Six metal-organic architectures from a 5-methoxyisophthalate linker: assembly, structural variety and catalytic features.

A methoxy-functionalized isophthalic acid, 5-methoxy isophthalic acid (H2mia), was used a versatile linker for assembling six new metal(ii) compounds under hydrothermal conditions. The obtained products were [Cu2(µ2-mia)2(phen)2(H2O)2]·2H2O (1), [Mn(µ3-mia)(phen)]n (2), [Co(µ2-mia)(2,2'-bipy)(H2O)]n·nH2O (3), [Co(µ3-mia)(µ2-4,4'-bipy)]n·nH2O (4), [Co(µ3-mia)(py)2]n (5), and [Cd(µ2-mia)(py)(H2O)2]n·nH2O (6), where phen(1,10-phenanthroline), 2,2'-bipy(2,2'-bipyridine), 4,4'-bipy(4,4'-bipyridine) or py(pyridine) were incorporated as auxiliary ligands. The crystal structures of 1-6 range from 0D (1) and 1D (2, 3, 5, 6) CPs to a 2D network (4) with a variety of topological types. The catalytic behavior of 1-6 was studied in the cyanosilylation reaction between trimethylsilyl cyanide and aldehydes, resulting in up to 99% yields of products under optimized conditions. Various reaction parameters as well as catalyst recycling and substrate scope were investigated. This study widens the use of H2mia as a versatile dicarboxylate linker for assembling a diversity of functional metal-organic architectures with remarkable structural features and catalytic properties.

H-Bonded and metal(ii)-organic architectures assembled from an unexplored aromatic tricarboxylic acid: structural variety and functional properties.

This study reports the application of an aromatic tricarboxylic acid, 2,5-di(4-carboxylphenyl)nicotinic acid (H3dcna) as a versatile and unexplored organic building block for assembling a new series of metal(ii) (M = Co, Ni, Zn, Fe, and Mn) complexes and coordination polymers, namely [M(Hdcna)(phen)2(H2O)]·H2O (M = Co (1), Ni (2)), [Zn(µ-Hdcna)(phen)]n (3), [Co(µ-Hdcna)(bipy)(H2O)2]n·nH2O (4), [Zn2(µ-Hdcna)2(bipy)2(H2O)4]·6H2O (5), [Zn(µ3-Hdcna)(H2biim)]n (6), [Ni2(Hdcna)2(µ-bpb)(bpb)2(H2O)4] (7), [Fe(µ4-Hdcna)(µ-H2O)]n·nH2O (8), and [Mn3(µ5-dcna)2(bipy)2(H2O)2]n·2nH2O (9). Such a diversity of products was hydrothermally prepared from the corresponding metal(ii) salts, H3dcna as a principal multifunctional ligand, and N-donor mediators of crystallization (1,10-phenanthroline, phen; 2,2'-bipyridine, bipy; 2,2'-biimidazole, H2biim; or 1,4-bis(pyrid-4-yl)benzene, bpb). The obtained products 1-9 were fully characterized by standard methods (elemental analysis, FTIR, TGA, PXRD) and the structures were established by single-crystal X-ray diffraction. These vary from the discrete monomers (1, 2) and dimers (5, 7) to the 1D (3, 4, 6) and 2D (8, 9) coordination polymers (CPs). Structural and topological characteristics of hydrogen-bonded or metal-organic architectures in 1-9 were highlighted, revealing that their structural multiplicity depends on the type of metal(ii) source and crystallization mediator. Thermal stability as well as luminescent, magnetic, or catalytic properties were explored for selected compounds. In particular, the zinc(ii) derivatives 3, 5, and 6 were applied as efficient heterogeneous catalysts for the cyanosilylation of aldehydes with trimethylsilyl cyanide at room temperature. The catalytic reactions were optimized by tuning the different reaction parameters (solvent composition, time, catalyst loading) and the substrate scope was also explored. Compound 5 revealed superior catalytic activity leading to up to 75% product yields, while maintaining its original performance upon recycling for at least four reaction cycles. Finally, the obtained herein products represent the unique examples of coordination compounds derived from H3dcna, thus opening up the use of this multifunctional tricarboxylic acid for generating complexes and coordination polymers with interesting structures and functional properties.

