A discrete tetranuclear manganese(II) complex, {(H₃O)₂Mn₄(4-Haba)₂(4-aba)₆(SCN)₄(H₂O)₂]} (1) and a two-dimensional coordination polymer [Mn(3-aba)₂]_n (2) (4-Haba = 4-aminobenzoic acid, 3-Haba = 3-aminobenzoic acid), have been synthesized and characterized by elemental analyses, IR, X-ray crystallography, and magnetic susceptibility. In complex 1, 4-aba in three types of coordination modes connects Mn^II centers to form a discrete tetranuclear anionic molecule. Hydrogen bonding interaction links the tetranuclear units to generate a one-dimensional supramolecular chain. In complex 2, 3-aba in an exo-tridentate mode bridges six-coordinate Mn^II centers forming a two-dimensional coordination architecture. Studies of the magnetic susceptibilities of 1 and 2 reveal weak antiferromagnetic exchange interactions between adjacent Mn^II centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Reactions of the p-sulfonatothiacalix[4]arene salt (Na₄H₄TCAS) and MSO₄ (M = Co, Cu) in the presence of 2,2′-bipyrazine (2,2′-bpz) generated 2D coordination networks formed by tetranuclear cluster subunits, namely{[Co(2,2′-bpz)(H₂O)₄]²⁺[Co₄(TCAS)(μ₄-SO₄)(H₂O)₄]^2–·10.75H₂O}_n (1) and {[Cu(2,2′-bpz)(H₂O)₃]²⁺[Cu₄(TCAS)(μ₄-SO₄)(H₂O)₄]^2–·16H₂O}_n (2). X-ray diffraction analyses reveal that both these complexes include metal–2,2′-bipyrazine complexes into the hydrophobic cavities of p-sulfonatothiacalix[4]arenes as guests through supramolecular interactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

A chiral Cu^II dinuclear complex [Cu₂(L-shis)₂]·4H₂O (H₂shis = N-salicylidenylhistidine) has been synthesized. The dinuclear units are assembled into a 3D hydrogen-bonded supramolecular structure with 1D chiral channels through hydrogen bonds between imidazole N–H groups and carboxylate oxygen atoms. 1D left-handed helical water chains in an AABB fashion, anchored through weak hydrogen-bonding interactions with the host complex, are embodied in the chiral channels. X-ray powder diffraction shows the porous structure is destroyed when the lattice water molecules are removed thermally from the channels. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Reaction of 4,4'-bipyridine N,N'-dioxide (bpno) and lead(II) nitrate with or without dicyanamido ions (dca) in aqueous solution yielded polymeric complexes {Pb₂(bpno)₄(dca)₂(NO₃)₂Pb₂(bpno)₄(NO₃)₄·5H₂O}_n (1) and {Pb(bpno)(NO₃)₂·H₂O}_n (2), respectively. The single-crystal X-ray analyses show that the structures of both complexes consist of dinuclear Pb^II units which are bridged through bpno ligands in novel modes to extend their topologies. Compound 1 exhibits a bilayered rhombus grid, while 2 displays a monolayered rhombus grid. The different excitations of solid samples of 1 and 2, at room temperature, produced intense emission bands which are almost the same in appearance with peak maxima at 616 nm and 617 nm, respectively. Both low-energy emissions were determined to be phosphorescence by their long decay lifetime