecules of solvation. Conjoined six‐membered ring systems generate a one‐dimensional coordination polymeric chain which extends along b and interspecies water O—H...O hydrogen‐bonding interactions give the overall two‐dimensional layers which lie parallel to (001). In hemihydrate complex (II), the irregular octahedral RbO₅Cl coordination about Rb⁺ comprises a single bridging water molecule which lies on a twofold rotation axis, a bidentate O_carboxy,Cl‐chelate interaction and three bridging carboxylate O‐atom bonding interactions from the 2,4‐D ligand. A two‐dimensional coordination polymeric layer structure lying parallel to (100) is formed through a number of conjoined cyclic bridges, including a centrosymmetric four‐membered Rb₂O₂ ring system with an Rb...Rb separation of 4.3312 (5) Å. The coordinated water molecule forms intralayer aqua–carboxylate O—H...O hydrogen bonds. Complex (III) comprises two crystallographically independent (Z′ = 2) irregular CsO₆Cl coordination centres, each comprising two O‐atom donors (carboxylate and phenoxy) and a ring‐substituted Cl‐atom donor from the 2,4‐D ligand species in a tridentate chelate mode, two O‐atom donors from bridging carboxylate groups and one from a bridging water molecule. However, the two 2,4‐D ligands are conformationally very dissimilar, with one phenoxyacetate side chain being synclinal and the other being antiperiplanar. The minimum Cs...Cs separation is 4.4463 (5) Å. Structure extension gives coordination polymeric layers which lie parallel to (001) and are stabilized by intralayer water–carboxylate O—H...O hydrogen bonds.     

Two‐dimensional coordination polymeric structures in caesium complexes with ring‐substituted phenoxyacetic acids

The two‐dimensional polymeric structures of the caesium complexes with the phenoxyacetic acid analogues (4‐fluorophenoxy)acetic acid, (3‐chloro‐2‐methylphenoxy)acetic acid and the herbicidally active (2,4‐dichlorophenoxy)acetic acid (2,4‐D), namely poly[[μ₅‐(4‐fluorophenoxy)acetato][μ₄‐(4‐fluorophenoxy)acetato]dicaesium], [Cs₂(C₈H₆FO₃)₂]_n, (I), poly[aqua[μ₅‐(3‐chloro‐2‐methylphenoxy)acetato]caesium], [Cs(C₉H₈ClO₃)(H₂O)]_n, (II), and poly[[μ₇‐(2,4‐dichlorophenoxy)acetato][(2,4‐dichlorphenoxy)acetic acid]caesium], [Cs(C₈H₅Cl₂O₃)(C₈H₆Cl₂O₃)]_n, (III), are described. In (I), the Cs⁺ cations of the two individual irregular coordination polyhedra in the asymmetric unit (one CsO₇ and the other CsO₈) are linked by bridging carboxylate O‐atom donors from the two ligand molecules, both of which are involved in bidentate chelate O_carboxy,O_phenoxy interactions, while only one has a bidentate carboxylate O,O′‐chelate interaction. Polymeric extension is achieved through a number of carboxylate O‐atom bridges, with a minimum Cs...Cs separation of 4.3231 (9) Å, giving layers which lie parallel to (001). In hydrated complex (II), the irregular nine‐coordination about the Cs⁺ cation comprises a single monodentate water molecule, a bidentate O_carboxy,O_phenoxy chelate interaction and six bridging carboxylate O‐atom bonding interactions, giving a Cs...Cs separation of 4.2473 (3) Å. The water molecule forms intralayer hydrogen bonds within the two‐dimensional layers, which lie parallel to (100). In complex (III), the irregular centrosymmetric CsO₆Cl₂ coordination environment comprises two O‐atom donors and two ring‐substituted Cl‐atom donors from two hydrogen bis[(2,4‐dichlorophenoxy)acetate] ligand species in a bidentate chelate mode, and four O‐atom donors from bridging carboxyl groups. The duplex ligand species lie across crystallographic inversion centres, linked through a short O—H...O hydrogen bond involving the single acid H atom. Structure extension gives layers which lie parallel to (001). The present set of structures of Cs salts of phenoxyacetic acids show previously demonstrated trends among the alkali metal salts of simple benzoic acids with no stereochemically favourable interactive substituent groups for formation of two‐dimensional coordination polymers.     