Hydrothermal generation, structural versatility and properties of metal(ii)-organic architectures driven by a pyridine-tricarboxylic acid.

An aromatic tricarboxylic acid, 4-(6-carboxy-pyridin-3-yl)-isophthalic acid (H3cpia), was applied as a building block for the hydrothermal syntheses of a new series of twelve metal(ii) (M = Mn, Co, Ni, Zn, Cd, Pb) coordination compounds, namely [Mn(H2cpia)2(H2O)2] (1), [M(Hcpia)(phen)(H2O)2] (M = Co, 2; Ni, 3; Zn, 4), [Zn(Hcpia)(2,2'-bipy)(H2O)2]5·4H2O (5), [Zn2(µ-Hcpia)2(2,2'-bipy)2] (6), [M(µ-Hcpia)(phen)(H2O)]n (M = Co, 7; Cd, 8), {[Pb(µ4-Hcpia)]·2H2O}n (9), [Cd4(µ3-cpia)2Cl2(phen)6(H2O)2]·10H2O (10), {[Zn3(µ3-cpia)2(phen)3]·10H2O}n (11), and {[Zn4(µ4-cpia)2(µ-OH)2(µ-4,4'-bipy)2]·4,4'-bipy·2H2O}n (12). These products were assembled from aqueous mixtures containing metal(ii) chlorides, H3cpia as a main tricarboxylic acid block, sodium hydroxide and an optional N-donor crystallization mediator (i.e., 1,10-phenanthroline, phen; 2,2'-bipyridine, 2,2'-bipy; or 4,4'-bipyridine, 4,4'-bipy). Compounds 1-12 were fully characterized by standard solid-state methods (IR spectroscopy, elemental analysis, TGA, PXRD, and single-crystal X-ray diffraction). Their structures range from discrete 0D monomers (1-5), dimer (6) or tetramer (10) to 1D coordination polymers (7, 8, and 11) and 2D metal-organic layers (9 and 12). Structural and topological features of H-bonded and metal-organic architectures were highlighted, showing that the structural diversity of 1-12 is influenced by the type of metal(ii) node, the level of deprotonation of H3cpia, reaction temperature, and presence of crystallization mediator. Thermal behavior, magnetic, luminescent and photocatalytic properties of selected compounds were investigated and discussed. In fact, cobalt(ii) coordination polymer 7 acts as a stable and recycable photocatalyst for the oxidative UV-light-assisted degradation of an organic dye in aqueous medium; methylene blue was used as a model dye pollutant in waste water. Finally, the obtained products 2 and 4-12 represent the first examples of Co, Zn, Cd, and Pb coordination compounds derived from H3cpia, thus introducing its application as a multifunctional picolinate-isophthalate building block for the generation of metal-organic architectures.

A new series of Cd(ii) metal-organic architectures driven by soft ether-bridged tricarboxylate spacers: synthesis, structural and topological versatility, and photocatalytic properties.

