Synthesis, crystal structures, and thermal and spectroscopic properties of two Cd(II) metal-organic frameworks with a versatile ligand

Two new metal-organic frameworks, namely, [Cd(L)(H2O)] n (1) and {[Cd0.5(L)(4,4′-bipy)0.5][Cd0.5(H2O)(4,4′-bipy)0.5]·H2O} n (2), where H2L = N-pyrazinesulfonyl-glycine and 4,4′-bipy = 4,4′-bipyridine, have been synthesized and characterized by single-crystal X-ray diffraction, IR spectroscopy, elemental, thermogravimetric, and photoluminescent analysis. X-ray diffraction crystallographic analyses indicate that 1 displays a distorted octahedral metal coordination in a 3-connected (4, 82) topology, while the molecular structure of 2 has a 4-connected (4, 4) topology with two perfectly octahedrally coordinated Cd centers. The L2– ligand serves as a N,N,O-tridentate, μ 2-pyrazine-bridging, and μ 2-carboxylate-bridging ligand in 1, and as a N,O-bidentate and μ 2-carboxylate-bridging ligand in 2. In the crystal, a 3D supramolecular architecture is formed by O–H···O hydrogen bond interactions in 1, but through O–H···O as well as π···π stacking in 2. The two compounds show intense fluorescence 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.

Three Coordination Polymers Built by Methoxyphenyl Imidazole Dicarboxylate: Solvothermal Syntheses, Crystal Structures, and Properties

Three coordination polymers [Sr(p-H2MOPhIDC)2]n (1) (p-H3MOPhIDC = 2-p-methoxyphenyl-1H-imidazole-4,5-dicarboxylic acid), {[Cd2(p-HMOPhIDC)2(4,4′-bipy)]⋅H2O}n (4,4′-bipy = 4,4′-bipyridine) (2), and [Zn(p-HMOPhIDC)(4,4′-bipy)]n (3) have been solvothermally synthesized, and structurally characterized by single-crystal X-ray diffraction. Polymer 1 indicates a three-dimensional framework, which can be simplified as a 6-connected lattice. Polymer 2 is also a three-dimensional framework, and contains mixed bridging ligands HMOPhIDC2– and 4,4′-bipy. Polymer 3 exhibits a sheet structure bearing infinite rectangles. The coordination modes of the p-H3MOPhIDC ligand, and the thermal and solid-state photoluminescence properties of the polymers have been investigated as well.

Synthesis, Structure, and Properties of a Chiral Zinc(II) Metal-Organic Framework Featuring Linear Trinuclear Secondary Building Blocks

A chiral metal-organic framework formulated as [Zn3(L-TMTA)2(4,4′-bpy)4]·24H2O (1) was prepared from the reaction of Zn(NO3)2·6H2O with trimesoyltri(L-alanine) (L-TMTAH3) in the presence of 4,4′-bipyridine (4,4′-bpy). Compound 1 features linear trinuclear secondary building blocks [Zn3(syn-syn-COO)2(μ2,η3-COO)2]2+. Each linear trinuclear secondary building block is further linked to another eight ones around it by four L-TMTA3– ligands and eight 4,4′-bpy ligands, leading to the construction of a uninodal three-dimensional framework with triangular prism-like one-dimensional channels. Dehydrated compound 1 displays remarkable adsorption selectivity on CO2 and water vapour over N2 gas.