Influence of the anion on the coordination mode of an unsymmetrical N-heterocyclic ligand in Cd(II) complexes: From discrete molecule to one- and two-dimensional structures

High H2O-Assisted Proton Conduction in One Highly Stable Sr(II)-Organic Framework Constructed by Tetrazole-Based Imidazole Dicarboxylic Acid

Solid electrolyte materials with high structural stability and excellent proton conductivity (σ) have long been a popular and challenging research topic in the fuel cell field. This problem can be addressed because of the crystalline metal-organic frameworks' (MOFs') high structural stability, adjustable framework composition, and dense H-bonded networks. Herein, one highly stable Sr(II) MOF, {[Sr(H2tmidc)2(H2O)3]·4H2O}n (1) (H3tmidc = 2-(1H-tetrazolium-1-methylene)-1H-imidazole-4,5-dicarboxylic acid) was successfully fabricated, which was structurally characterized by single-crystal X-ray diffraction and electrochemically examined by the AC impedance determination. The results demonstrated that the σ of the compound manifested a positive dependence on temperature and humidity, and the optimal proton conductivity is as high as 1.22 × 10-2 S/cm under 100 °C and 98% relative humidity, which is at the forefront of reported MOFs with ultrahigh σ. The analysis of the proton conduction mechanism reveals that numerous tetrazolium groups, carboxyl groups, coordination, and crystallization water molecules in the framework are responsible for the high efficiency of proton transport. This work offers a fresh perspective on how to create novel crystalline proton conductive materials.

Crystal structure of diiodido-bis(6,6′-dimethoxy-2,2′-(ethane-1,2-diylbis(nitrilomethanylylidene)) diphenolato)tricadmium(II), C36H36Cd3I2N4O8

C36H36Cd3I2N4O8, orthorhombic, Pbca (no. 61), a = 18.909(4) Å, b = 16.149(3) Å, c = 26.050(5) Å, V = 7955(3) Å3, Z = 8, Rgt (F) = 0.0439, wRref (F 2) = 0.0752, T = 293(2) K.

Single crystal growth of water-soluble metal complexes with the help of the nano-crystallization method

Let pipetting robots set up nano crystallization trials of water-soluble metal complexes in order to obtain single crystals!

Coordination of 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone to zinc and cadmium: Monotonic and non-monotonic bond length variations for [H(sebenzimMe)]2MCl2 complexes (M = Zn, Cd, Hg)

The reactions of 1-methyl-1,3-dihydro-2H-benzimidazole-2-selone, H(sebenzimMe), towards the zinc and cadmium halides, MX2 (M = Zn, Cd; X = Cl, Br, I), afford the adducts, [H(sebenzimMe)]2MX2, which have been structurally characterized by X-ray diffraction. The halide ligands of each of these complexes participate in hydrogen bonding interactions with the imidazole N-H moieties, although the nature of the interactions depends on the halide. Specifically, the chloride and bromide derivatives, [H(sebenzimMe)]2ZnX2 and [H(sebenzimMe)]2CdX2 (X = Cl, Br), exhibit two intramolecular N-H•••X interactions, whereas the iodide derivatives, [H(sebenzimMe)]2ZnI2 and [H(sebenzimMe)]2CdI2, exhibit only one intramolecular N-H•••I interaction. Comparison of the M-Se and M-Cl bond lengths of the chloride series, [H(sebenzimMe)]2MCl2 (M = Zn, Cd, Hg), indicates that while the average M-Cl bond lengths progressively increase as the metal becomes heavier, the variation in M-Se bond length exhibits a non-monotonic trend, with the Cd-Se bond being the longest. These different trends provide an interesting subtlety concerned with use of covalent radii in predicting bond length differences. In addition to tetrahedral [H(sebenzimMe)]2CdCl2, [H(sebenzimMe)]3,CdCl2•[H(sebenzim)Me]4CdCl2, which features both five-coordinate and six-coordinate coordinate centers, has also been structurally characterized. Finally, the reaction between CdI2 and H(sebenzimMe) at elevated temperatures affords the 1-methylbenzimidazole complex, [H(sebenzimMe)]-[H(benzimMe)]CdI2, a transformation that is associated with cleavage of the C-Se bond.

Crystal structure of bis(acetato-κO)bis{2-((1H-tetrazol-1-yl)methyl)-1H-benzo[d]imidazole-κN}zinc(II), C22H22N12O4Zn

C22H22N12O4Zn, monoclinic, P21/c (no. 14), a = 9.864(2) Å, b = 8.6657(17) Å, c = 30.803(8) Å, β = 106.67(3)°, V = 2522.3(10) Å3, Z = 4, R gt(F) = 0.0630, wR ref(F 2) = 0.1625, T = 293(2) K.