Two multifunctional, ether-bridged tricarboxylic acids, 2-(4-carboxylphenoxy)terephthalic acid (H3cpta) and 2-(3,5-dicarboxylatobenzyloxy)benzoic acid (H3dbba), were used as unexplored and highly versatile building blocks for the hydrothermal generation of a novel series of cadmium(ii) metal-organic architectures. These were formulated as [Cd(µ-Hcpta)(phen)(py)]n (1), {[Cd3(µ5-cpta)2(phen)3]·8H2O}n (2), {[Cd3(µ5-cpta)2(2,2'-bipy)3]·6H2O}n (3), {[Cd(µ3-cpta)(Hbpa)]·2H2O}n (4), {[Cd6(µ4-cpta)2(µ6-cpta)2(H2biim)2(H2O)6]·5H2O}n (5), [Cd3(µ4-cpta)2(µ-prz)(H2O)4]n (6), {[Cd3(µ4-dbba)2(phen)3]·H2O}n (7), and {[Cd3(µ3-dbba)2(2,2'-bipy)3(H2O)3]·2H2O}n (8) on the basis of single-crystal X-ray diffraction, elemental analysis, FTIR, PXRD, and TGA data. Products 1-8 were assembled in the presence of N-donor crystallization mediators selected from pyridine (py), 1,10-phenanthroline (phen), 2,2'-bipyridine (2,2'-bipy), bis(4-pyridyl)amine (bpa), 2,2'-biimidazole (H2biim), or piperazine (prz). The nature of the crystallization mediator and/or the type of principal tricarboxylate building block have a significant effect on the structural diversity, dimensionality, and topology of the resulting cadmium-organic architectures. These span from 1D (1, 8) and 2D (7) coordination polymers to 3D metal-organic frameworks (2-6) with intricate topologies (3,4,5T64 in 2 and 3, utp (103)-d in 4, 3,4,4T9 in 6) that also include unprecedented types in 5 and 7. Besides, MOF 6 features a 3D + 3D two-fold interpenetrated framework. Luminescent and photocatalytic properties of selected materials were investigated, showing that coordination polymer 7 is a promising photocatalyst for the UV-light-driven degradation of methylene blue as a model organic dye pollutant. Moreover, products 7 and 8 are the first examples of structurally characterized coordination compounds derived from H3dbba.

A new series of Co, Ni, Zn, and Cd metal-organic architectures driven by an unsymmetrical biphenyl-tricarboxylic acid: hydrothermal assembly, structural features and properties.

This study reports the hydrothermal synthesis of a novel series of twelve coordination compounds, namely, {[Cd(µ-Hnbtc)(H2O)4]·H2O}n (1), [Zn2(µ-Hnbtc)2(phen)2]·2H2O (2), [Zn(Hnbtc)(phen)2(H2O)]·4.5H2O (3), [Ni(Hnbtc)(phen)2(H2O)]·6H2O (4), [Zn2(µ-Hnbtc)2(2,2'-bipy)2]·2H2O (5), [Cd3(µ5-nbtc)(µ6-nbtc)(2,2'-bipy)2(H2O)]n (6), {[Zn3(µ3-nbtc)2(phen)3(H2O)2]·4H2O} (7), [Co(H2O)6][Co2(nbtc)2(µ-4,4'-bipy)(4,4'-bipy)2(H2O)6]·8H2O (8), {[Ni3(µ4-nbtc)2(µ-4,4'-bipy)2.5(µ-H2O)(H2O)3]·4H2O}n (9), {[Cd2(µ4-nbtc)(µ-OH)(2,2'-bipy)2]·H2O}n (10), [Cd2(µ4-nbtc)(µ-OH)(phen)2(H2O)]n (11), and {[Zn2(µ5-nbtc)(µ3-OH)(µ-4,4'-bipy)]·4,4'-bipy·H2O}n (12), which are derived from 3'-nitro-biphenyl-2,4,4'-tricarboxylic acid (H3nbtc) as a virtually unexplored building block. These compounds were generated in aqueous medium from the corresponding metal(ii) chlorides as a metal source, H3nbtc as a principal building block, NaOH as a base, and simple N,N-donor aromatic ligands as crystallization mediators (i.e., 1,10-phenanthroline, phen; 2,2'-bipyridine, 2,2'-bipy; or 4,4'-bipyridine, 4,4'-bipy). All products 1-12 were completely characterized in the solid state by IR spectroscopy, elemental and thermogravimetric (TGA) analyses, powder (PXRD) and single-crystal X-ray diffraction. Structures of 1-12 range from discrete 0D dimers (2 and 5) or monomers (3, 4, and 8) to 1D coordination polymers (CPs, 1, 6, 7, 10, and 11) and 3D metal-organic frameworks (MOFs, 9 and 12). A broad structural diversity of 1-12 is guided by the type of the metal(ii) node, the molar ratio between H3nbtc and sodium hydroxide, and the kind of crystallization mediator. Topological analysis and classification of metal-organic underlying nets was made, disclosing the following topological types: 2C1 (in 1 and 7), 1M2-1 (in 2 and 5), SP1-periodic net (in 10 and 11), tfz-d (in 12), and some topologically unique nets (in 6 and 9). Luminescence behavior of 1-3, 5-7, and 10-12 was studied in the solid state. Magnetic properties of a Ni(ii) MOF 9 were also investigated and modeled. All obtained products 1-12 represent the first structurally characterized examples of coordination compounds derived from H3nbtc, thus opening up its application in coordination chemistry as a novel tricarboxylate building block.

