Coordination-directed one-dimensional coordination polymers generated from a new oxadiazole bridging ligand and HgX2 (X=Cl, Br and I).

A new 1,3,4-oxadiazole bridging bent organic ligand, 2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole, C(28)H(24)N(4)O(3), L, has been used to create three novel one-dimensional isomorphic coordination polymers, viz. catena-poly[[[dichloridomercury(II)]-µ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgCl(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), catena-poly[[[dibromidomercury(II)]-µ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgBr(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n), and catena-poly[[[diiodidomercury(II)]-µ-2,5-bis{5-methyl-2-[(4-pyridyl)methoxy]phenyl}-1,3,4-oxadiazole] methanol monosolvate], {[HgI(2)(C(28)H(24)N(4)O(3))]·CH(3)OH}(n). The free L ligand itself adopts a cis conformation, with the two terminal pyridine rings and the central oxadiazole ring almost coplanar [dihedral angles = 5.994 (7) and 9.560 (6)°]. In the Hg(II) complexes, however, one of the flexible pyridylmethyl arms of ligand L is markedly bent and helical chains are obtained. The Hg(II) atom lies in a distorted tetrahedral geometry defined by two pyridine N-atom donors from two L ligands and two halide ligands. The helical chains stack together via interchain π-π interactions that expand the dimensionality of the structure from one to two. The methanol solvent molecules link to the complex polymers through O-H···N and O-H···O hydrogen bonds.

Two threefold interpenetrated two-dimensional frameworks based on a flexible imidazole-containing ligand and benzene-1,4-dicarboxylate.

The open-chain polyether-bridged flexible ligand 1,2-bis[2-(1H-1,3-imidazol-1-ylmethyl)phenoxy]ethane (L) has been used to create two two-dimensional coordination polymers under hydrothermal reaction of L with Cd(II) or Co(II), in the presence of benzene-1,4-dicarboxylic acid (H(2)bdc). In poly[[(µ(2)-benzene-1,4-dicarboxylato){µ-1,2-bis[2-(1H-1,3-imidazol-1-ylmethyl)phenoxy]ethane}cadmium(II)] dihydrate], {[Cd(C(8)H(4)O(4))(C(22)H(22)N(4)O(2))]·2H(2)O}(n), (I), and the cobalt(II) analogue {[Co(C(8)H(4)O(4))(C(22)H(22)N(4)O(2))]·2H(2)O}(n), (II), the Cd(II) and Co(II) cations are six-coordinated by four carboxylate O atoms from two different bdc(2-) dianions in a chelating mode and two N atoms from two distinct L ligands. The metal ions, bdc(2-) dianions and L ligands each sit across crystallographic twofold axes. The bdc(2-) coordination mode and the coordinating orientation of the L ligand play an important role in constructing the novel two-dimensional framework. Complexes (I) and (II) are threefold interpenetrated two-dimensional frameworks; their structures are almost isomorphous, while the bond lengths, angles and hydrogen bonds are different in (I) and (II).

Bis(µ-2-{5-[(pyridin-4-ylmethyl)sulfanyl]-1,3,4-oxadiazol-2-yl}phenolato)bis[(acetylacetonato)copper(II)]: a novel binuclear metallocycle.

The new asymmetric ligand 2-{5-[(pyridin-4-ylmethyl)sulfanyl]-1,3,4-oxadiazol-3-yl}phenol (HL) has been used to synthesize the novel discrete title binuclear metallocycle, [Cu(2)(C(14)H(10)N(3)O(2)S)(2)(C(5)H(7)O(2))(2)] or Cu(2)L(2)(acac)(2) (acac is acetylacetonate). Each Cu(II) centre is five-coordinate and adopts a square-pyramidal geometry. Two ligands are connected by two Cu(II) cations to form the dinuclear metallocycle, which lies across a crystallographic inversion centre. Discrete molecules are linked into a two-dimensional structure through weak Cu···S, C-H···π and π-π interactions.

