Poly[μ-aqua-diaqua(μ(3)-1H-benzimid-azole-5-carboxylato-κN:O,O')(μ(2)-1H-benzimidazole-5-carboxylato-κN:O:O')-μ(5)-sulfato-μ(4)-sulfato-tri-cadmium].

The asymmetric unit of the title compound, [Cd(3)(C(8)H(5)N(2)O(2))(2)(SO(4))(2)(H(2)O)(3)](n), contains three Cd(II) ions, two sulfate anions, two 1H-benzimidazole-5-carboxyl-ate (H(2)bic) ligands and three coordinated water mol-ecules. One Cd(II) ion is six-coordinated and exhibits a distorted octa-hedral geometry, while the other two Cd(II) ions are seven-coordinated, displaying a distorted penta-gonal-bipyramidal geometry. The Cd(II) ions are bridged by two types of sulfate anions, producing inorganic chains along [100].

A one-dimensional triaqua-europium(III)-1H,3H-benzimidazol-3-ium-5,6-dicarboxyl-ate-sulfate polymeric structure.

In the title coordination polymer, catena-poly[[[triaqua-europium(III)]-bis-(μ-1H,3H-benzimidazol-3-ium-5,6-dicarb-oxyl-ato-κ(3)O(5),O(5'):O(6))-[triaqua-europium(III)]-di-μ-sulfato-κ(3)O:O,O';κ(3)O,O':O'] hexahydrate], [Eu(2)(C(9)H(5)N(2)O(4))(2)(SO(4))(2)(H(2)O)(6)]·6H(2)O}(n), the 1H,3H-benzimidazol-3-ium-5,6-dicarb-oxy-l-ate ligand is protonated at the imidazole group (H(2)bdc). The Eu(III) ion is coordinated by nine O atoms from two H(2)bdc ligands, two sulfate anions and three water mol-ecules, displaying a bicapped trigonal prismatic geometry. The carboxyl-ate groups of the H(2)bdc ligands and the sulfate anions link the Eu(III) ions, forming a chain along [010].

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(C(9)H(4)N(2)O(4))(C(9)H(5)N(2)O(4))(H(2)O)(3)]·2H(2)O}(n), one of the 1H-benzimidazole-5,6-dicarboxyl-ate (Hbdc) ligands is protonated at the imidazole group (H(2)bdc). The Eu(III) ion is eight-coordinated by two O atoms from two Hbdc ligands, three O atoms from two H(2)bdc ligands and three water mol-ecules, showing a distorted square-anti-prismatic geometry. The Eu(III) ions are bridged by the carboxyl-ate groups of the Hbdc and H(2)bdc ligands, forming a chain along [110], with an Eu⋯Eu separation of 5.

Poly[diaquabis-(μ(4)-fumarato-κO:O:O:O)(μ(4)-fumarato-κO:O,O:O:O,O)(μ(2)-fumaric acid-κO:O)dipraseodymium(III)].

The title complex, [Pr(2)(C(4)H(2)O(4))(3)(C(4)H(4)O(4))(H(2)O)(2)](n), was synthesized by reaction of praseodymium(III) nitrate hexa-hydrate with fumaric acid in a water-ethanol (4:1) solution. The asymmetric unit comprises a Pr(3+) cation, one and a half fumarate dianions (L(2-)), one half-mol-ecule of fumaric acid (H(2)L) and one coordinated water mol-ecule. The carboxyl-ate groups of the fumarate dianion and fumaric acid exhibit different coordination modes.

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

In the title coordination polymer, [Ag(C(14)H(8)NO(2))](n), the Ag(I) cation is coordinated by two O atoms and one N atom from two symmetry-related acridine-9-carboxyl-ate 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 inter-actions [centroid-to-centroid distances 3.

Hemi(4,4'-bipyridinium) hexa-fluorido-phosphate bis-(4-amino-benzoic acid) 4,4'-bipyridine monohydrate.

In the title compound, 0.5C(10)H(10)N(2) (2+)·PF(6) (-)·C(10)H(8)N(2)·2C(7)H(7)NO(2)·H(2)O, the cation is located on a center of symmetry. The crystal structure is determined by a complex three-dimensional network of inter-molecular O-H⋯O, O-H⋯N, N-H⋯N and N-H⋯F hydrogen bonds.