Hydrothermal assembly, structures, topologies, luminescence, and magnetism of a novel series of coordination polymers driven by a trifunctional nicotinic acid building block.

In this work, a trifunctional N,O-building block, 5-(4-carboxyphenoxy)nicotinic acid (H2cpna), that combines three distinct types of functional groups (COOH, N-pyridyl, and O-ether) was used for the hydrothermal assembly of thirteen new coordination compounds: [Co(µ3-Hcpna)2]n (1), [Mn(µ4-cpna)(H2O)]n (2), [Mn(µ4-cpna)(H2O)2]n (3), [Mn(µ-cpna)(2,2'-bipy)(H2O)2]n (4), {[Ni(µ3-cpna)(2,2'-bipy)(H2O)]2·H2O}n (5), {[Cd(µ3-cpna)(2,2'-bipy)]·2H2O}n (6), [Zn2(µ-cpna)2(2,2'-bipy)2] (7), [Cu(µ-cpna)(2,2'-bipy)(H2O)]n (8), {[Mn(µ-cpna)(phen)2]·6H2O}n (9), {[Ni(µ3-cpna)(phen)(H2O)]·H2O}n (10), [Zn2(µ-cpna)2(phen)2] (11), {[Pb(µ3-cpna)(phen)]·H2O}n (12), and [Ni(µ3-cpna)(4,4'-bipy)0.5(H2O)]n (13). These products were synthesized from the corresponding metal(ii) chlorides, H2cpna, NaOH, and optional N-donor supporting ligands or templates {bis(4-pyridyl)amine (bpa), 2,2'-bipyridine (2,2'-bipy), 4,4'-bipyridine (4,4'-bipy), or 1,10-phenanthroline (phen)}. Products 1-13 were characterized in the solid state by standard methods, including elemental and thermogravimetric analysis (TGA), IR spectroscopy, and powder (PXRD) and single-crystal X-ray diffraction. The structures of 1-13 feature distinct structural types, namely the 3D metal-organic frameworks (MOFs 1-3), the 2D coordination polymers (5, 6, 10, 12, and 13), the 1D coordination polymers (4, 8, and 9), and the 0D discrete cyclic dimers (7 and 11). Such a wide structural diversity of 1-13 is driven by various factors, including the type of the metal(ii) node, the deprotonation degree of H2cpna, and/or the type of supporting ligand or template. Notably, an addition of bpa can tune the structure of MOF 3 by the template effect. Topological classification of underlying metal-organic networks was performed, leading to several distinct topological nets: rtl (in 1), hxg-d-4-C2/m (in 2), sra (in 3), 2C1 (in 4, 8 and 9), fes (in 5, 10, and 12), hcb (in 6), and 3,4L83 (in 13). The magnetic behavior of 1-5, 8-10, and 13 was studied and theoretically modeled, disclosing antiferromagnetic interactions. The luminescence behavior of 6, 7, 11, and 12 was also investigated.

Lanthanide coordination polymers based on 5-(2'-carboxylphenyl) nicotinate: syntheses, structure diversity, dehydration/hydration, luminescence and magnetic properties.