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-κ⁴O¹,O^1':O²,O^2')[μ-2-(1H-imidazol-1-ylmethyl)-6-methyl-1H-benzimidazole-κ²N²:N³]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-bdic^2-) ligands and by one water molecule, leading to a CdN₂O₅ distorted pentagonal bipyramidal coordination environment. The immb and 1,2-bdic^2- ligands bridge Cd^II ions and form a two-dimensional network structure. O-H...O and N-H...O hydrogen bonds stabilize the structure. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviour and fluorescence properties of the title polymer have been investigated.

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

Careful choice of the organic ligands is one of the most important parameters in the rational design and synthesis of coordination polymers. Aromatic polycarboxylates have been widely used in the preparation of metal-organic polymers since they can utilize various coordination modes to form diverse structures and can act as hydrogen-bond acceptors and donors in the assembly of supramolecular structures. Nitrogen-heterocyclic organic compounds have also been used extensively as ligands for the construction of polymers with interesting structures. In the polymers catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN³}cobalt(II)]-μ₂-benzene-1,4-dicarboxylato-κ²O¹:O⁴] dihydrate], {[Co(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n, (I), and catena-poly[[[diaquabis{2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole-κN³}nickel(II)]-μ₂-benzene-1,4-dicarboxylato-κ²O¹:O⁴] dihydrate], {[Ni(C₈H₄O₄)(C₁₂H₁₁N₄)₂(H₂O)₂]·2H₂O}_n, (II), the Co^II or Ni^II ion lies on an inversion centre and exhibits a slightly distorted octahedral coordination geometry, coordinated by two N atoms from two imidazole rings and four O atoms from two monodentate carboxylate groups and two water molecules. The dicarboxylate ligands bridge metal ions forming a polymeric chain. The 2-[(1H-imidazol-1-yl)methyl]-6-methyl-1H-benzimidazole ligands coordinate to the Co^II or Ni^II centres in monodentate modes through an imidazole N atom and are pendant on opposite sides of the main chain. The two structures are isomorphous. In the crystal, the one-dimensional chains are further connected through O-H...O, O-H...N and N-H...O hydrogen bonds, leading to a three-dimensional supramolecular architecture. In addition, the IR spectroscopic properties, PXRD patterns, thermogravimetric behaviours and fluorescence properties of both polymers have been investigated.

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

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

A new one-dimensional Cd(II) 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-κ(4)O(1),O(1'):O(2),O(2')]-cadmium(II)-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ(2)N(2):N(3);κ(2)N(3):N(2)] 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-bdic(2-)) ligands and two N atoms from two symmetry-related imb ligands. Two Cd(II) ions are connected by two benzene-1,2-dicarboxylate ligands to generate a binuclear [Cd2(1,2-bdic)2] unit. The binuclear units are further connected into a one-dimensional chain by pairs of bridging imb ligands. These one-dimensional chains are further connected through N-H...O hydrogen bonds and π-π interactions, leading to a two-dimensional layered structure. The dimethylformamide solvent molecules are organized in dimeric pairs via weak interactions. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

A new one-dimensional Zn(II) coordination polymer based on 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole and benzene-1,2-dicarboxylate

Multidentate N-heterocyclic compounds form a variety of metal complexes with many intriguing structures and interesting properties. The title coordination polymer, catena-poly[zinc(II)-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole}-κ(2)N(3):N(3');N(3'):N(3)-zinc(II)-bis(μ-benzene-1,2-dicarboxylato)-κ(2)O(1):O(2);κ(3)O(1),O(1'):O(2)], [Zn2(C8H4O4)2(C11H10N4)2]n, has been synthesized by the reaction of Zn(NO3)2 with 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) and benzene-1,2-dicarboxylic acid (H2bdic) under hydrothermal conditions. There are two crystallographically distinct imb ligands [imb(A) and imb(B)] in the structure which adopt very similar coordination geometries. The imb(A) ligand bridges two symmetry-related Zn1 ions, yielding a binuclear [(Zn1)2{imb(A)}2] unit, and the imb(B) ligand bridges two symmetry-related Zn2 ions resulting in a binuclear [(Zn2)2{imb(B)}2] unit. The above-mentioned binuclear units are further connected alternately by pairs of bridging bdic(2-) ligands, forming an infinite one-dimensional chain. These one-dimensional chains are further connected through N-H···O hydrogen bonds, leading to a two-dimensional layered structure. In addition, the title polymer exhibits good fluorescence properties in the solid state at room temperature.

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-κ(2)N:N'}(μ-5-carboxybenzene-1,3-dicarboxylato-κ(2)O(1):O(3))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 (Hbtc(2-)) ligands in a slightly distorted tetrahedral geometry. The Zn(II) ions are bridged by Hbtc(2-) and bmi ligands, leading to a 4-connected two-dimensional network with the topological notation (4(4).6(2)). 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.

