Four-connected Nodes Research Articles

3D metal–organic frameworks incorporating water-soluble tetra-p-sulfonatocalix[4]arene

Water-soluble tetra-p-sulfonatocalix[4]arene, acting as a four-connected node, bridges the rare earth cations into a 3D porous MOF in which 1D smaller circular hydrophilic channels and larger quadratic ones are lined up along the c axis and interconnected to each other by the calixarene cavities and other interstices.

Dehydration and rehydration behavior of a trinodal topological 3-D framework of Cd(II) benzimidazole-5,6-dicarboxylate

A hydrothermal reaction of benzimidazole-5,6-dicarboxylic acid (H3BimDc) with Cd(NO3)2·4H2O in an aqueous solution in the presence of NH3·H2O yielded a 3-D coordination framework [Cd1.5(BimDc)(H2O)2]·2H2O (1). Complex 1 shows a (3,4,5)-connected net topology in which the ligand BimDc3− acts as five-connecting node, and two independent Cd(II) centres act as three-connecting node and four-connecting node, respectively. The Schlafli symbol of this trinodal network can be described as (4·6·8)2(42·62·82) (42·65·83)2. The dehydration and rehydration behavior of 1 has been studied by means of thermogravimetric analysis (TG), variable temperature (VT) X-ray powder diffraction patterns (XPRD), as well as single-crystal X-ray diffraction methods. It was found that the two lattice water molecules and one of the two coordinative water molecules can be reversibly dehydrated and rehydrated through a single-crystal-to-single-crystal procedure for the loss of the first water molecule, and two crystal-to-crystal procedures for the loss of the second and third water molecules. The coordination framework decomposes along with the loss of the last water molecule. The luminescence property of 1 has also been investigated.

Assembly of [CunIn]-based coordination polymers from cracking the 3D framework of bulk CuI via flexible N-heterocyclic ligands

Solvothermal reactions of CuI with four flexible N-heterocyclic ligands, 1,2-bis(4-pyridyl)ethane (bpe), 1,1'-(1,4-butanediyl)bis-1H-benzimidazole (bbbm), 1,1'-(1,4-butanediyl)bis-1H-benzotriazole (bbbt), and 1,1'-(1,5-pentanediyl)bis-1H-benzimidazole (pbbm), afforded four new [Cu(n)I(n)]-based coordination polymers, [Cu3I(mu-I)(mu3-I)(bpe)3]n (1), {[CuI(bbbm)1.5].0.25MeCN}n (2), and [Cu4(mu3-I)4L2]n (3: L = bbbt; 4: L = pbbm), respectively. Compounds 1-4 were characterized by elemental analysis, IR and X-ray crystallography. 1 consists of an unique 2D network in which 1D [CuI(bpe)]n zigzag chains are embroidered alternatively onto the two faces of a 2D [Cu4(mu-I)2(mu3-I)2(bpe)2]n layer through pairs of bpe bridges. 2 contains a 66-membered metallomacrocyclic [CuI(bbbm)1.5]6 unit that fuses with its neighbouring ones via sharing Cu atoms to form a 2D (6,3) layer network. 3 or 4 contains a cubanelike [Cu4(mu3-I)4] core, which works as a cross-shaped four-connecting node to link its four equivalent units to form a 2D (4,4) cross-shaped network () or acts as a Y-shaped three-connecting node to connect its three equivalent ones to form a 1D double chain (). In addition, the photoluminescent properties of in solid state at ambient temperature were also investigated.

Formation of Infinite Linear Mercury Metal Chains Assisted by Face-to-Face π−π (Aryl−Aryl) Stacking Interactions

Polymeric mercury compounds, [HgCl2(bpym)]n (1, bpym = 5,5′-bipyrimidine), [Hg2Br4(bpym)]n (2), and [HgX2(bpyz)]n (3-Cl, X = Cl; 3-Br, X = Br; bpyz = 2,2′-bipyrazine), which are composed of linear mercury chains were assembled from HgX2 (X = Cl, Br) and either 5,5′-bipyrimidine or 2,2′-bipyrazine at ambient temperature. Single-crystal X-ray diffraction analysis revealed that 1 presents a two-dimensional layer structure involved with one-dimensional linear mercury chains at a mercurophilic distance of 3.77 A. It is linked by bridging chlorides and stabilized by weak, slipped face-to-face π−π (aryl−aryl) interactions between the coordinated bpym ligands. These layers are interdigitated-stacked into a three-dimensional supramolecular architecture through C−H···N and C−H···Cl−Hg hydrogen bonding interactions. Compound 2 has a two-dimensional (4,4) layer structure comprised of four-connected bpym nodes and linear Br−Hg−Br linkers. The layers are stagger-stacked in a three-dimensional supramolecular network, th...

