Synthesis and structural characterization of two dimensional cadmium(II) coordination polymers

Reactions of Cd(NO₃)₂?·?4H₂O with NH₄SCN, ppz (ppz?=?piperazine) and bpa (bpa?=?bis(4-pyridyl)ethane) in CH₃OH afforded the cavity-containing rectangular grids {Cd(SCN)₂(ppz)} _n (1) and {Cd(NCS)₂(bpa)} _n (2). The ppz ligand in 1 is coordinated to the metal through both nitrogen atoms to form the 1-D zig-zag chain structure and distorted {CdN₄S₂} octahedral coordination geometry at each Cd center is completed by pairs of bidentate thiocyanato ligands. Complex 2 has the 2-D arrangement constructed through 1-D double μ(N,S) end-to-end bridging thiocyanato groups bridging Cd(II) chains interconnected through disordered bpa ligands.     

Tuning the topological net of two new copper(II) coordination polymers based on a paddle-wheel secondary building unit via altering the auxiliary ligands

Two new coordination polymers, [Cu(BDC)(L₁)_0.5]_n (1) and [Cu(BDC)(L₂)_0.5]_n (2) [H₂BDC=5-methyl-1,3-benzenedicarboxylic acid, L₁=1,4-bis(2-methyl-imidazol-1-yl) butane and L₂=1,4-bis(1-imidazol-yl)-2,5-dimethylbenzene], were synthesized from Cu(II), H₂BDC, and L₁/L₂. The carboxylate groups in 1 and 2 are bis-monodentate. By changing the N-donor ligands, 1 and 2 exhibit different topologies from a rob topological net to a twofold interpenetrating pcu net; however, they possess the same paddle-wheel secondary building unit in which Cu(II) has square-pyramidal geometry. The thermal stabilities of 1 and 2 are investigated.     

The influence of pH on coordination of phthalate to copper(II)

Two phthalate structures and a copper coordination polymer, (phth)₂(H₂O)₂ (1), (phth)₂(H₂O)₃ (2), and Cu(phth)₂(H₂O)₂ (3) [phth = phthalate], have been synthesized hydrothermally. The complexes were studied by single crystal X-ray analysis, elemental analysis, IR spectra and TG-DTG. Single crystal X-ray analysis reveals that 1 belongs to the orthorhombic system, space group Pca2(1), 2 is the monoclinic system, space group C2/c and 3 has four-coordinate Cu(II). The copper complex forms a one-dimensional zigzag chain via π–π stacking interaction of phthalates. Adjacent zigzag chains may be paired by supramolecular recognition and attraction through both π–π stacking and hydrogen bonding interactions into molecular zippers, further interlinked into a three-dimensional supramolecular network by these noncovalent interactions.     

Synthesis, structure, and fluorescence of two cadmium(II)-citrate coordination polymers with different coordination architectures

Two novel Cd(II)-citrate complexes were obtained with different metal/ligand ratios through hydrothermal method. Their structures were determined by single-crystal X-ray diffraction analysis. Although their topological structures are both 2-D layer network assemblies, both central Cd(II) ions and Hcit³⁻ ligands display completely different coordination modes. In polymeric complex 1, Hcit³⁻ serves as a μ₁₀-bridged and central Cd(II) ions adopt 6- and 8-coordinated configurations. In contrast, a μ₉-bridged and 6- and 7-coordinated environments between Cd(II) and Hcit³⁻ are established in the polymeric complex 2. Two Complexes remain stable up to approximately 300 °C. The complex 1 exhibits strong fluorescent emission band at 450 nm (λ=346 nm) as well as complex 2 exhibits strong fluorescent emission band at 430 (λ=346 nm).     

Syntheses and coordination chemistry of methylpyridylphosphine oxide ligands with copper(II)

The coordination properties of three heterofunctional phosphine oxide ligands, 2-methylpyridyldiphenylphosphine oxide (L1), phenylphosphino-bis-2-methylpyridine oxide (L2) and phenylphosphino-bis-2-methylpyridine N,N′,P-trioxide (L3) with Cu(II) is described. The X-ray crystal structures of the compounds display a distorted octahedral geometry, which exhibit Jahn–Teller distortions. In compounds 1 and 2, the L1 and L2 ligands react with Cu(BF₄)₂ in a 2:1 ligand to metal ratio, respectively, with the BF₄ anions interacting with the metal center. L3 reacts with Cu(BF₄)₂ in 1:1 and 2:1 ligand/metal ratios to form compounds 3 and 4, respectively. Addition of either 2,2′-bipyridine or 4,4′-bipyridine to reaction solutions containing Cu(BF₄)₂ and L3 produces a discrete molecule (5) and a polymeric structure (7), respectively. The reaction of both bipyridines in the presence of Cu(BF₄)₂ and L3 gives rise to a discrete molecule (6) characterized by two octahedral coppers interconnected by the 4,4′-bipyridine. The electrochemical and photophysical properties of all compounds were investigated by cyclic voltammetry (CV) and UV–Vis, as they exhibited no emission or excitation in fluorimetric experiments.     