Twelve lanthanide coordination polymers associated with the organic ligand 5-(2'-carboxylphenyl) nicotinic acid (H2cpna): {[Ln(Hcpna)(cpna)(phen)]·H2O}n (Ln = Sm (1), Tb (2), Ho (3), phen = 1,10-phenanthroline), {[Sm(Hcpna)(cpna)(phen)]·2H2O}n (4), {[Ln2(cpna)3(H2O)3]·4H2O}n (Ln = Y (5), Tb(6), Dy (7), Ho (8)), [Lu2(cpna)3(H2O)2]n (9), {[Y2(cpna)3(phen)2(H2O)]·H2O}n (10), and [Ln(cpna)(phen)(NO3)]n (Ln = Tm (11), Lu (12)) have been prepared by hydrothermal methods and structurally characterized. The structure analyses reveal that complexes 1­3 are isostructural and possess unique three-dimensional (3D) frameworks based on the dodecanuclear Sm/Tb/Ho macrocycles. Complex 4 exhibits a one-dimensional (1D) wheel-chain structure, which further builds three-dimensional (3D) supramolecular architecture via O­HN hydrogen-bonding interactions. Complexes 5­8 are also isostructural and display three-dimensional (3D) open frameworks, which possess two types of channels along the a- and b-axis, respectively. Complexes 9 and 10 feature three-dimensional (3D) frameworks and are created from tetranuclear and dinuclear units, respectively. Complexes 11 and 12 are isostructural and demonstrate one-dimensional (1D) double chain structures, which further build three-dimensional (3D) supramolecular architecture via C­H···O hydrogen-bonding. The results show that the pH value of the reaction system, anion, auxiliary ligand and lanthanide contraction play a significant role in determining the structures of the complexes. In addition, the results of luminescent measurements for compounds 2 and 6 in the solid state at room temperature indicate that the different types of structures have a dissimilar influence on their characteristic luminescence. The magnetic properties of compounds 1, 3, 4, 7 and 11 have been investigated. Furthermore, thermal stabilities for 1­12 and the dehydration/hydration properties of compound 6 have also been studied.

Poly[diaqua-bis-(nitrato-κ²O,O')bis-(1,10-phenanthroline-κ²N,N')-µ3-succinato-dicadmium].

In the title coordination polymer, [Cd2(C4H4O4)(NO3)2(C12H8N2)2(H2O)2](n), the Cd(II) ion is seven-coordinated within a distorted penta-gonal-bipyramidal O5N2 environment. The succinate anions, located on an inversion centre, adopt a bis-monodentate bridging mode, leading to the formation of rods along [100]. The rods are connected by O-H⋯O hydrogen bonds between the coordinating water mol-ecules and nitrate O atoms of adjacent rods; the same type of hydrogen bonds are also observed between water and carboxyl-ate O atoms within the rods. π-π stacking inter-actions with a minimum plane-to-plane separation of 3.462 (2) Šoccur between phenanthroline ligands.

N-[2-(2-Hy-droxy-eth-oxy)pheneth-yl]phthalimide.

The title compound, C(18)H(17)NO(4), was obtained accidentally through acid-catalysed aromatization of a phthalimide-substituted 2-(1-hy-droxy-eth-yl)cyclo-hex-2-enone. It exhibits an intra-molecular O-H⋯O(c) (c = carbonyl) hydrogen bond and forms a three-dimensional network structure via π-π stacking inter-actions between adjacent benzene rings (phthalimide-to-phenyl-ene and phthalimide-to-phthalimide), with centroid-centroid distances of 3.8262 (6) and 3.6245 (5) Å.

Di-µ-benzoato-κO,O':O';κO:O,O'-bis-[(benzoato-κO,O')(1,10-phenanthroline-κN,N')cadmium].