Two‐dimensional coordination polymeric structures in the sodium,potassium and rubidium complex salts with (4‐fluorophenoxy)acetic acid

The structures of the sodium, potassium and rubidium complex salts of (4‐fluorophenoxy)acetic acid (PFPA), namely poly[μ‐aqua‐aqua‐μ‐[2‐(4‐fluorophenoxy)acetato]‐κ³O ¹,O ²:O^1′‐sodium], [Na(C₈H₆FO₃)(H₂O)₂]_n , (I), and isotypic poly[μ₅‐[2‐(4‐fluorophenoxy)acetato]‐κ⁵O ¹,O ²:O ¹,O ^1′:O ^1′:O ^1′:O^1′‐potassium], [K(C₈H₆FO₃)]_n , (II), and poly[μ₅‐[2‐(4‐fluorophenoxy)acetato]‐κ⁵O ¹,O ²:O ¹,O ^1′:O ^1′:O ^1′:O^1′‐rubidium], [Rb(C₈H₆FO₃)]_n , (III), have been determined and their coordination polymeric structures described. In the structure of (I), the very distorted octahedral NaO₆ coordination polyhedron comprises two bidentate chelating O‐atom donors (carboxylate and phenoxy) of the PFPA ligand and three O‐atom donors from water molecules, one monodentate and the other μ₂‐bridging between inversion‐related Na centres in a cyclic manner. A bridging carboxylate donor generates two‐dimensional polymer layers lying parallel to (001), in which intralayer water O—H…O hydrogen‐bonding associations are also present. Structures (II) and (III) are isotypic, each having an irregular M O₇ stereochemistry, with the primary metal–ligand bidentate chelate similar to that in (I) and extended into a two‐dimensional polymeric layered structure, lying parallel to (100), through five additional bridging carboxylate O atoms. Two of these bonds are from an O ,O ′‐bidentate chelate interaction and the other three are from μ₃‐O‐atom bridges, generating cyclic links with short M …M separations [3.9064 (17) Å for (II) and 4.1001 (8) for (III)], the shortest being a centrosymmetric four‐membered cyclic link. In the crystals of (I)–(III), intralayer C—H…F interactions are present, but no π–π ring interactions are found.     

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‐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.     

Supramolecular architectures in CoII and CuII complexes with thiophene‐2‐carboxylate and 2‐amino‐4,6‐dimethoxypyrimidine ligands

The coordination chemistry of mixed‐ligand complexes continues to be an active area of research since these compounds have a wide range of applications. Many coordination polymers and metal–organic framworks are emerging as novel functional materials. Aminopyrimidine and its derivatives are flexible ligands with versatile binding and coordination modes which have been proven to be useful in the construction of organic–inorganic hybrid materials and coordination polymers. Thiophenecarboxylic acid, its derivatives and their complexes exhibit pharmacological properties. Cobalt(II) and copper(II) complexes of thiophenecarboxylate have many biological applications, for example, as antifungal and antitumor agents. Two new cobalt(II) and copper(II) complexes incorporating thiophene‐2‐carboxylate (2‐TPC) and 2‐amino‐4,6‐dimethoxypyrimidine (OMP) ligands have been synthesized and characterized by X‐ray diffraction studies, namely (2‐amino‐4,6‐dimethoxypyrimidine‐κN)aquachlorido(thiophene‐2‐carboxylato‐κO)cobalt(II) monohydrate, [Co(C₅H₃O₂S)Cl(C₆H₉N₃O₂)(H₂O)]·H₂O, (I), and catena‐poly[copper(II)‐tetrakis(μ‐thiophene‐2‐carboxylato‐κ²O:O′)‐copper(II)‐(μ‐2‐amino‐4,6‐dimethoxypyrimidine‐κ²N¹:N³)], [Cu₂(C₅H₃O₂S)₄(C₆H₉N₃O₂)]_n, (II). In (I), the Co^II ion has a distorted tetrahedral coordination environment involving one O atom from a monodentate 2‐TPC ligand, one N atom from an OMP ligand, one chloride ligand and one O atom of a water molecule. An additional water molecule is present in the asymmetric unit. The amino group of the coordinated OMP molecule and the coordinated carboxylate O atom of the 2‐TPC ligand form an interligand N—H…O hydrogen bond, generating an S(6) ring motif. The pyrimidine molecules also form a base pair [R₂²(8) motif] via a pair of N—H…N hydrogen bonds. These interactions, together with O—H…O and O—H…Cl hydrogen bonds and π–π stacking interactions, generate a three‐dimensional supramolecular architecture. The one‐dimensional coordination polymer (II) contains the classical paddle‐wheel [Cu₂(CH₃COO)₄(H₂O)₂] unit, where each carboxylate group of four 2‐TPC ligands bridges two square‐pyramidally coordinated Cu^II ions and the apically coordinated OMP ligands bridge the dinuclear copper units. Each dinuclear copper unit has a crystallographic inversion centre, whereas the bridging OMP ligand has crystallographic twofold symmetry. The one‐dimensional polymeric chains self‐assemble via N—H…O, π–π and C—H…π interactions, generating a three‐dimensional supramolecular architecture.     