Poly[[aqua-(μ(2)-oxalato)(μ(2)-2-oxido-pyridinium-3-carboxylato)dysprosium(III)] monohydrate].

In the title complex, {[Dy(C(6)H(4)NO(3))(C(2)O(4))(H(2)O)]·H(2)O}(n), the Dy(III) ion is coordinated by seven O atoms from two 2-oxidopyridinium-3-carboxylate ligands, two oxalate ligands and one water mol-ecule, displaying a distorted bicapped trigonal-prismatic geometry. The carboxyl-ate groups of the 2-oxidopyridinium-3-carboxylate and oxalate ligands link dysprosium metal centres, forming layers parallel to (100). These layers are further connected by inter-molecular O-H⋯O hydrogen-bonding inter-actions involving the coordin-ated water mol-ecules, forming a three-dimensional supra-molecular network.

4-(4-Pyrid-yl)pyridinium 3',4,4'-tricarboxy-biphenyl-3-carboxyl-ate dihydrate.

In the title compound, C(10)H(9)N(2) (+)·C(16)H(9)O(8) (-)·2H(2)O, both the cation and anion possess crystallographically imposed centres of symmetry, causing the nitro-gen-bound H atom in the 4-(4-pyrid-yl)pyridinium cation and the acidic H atom of the carboxyl-ate groups at the 3 and 3' positions in the anion to be disordered over two positions with equal occupancies. In the crystal packing, the cations, anions and water mol-ecules are connected by O-H⋯O, C-H⋯O and N-H⋯N hydrogen bonds, forming layers parallel to (20). These layer are further connected into a three-dimensional supra-molecular network by O-H⋯O hydrogen bonds involving the water mol-ecules as H-atom donors and by weak π-π stacking inter-actions between neighbouring benzene and pyridine rings, with centroid-centroid distances of 3.

Poly[diaqua-bis(μ(3)-1H-benzimidazole-5,6-dicarboxyl-ato-κN:O,O:O)bis-(μ(2)-1H,3H-benzimidazolium-5,6-dicarboxyl-ato-κO,O:O)digadolinium(III)].

In the title complex, [Gd(2)(C(9)H(4)N(2)O(4))(2)(C(9)H(5)N(2)O(4))(2)(H(2)O)(2)](n), two of the benzimidazole-5,6-dicarboxyl-ate ligands are pro-ton-ated at the imidazole groups. Each Gd(III) ion is coordinated by six O atoms and one N atom from five ligands and one water mol-ecule, displaying a distorted bicapped trigonal-prismatic geometry. The Gd(III) ions are linked by the carboxyl-ate groups and imidazole N atoms, forming a layer parallel to (001).

Poly[bis-(4,4'-bipyridine)(μ(3)-4,4'-dicarboxybiphenyl-3,3'-di-carboxyl-ato)iron(II)].

In the polymeric title complex, [Fe(C(16)H(8)O(8))(C(10)H(8)N(2))(2)](n), the iron(II) cation is coordinated by four O atoms from three different 4,4'-dicarboxybiphenyl-3,3'-di-carboxyl-ate ligands and two N atoms from two 4,4'-bipyridine ligands in a distorted octa-hedral geometry. The 4,4'-dicarboxybiphenyl-3,3'-di-carboxyl-ate ligands bridge adjacent cations, forming chains parallel to the c axis. The chains are further connected by inter-molecular O-H⋯N hydrogen bonds, forming two-dimensional supra-molecular layers parallel to (010).

Poly[[diaqua-bis(μ(2)-isonicotinato-κN:O)bis-(μ(3)-isonicotinato-κN:O:O')neodymium(III)disilver(I)] nitrate monohydrate].

In the title complex, {[Ag(2)Nd(C(6)H(4)NO(2))(4)(H(2)O)(2)]NO(3)·H(2)O}(n), the Nd(III) ion is coordinated by eight O atoms from six isonicotinate ligands and two water mol-ecules in a distorted square anti-prismatic geometry. Each Ag(I) ion is coordinated by two N atoms from two different isonicotinate ligands. The crystal structure exhibits a two-dimensional heterometallic polymeric layer.