The dinuclear title compound, [Cd(2)(C(7)H(5)O(2))(4)(C(12)H(8)N(2))(2)], lies on a crystallographic twofold axis. The Cd(II) ions are connected by two bridging benzoate anions and each ion is seven-coordinated by five O atoms from three benzoate ligands and by two N atoms from 1,10-phenanthroline. The benzoate ligands adopt two different coordination modes, acting as bidentate and bridging tridentate ligands. The discrete neutral mol-ecules further extend their structure into a three-dimensional supra-molecular framework by inter-molecular π-π [inter-planar distances of 3.392 (4) Å] and C-H⋯π stacking inter-actions [H-mean plane = 2.567 (4) and 2.781 (4) Å].

Poly[[triaqua-(µ(3)-4-oxidopyridine-2,6-dicarboxyl-ato)thulium(III)] monohydrate].

In the title coordination polymer, {[Tm(C(7)H(2)NO(5))(H(2)O)(3)]·H(2)O}(n), the Tm(III) atom is eight-coordinated by a tridentate 4-oxidopyridine-2,6-dicarboxyl-ate trianion, two monodentate anions and three water mol-ecules, forming a distorted bicapped trigonal-prismatic TmNO(7) coordination geometry. The anions bridge adjacent Tm(III) ions into double chains. Adjacent chains are further connected into sheets. O-H⋯O hydrogen bonds involving both coordinated and uncoordinated water mol-ecules generate a three-dimensional supra-molecular framework.

Poly[[triaqua-(µ(3)-4-oxidopyridine-2,6-dicarboxyl-ato)holmium(III)] mono-hydrate].

In the title coordination polymer, {[Ho(C(7)H(2)NO(5))(H(2)O)(3)]·H(2)O}(n), the Ho(III) atom is eight-coordinated by a tridentate 4-oxidopyridine-2,6-dicarboxyl-ate trianion, two monodentate anions and three water mol-ecules, forming a distorted bicapped trigonal-prismatic HoNO(7) coordination geometry. The anions bridge adjacent Ho(III) ions into double chains. Adjacent chains are further connected into sheets. O-H⋯O hydrogen bonds involving both coordinated and uncoordinated water mol-ecules generate a three-dimensional supra-molecular framework.

Di-µ-benzoato-κO,O':O;κO:O,O'-bis-[(benzoato-κO,O')(1,10-phenanthroline-κN,N')lead(II)].

In the centrosymmetric dinuclear title compound, [Pb(2)(C(7)H(5)O(2))(4)(C(12)H(8)N(2))(2)], two Pb(2+) ions are connected by two tridentate bridging benzoate anions. The Pb(2+) ion is seven-coordinated by five O atoms from three benzoate anions and two N atoms from the 1,10-phenanthroline ligands. The benzoate anions adopt two different coordination modes, one bidentate-chelating and one tridentate bridging-chelating. The three-dimensional supra-molecular framework is achieved by inter-molecular π-π stacking inter-actions, with a shortest centroid-centroid distance of 3.617 (4) Å.

Poly[diaqua-tris-(µ(4)-1,3-phenyl-ene-diacetato)-dicerium(III)].

In the title coordination polymer, [Ce(2)(C(10)H(8)O(4))(3)(H(2)O)(2)](n), each Ce(III) atom is nine-coordinated by eight O atoms from six different 1,3-phenyl-enediacetate (pda) bivalent anions and one O atom from a coordinated water mol-ecule, forming a distorted tricapped trigonal-prismatic coordination geometry. Eight Ce(III) ions and twelve pda ligands form a large [Ce(8)(pda)(12)] ring, and four Ce(III) ions and six pda ligands form a small [Ce(4)(pda)(6)] ring. The rings are further connected by the coordination inter-actions of pda ligands and Ce(III), generating a three-dimensional supra-molecular framework.

Poly[[triaqua-(µ(3)-4-oxidopyridine-2,6-dicarboxyl-ato)terbium(III)] monohydrate].