Crystal structures and luminescence properties of two Cd(II) complexes based on 2-(1H-imidazol-1-methyl)-6-methyl-1H-benzimidazole

Two new complexes, {[Cd(immb)I2]·DMF} n (1) and {[Cd3(immb)(btc)2]·H2O} n (2) (immb = 2-(1H-imidazol- 1-methyl)-6-methyl-1H-benzimidazole, btc = 1,2,3-benzenetricarboxylate, DMF = dimethyl formamide), have been synthesized and characterized. Single crystal X-ray diffraction shows that 1 exhibits a chain structure constructed by immb ligands bridging Cd(II) ions. In 2, Cd(II) ions are linked by immb ligands with bridging mode and btc3– anions with the μ 2-η 2:η 1 bonding pattern leading to a 2D structure. Luminescent properties have been investigated in the solid state at room temperature.

A two-dimensional layered Cd(II) coordination polymer with a three-dimensional supramolecular architecture incorporating mixed multidentate N- and O-donor ligands

The combination of N-heterocyclic and multicarboxylate ligands is a good choice for the construction of metal-organic frameworks. In the title coordination polymer, poly[bis{μ2-1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole-κ(2)N(3):N(4)}(μ4-butanedioato-κ(4)O(1):O(1'):O(4):O(4'))(μ2-butanedioato-κ(2)O(1):O(4))dicadmium], [Cd(C4H4O4)(C9H8N6)]n, each Cd(II) ion exhibits an irregular octahedral CdO4N2 coordination geometry and is coordinated by four O atoms from three carboxylate groups of three succinate (butanedioate) ligands and two N atoms from two 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) ligands. Cd(II) ions are connected by two kinds of crystallographically independent succinate ligands to generate a two-dimensional layered structure with bimt ligands located on each side of the layer. Adjacent layers are further connected by hydrogen bonding, leading to a three-dimensional supramolecular architecture in the solid state. Thermogravimetric analysis of the title polymer shows that it is stable up to 529 K and then loses weight from 529 to 918 K, corresponding to the decomposition of the bimt ligands and succinate groups. The polymer exhibits a strong fluorescence emission in the solid state at room temperature.

A one-dimensional zinc(II) coordination polymer based on mixed multidentate N- and O-donor ligands

In the title coordination polymer, catena-poly[[bis[{1-[(1H-benzimidazol-2-yl-κN(3))methyl]-1H-tetrazole}zinc(II)]-bis(μ4-pentane-1,5-dioato-1:2:1':2'κ(4)O(1):O(1'):O(5):O(5'))] methanol disolvate], {[Zn(C5H6O4)(C9H8N6)]·CH3OH}n, each Zn(II) ion is five-coordinated by four O atoms from four glutarate ligands and by one N atom from a 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) ligand, leading to a slightly distorted square-pyramidal coordination environment. Two Zn(II) ions are linked by four bridging glutarate carboxylate groups to generate a dinuclear [Zn2(CO2)4] paddle-wheel unit. The dinuclear units are further connected into a one-dimensional chain via the glutarate ligands. The bimt ligands coordinate to the Zn(II) ions in a monodentate mode and are pendant on both sides of the main chain. In the crystal, the chains are linked by O-H···O and N-H···O hydrogen bonds into a two-dimensional layered structure. Adjacent layers are further packed into a three-dimensional network through van der Waals forces. A thermogravimetric analysis was carried out and the photoluminescent behaviour of the polymer was investigated.

catena-Poly[[(diiodidocadmium)-μ-{1-[(1H-benzimidazol-2-yl)meth-yl]-1H-imidazole-κN:N'}] N,N-dimethyl-formamide monosolvate]

In the title complex, {[CdI(2)(C(11)H(10)N(4))]·C(3)H(7)NO}(n), the Cd(II) ion is four-coordinated by two N atoms from two 1-[(1H-benzimidazol-1-yl)meth-yl]-1H-imidazole (bmi) ligands and by two terminal I(-) anions in a distorted tetra-hedral geometry. One of the two I(-) anions is disordered over two sets of sites, with refined occupancies of 0.66 (5) and 0.34 (5). The Cd(II) ions are bridged by bmi ligands, leading to the formation of a chain along [001]. Dimethyl-formamide solvent mol-ecules are located between these chains. Classical N-H⋯O hydrogen bonding between the bmi ligands and the solvent mol-ecules leads to a consolidation of the structure.

Synthesis, Crystal Structures and Photoluminescence Properties of three Zn(II) Complexes Derived from an Unsymmetrical N-Heterocyclic Ligand

The Zn(II) complexes: [Zn(Hbimtz)2Cl2]·H2O, [Zn2(Hbimtz)4Cl4]·H2O, and {[Zn2(H2O)4(SO4)2(Hbimtz)2]·(H2O)2.5}n, where Hbimtz = 1-[(1H-benzimidazole-2-yl)methyl]-1,2,3,4-tetrazole, have been synthesised and their structures determined. The mononuclear complexes have four–coordinated Zn(II) centres with two benzimidazole N atoms from Hbimtz and two terminal Cl atoms, while the Zn(II) centre of the dinuclear complex is ligated by N atoms of Hbimtz and O atoms of sulfate and water molecules in distorted octahedral geometry. The thermal stability and luminescent properties of the three complexes are also discussed.