Two novel supramolecular isomers based on 2,2′-biimidazole derivative and zinc ions: Syntheses, structures and luminescent properties

Two Zn(II)-2,2′-biimidazole derivative supramolecular isomers 1 and 2 formulated as [Zn(L)] · 2H 2O (H 2L = 4,4′-(1H,1′ H-2,2′-biimidazole-1,1′-diylbis(methylene))dibenzoic acid) have been synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Complex 1 exhibits a 2D four-connected network with (4 3.6 3) topology when the zinc center and the L 2− ligand act as four-connected nodes (or a distorted (4,4) grid if the [Zn 2(imidazole) 4] units are considered as four-connected nodes). Complex 2 shows a novel four-connected twofold interpenetrated net with (4 2.6 2.8 2) topology when the zinc center and the L 2− ligand act as four-connected nodes (or a twofold interpenetrated α-Po topology when [Zn 2(imidazole) 4] units are identified as six-connected nodes). Moreover, complexes 1 and 2 both exhibit strong luminescent properties at room temperature.

A double-layered zinc(II) coordination polymer with the ligand 3,5-bis(carboxylatomethoxy)benzoate

In the title compound, poly[hexaaquabis[mu(4)-3,5-bis(carboxylatomethoxy)benzoato]trizinc(II)], [Zn(3)(C(11)H(7)O(8))(2)(H(2)O)(6)](n), there are two crystallographically distinct Zn(II) cations which are bridged by polycarboxylate ligands in a mu(4)-bridging mode. A pair of ligands bridges adjacent Zn atoms to give centrosymmetric dimetal building blocks which act as four-connected nodes to be further interlinked into a two-dimensional double-layered framework with (4,4) topology. Other Zn atoms, lying on inversion centres, occupy the cavities of this topological structure. This submission shows a versatile polycarboxylate ligand with rigid and flexible functional groups, the co-operation and complementarity of which would meet the coordination requirements of a variety of topological structures.

Solid chemistry of the Zn II/1,2,4-triazolate/anion system: Separation of 2D isoreticular layers tuned by the terminal counteranions X ( X=Cl −, Br −, I −, SCN −)

An array of 2D isoreticular layers, viz. [Zn(atrz) X] ∞ ( 1· X; X=Cl −, Br −, I −; atrz=3-amino-1,2,4-triazole anion), [Zn 4(atrz) 4(SCN) 4·H 2O] ∞ ( 1·SCN·H 2O) and [Zn(trz) X] ∞ ( 2· X; X=Cl −, Br −, I −; trz=1,2,4-triazole anion), have been hydrothermally synthesized and structurally characterized. Compounds 1· X and 1·SCN·H 2O are constructed from binuclear planar Zn 2(atrz) 2 subunits and exhibit (4,4) topological network when the subunits are simplified as four-connected nodes. Based on changing the terminal counteranions X ( X=Cl −, Br −, I −, SCN −), the average interlayer separations of 1· X and 1·SCN·H 2O are enlarged, which equal to 5.851, 6.153, 6.651 and 8.292 Å, respectively. As a result, H 2O molecules reside in the spaces between two adjacent layers of 1·SCN·H 2O. 2 and 1 are the isomorphous structures. In common with 1, the interlayer separations of 2· X are widened with increasing the ion radius. Solid-state luminescence properties and thermogravimetric analyses of 1 and 2 were investigated, respectively.