at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The novel coordination polymer [Co₄(TCAS)(μ₄-SO₄)(4,4′-Hbipy)₂]_n (TCAS = the octaanion of p-sulfonatothiacalix[4]arene) (1) has been synthesized hydrothermally and characterized. X-ray diffraction analyses reveal a two-dimensional (2D) layer structure built from the [Co₄(TCAS)(μ₄-SO₄)]^2– unit. The tetranuclear cobalt(II) clusters bridged by the μ₄-SO₄^2– and phenoxy groups of the same TCAS provide a unique trapeziform magnetic mode; magnetic studies in the temperature range 2–300 K show weak antiferromagnetic interactions between the four cobalt(II) centers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Self-assemblies of the conformationally labile ditopic ligand 1,3-bis(4-pyridylthio)propan-2-one (L) with square-planer nodes Co^II, Ni^II and with linear nodes Ag^I have afforded three new coordination polymers, {[Ni(L)₂Cl₂]}_∞ (1), {[Co(L)₂-(SCN)₂]·(DMF)₂}_∞ (2) and {[AgL]NO₃}_∞ (3), respectively. Structural analyses of these polymers and conformational analyses of L have revealed that metal-assisted conformational selectivity and unique combinations of conformational isomers of L around the metal nodes probably play the key role in determining the structural topologies. In 1, a C₂ symmetric array of two sorts of conformational isomers of L around Ni^II centers results in a 3D interpenetrating framework, while in 2 a combination of two types of conformational isomers of L around the inversion center Co^II provides a 3D interpenetrating architecture of CdSO₄-like topology. In 3, L presents only a typical conformation, with higher steric energy, that links linear nodes Ag^I, leading to a 1D U-like chain. The magnetic properties of 1 and 2, as well as the interesting fluorescent properties of 3, have also been investigated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Hydrothermal reactions of InCl₃ with 1,3,5-benzenetricarboxylic acid (H₃BTC) or pyromellitic dianhydride produced [In₂(BTC)₂(H₂O)₂]_n·2nH₂O (1) and [In₂(H₂BTEC)₂(OH)₂]_n·2nH₂O (2), respectively (H₄BTEC = 1,2,4,5-benzenetetracarboxylic acid). The structure of 1 is a 2D double-layer network, while that of 2 is a 3D framework constructed from chains of corner-linked octahedra. Intense greenish-blue emissions at 494 nm (λ_ex = 325 nm) for 1 and 489 nm (λ_ex = 337 nm) for 2 were observed in the solid state. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The self-assembly of a racemic exo-bidentate ligand 2,2′-bis(4-pyridylmethyloxy)-1,1′-binaphthyl, namely Rac-L, with cadmium(II) salt gave rise to a new one-dimensional polymer, which has been characterized by single crystal X-ray diffraction analysis. The polymer crystallizes in a triclinic space group P-1 with unit cell parameters: a=0.6976(1) nm, b=1.30160(14) nm, c=1.71146(17) nm,α=105.141(3) °,β=94.263(5)°,γ=100.405(4)°, V=1.4633(2) nm³, Z=2, C₃₂H₂₉CdCl₂N₂O_4.5, M=696.88, D_c=1.584 g/cm³, F(000) =708, μ(Mo Kα) =0.972 mm⁻¹. The final R and wR are 0.0498 and 0.1282 for 5079 observed reflections with I≥δ(I).