Synthesis and characterization of new coordination polymers with tunable luminescent properties generated from bent 1,2,4-triazole-bridged N,N'-dioxides and Ln(III) salts.

A new bent 1,2,4-triazole-bridged N,N'-dioxide ligand, namely, 3,5-bis(3-pyridyl-N-oxide)-4-amino-1,2,4-triazole (L2), was designed and synthesized by the oxidation of 3,5-bis(3-pyridyl)-4-amino-1,2,4-triazole with H(2)O(2) in the presence of HOAc at ambient temperatures. Eleven Ln(III)-based coordination polymers have been successfully prepared by the solution reactions of L2 with various Ln(III)-perchlorates. The structures of these new Ln(III) polymers clearly reflect the effect of the lanthanide contraction. Compounds 1-6 feature a two-dimensional net, in which the Ln(III) atoms adopt a nine-coordinate {LnO(9)} sphere due to their larger ionic radii, whereas the Ln(III) centers in the one-dimensional double-stranded chains of 7-11 with smaller ionic radii lie in a {LnO(8)} coordination environment. In addition, the tunable emission intensity was realized on 7 by controlling the type of the involved counterion on the basis of a reversible solid-state anion exchange. Such reversible solid-state anion exchange might provide an alternative approach to tuning the luminescence.

catena-Poly[[[tetraaquazinc(II)]-mu-4-amino-3,5-di-3-pyridyl-4H-1,2,4-triazole] sulfate monohydrate] and poly[[bis(mu-4-amino-3,5-di-4-pyridyl-4H-1,2,4-triazole)diaquacopper(II)] dinitrate octahydrate].

The isomeric bent triazole-containing ligands 4-amino-3,5-di-3-pyridyl-4H-1,2,4-triazole (L1) and 4-amino-3,5-di-4-pyridyl-4H-1,2,4-triazole (L2) have been used to create the two novel title complexes catena-poly[[[tetraaquazinc(II)]-mu-4-amino-3,5-di-3-pyridyl-4H-1,2,4-triazole] sulfate monohydrate], {[Zn(C(12)H(10)N(6))(H(2)O)(4)]SO(4).H(2)O}(n), (I), and poly[[diaquabis(mu-4-amino-3,5-di-4-pyridyl-4H-1,2,4-triazole)copper(II)] dinitrate octahydrate], {[Cu(C(12)H(10)N(6))(2)(H(2)O)(2)](NO(3))(2).8H(2)O}(n), (II). The Zn(II) and Cu(II) atoms are all six-coordinated in approximately octahedral environments. Compound (I) presents a sinusoidal chain generated by ZnO(4) cores which are bridged by L1 ligands in a cisoid conformation. These sinusoidal chains are bound to each other by O-H...O hydrogen bonds between coordinated water molecules of neighboring chains into a two-dimensional network. These layers stack in an ...ABAB... sequence and are further linked into a three-dimensional framework through O-H...N hydrogen bonds between coordinated water molecules and the N atoms of the triazole rings. In (II), the Cu(II) centers are bridged by the L2 ligands to form a two-dimensional network with square grids. All of the two-dimensional nets also stack alternately along the crystallographic a axis. Neighboring layers are further linked into a three-dimensional framework via interlayer N-H...N hydrogen bonds between -NH(2) groups of the triazole rings and the N atoms in the triazole rings.

Cocrystallization of two tautomers: 4-(1-{[4-(dimethylamino)benzylidene]hydrazono}ethyl)benzene-1,3-diol and 6-[(E)-1-{[4-(dimethylamino)benzylidene]hydrazino}ethylidene]-3-hydroxycyclohexa-2,4-dien-1-one (1/1).

Two different tautomeric forms of a new Schiff base, C(17)H(19)N(3)O(2).C(17)H(19)N(3)O(2), are present in the crystal in a 1:1 ratio, namely the enol-imine form 4-(1-{[4-(dimethylamino)benzylidene]hydrazono}ethyl)benzene-1,3-diol and the keto-amine form 6-[(E)-1-{[4-(dimethylamino)benzylidene]hydrazino}ethylidene]-3-hydroxycyclohexa-2,4-dien-1-one. The tautomers are formed by proton transfer between the hydroxy O atom and the imine N atom and are hydrogen bonded to each other to form a one-dimensional zigzag chain along the crystallographic b axis via intermolecular hydrogen bonds.