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 linear heterometallic bismuth–copper coordination polymer containing two types of organic ligands

In the linear coordination polymer catena‐poly[[[aqua(1,10‐phenanthroline‐κ²N,N′)copper(II)]‐μ‐pyridine‐2,6‐dicarboxylato‐κ⁴O²:O^2′,N,O⁶‐[(nitrato‐κ²O,O′)bismuth(III)]‐μ‐pyridine‐2,6‐dicarboxylato‐κ⁴O²,N,O⁶:O^6′] dihydrate], {[Bi^IIICu^II(C₇H₃NO₄)₂(NO₃)(C₁₂H₈N₂)(H₂O)]·2H₂O}_n, the Bi^III cation is O,N,O′‐chelated by the two pyridine‐2,6‐dicarboxylate ligands and O,O′‐chelated by the nitrate anion, the nine coordinating atoms conferring a tricapped trigonal prismatic environment on the metal centre. Each pyridine‐2,6‐dicarboxylate ligand uses one of its carboxylate O atoms to bind to an aqua(1,10‐phenanthroline)copper(II) unit, the Cu—O dative bonds giving rise to the formation of a ribbon motif. The Cu^II cation exhibits a square‐pyramidal geometry. The ribbon motif propagates along the shortest axis of the triclinic unit cell and the solvent water molecules are hydrogen bonded to the same ribbon.     

The three‐dimensional hydrogen‐bonded structures in the ammonium and sodium salt hydrates of 4‐aminophenylarsonic acid

The structures of two hydrated salts of 4‐aminophenylarsonic acid (p‐arsanilic acid), namely ammonium 4‐aminophenylarsonate monohydrate, NH₄⁺·C₆H₇AsNO₃⁻·H₂O, (I), and the one‐dimensional coordination polymer catena‐poly[[(4‐aminophenylarsonato‐κO)diaquasodium]‐μ‐aqua], [Na(C₆H₇AsNO₃)(H₂O)₃]_n, (II), have been determined. In the structure of the ammonium salt, (I), the ammonium cations, arsonate anions and water molecules interact through inter‐species N—H...O and arsonate and water O—H...O hydrogen bonds, giving the common two‐dimensional layers lying parallel to (010). These layers are extended into three dimensions through bridging hydrogen‐bonding interactions involving the para‐amine group acting both as a donor and an acceptor. In the structure of the sodium salt, (II), the Na⁺ cation is coordinated by five O‐atom donors, one from a single monodentate arsonate ligand, two from monodentate water molecules and two from bridging water molecules, giving a very distorted square‐pyramidal coordination environment. The water bridges generate one‐dimensional chains extending along c and extensive interchain O—H...O and N—H...O hydrogen‐bonding interactions link these chains, giving an overall three‐dimensional structure. The two structures reported here are the first reported examples of salts of p‐arsanilic acid.     

