Rong-Hua Zeng

Reversible Anion Exchange and Sensing in Large Porous Materials Built from 4,4′-Bipyridine via π···π and H-Bonding Interactions

Two unusual d10 compounds, [Zn2(bipy)3(H2O)8(ClO4)2(paba)2].2(bipy).4H2O (1) and [Cd2(bipy)4(H2O)6(ClO4)2(paba)2].(bipy).5H2O (2) (bipy = 4,4-bipyridine, paba = p-aminobenzoate), were obtained from reaction of the metal salts, bipy and paba in an EtOH/H2O mixture. The bipy ligands in the two compounds exhibit two new modes of coordinating to transition metal ions, resulting in the formation of large porous frameworks. Immersion of single crystals of 1 in an aqueous solution of NH4PF6 results in the formation of its hexafluorophosphate derivative 3 as shown by single crystal diffraction. Immersion of crystals of 3 in NaClO4 regenerates 1. Furthermore, compound 1 also shows interesting anion sensing properties in an EtOH/H2O mixture.

Synthesis, crystal structure, and characterization of two lanthanide coordination polymers based on isonicotinate ligand

Two new europium complexes [Eu(inic)3(H2O)] (1) and [Eu(inic)3] (2) [inic = isonicotinate] have been structurally determined by single-crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy, fluorescence, and thermogravimetric analysis. In the two complexes, bifunctional isonicotinate ligands interlink europium metal ions to construct 2-D (for 1) and 3-D (for 2) coordination polymeric networks.

Poly[hexa­aqua­tri-μ-malonato-didysprosium(III)]

The title compound, [Dy2(C3H2O4)3(H2O)6]n, forms a coordination polymeric structure comprising hydrated dysprosium ions and malonate ligands. In the asymmetric unit, there are one dysprosium ion, one and a half malonate ligands, and three water molecules. Each DyIII atom is coordinated by six O atoms from four malonate ligands and by three water molecules, and displays a tricapped trigonal–prismatic coordination geometry. The malonate ligands adopt two types of coordination mode, linking dysprosium centres to form a three-dimensional coordination polymer. The extensive network of hydrogen bonds in this polymer enhances the structural stability.

Poly[aqua­[μ-N′-(carboxymethyl)ethylene­diamine-­N,N,N′-triacetato]neodymium(III)]

In the title complex, [Nd(C10H13N2O8)(H2O)]n, each NdIII ion is coordinated by six O atoms and two N atoms from one N′-(carboxymethyl)ethylenediamine-N,N,N′-triacetate (edta) ligand and one water molecule, displaying a bicapped trigonal-prismatic geometry. The edta ligands link the neodymium metal centres, forming polymeric chains running along the a axis of the unit cell. These chains are further assembled via intermolecular O—H⋯O hydrogen-bonding interactions into a three-dimensional supramolecular network.

4-(1H-Benzo[d]imidazol-2-yl)phenol

In the title compound, C13H10N2O, the benzimidazole system is nearly coplanar with the phenol ring, with a small dihedral angle of 8.11u2005(5)°. Interxadmolecular N—H⋯O and O—H⋯N hydrogen bonding helps to stabilize the crystal structure.

Diaquabis[5-(pyrazin-2-yl)tetrazolato]cobalt(II)

In the title complex, [Co(C5H3N3)2(H2O)2], prepared in a one-pot synthesis, the CoII atom (site symmetry overline{1}), is coordinated by four N atoms from two 5-(2-pyrazinxadyl)tetraxadzolate ligands and by two water molxadecules in a distorted trans-CoO2N4 octaxadhedral geometry. A supraxadmolecular network is formed via interxadmolecular O—H⋯N hydrogen bonds.

A one-dimensional triaqua­europium(III)–1H,3H-benzimidazol-3-ium-5,6-dicarboxyl­ate–sulfate polymeric structure

In the title coordination polymer, catena-poly[[[triaquaeuropium(III)]-bis(μ-1H,3H-benzimidazol-3-ium-5,6-dicarboxylato-κ3 O 5,O 5′:O 6)-[triaquaeuropium(III)]-di-μ-sulfato-κ3 O:O,O′;κ3 O,O′:O′] hexahydrate], [Eu2(C9H5N2O4)2(SO4)2(H2O)6]·6H2O}n, the 1H,3H-benzimidazol-3-ium-5,6-dicarboxylate ligand is protonated at the imidazole group (H2bdc). The EuIII ion is coordinated by nine O atoms from two H2bdc ligands, two sulfate anions and three water molecules, displaying a bicapped trigonal prismatic geometry. The carboxylate groups of the H2bdc ligands and the sulfate anions link the EuIII ions, forming a chain along [010]. These chains are further connected by N—H⋯O and O—H⋯O hydrogen bonds and π–π interactions between the imidazole and benzene rings [centroid–centroid distances = 3.997u2005(4), 3.829u2005(4) and 3.573u2005(4)u2005Å] into a three-dimensional supramolecular network.

2-Hydroxy-3-methoxybenzoic acid

The title compound, C8H8O4, has an intraxadmolecular O—H⋯O hydrogen bond. Interxadmolecular O—H⋯O hydrogen bonding gives rise to a dimeric structure, which is further extended into infinite stacks parallel to the a axis via π–π interxadactions between the aromatic rings of neigboring molxadecules.

catena-Poly[[[triaqua-europium(III)]-μ-(1H-benzimidazole-5,6-dicarboxyl-ato-κO:O)-μ-(1H,3H-benzimidazol-3-ium-5,6-dicarboxyl-ato-κO:O,O)] dihydrate].

In the title one-dimensional coordination polymer, {[Eu(C9H4N2O4)(C9H5N2O4)(H2O)3]·2H2O}n, one of the 1H-benzimidazole-5,6-dicarboxylate (Hbdc) ligands is protonated at the imidazole group (H2bdc). The EuIII ion is eight-coordinated by two O atoms from two Hbdc ligands, three O atoms from two H2bdc ligands and three water molecules, showing a distorted square-antiprismatic geometry. The EuIII ions are bridged by the carboxylate groups of the Hbdc and H2bdc ligands, forming a chain along [110], with an Eu⋯Eu separation of 5.4594u2005(3)u2005Å. These chains are further connected by intermolecular O—H⋯O, N—H⋯O and N—H⋯N hydrogen bonds, as well as π–π interactions between the imidazole and benzene rings [centroid–centroid distances = 3.558u2005(3), 3.906u2005(2), 3.397u2005(3), 3.796u2005(2) and 3.898u2005(2)u2005Å], into a three-dimensional supramolecular network.

catena-Poly[silver(I)-μ-acridine-9-carboxyl-ato-κN:O,O'].

In the title coordination polymer, [Ag(C14H8NO2)]n, the AgI cation is coordinated by two O atoms and one N atom from two symmetry-related acridine-9-carboxylate ligands in a distorted trigonal-planar geometry. The metal atoms are connected by the ligands to form chains running parallel to the b axis. π–π stacking interactions [centroid-to-centroid distances 3.757u2005(2)–3.820u2005(2)u2005Å] and weak Ag⋯O interactions further link the chains to form a layer network parallel to the ab plane. The AgI cation is disordered over two positions, with refined site-occupancy factors of 0.73u2005(3):0.27u2005(3).