Solvent Effects on the Assembly of [Cu2I2]- or [Cu4I4]-Based Coordination Polymers: Isolation, Structures, and Luminescent Properties

Four [Cu2I2]- or [Cu4I4]-based coordination polymers, [CuI(bpp)]n (1), {[Cu3I3(bpp)3]·2aniline·MeCN}n (2), {[Cu2I2(bpp)2]·2aniline}n (3), and [Cu4I4(bpp)2]n (4), were prepared by solvothermal reactions of CuI or Cu2(OH)2CO3 with 1,3-bis(4-pyridyl)propane (bpp) in different solvent systems. The preparation of 2 or 3 is involved in the in situ formation of aniline molecules and the reduction of Cu(II) to Cu(I). These compounds were characterized by elemental analysis, IR, and single crystal X-ray diffraction. Compound 1 consists of [Cu2I2] dimeric cores that link the neighboring ones via bpp bridges to form a one-dimensional double-bridged polymeric chain. Compound 2 or 3 has a similar chain structure in which the shape and size of the [Cu2I2(bpp)2]2 cavities that are occupied by MeCN/aniline or aniline solvent molecules are different from those of 1. Compound 4 has an intriguing two-dimensional 4-fold interpenetrated network in which each cubanelike [Cu4I4] core acts as a rare “seesaw”-shaped four-connecting node to interconnect four other equivalent ones via bpp bridges. The results did provide interesting insights into solvent effects on the construction of cluster-based coordination polymers. In addition, the photoluminescent properties of 1−4 in the solid state at ambient temperature were also investigated.

A (4,8)-Connected Fluorite Topology Framework Based on Mononuclear and Dinuclear Metal Centers

A (4,8)-connected metal-organic framework has been constructed using an asymmetrical ligand based on dinuclear cadmium clusters as eight-connected nodes and mononuclear cadmium atoms as four-connected nodes, and it represents the flu topology network.

Bis{μ-(E)-2-[(2-pyridylamino)(2-pyridylimino)methyl]benzato}bis[acetatozinc(II)] tetrahydrate

In the C(2)-symmetric dinuclear title complex, [Zn(2)(C(18)H(13)N(4)O(2))(2)(C(2)H(3)O(2))(2)] x 4 H(2)O, each Zn(II) ion is five-coordinated in a distorted trigonal bipyramidal fashion by one carboxylate O atom from one benzoate ligand, one imine N atom and two pyridyl N atoms from a second benzoate ligand, and one O atom from an acetate anion. The two Zn atoms are bridged by the two benzoate ligands, forming a dinuclear structure with a 14-membered macrocycle. Adjacent dinuclear units are further connected by extensive hydrogen bonds involving the solvent water molecules, giving a three-dimensional hydrogen-bonded framework. The framework can be regarded as an example of the four-connected node network of the PtS topology.

A coordination polymer with a (3,4)-connected (4·62)2(42 ·62 ·82) 2D network: synthesis, crystal structure and luminescent properties

The 2D Zn(II) coordination polymer with 2,3-dicarboxypyridine acid (2,3-H2PDC) and dimethylamine (DMA) [Zn(2,3-PDC)(DMA)] n (1) was synthesized under solvothermal conditions and characterized by FT-IR spectroscopy, TGA and luminescent analysis. X-ray crystallographic studies of 1 reveal that this metal-organic complex has an interesting (3,4)-connected 2D network with binary nodes. The Zn ions are four-connected nodes and the 2,3-PDC ligands are three-connected nodes. Luminescent study indicates 1 has an emissive maximum at 403 nm in the solid state at room temperature.

Synthesis and structural characterisation of lanthanide coordination polymers featuring 4,4′,6,6′-tetra-carboxy-2,2′-bipyridine and rare network topology