One‐pot concomitant preparation of two copper(II) coordination polymers with different configurations of bridging bithiophene ligands

By employing the conjugated bithiophene ligand 5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene (bibp), which can exhibit trans and cis conformations, two different Cu^II coordination polymers, namely, poly[[μ‐5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene‐κ²N:N′](μ₂‐4,4′‐oxydibenzoato‐κ²O:O′)copper(II)], [Cu(C₁₄H₈O₅)(C₁₄H₁₀N₄S₂)]_n or [Cu(bibp)(oba)]_n, (I), and catena‐poly[μ‐aqua‐bis[μ‐5,5′‐bis(1H‐imidazol‐1‐yl)‐2,2′‐bithiophene‐κ²N:N′]bis(μ₃‐4,4′‐oxydibenzoato)‐κ³O:O′:O′′;κ⁴O:O′,O′′:O′‐dicopper(II)], [Cu₂(C₁₄H₈O₅)₂(C₁₄H₁₀N₄S₂)(H₂O)]_n or [Cu₂(bibp)(oba)₂(H₂O)]_n, (II), have been prepared through one‐pot concomitant crystallization and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, powder X‐ray diffraction (PXRD) and thermogravimetric (TG) analysis. Single‐crystal X‐ray diffraction indicates that the most interesting aspect of the structure is the existence of sole trans and cis conformations of the bibp ligand in a single net of (I) and (II), respectively. Compound (I) displays a threefold interpenetrating three‐dimensional framework with a 4‐connected {6⁵.8} cds topology, whereas (II) features a one‐dimensional chain structure. In the crystal of (II), the polymeric chains are further extended through C—H…O hydrogen bonds and C—H…π interactions into a three‐dimensional supramolecular architecture. In addition, strong intramolecular O—H…O hydrogen bonds formed between the bridging water molecules and the carboxylate O atoms improve the stability of the framework of (II). Furthermore, solid‐state UV–Vis spectroscopy experiments show that compounds (I) and (II) exhibit optical band gaps which are characteristic for optical semiconductors, with values of 2.70 and 2.26 eV, respectively.     

The coordination complex structures and hydrogen bonding in the three‐dimensional alkaline earth metal salts (Mg,Ca, Sr and Ba) of (4‐aminophenyl)arsonic acid

(4‐Aminophenyl)arsonic acid (p‐arsanilic acid) is used as an antihelminth in veterinary applications and was earlier used in the monosodium salt dihydrate form as the antisyphilitic drug atoxyl. Examples of complexes with this acid are rare. The structures of the alkaline earth metal (Mg, Ca, Sr and Ba) complexes with (4‐aminophenyl)arsonic acid (p‐arsanilic acid) have been determined, viz. hexaaquamagnesium bis[hydrogen (4‐aminophenyl)arsonate] tetrahydrate, [Mg(H₂O)₆](C₆H₇AsNO₃)·4H₂O, (I), catena‐poly[[[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]‐[diaquacalcium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ]] dihydrate], {[Ca(C₆H₇AsNO₃)₂(H₂O)₂]·2H₂O}_n , (II), catena‐poly[[triaquastrontium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Sr(C₆H₇AsNO₃)₂(H₂O)₃]_n , (III), and catena‐poly[[triaquabarium]‐bis[μ₂‐hydrogen (4‐aminophenyl)arsonato‐κ²O :O ′]], [Ba(C₆H₇AsNO₃)₂(H₂O)₃]_n , (IV). In the structure of magnesium salt (I), the centrosymmetric octahedral [Mg(H₂O)₆]²⁺ cation, the two hydrogen p‐arsanilate anions and the four water molecules of solvation form a three‐dimensional network structure through inter‐species O—H and N—H hydrogen‐bonding interactions with water and arsonate O‐atom and amine N‐atom acceptors. In one‐dimensional coordination polymer (II), the distorted octahedral CaO₆ coordination polyhedron comprises two trans‐related water molecules and four arsonate O‐atom donors from bridging hydrogen arsanilate ligands. One bridging extension is four‐membered via a single O atom and the other is eight‐membered via O :O ′‐bridging, both across inversion centres, giving a chain coordination polymer extending along the [100] direction. Extensive hydrogen‐bonding involving O—H…O, O—H…N and N—H…O interactions gives an overall three‐dimensional structure. The structures of the polymeric Sr and Ba complexes (III) and (IV), respectively, are isotypic and are based on irregular M O₇ coordination polyhedra about the M ²⁺ centres, which lie on twofold rotation axes along with one of the coordinated water molecules. The coordination centres are linked through inversion‐related arsonate O :O ′‐bridges, giving eight‐membered ring motifs and forming coordination polymeric chains extending along the [100] direction. Inter‐chain N—H…O and O—H…O hydrogen‐bonding interactions extend the structures into three dimensions and the crystal packing includes π–π ring interactions [minimum ring centroid separations = 3.4666 (17) Å for (III) and 3.4855 (8) Å for (IV)].     