In the title coordination polymer, {[Tb(C(7)H(2)NO(5))(H(2)O)(3)]·H(2)O}(n), the Tb(III) atom is eight-coordinated by a tridentate 4-oxidopyridine-2,6-dicarboxyl-ate trianion, two adjacent monodentate anions and three water mol-ecules, forming a distorted bicapped trigonal-prismatic TbNO(7) coordination environment. The anions bridge adjacent Tb(III) ions into double chains. Adjacent chains are further connected into sheets parallel to (10). O-H⋯O hydrogen bonds involving both coordinated and uncoordinated water mol-ecules generate a three-dimensional network.

Poly[diaqua-tris-(µ(4)-1,3-phenyl-enediacetato)-dineodymium(III)].

In the title coordination polymer, [Nd(2)(C(10)H(8)O(4))(3)(H(2)O)(2)](n), each of the two Nd(III) ions is nine-coordinated by eight O atoms from six different 2,2'-(m-phenyl-ene)diacetate (pda) bivalent anions and by one O atom from a water mol-ecule, forming a distorted tricapped trigonal-prismatic coordination geometry. Eight Nd(III) ions and 12 pda ligands form a large [Nd(8)(pda)(12)] ring, and four Nd(III) ions and six pda ligands form a small [Nd(4)(pda)(6)] ring. These rings are further connected by the coordination inter-actions of pda ligands and Nd(III), generating a three-dimensional supra-molecular framework.

Poly[[triaqua-(µ(3)-4-oxidopyridine-2,6-dicarboxyl-ato)europium(III)] monohydrate].

In the title coordination polymer, {[Eu(C(7)H(2)NO(5))(H(2)O)(3)]·H(2)O}(n), the Eu(III) atom is eight-coordinated by a tridentate 4-oxidopyridine-2,6-dicarboxyl-ate (hpc) trianion, two monodentate hpc anions and three water mol-ecules, forming a distorted bicapped trigonal-prismatic coordination geometry. The hpc ligands bridge adjacent Eu(III) ions, forming infinite double chains. Adjacent chains are further connected by hpc ligands into sheets. O-H⋯O hydrogen bonds then generate a three-dimensional supra-molecular framework.

Triaqua-(1,10-phenanthroline-2,9-dicarboxyl-ato)cobalt(II) dihydrate.

The title compound, [Co(C(14)H(6)N(2)O(4))(H(2)O)(3)]·2H(2)O, has two-fold crystallographic symmetry. The Co(II) atom is in a distorted penta-gonal-bipyramidal coordination environment with two N atoms and two O atoms from a tetradentate 1,10-phenanthroline-2,9-dicarboxyl-ate ligand and one O atom from a water mol-ecule forming the penta-gonal plane, and two O atoms from two water mol-ecules occupying axial positions. In the crystal, adjacent mol-ecules are linked by O-H⋯O hydrogen bonds, forming a three-dimensional network.

Piperazine-1,4-diium bis-(hydrogen 2-propyl-1H-imidazole-4,5-dicarbox-ylate) monohydrate.

The title compound, C(4)H(12)N(2) (2+)·2C(8)H(9)N(2)O(4) (-)·H(2)O, is a hydrated proton-transfer compound obtained from 2-propyl-1H-imidazole-4,5-dicarb-oxy-lic acid and piperazine. The asymmetric unit contains one half-cation, one anion and half a water mol-ecule. There is a centre of inversion at the centre of the cation ring and the water molecule O atom lies on a twofold rotation axis. In the crystal, inter-molecular N-H⋯O and N-H⋯N hydrogen bonds help to construct a three-dimensional framework. Almost symmetrical, intramolecular O-H⋯O inter-actions are also observed.

3D porous metal-organic framework exhibiting selective adsorption of water over organic solvents.

A 3D porous metal-organic framework (MOF) with 1D open channels has been constructed hydrothermally using Zn(II) and a rigid planar ligand IDC(3)- (imidazole-4,5-dicarboxylate). This MOF can adsorb water selectively over organic solvents and can be regenerated and reused. It also represents a rare example of a MOF with open channels that form/collapse reversibly upon hydration/dehydration.