Reported herein is a synthetic and structural study of the coordination chemistry of 4,4′,6,6′-tetracarboxylic acid-2,2′-bipyridine (H4tcbp) with some lanthanide ions. The reaction of H4tcbp under acidic hydrothermal conditions with Ln(III) (Ln = La, Eu and Gd) in 1:1 stoichiometric ratio led to the formation of crystalline {[La(Htcbp)(H2O)3]·H2O}, 1, {[La(Htcbp)(H2O)]}, 2, {[Eu(Htcbp)(H2O)]·2 H2O}, 3 and {[Gd(Htcbp)(H2O)]·2 H2O}, 4; which were structurally characterised. Using a 1:1 H2O/DMF-solution in combination with Eu(III) and H4tcbp gave {[Eu(tcbp)(H2O)]·(Me2NH2)}, 5, which was also structurally characterised. The acidic conditions in 1–4 yielded 1:1 neutral {Ln:Htcbp} complexes whereas in 5 the H4tcbp ligand is fully deprotonated and charge neutrality is brought about by the presence of a dimethylammonium cation (arising through the hydrolysis of the DMF solvent). Complex 1 forms a 1D coordination polymer which cross-links through extensive hydrogen bonding to form a complicated 3D network. Each {Ln(Htcbp)} moiety in 2 acts as a four-connecting node and forms a 2D sheet with (4,4)-topology, which is different to the 2D sheets with (4,4)-topology formed in isostructural 3 and 4. Within 5 each [Eu(tcbp)]− moiety acts as a 5-connecting node forming a heretofore unprecedented 2D 5-connected network with (33.43.54) topology. Furthermore, each 2D sheet in 2–5 features an array of hydrogen bonded contacts both within and between neighbouring sheets to give complicated 3D networks.

Construction of different dimensional inorganic–organic hybrid materials based on polyoxometalates and metal–organic units via changing metal ions: from non-covalent interactions to covalent connections

Five POM-based hybrid materials have been designed and synthesized based on different metal ions under hydrothermal conditions, namely, [Zn(Hfcz)(H(2)O)(3)](H(3)fcz)(SiMo(12)O(40)).3H(2)O (1), [Cd(2)(Hfcz)(6)(H(2)O)(2)](SiMo(12)O(40)).H(2)O (2), [Co(2)(Hfcz)(2)(SiW(12)O(40))](H(3)fcz)(2)(SiW(12)O(40)).10H(2)O (3), [Ni(2)(Hfcz)(4)(H(2)O)(2)](SiW(12)O(40)).5H(2)O (4) and [Ag(4)(Hfcz)(2)(SiMo(12)O(40))] (5), where Hfcz is fluconazole [2-(2,4-difluorophenyl)-1,3-di(1H-1,2,4-triazol-1-yl)propan-2-ol]. Their crystal structures have been determined by X-ray diffraction, elemental analyses, IR spectra, and thermogravimetric analyses (TGA). There are 1D mono and double chain-like metal-organic units in compounds 1 and 2, respectively. Polyoxometalates and metal-organic units co-crystallize through hydrogen bonds. In compound 3, metal-organic sheets are pillared by one kind of polyanion through covalent connections to generate a sandwich double-sheet. The other kind of polyanion acts as a counter-ion and lies in two adjacent sandwich double-sheets through non-covalent interactions. Polyanions covalently link metal-organic sheets to extend to an unusual 3D 5-connected framework with the (4(4).6(6)) topology in 4. In compound 5, polyanions link metal-organic chains to form a sheet through covalent connections. It is interesting that compound 5 shows an intricate (4,5,10)-connected framework with (4(4).6(2))(4)(4(8).6(2))(2)(4(14).6(19).8(12)) topology based on two kinds of Ag cations as four-connected and five-connected nodes, and polyanions as ten-connected nodes, when AgO interactions are considered. It represents the highest connected network topology presently known for polyoxometalate systems. The structural differences among 1-5 indicate the importance of different metal-organic units, coordination modes of polyanions for framework formation, and the interactions between polyanions and metal-organic units. In addition, the luminescent properties of compounds 1, 2 and 5, and electrochemical behaviours of compounds 1-5 have been investigated.

A novel (4,8)-connected 3D polyoxometalate-based metal–organic framework containing an in situ ligand

A novel (4,8)-connected 3D polyoxometalate-based metal–organic framework has been constructed using an in situ-generated ligand based on copper cations as square-planar four-connected nodes and Keggin polyanions as cubical eight-connected nodes.

