Syntheses, structures, and photoluminescence of two Cd(II) coordination polymers constructed from analogue (pyridyl)imidazole derivative and polycarboxylate acid

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 new one-dimensional CuII complex with a three-dimensional supramolecular architecture incorporating benzene-1,3-dicarboxylate and 1-[(1H-benzotriazol-1-yl)methyl]-1H-imidazole

Subtle modifications of N-donor ligands can result in complexes with very different compositions and architectures. In the complex catena-poly[[bis{1-[(1H-benzotriazol-1-yl)methyl]-1H-imidazole-κN³}copper(II)]-μ-benzene-1,3-dicarboxylato-κ³O¹,O^1':O³], {[Cu(C₈H₄O₄)(C₁₀H₉N₅)₂(H₂O)]·2H₂O}_n, each Cu^II ion is six-coordinated by two N atoms from two crystallographically independent 1-[(1H-benzotriazol-1-yl)methyl]-1H-imidazole (bmi) ligands, by three O atoms from two symmetry-related benzene-1,3-dicarboxylate (bdic^2-) ligands and by one water molecule, leading to a distorted CuN₂O₄ octahedral coordination environment. The Cu^II ions are connected by bridging bdic^2- anions to generate a one-dimensional chain. The bmi ligands coordinate to the Cu^II ions in monodentate modes and are pendant on opposite sides of the main chain. In the crystal, the chains are linked by O-H...O and O-H...N hydrogen bonds, as well as by π-π interactions, into a three-dimensional network. A thermogravimetric analysis was carried out and the fluorescence behaviour of the complex was also investigated.