Two flexible exo-bidentate ligands, 2,2′-bis(3-pyridylmethyleneoxy)-1,1′-biphenylene (3,3′-bpp) and 2,2′-bis(4-pyridylmethyleneoxy)-1,1′-biphenylene (4,4′-bpp), were synthesized and employed for the preparation of coordination polymers. Seven metal-organic complexes, [Zn₂(3,3′-bpp)₂Cl₄] (1), [Zn₂(3,3′-bpp)₂Br₄] (2), [Zn(4,4′-bpp)Cl₂]_n (3), [Zn(4,4′-bpp)Br₂]_n (4), [Co(4,4′-bpp)₂(SCN)₂]_n (5), {[Cd(4,4′-bpp)₂(SCN)₂]·2H₂O}_n (6) and [Cd(4,4′-bpp)(dca)₂]_n (7) (dca⁻ = dicyanamide), have been obtained through self-assembly reactions of 3,3′-bpp or 4,4′-bpp with the divalent metal ions Zn^II, Co^II and Cd^II. Crystal structure analyses reveal that 1 and 2 are dinuclear metallomacrocycles, are isomorphous and possess a layer network built from metallomacrocycles through π−π interactions. In drastic contrast, 3 and 4 exhibit a three-dimensional structure consisting of one-dimensional polymeric chains held together through π−π interactions between adjacent pyridyl rings. The metal-organic frameworks of 5, 6, and 7 possess unusual topologies: Complex 5 is a two-dimensional polymer based on folded rectangular boxes and zigzag chains, whereas 6 is a polycatenated species consisting of inclined interpenetrating two-dimensional layers, and each layer is constructed by the alternating assembly of left-hand (M) and right-hand (P) cylindrical 2₁ helices. In 7, dca⁻ connects Cd^II centers forming a two-dimensional {Cd(dca)₂}_n layer, which is fused with (M)- and (P)-Cd-(4,4′-bpp) helical chains into a three-dimensional structure. The results suggest that the nature of organic ligands and the coordination preferences of transitional metal ions have a great influence on the structures of metal-organic complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Two new 2-D metal-binicotinate coordination polymers, namely, [Cd^II(bpdc)]_n (1) and {[Zn^II₈(bpdc)₈(H₂O)₈](H₂O)₈}_n (2) (H₂bpdc = binicotinic acid) have been synthesized using hydrothermal and three-layer diffusion methods, respectively. Single-crystal X-ray analyses revealed that both are extended grid networks of the (4,4) topology. Their structures alter with the configuration and function of bpdc. The achiral, free H₂bpdc has axial chirality induced by metal coordination in 1, and bpdc connects to four metal centers forming a 2-D (4,4) net with three kinds of apertures generated through self-assembly. In 2, however, bpdc connects to three metal centers, fabricating a microporous framework containing hydrophilic channels. Studies on the solid emission spectra of the free ligand, 1, and 2 confirmed, that the configuration of bpdc resulting from metal-directed coordination has a profound effect on the fluorescence emissions of 1 and 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Assembly of axially chiral (S)-2,2′-bis(3-pyridylmethyleneoxy)-1,1′-binaphthalene [(S)-L₁] and (S)-2,2′-bis(4-pyridylmethyleneoxy)-1,1′-binaphthalene [(S)-L₂] with AgNO₃ resulted in a double-stranded helical coordination polymer encapsulating guest water molecules and a helix-like complex with inter-immersion clefts, respectively, in which helical chirality is due to axial chirality of the 1,1′-bi-2-naphthol scaffold. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Two novel cadmium(II) coordination polymers, [Cd₂(bpda)₂(dpe)]_n (1) and [Cd₂{(R)-Hdmpa}₂{(S)-Hdmpa}₂(dpe)₃]_n (2), [H₂bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid, H₂dmpa = 6,6′-dimethyl-1,1′-biphenyl-2,2′-dicarboxylic acid, and dpe = 1,2-di(4-pyridyl)ethylene] have been prepared by hydrothermal reactions of both Cd(NO₃)₂·4H₂O and dpe with H₂bpda and H₂dmpa, respectively. 1 is a threefold interpenetrating three-dimensional coordination network composed of paddle-wheel tetracarboxylate dicadmium(II) units bridged by dpe. 2 affords an example of ligand self-discrimination in an assembly process, in which dpe connects the [Cd{(R)-Hdmpa}{(S)-Hdmpa}] building units to generate a one-dimensional ladder structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Ionen im Käfig: Durch Hydrothermalreaktionen entstehen die beiden neuartigen 3D-Heterometall-Netzwerke [{[Gd₄(ip)₇(H₂O)₂][Cu(bpy)₂]₂}_n] (1, bpy=2,2′-Bipyridin, H₂ip=Isophthalsäure; siehe Bild mit [Cu(bpy)₂] als Kalottenmodell und Gd-Polyedern) und [{Gd₃Cu(ip)₅(Hip)(bpy)}_n]⋅n H₂O (2). In den geladenen Käfigen von 1 befinden sich zwei Cu^I-Komplexkationen, die geladenen Kavitäten von 2 enthalten Cu^II-Komplexkationen.