Hydrogen-bonded frameworks of bis(2-carboxypyridinium) hexafluorosilicate and bis(2-carboxyquinolinium) hexafluorosilicate dihydrate

In bis(2-carboxypyridinium) hexafluorosilicate, 2C(6)H(6)NO(2)+.SiF6(2-), (I), and bis(2-carboxyquinolinium) hexafluorosilicate dihydrate, 2C(10)H(8)NO(2)+.SiF6(2-).2H2O, (II), the Si atoms of the anions reside on crystallographic centres of inversion. Primary inter-ion interactions in (I) occur via strong N-H...F and O-H...F hydrogen bonds, generating corrugated layers incorporating [SiF6](2-) anions as four-connected net nodes and organic cations as simple links in between. In (II), a set of strong N-H...F, O-H...O and O-H...F hydrogen bonds, involving water molecules, gives a three-dimensional heterocoordinated rutile-like framework that integrates [SiF6](2-) anions as six-connected and water molecules as three-connected nodes. The carboxyl groups of the cation are hydrogen bonded to the water molecule [O...O = 2.5533 (13) A], while the N-H group supports direct bonding to the anion [N...F = 2.7061 (12) A].

Synthesis, Structure, and Luminescent and Magnetic Properties of Novel Lanthanide Metal−Organic Frameworks with Zeolite-like Topology

A series of microporous lanthanide metal-organic frameworks [Ln(BTC)(DMF)(2) x H(2)O, Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5), Yb (6); DMF = N,N'-dimethylformamide] with 4 x 4 x 4 x 6 x 6 x 8 topology, which is very common in the zeolite topologies, have been synthesized under mild conditions. The single-crystal X-ray diffraction analysis reveals that they exhibit the same three-dimensional (3D) architecture and crystallize in monoclinic symmetry space group C2/c. Organic and inorganic four-connected nodes link each other to form a 3D open framework. The framework contains approximate 13 Angstrom x 7 Angstrom rectangle channels along the [1,1,0] and [1,-1,0] directions, respectively. The luminescent properties of these complexes have been studied, and complex 1 shows a Tb(3+) characteristic emission in the range of 450-650 nm at room temperature. Complexes 1-5 exhibit antiferromagnetic interaction between Ln(3+) ions. The water sorption isotherm shows that about 15 water molecules per unit cell can be adsorbed into the micropores of dehydrated complex 4.

Novel (4 2 · 8 4)(4 3 · 6 3) 2(4 6 · 6 3 · 8 6) 2 topology network built up from the highly connective pyridine-2,4,6-tricarboxylate ligand

A new manganese polymer Mn 3(ptc) 2(H 2O) 4 ( 1) (H 3ptc = Pyridine-2,4,6-tricarboxylic acid) has been solvothermally synthesized and characterized by single-crystal diffraction, IR, TGA and elemental analysis. Compound 1 crystallizes in the triclinic space group P 1 ¯ and shows a fairly complicated structure, which should be attributed to the high connectivity of H 3ptc ligand. Meanwhile, we defined a novel trinodal (4 2 · 8 4)(4 3 · 6 3) 2(4 6 · 6 3 · 8 6) 2 topology net, two types of Mn(II) ions in different chemical environment and ptc 3− anion act as four-connected, four-connected and six-connected node, respectively. The magnetic measurement in the temperature range of 2–300 K displays weak antiferromagnetic coupling interaction between the Mn(II) ions.

Novel Alternating Ferro-Ferromagnetic Two-Dimensional (4,4) and Photoluminescent Three-Dimensional Interpenetrating PtS-Type Coordination Networks Constructed from a New Flexible Tripodal Ligand as a Four-Connected Node

Two novel two-dimensional (2D) and one three-dimensional (3D) coordination polymers[Ni(HTTG)(H2O)2]n (1), [Co(HTTG)(H2O)2]n (2), and [Cd(HTTG)]n (3)have been hydrothermally synthesized by self-assembly of an unexplored tripodal ligand H3TTG (N,N‘,N‘ ‘-1,3,5-triazine-2,4,6-triyltris-glycine) and corresponding metal salts. X-ray diffraction analysis reveals that the three polymers exhibit novel frameworks due to diverse coordination conformations and different acid forms of the flexible tricaboxylate ligands. The isostructural complexes 1 and 2 possess 2D frameworks with M(H2O)2(CO2)2 chains bridged by the ligands, and the resulting 3D networks were extended through R22(8) hydrogen bonds between the undeprotonated carboxylate groups and the triazine rings as well as π···π interactions between the triazine rings. Complex 3 shows a 3D interpenetrating compact network with inorganic Cd2O2 chains interconnected by the flexible organic ligands. Topological analysis indicates that in all three complexes the tripo...