Poly[(6-carboxy-picolinato-κO,N,O)(μ(3)-pyridine-2,6-dicarboxyl-ato-κO,N,O:O:O)dysprosium(III)].

In the title complex, [Dy(C(7)H(3)NO(4))(C(7)H(4)NO(4))](n), one of the ligands is fully deprotonated while the second has lost only one H atom. Each Dy(III) ion is coordinated by six O atoms and two N atoms from two pyridine-2,6-dicarboxyl-ate and two 6-carboxy-picolinate ligands, displaying a bicapped trigonal-prismatic geometry. The average Dy-O bond distance is 2.

Poly[[aqua-(μ(2)-oxalato)(μ(2)-2-oxido-pyridinium-3-carboxylato)holmium(III)] monohydrate].

In the title complex, {[Ho(C(2)O(4))(C(6)H(4)NO(3))(H(2)O)]·(H(2)O)}(n), the Ho(III) ion is coordinated by three O atoms from two 2-oxidopyridinium-3-carboxylate ligands, four O atoms from two oxalate ligands and one water mol-ecule in a distorted bicapped trigonal-prismatic geometry. The 2-oxidopyridin-ium-3-carboxylate and oxalate ligands link the Ho(III) ions into a layer in (100). These layers are further connected by inter-molecular O-H⋯O hydrogen bonds involving the coordinated water mol-ecules to assemble a three-dimensional supra-molecular network.

Poly[diaqua-(μ(2)-oxalato-κO,O:O,O)(μ(2)-pyrazine-2-carboxyl-ato-κN,O:O,O')neodymium(III)].

In the title complex, [Nd(C(5)H(3)N(2)O(2))(C(2)O(4))(H(2)O)(2)](n), the Nd(III) atom is ten-coordinated by one N atom and three O atoms from two pyrazine-2-carboxyl-ate ligands, four O atoms from two oxalate ligands and two water mol-ecules in a distorted bicapped square-anti-prismatic geometry. The two crystallographically independent oxalate ligands, each lying on an inversion center, act as bridging ligands, linking Nd atoms into an extended zigzag chain. Neighboring chains are linked by the pyrazine-2-carboxyl-ate ligands into a two-dimensional layerlike network in the (10) plane.

Reversible shrinkage and expansion of a blue photofluorescent cadmium coordination polymer and in situ tetrazole ligand synthesis.

The metal-organic framework [Cd15(5MT)18(OH)4(SO4)4] (5-MT = 5-methyl-1H-tetrazole) with an unprecedented Cd(3)(micro3-OH)(micro3-SO4) core and two kinds of tetrazole coordination modes was formed by self-assembly and in situ synthesis of the 5-MT tetrazole ligand; the structure exhibits an unusual 3(9) x 4(12) x 5(15) topological network and shows reversible shrinkage and expansion in a crystal-to-crystal dehydration/rehydration process.

4,4'-Bipyridinium bis(perchlorate)-4-aminobenzoic acid-4,4'-bipyridine-water (1/4/2/2).

In the structure of the title compound, C(10)H(10)N(2) (2+)·2ClO(4) (-)·4C(7)H(7)NO(2)·2C(10)H(8)N(2)·2H(2)O, the 4,4'-bipyridinium cation has a crystallographically imposed centre of symmetry. The cation is linked by N-H⋯N hydrogen bonds to adjacent 4,4'-bipyridine mol-ecules, which in turn inter-act via O-H⋯N hydrogen bonds with 4-amino-benzoic acid mol-ecules, forming chains running parallel to [30]. The chains are further connected into a three-dimensional network by N-H⋯O and O-H⋯O hydrogen-bonding inter-actions involving the perchlorate anion, the water mol-ecules and the 4-amino-benzoic acid mol-ecules.

Poly[diaqua-μ-oxalato-μ-pyrazine-2-carbox-yl-ato-lanthanum(III)].