Ions in cages: Hydrothermal reactions give two novel 3D heterometallic frameworks, [{[Gd₄(ip)₇(H₂O)₂][Cu(bpy)₂]₂}_n] (1, bpy=2,2′-bipyridine, H₂ip=isophthalic acid; see structure, space filling models: [Cu(bpy)₂], polyhedra: Gd) and [{Gd₃Cu(ip)₅(Hip)(bpy)}_n]⋅n H₂O (2). The structure of 1 consists of charged cages containing two encapsulated Cu^I complex cations, whereas that of 2 contains charged cavities in which Cu^II complex cations are bound.

Three new organic/inorganic coordination polymers, [{Cu(4-DPDS)₂(H₂O)}·2NO₃·3H₂O]_n (1), [{Cu(4-DPDS)₂(SO₄)}· 1.5H₂O·CH₃OH]_n (2), and [Cd(4-DPDS)₂Cl₂]_n (3), have been synthesized by using the flexible ligand 4,4′-dipyridyl disulfide (4-DPDS). Complex 1 crystallized in the Ibca space group: a = 10.5275(6), b = 20.2670(1), c = 27.235(1) Å, V = 5811.5(6) ų, Z = 16. Complex 2 crystallized in the Pnna space group: a = 10.547(2), b = 14.201(2), c = 19.667(3) Å, V = 2945.8(8) ų, Z = 8. Complex 3 crystallized in the P2₁/c space group: a = 7.6146(3), b = 18.2606(8), c = 9.3203(2) Å, β = 100.26(1)°, V = 1275.24(8) ų, Z = 4. The three coordination polymers display a variety of structural architectures, ranging from double-stranded chains (1) to two-dimensional channels (2) and two-dimensional, puckered, grid-like arrays (3). Magnetic characterizations show that complex 1 exhibits antiferromagnetic interactions while 2 is ferromagnetic. Solid-state fluorescence results reveal that 3 exhibits fluorescence emissions at 418 and 575 nm (λ_ex = 314 nm). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Two novel cadmium(II) coordination compounds, [Cd(bpe)_1.5(NO₂-BDC)]·0.25H₂O (1) and [Cd(bpp)(NO₂-BDC)(H₂O)]·0.25H₂O (2) [NO₂-BDCH₂ = 5-nitro-1,3-benzenedicarboxylic acid, bpe = 1,2-bis(4-pyridyl)ethane, bpp = 1,3-bis(4-pyridyl)propane] have been hydrothermally synthesized by reaction of cadmium chloride and NO₂-BDC with the homologous ligands bpe and bpp, respectively. The former compound displays a remarkable three-dimensional architecture sustained by the catenation of 2D bilayers, while the latter exhibits a unique twofold interpenetrating three-dimensional architecture. The thermal and fluorescence properties associated with their crystal structures have been measured. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Five cadmium(II) coordination polymers formed from dadpm (dadpm = 4,4′-diaminodiphenylmethane), namely, [Cd(dadpm)(I)₂]_n (1), [{Cd(dadpm)₂(Cl)}(dca)]_n (2) [dca = dicyanamide anion, N(CN)₂⁻], [{Cd(dadpm)₂(Br)}(dca)]_n (3), [Cd(dadpm)(SCN)₂]_n (4) and [Cd(dadpm)(dca)₂]_n (5) have been synthesized and characterized by NMR, IR, and fluorescence spectroscopy as well as TG analysis. The ligand dadpm in 1 bridges the metal centers to form a zigzag chain where the halide anion I⁻ acts as a terminal ligand. Weak Cd···I interactions between adjacent chains extend the zig-zag chains into a wave-like layer. Complexes 2 and 3 are isomorphous, the metal centers are bridged by dadpm to generate a double-stranded chain containing the metallacycles of [Cd₂(dadpm)₂], and the halide anions (Cl⁻ in 2 and Br⁻ in 3) link adjacent chains into 2D layer structures in a trans mode. Dicyanamide anions in the two complexes lie between the layers as supported anions and link the adjacent layers into 3D structures through hydrogen bonds. In complex 4, the metal centers are bonded by the thiocyanate anions to form double-stranded chains, which are linked by dadpm in different orientations resulting in a cross-linked 3D structure. In 5, dicyanamide anions connect the cadmium(II) centers to form a [Cd(dca)₂]_n 2D layer, which contains 24-membered ring units [Cd₄(μ_1,1-dca-N,N)₄]. The dadpm ligand links the adjacent layers into an α-Po-like 3D network structure. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

A penta-coordinated Cu(II) complex with mixed ligands 4, 4′-bipyridine (4,4′-bpy) and 2-pyrazine-5-carboxylate anion (2-pzc), [Cu(4,4′-bpy)(2-pzc)(H₂O)]CIO₄·H_zO (1), has been solvothermally synthesized and characterized. Complex 1 crystallizes in the monoclinic space group P2₁/n with a = 0.82996(2) nm, b = 1.58156(5) nm, c = 1.53837(1) nm, β = 103.536(2)°, V = 1.96322(8) nm³, M_r = 478.30, Z = 4, D_c = 1.618 g/cm³, final R = 0.0544 and wR = 0.1487. The Structure of 1 indicates that the central Cu(II) atom is penta-coordinated by two N atoms from two 4,4′-bpy ligands, and one N atom and one oxygen atom of the 2-pzc ligand in the equatorial plane, and one oxygen atom of the coordinated water molecule at the axial position. The coordination geometry of Cu(II) atom could be considered as a slightly distorted square-pyramidal environment. The 4, 4′-bpy ligands bridge the Cu(II) centers to form a one-dimensional chain, and 2-pzc acts as a terminal chelated ligand, and #±# interaction between the pyrazine rings of 2-pzc ligands of adjacent chains links the chains into a 2D sheet. Furthermore, the hydrogen bonds among the oxygen atoms of the uncoordinated water molecules and the N atoms and O atoms of 2-pzc ligands and the oxygen atoms of the coordinated water molecules link the sheets into the ultimate 3D network of complex 1.