Malonato-bridged hexamethylenetetramine coordination polymers containing Mn(II) and Cu(II)

Two malonato-bridged hexamethylenetetramine coordination polymers, M₂(hmt)(H₂O)₂(mal)₂ [hmt?=?hexamethylenetetramine, mal?=?malonate(2-), M?=?Mn (1), Cu (2)] were prepared and structurally characterized. The isostructural complexes are orthorhombic, space group Imm2, with a?=?7.104(1), b?=?15.982(3), c?=?7.702(1)?Å, Z?=?2, D _calc?=?1.862?g?cm^?3(1) and a?=?6.962(3), b?=?15.500(7), c?=?7.627(3)?Å, Z?=?2, D _calc?=?2.047?g?cm^?3for 2. The transition metals are octahedrally coordinated by one nitrogen atom of an hmt ligand and five oxygen atoms of a water molecule and three malonate anions. The latter coordinate in chelating/bis-monodentate mode to give 2D layers with a (4,?4) topology, and which are pillared by bridging bidentate hmt ligands to generate an open 3D framework with channels extending in the [001] direction. Over the temperature range 5–300?K, 2 behaves paramagnetically, following the Curie–Weiss law χ_m(T???θ)?=?4.521(6)?cm³mol^?1K with a Weiss constant θ?=??4.8(2)?K.     

Synthesis and structures of cadmium(II) complexes of a series of multinucleating N/S donor ligands

The coordination chemistry of a series of bis-bidentate ligands with cadmium(II) ions has been investigated. The ligands, containing two N,S-donor chelating (pyrazolyl/thioether) fragments, have afforded complexes of a variety of structural types (dinuclear M₂L₂ ‘mesocate’ complexes, a one-dimensional chain coordination polymer and a simple mononuclear complex) according to whether the bis-bidentate ligands act as bridges spanning two metal ions, or a tetradentate chelate to a single metal ion. The p-phenylene and m-biphenyl spaced ligands L¹ and L³ form dinuclear M₂L₂ complexes where the ligands are arranged in a ‘side-by-side’ fashion. In contrast the m-phenylene spaced ligand L² forms a one-dimensional coordination polymer where the ligands adopt a highly folded conformation. The 1,8-naphthalene spaced ligand L⁴ adopts a tetradendate chelating mode and affords a simple mononuclear complex.     

Ultrasound assisted syntheses of a nano-structured two-dimensional mixed-ligand cadmium(II) coordination polymer and direct thermolyses for the preparation of cadmium(II) oxide nanoparticles

A nano-sized mixed-ligand Cd(II) coordination polymer, {[Cd(bpa)(4,4′-bipy)₂(H₂O)₂](ClO₄)₂}_n (1); bpa = trans-1,2-bis(4-pyridyl)ethane and 4,4′-bipy = 4,4′-bipyridine, has been synthesized by a sonochemical method and characterized by IR and ¹H NMR spectroscopy. Compound 1 grows in one dimension by two different bridging ligands, 4,4′-bipy and bpa. The thermal stability of compound 1 in the bulk form and nano-sized was studied by thermogravimetric (TG) and differential thermal analysis (DTA). The crystallinity of this compound was studied by X-ray powder diffraction and compared with an XRD simulation of the single crystal data. CdO nanoparticles were obtained by direct calcination at 500 °C and decomposition in oleic acid at 200 °C of the nano-sized compound 1. The obtained cadmium(II) oxide nano-particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM).     

Cu(II) coordination polymers incorporating 3-aminopyridine and flexible aliphatic dicarboxylate ligands: Synthesis,structure and magnetic properties

The synthesis, structural chemistry and magnetic properties of a series of new Cu(II) polymers with α,ω-dicarboxylic acids (sebacic (H₂seb), suberic (H₂sub), succinic (H₂suc) and adipic (H₂adip)) and 3-aminopyridine (3-apy) are described: [Cu(Hsub)₂(3-apy)₂·2CH₃OH]_n (1); [Cu(Hseb)₂(3-apy)₂·4CH₃OH]_n (2); [Cu(Hsuc)₂(3-apy)₂]_n (3); [Cu(adip)(3-apy)₂]_n·n(H₂adip) (4). All four compounds feature a bis-monodentate bridging mode of the coordinated dicarboxylate moiety. Compounds 1 and 2 exhibit linear chains, whereas compound 3 shows two-dimensional structure. The 3-apy ligand acts as terminal ligand in 1–3. Compound 4 contains a doubly deprotonated adipate (adip²⁻) that connects Cu centers into linear chains. Additionally, 3-apy acts as a bridge in 4, resulting in the formation of parallel two-dimensional layers distant enough to host neutral molecules of adipic acid. Magnetic susceptibility measurements of compounds 1 and 3 show Curie law behavior indicating that the S = 1/2 Cu(II) spin carriers are magnetically well isolated by the dicarboxylate ligands.     