New d10metal–organic coordination polymers with 9,10-bis(triazol-1-ylmethyl)anthracene (L): Syntheses, crystal structures, and luminescent properties

In our continuous efforts to explore the effects of metal ions, ligand structures, counter-anions on the structure and properties of metal–organic complexes, six new d10 metal coordination polymers with an anthracene-triazole ligand, 9,10-bis(triazol-1-ylmethyl)anthracene (L), {[Cu(L)I]}∞ (1), {[Ag(L)(BF4)]}∞ (2), {[Zn(L)(NO3)2]}∞ (3), {[Zn(L)(CH3OH)2(ClO4)2(H2O)]}∞ (4), {[Cd(L)(CH3OH)2(ClO4)2(H2O)]}∞ (5) and {[Hg(L)(Br2)]}∞ (6), were synthesized and structurally characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction. 1–3 and 6 have similar one-dimensional (1-D) chain structures in which 1, 3 and 6 were further linked into infinite two-dimensional (2-D) sheets by inter-chain C–H⋯I, π⋯π or C–H⋯Br weak interactions, respectively, while 2 was extended into three-dimensional (3-D) supramolecular network by Ag⋯F and Ag⋯N weak interactions. 4 and 5 possess similar (4,4) 2-D sheet structure containing only one type of rhombic grid, and the Zn/Cd atoms are regarded as the four-connected nodes and the ligand as bridges. Obviously, the structural differences among them are attributable to the different metal ions and counter anions. In 1–6, L adopts a trans-gauche conformation with the shortest N⋯N distance between the two N donors. Furthermore, the fluorescent properties of 1–6 and ligand L have been investigated.

Metal Nuclearity Modulated Four‐, Six‐, and Eight‐Connected Entangled Frameworks Based on Mono‐, Bi‐, and Trimetallic Cores as Nodes

To investigate the relationship between network connectivity and metal nuclearity, we designed and synthesized a series of three-dimensional (3D) entangled coordination frameworks based on different metal cores, namely [Zn(2)(bdc)(2)(L)(2)]2H(2)O (1), [Zn(bdc)(L)(0.5)] (2), [Zn(oba)(L)(0.5)] (3) and [Cd(3)(bdc)(3)(L)(2)(H(2)O)(2)] (4) by self-assembly of d(10) metal salts with the flexible long-chain ligand 1,4-bis(1,2,4-triazol-1-yl)butane (L), and with the rigid and nonrigid aromatic dicarboxylate ligands 1,4-benzenedicarboxylate (bdc) and 4,4'-oxybis(benzoate) (oba). Compound 1 exhibits a threefold interpenetrated diamondoid array typically based on a tetrahedral second building unit (SBU) at a single Zn center. Compound 2 adopts a threefold interpenetrated alpha-polonium-type network that is built from bimetallic cores as six-connected vertices. The structure of 3 also consists of dinuclear units; it comprises a novel (3,4)-connected threefold interpenetrated net with complex (4610)(46(2)10(3)) topology when single zinc centers act as four-connected nodes (or the alpha-Po topology if dinuclear units are considered as six-connected nodes). Compound 4, derived from a crosslinked fivefold interpenetrated diamond-like substructure, is an unusual example of a self-penetrating coordination framework displaying an unprecedented eight-connected 4(20)6(8) topology with trinuclear cadmium clusters as eight-connected nodes which, to our knowledge, not only defines a new topology for eight-connected coordination networks, but also represents the highest connected topology presently known for self-penetrating systems. Detailed structural comparison of these complexes indicates that the increase in metal nuclearity induces the progressive increase in the connectivities of the ultimate nets: that is, the metal nuclearity plays a significant role in tuning the connectivity of a specific network. The thermal and luminescent properties of these compounds are discussed.