Self-inclusion structure of 5,11,17,23-tetrakis(azidomethyl)-25,26,27,28-tetrahydroxycalix[4]arene, and 5,11,17,23-tetra-tert-butyl-25,27-bis(chloroacetoxy)-26,28-bis(2-pyridylmethoxy)calix[4]arene.

In the structures of the two title calix[4]arene derivatives, C(32)H(28)N(12)O(4), (I), and C(60)H(68)Cl(2)N(2)O(6), (II), compound (I) adopts an open-cone conformation in which there are four intramolecular O-H...O hydrogen bonds, while compound (II) adopts a distorted chalice conformation where the two pendant pyridyl rings, one of which is disordered, are almost mutually perpendicular, with an interplanar angle of 79.2 (2) or 71.4 (2) degrees . The dihedral angles between the virtual plane defined by the four bridging methylene C atoms and the phenol rings are 120.27 (7), 124.03 (6), 120.14 (8) and 128.25 (7) degrees for (I), and 95.99 (8), 135.93 (7), 97.21 (8) and 126.10 (8) degrees for (II). In the supramolecular structure of (I), pairs of molecules associate by self-inclusion, where one azide group of the molecule is inserted into the cavity of the inversion-related molecule, and the association is stabilized by weak intermolecular C-H...N hydrogen bonds and pi(N(3))-pi(aromatic) interactions. The molecular pairs are linked into a two-dimensional network by a combination of weak intermolecular C-H...N contacts. Each network is further connected to its neighbor to produce a three-dimensional framework via intersheet C-H...N hydrogen bonds. In the crystal packing of (II), the molecular components are linked into an infinite chain by intermolecular C-H...O hydrogen bonds. This study demonstrates the ability of calix[4]arene derivatives to form self-inclusion structures.

A novel three-dimensional framework constructed by 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole and infinite chains of hydrogen-bonded water molecules.

A novel three-dimensional framework of 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole dihydrate, C(11)H(10)N(4).2H(2)O or L.2H(2)O, (I), in which L acts as both hydrogen-bond acceptor and donor in the supramolecular construction with water, has been obtained by self-assembly reaction of L with H(2)O. The two independent water molecules are hydrogen bonded alternately with each other to form a one-dimensional infinite zigzag water chain. These water chains are linked by the benzimidazole molecules into a three-dimensional framework, in which each organic molecule is hydrogen bonded by three water molecules. This study shows that the diversity of hydrogen-bonded patterns plays a crucial role in the formation of the three-dimensional framework. More significantly, as water molecules are important in contributing to the conformation, stability, function and dynamics of biomacromolecules, the infinite chains of hydrogen-bonded water molecules seen in (I) may be a useful model for water in other chemical and biological processes.

A two-dimensional network formed by self-associating silver(I) perchlorate with 3-[4-(2-thienyl)-2H-cyclopenta[d]pyridazin-1-yl]benzonitrile.

In the organometallic silver(I) supramolecular complex poly[[silver(I)-mu(3)-3-[4-(2-thienyl)-2H-cyclopenta[d]pyridazin-1-yl]benzonitrile] perchlorate methanol solvate], {[Ag(C(18)H(11)N(3)S)](ClO(4)).CH(3)OH}(n), there is only one type of Ag(I) center, which lies in an {AgN(2)Spi} coordination environment. Two unsymmetric multidentate 3-[4-(2-thienyl)-2H-cyclopenta[d]pyridazin-1-yl]benzonitrile (L) ligands link two Ag(I) atoms through pi-Ag(I) interactions into an organometallic box-like unit, from which two 3-cyanobenzoyl arms stretch out in opposite directions and bind two Ag(I) atoms from neighboring box-like building blocks. This results in a novel two-dimensional network extending in the crystallographic bc plane. These two-dimensional sheets stack together along the crystallographic a axis to generate parallelogram-like channels. The methanol solvent molecules and the perchlorate counter-ions are located in the channels, where they are fixed by intermolecular hydrogen-bonding interactions. This architecture may provide opportunities for host-guest chemistry, such as guest molecule loss and absorption or ion exchange. The new fulvene-type multidentate ligand L is a good candidate for the preparation of Cp-Ag(I)-containing (Cp is cyclopentadienyl) organometallic coordination polymers or supramolecular complexes.