A two‐dimensional zinc(II) coordination polymer based on mixed dimethyl succinate and bipyridine ligands: synthesis,structure, thermostability and luminescence properties

From the viewpoint of crystal engineering, the construction of crystalline polymeric materials requires a rational choice of organic bridging ligands for the self‐assembly process. Multicarboxylate ligands are of particular interest due to their strong coordination activity towards metal ions, as well as their various coordination modes and versatile conformations. The structural chemistry of dicarboxylate‐based coordination polymers of transition metals has been developed through the grafting of N‐containing organic linkers into carboxylate‐bridged transition metal networks. A new luminescent two‐dimensional zinc(II) coordination polymer containing bridging 2,2‐dimethylsuccinate and 4,4′‐bipyridine ligands, namely poly[[aqua(μ₂‐4,4′‐bipyridine‐κ²N:N′)bis(μ₃‐2,2‐dimethylbutanedioato)‐κ⁴O¹,O^1′:O⁴:O^4′;κ⁵O¹:O¹,O⁴:O⁴,O^4′‐dizinc(II)] dihydrate], {[Zn₂(C₆H₈O₄)₂(C₁₀H₈N₂)(H₂O)]·2H₂O}_n, has been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction and elemental, IR and thermogravimetric analyses. In the structure, the 2,2‐dimethylsuccinate ligands link linear tetranuclear Zn^II subunits into one‐dimensional chains along the c axis. 4,4′‐Bipyridine acts as a tethering ligand expanding these one‐dimensional chains into a two‐dimensional layered structure. Hydrogen‐bonding interactions between the water molecules (both coordinated and free) and carboxylate O atoms strengthen the packing of the layers. Furthermore, the luminescence properties of the complex were investigated. The compound exhibits a blue photoluminescence in the solid state at room temperature and may be a good candidate for potential hybrid inorganic–organic photoactive materials.     

Two cadmium(II) fluorous coordination compounds tuned by different bipyridines

Fluorine is the most electronegative element and can be used as an excellent hydrogen‐bond acceptor. Fluorous coordination compounds exhibit several advantageous properties, such as enhanced high thermal and oxidative stability, low polarity, weak intermolecular interactions and a small surface tension compared to hydrocarbons. C—H…F—C interactions, although weak, play a significant role in regulating the arrangement of the organic molecules in the crystalline state and stabilizing the secondary structure. Two cadmium(II) fluorous coordination compounds formed from 2,2′‐bipyridine, 4,4′‐bipyridine and pentafluorobenzoate ligands, namely catena‐poly[[aqua(2,2′‐bipyridine‐κ²N ,N ′)(2,3,4,5,6‐pentafluorobenzoato‐κO )cadmium(II)]‐μ‐2,3,4,5,6‐pentafluorobenzoato‐κ²O :O ′], [Cd(C₇F₅O₂)₂(C₁₀H₈N₂)(H₂O)]_n , (1), and catena‐poly[[diaquabis(2,3,4,5,6‐pentafluorobenzoato‐κO )cadmium(II)]‐μ‐4,4′‐bipyridine‐κ²N :N ′], [Cd(C₇F₅O₂)₂(C₁₀H₈N₂)(H₂O)₂]_n , (2), have been synthesized solvothermally and structurally characterized. Compound (1) shows a one‐dimensional chain structure composed of Cd—O coordination bonds and is stabilized by π–π stacking and O—H…O hydrogen‐bond interactions. Compound (2) displays a one‐dimensional linear chain structure formed by Cd—N coordination interactions involving the 4,4′‐bipyridine ligand. Adjacent one‐dimensional chains are extended into two‐dimensional sheets by O—H…O hydrogen bonds between the coordinated water molecules and adjacent carboxylate groups. Moreover, the chains are further linked by C—H…F—C interactions to afford a three‐dimensional network. In both structures, hydrogen bonding involving the coordinated water molecules is a primary driving force in the formation of the supramolecular structures.     