Two novel metallomacrocycles made up of difunctional 4,4′-diaminodiphenylmethane (DADPM) or 4,4′-diaminodiphenyl ether (DADPE) and cubane-like Cu₄I₄ cluster units have been prepared by the reaction of CuI and DADPM or DADPE in MeCN/H₂O. The X-ray crystal structural analyses show that the topology of the cubane-like Cu₄I₄ cluster units is maintained in the assembly process.

Five cadmium(II) complexes, [CdClL·H₂O]_n (1), [CdBrL·H₂O]_n (2), CdI₂(HL)₂ (3), {[Cd(dca)₂(HL)₂]·2H₂O}_n (dca⁻ = dicyanamide) (4), and (H₂L)₂[CdCl₄(H₂O)₂] (5), have been synthesized by the reaction between 4-aminobenzoic acid (HL) and Cd²⁺. In 1 and 2, L⁻ serves as a tridentate ligand and bridges six-coordinate Cd^II centers to form [Cd^II−L]_n chains; halide anions link adjacent chains into two-dimensional layers. Complex 3 is a typical metallic carboxylic acid synthon. In 3, HL acts as a monodentate ligand coordinating to Cd^II through the nitrogen atom, and the head-to-tail hydrogen bonds of carboxylic groups result in a zigzag chain. The weak Cd···I interactions between adjacent chains extend the zigzag chain-like structure into a two-dimensional structure. Complex 4 consists of [Cd(dca)₂(HL)₂]_n chains and free water molecules. The twelve-membered rings formed by water molecules and carboxylic groups through hydrogen bonds link the adjacent chains to yield a two-dimensional layer. Complex 5 consists of discrete [CdCl₄(H₂O)₂]²⁻ anions and H₂L⁺ organic cations, which are linked by intermolecular hydrogen-bonding interactions to form a three-dimensional structure. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

A zinc(II) complex [Zn(bdc)(py)·H₂O]_a (bdc=1,4-benzenedicarboxylate, py=pyridine) has been prepared and characterized. Single crystal X-ray diffraction analysis reveals that the complex crystallizes in the monoclinic space group P2₁/n with a = 0.84823(3), b = 0.91440(3), c = 1.65141(2) ran, β = 91.243(2)°, V= 1.28057(6) nm³, Z = 4. The coordination geometry at each Zn(II) center is a distorted tetrahedron. Two independent bdc ligands in a herringbone pattern link alternatively four-coordinated Zn(II) centers into a one-dimensional polymeric chain. Hydrogen bonds among coordinated water molecules and uncoordinated oxygen atoms of two independent bdc ligands from different polymeric chains extend one-dimensional polymeric chains into a three-dimensional structure.

The supramolecular silver(I)-thiolate complex [Ag(μ₂-SC₄N₂H₄)₂(SCN)]_n has been prepared from the reaction of AgSCN and pyrimidine-2-thiol in DMF. X-ray diffraction analysis shows that the supramolecular structure exhibits one-dimensional chain through the secondary Ag-S interactions and the chains are further linked by strong hydrogen bonds to form a three dimensional network. The luminescence effect from the silver-centered state of SAg LMCT in solid state is different from that in solution due to the secondary Ag-S interactions.

Hydrothermal reactions of MoO₃, CuO, and pyrazine-2-carboxylic acid (Hpzca) resulted in two polymeric complexes, {[Cu₅(pzca)₆(H₂O)₄][Mo₈O₂₆]}_n (1; pzca=pyrazine-2-carboxylate) and [Mo₃Cu₂O₁₀(pz)]_n (2; pz=pyrazine). The former crystallized in the monoclinic space group P2₁/c with a=10.805(3) Å, b=13.061(5) Å, c=13.337(10) Å, β=90.20(4)°, V=2729(2) ų, and Z=2. The later crystallized in the orthorhombic space group Pnma with a=12.385(2) Å, b=7.6044(9) Å, c=12.7880(14) Å, V=1204.4(2) ų, and Z=4. X-Ray diffraction analysis revealed that 1 possesses a two-dimensional wave-like structure, formed from a zigzag one-dimensional chain, and 2 is a three-dimensional network structure formed from a one-dimensional chain and a pz bridging ligand. The temperature-dependent magnetic behavior of 1 was studied.

A new versatile multidentate nonchelating ligand, 1,2-bis[(2-pyrimidinyl)sulfanylmethyl]benzene (bpsb), was designed and prepared for supramolecular syntheses. Anion-controlled self-assembly between silver salt and bpsb resulted in a single stranded helical polymer [Ag₄(bpsb)₂(NO₃)₄]_n and a 2D lamellar network polymer [Ag₂(bpsb)₃(ClO₄)₂]_n (shown here) containing crownlike cavities.