A novel two-dimensional framework based on unprecedented cadmium(II) chains.

The bent ligand 4-[(1H-1,2,4-triazol-1-yl)methyl]benzoic acid (HL) has been used to create the novel two-dimensional coordination polymer poly[mu(2)-aqua-mu(2)-chlorido-{mu(2)-4-[(1H-1,2,4-triazol-1-yl)methyl]benzoato}cadmium(II)], [Cd(C(10)H(8)N(3)O(2))Cl(H(2)O)](n), under hydrothermal reaction of HL with cadmium chloride. The crystallographically unique Cd atom is seven-coordinated in an approximately pentagonal-bipyramidal environment of two carboxylate O atoms, two water O atoms, two Cl atoms and one triazole N atom. A notable feature is the presence of zigzag ...Cd...Cd... inorganic chains, in which neighboring Cd(II) ions are doubly bridged by pairs of mu(2)-Cl atoms and mu(2)-H(2)O ligands in an alternating fashion. To the authors' knowledge, this is the first example containing this bridging mode in a cadmium(II) framework. The chains are connected to one another through the bridging L(-) ligand into a two-dimensional undulating network. All of the two-dimensional nets stack exactly together in an ...AA... stacking sequence along the crystallographic b axis. Neighboring layers are further linked into a three-dimensional framework via interlayer hydrogen-bonding interactions.

Two bicyclic dinuclear complexes generated from 3,3'-[1,3,4-thiadiazole-2,5-diyldi(thiomethylene)]dibenzoic acid (L) and dimethylformamide (DMF): [Cu(L)(DMF)]2and [Zn(L)(DMF)]2.

A new 1,3,4-thiadiazole bridging ligand, namely 3,3'-[1,3,4-thiadiazole-2,5-diyldi(thiomethylene)]dibenzoic acid (L), has been used to create the novel isomorphous complexes bis{mu-3,3'-[1,3,4-thiadiazole-2,5-diyldi(thiomethylene)]dibenzoato}bis[(N,N-dimethylformamide)copper(II)], [Cu(2)(C(18)H(12)N(2)O(4)S(3))(2)(C(3)H(7)NO)(2)], (I), and bis{mu-3,3'-[1,3,4-thiadiazole-2,5-diyldi(thiomethylene)]dibenzoato}bis[(N,N-dimethylformamide)zinc(II)], [Zn(2)(C(18)H(12)N(2)O(4)S(3))(2)(C(3)H(7)NO)(2)], (II). Both exist as centrosymmetric bicyclic dimers constructed through the syn-syn bidentate bridging mode of the carboxylate groups. The two rings share a metal-metal bond and each of the metal atoms possesses a square-pyramidal geometry capped by the dimethylformamide molecule. The 1,3,4-thiadiazole rings play a critical role in the formation of a pi-pi stacking system that expands the dimensionality of the structure from zero to one. The thermogravimetric analysis of (I) indicates decomposition of the coordinated ligands on heating. Compared with the fluorescence of L in the solid state, the fluorescence intensity of (II) is relatively enhanced with a slight redshift, while that of (I) is quenched.

A binuclear Cu(II) metallacycle capable of discerning between pyrazine and its different methyl-substituted derivatives based on reversible intracage metal-ligand binding.