In the title complex, [La(C(5)H(3)N(2)O(2))(C(2)O(4))(H(2)O)(2)](n), the La(III) ion is coordinated by one N and three O atoms from two pyrazine-2-carboxylate ligands, by four O atoms from two oxalate ligands and by two O atoms of two water molecules, displaying a distorted bicapped square-anti-prismatic geometry. The carboxyl-ate groups of pyrazine-2-carboxyl-ate and oxalate ligands link the lanthanum metal centres, forming layers parallel to (10). The layers are further connected by inter-molecular O-H⋯O and N-H⋯O hydrogen-bonding inter-actions, forming a three-dimensional supra-molecular network.

Poly[diaqua-μ(2)-isonicotinato-μ(2)-oxalato-terbium(III)].

In the crystal structure of the title complex, [Tb(C(6)H(4)NO(2))(C(2)O(4))(H(2)O)(2)](n), the Tb(III) ion is coordinated by two O atoms from two isonicotinate (inic) anions, four O atoms of two oxalate anions, and two water mol-ecules, displaying a distorted square-antiprismatic geometry. The Tb(III) ion, the inic anion and the water mol-ecules occupy general positions. One of the two crystallographically independent oxalate anions is located on a center of inversion, whereas the second is located on the twofold rotation axis.

catena-Poly[[[diaqua-terbium(III)]-tri-μ(2)-isonicotinato-κO:O'] tris(perchlorate) monohydrate].

In the title complex, {[Tb(C(6)H(5)NO(2))(3)(H(2)O)(2)](ClO(4))(3)·H(2)O}(n), the Tb(III) ion is coordinated by six O atoms from six isonicotinate (inic) ligands and two water mol-ecules, displaying a bicapped trigonal-prismatic geometry. The inic ligands, which are protonated at the pyridine N atom, link the metal centres, forming a polymeric chain running parallel to the a axis. The chains are further assembled via intra- and inter-molecular O-H⋯O and N-H⋯O hydrogen-bonding inter-actions into a three-dimensional supra-molecular network involving the inic ligands, the water mol-ecules and the perchlorate anions.

Poly[hexa-aqua-tri-μ-malonato-didysprosium(III)].

The title compound, [Dy(2)(C(3)H(2)O(4))(3)(H(2)O)(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 mol-ecules. Each Dy(III) atom is coordinated by six O atoms from four malonate ligands and by three water mol-ecules, and displays a tricapped trigonal-prismatic coordination geometry.

2-Hydr-oxy-3-methoxy-benzoic acid monohydrate.

The asymmetric unit of the title compound, C(8)H(8)O(4)·H(2)O, contains two organic mol-ecules which are connected by the two water mol-ecules through O-H⋯O hydrogen bonds, forming an R(4) (4)(12) ring. Further O-H⋯O hydrogen bonds assemble these rings through R(6) (6)(18) rings, giving rise to infinite helical chains arranged around the b axis. These helical chains are assembled by offset π-π stacking inter-actions [centroid-centroid distance = 3.

Poly[aqua-[μ-N'-(carboxymethyl)ethylene-diamine--N,N,N'-triacetato]neodymium(III)].

In the title complex, [Nd(C(10)H(13)N(2)O(8))(H(2)O)](n), each Nd(III) ion is coordinated by six O atoms and two N atoms from one N'-(carboxymethyl)ethylene-diamine--N,N,N'-triacetate (edta) ligand and one water mol-ecule, 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 inter-molecular O-H⋯O hydrogen-bonding inter-actions into a three-dimensional supra-molecular network.

Poly[diaqua-bis[μ(2)-2,4-(dichloro-phenoxy)-acetato-κO:O']iron(II)].

In the title compound, [Fe(C(8)H(5)Cl(2)O(3))(2)(H(2)O)(2)](n), the Fe(II) atom is located on an inversion center. It is coordinated by four O atoms from four 2,4-dichloro-phenoxy-acetate ligands and two water mol-ecules, displaying a distorted octa-hedral geometry. The carboxyl-ate groups of the 2,4-dichloro-phenoxy-acetate ligands link the Fe atoms, forming a polymeric layered network in the bc plane.