A new linear bismuth coordination polymer based on 1,10‐phenanthroline‐2,9‐dicarboxylic acid: ionothermal synthesis,crystal structure and fluorescence properties

A new linear bismuth(III) coordination polymer, catena‐poly[[chloridobismuth(III)]‐μ₃‐1,10‐phenanthroline‐2,9‐dicarboxylato‐κ⁶O²:O²,N¹,N¹⁰,O⁹:O⁹], [Bi(C₁₄H₆N₂O₄)Cl]_n, has been obtained by an ionothermal method and characterized by elemental analysis, energy‐dispersive X‐ray spectroscopy, IR spectroscopy, thermal stability studies and single‐crystal X‐ray diffraction. The structure is constructed by Bi(C₁₄H₆N₂O₄)Cl fragments in which each Bi^III centre is seven‐coordinated by one Cl atom, four O atoms and two N atoms. The coordination geometry of the Bi^III cation is distorted pentagonal–bipyramidal (BiO₄N₂Cl), with one bridging carboxylate O atom and one Cl atom located in the axial positions. The Bi(C₁₄H₆N₂O₄)Cl fragments are further extended into a one‐dimensional linear polymeric structure via subsequent but different centres of symmetry (bridging carboxylate O atoms). Neighbouring linear chains are assembled via weak C—H...O and C—H...Cl hydrogen bonds, forming a three‐dimensional supramolecular architecture. Intermolecular π–π stacking interactions are observed, with centroid‐to‐centroid distances of 3.678 (4) Å, which further stabilize the structure. In addition, the solid‐state fluorescence properties of the title coordination polymer were investigated.     

The structure of {[Co(pht)(bpy)(H2O)]·3H2O}n (pht is phthalate and bpy is 4,4′‐bipyridine) and the role of solvent water clusters in structure stability

The Co^II cation in poly[[aqua(μ‐benzene‐1,2‐dicarboxylato‐κ³O¹,O²:O¹)(μ‐4,4′‐bipyridine‐κ²N:N′)cobalt(II)] trihydrate], {[Co(C₈H₄O₄)(C₁₀H₈N₂)(H₂O)]·3H₂O}_n, is octahedrally coordinated by two N atoms of two 4,4′‐bipyridine ligands, three O atoms from phthalate anions and a fourth O atom from a coordinated water molecule. The packing consists of planes of coordination polymers linked by hydrogen bonds mediated by three solvent water molecules; the linkage is achieved by the water molecules forming intricate oligomeric clusters which also involve the O atoms of the phthalate ligands.     

In situ single‐crystal to single‐crystal (SCSC) transformation of the one‐dimensional polymer catena‐poly[[diaqua(sulfato)copper(II)]‐μ2‐glycine] into the two‐dimensional polymer poly[μ2‐glycine‐μ4‐sulfato‐copper(II)]

The one‐dimensional coordination polymer catena‐poly[diaqua(sulfato‐κO)copper(II)]‐μ₂‐glycine‐κ²O:O′], [Cu(SO₄)(C₂H₅NO₂)(H₂O)₂]_n, (I), was synthesized by slow evaporation under vacuum of a saturated aqueous equimolar mixture of copper(II) sulfate and glycine. On heating the same blue crystal of this complex to 435 K in an oven, its aspect changed to a very pale blue and crystal structure analysis indicated that it had transformed into the two‐dimensional coordination polymer poly[(μ₂‐glycine‐κ²O:O′)(μ₄‐sulfato‐κ⁴O:O′:O′′:O′′)copper(II)], [Cu(SO₄)(C₂H₅NO₂)]_n, (II). In (I), the Cu^II cation has a pentacoordinate square‐pyramidal coordination environment. It is coordinated by two water molecules and two O atoms of bridging glycine carboxylate groups in the basal plane, and by a sulfate O atom in the apical position. In complex (II), the Cu^II cation has an octahedral coordination environment. It is coordinated by four sulfate O atoms, one of which bridges two Cu^II cations, and two O atoms of bridging glycine carboxylate groups. In the crystal structure of (I), the one‐dimensional polymers, extending along [001], are linked via N—H...O, O—H...O and bifurcated N—H...O,O hydrogen bonds, forming a three‐dimensional framework. In the crystal structure of (II), the two‐dimensional networks are linked via bifurcated N—H...O,O hydrogen bonds involving the sulfate O atoms, forming a three‐dimensional framework. In the crystal structures of both compounds, there are C—H...O hydrogen bonds present, which reinforce the three‐dimensional frameworks.     

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.     

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.     

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.