Squashy cage: A flexible, spongelike, and reversible metal-binding Cu(2)L(2) cage that can adjust its internal space in response to pyrazine and its derivatives based on a recognition sequence of pyrazine, 2,5-dimethylpyrazine, and 2-methylpyrazine (see figure) is described.

3,5-Bis(4-methoxy-phen-yl)-1H-1,2,4-triazole monohydrate.

In the title compound, C(16)H(15)N(3)O(2)·H(2)O, the two benzene rings and the triazole ring lie almost in the same plane, the triazole ring forming dihedral angles of 5.07 (9) and 5.80 (8)° with the benzene rings. In the crystal, there are three relatively strong inter-molecular O-H⋯N and N-H⋯O hydrogen bonds, which lead to the formation of a one-dimensional double chain running parallel to the a axis. Weak π-π inter-actions between the benzene rings of neighboring chains with a centroid-centroid distance of 3.893 (4) Šresult in the formation of layers parallel to the ac plane.

Bis{µ-2,5-bis-[4-(2-pyridylmethyl-amino)phen-yl]-1,3,4-oxadiazole}bis-[dichlorido-mercury(II)].

In the title centrosymmetric compound, [Hg(2)Cl(4)(C(26)H(22)N(6)O)(2)], each Hg(II) center adopts a distorted HgN(3)Cl(2) trigonal bipyramidal coordination geometry, formed by two pyridine N atoms, one imine N atom and two chloride anions. Within the organic ligand, the oxadiazole ring is nearly coplanar with the two benzene rings [dihedral angles = 5.9 (4) and 6.5 (4)°] and nearly perpendicular to the two pyridine rings with the same dihedral angle of 77.4 (4)°. The two organic ligands bridge two Hg(II) ions to form the macrocyclic complex. Inter-molecular N-H⋯Cl and N-H⋯N hydrogen bonding helps to stabilize the crystal structure.

4-[5-(4-Pyrid-yl)-1,3,4-oxadiazol-2-yl]pyridine N-oxide-isophthalic acid (1/1).

The title compound, C(12)H(8)N(4)O(2)·C(8)H(6)O(4), was synthesized from 4-[5-(4-pyrid-yl)-1,3,4-oxadiazol-2-yl]pyridine N-oxide and isophthalic acid. The two mol-ecules are linked through O-H⋯O and O-H⋯N hydrogen bonds. Weak intra-molecular π-π inter-actions between the two hydrogen-bonded chains result in the formation a one-dimensional supra-molecular curved tape (the face-to-face distance between the pyridine N-oxide ring and the benzene ring is 3.7 Å).

Ag(I) and Cu(II) discrete and polymeric complexes based on single- and double-armed oxadiazole-bridging organic clips.

Four new oxadiazole-bridging ligands (L1-L4) were designed and synthesized by the reaction of 2,5-bis(2-hydroxyphenyl)-1,3,4-oxadiazole with isonicotinoyl chloride and nicotinoyl chloride, respectively. L1 and L3 are unsymmetric single-armed ligands (4- or 3-pyridinecarboxylate arm), and L2 and L4 are symmetric double-armed ligands (4- or 3-pyridinecarboxylate arms). Nine new complexes, [Ag(L1)]PF6.CH3OH (1), [Ag(L1)]ClO4.CH3OH (2), Cu(L2)(NO3)2.2(CH2Cl2) (3), [Cu(L2)2](ClO4)2.2(CH2CCl2) (4), Cu(L2)Cl2 (5), [Cu4(L3)2(H2O)2](L3)4(ClO4)4 (6), [Ag(L4)(C2H5OH)]ClO4 (7), [Ag(L4)(C2H5OH)]BF4 (8), and [Ag(L4)(CH3OH)]SO3CF3 (9), were isolated from the solution reactions based on these four new ligands, respectively. L1, L2, and L3 act as convergent ligands and bind metal ions into discrete molecular complexes. In contrast, L4 exhibits a divergent spacer to link metal ions into one-dimensional coordination polymers. New coordination compounds were fully characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction. In addition, the luminescent and electrical conductive properties of these new compounds were investigated.