Topological diversification of two new Cd(II) photoluminescent coordination polymers via auxiliary N-donor ligands

Two new cadmium(II) coordination polymers, [Cd₂(nda)₂(L₁)] _n (1) and [Cd(nda)(L₂)_0.5] _n (2), were hydrothermally synthesized with 1,4-naphthalenedicarboxylic acid (H₂nda) and auxiliary N-donor coligands [L₁?=?1,5-bis(2-methyl-imidazol-1-yl)pentane and L₂?=?4,4′-bis(2-methyl-imidazol-1-ylmethyl)biphenyl]. Single-crystal X-ray diffraction analyses showed that the topological networks are different when the N-donor ligands are changed. Compound 1 showed a (4¹⁶.6⁵) topology and 2 showed a twofold interpenetrating pcu topology.     

Two- and three-dimensional aliphatic dicarboxylate copper coordination polymers with bis(3-pyridylmethyl)piperazine tethers

Divalent copper coordination polymers containing aliphatic dicarboxylate and bis(3-pyridylmethyl)piperazine (3-bpmp) tethering ligands exhibit different topologies depending on the length of the polymethylene chain and stoichiometric ratio. {[Cu(succinate)(3-bpmp)]·8H₂O}_n (1) and {[Cu(adipate)(3-bpmp)(H₂O)]·10H₂O}_n (4) both display (4,4) rhomboid grids, although the latter shows significant undulations to accommodate the additional girth of the dicarboxylate tethers. [Cu₂(succinate)₂(3-bpmp)_0.5(H₂O)]_n (2) and [Cu₂(glutarate)₂(3-bpmp)]_n (3) possess {Cu₂(OCO)₃} partial paddlewheel and {Cu₂(OCO)₄} complete paddlewheel carboxylate bridged dimeric units, respectively. However, 2 has a (6,3) brick-layered structure with a rare binodal moganite (mog) supramolecular topology, while 3 possesses a non-interpenetrated primitive cubic network. Intriguing co-crystallized water tapes are seen in 1 and 4. Thermal dehydration and decomposition behavior of 1–4 is also presented.     

Syntheses,structures and fluorescent properties of three copper cyanide coordination polymers based on N-heterocyclic ligands

Hydrothermal reactions of CuCN, K₃[Fe(CN)₆] with 2,2′-bipyridine, 1,10-phenanthroline or 2,6-bis(1,2,4-triazolyl)pyridine (btp) afford three coordination polymers, [Cu₇(CN)₇(bipy)₂] _n (1), [Cu₂(CN)₂(phen)] _n (2) and [Cu₃(CN)₃(btp)] _n (3). Complex 1 displays 1D polymeric ribbons which are assembled through Cu ··· Cu and π–π stacking interactions into a 3D framework. Complex 2 shows a 1D zigzag chain structure in which phen is a side ligand. In 3, the copper cyanide 2D polymeric networks are connected by tridentate btp to form a 3D metal-organic framework. These coordination polymers exhibit strong fluorescent emissions in the solid state.     

1D coordination polymers of silver(I) and copper(II) based on bis(N-heterocyclic carbene) ligands: Synthesis and structural studies

The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L¹H₂·I₂) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L²H₂·I₂), and their silver(I) and copper(II) coordination polymers, [L¹AgI]_n (1) and [L²Cu₂I₄]_n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L¹) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L²) and coplanar quadrilateral Cu₂I₂ units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds.     

Four silver-containing coordination polymers based on bis(imidazole) ligands

Four coordination polymers, [Ag(L¹)](m-Hbdc) (1), [Ag(L¹)]₂(p-bdc)?·?8H₂O (2), [Ag(Hbtc)(L¹)][Ag(L¹)]?·?2H₂O (3) and [Ag₂(L²)₂](OH-bdc)₂?·?4H₂O (4), where L¹?=?1,1′-(1,4-butanediyl)bis(imidazole), L²?=?1,2-bis(imidazol-1-ylmethyl)benzene, m-H₂bdc?=?1,3-benzenedicarboxylic acid, p-H₂bdc?=?1,4-benzenedicarboxylic acid, H₃btc?=?1,3,5-benzenetricarboxylic acid, and OH–H₂bdc?=?5-hydroxisophthalic acid, were synthesized under hydrothermal conditions. Compound 1 contains a–Ag-L¹–Ag-L¹–chain and a hydrogen-bonding interaction induced–(m-Hbdc)-(m-Hbdc)–chain. Compound 2 consists of two independent–Ag-L¹–Ag-L¹–chains. P-bdc anions are not coordinated. Hydrogen bonds form a 3D supramolecular structure. A novel (H₂O)₁₆ cluster is formed by lattice water molecules in 2. Compound 3 contains a–Ag-L¹–Ag-L¹–and a–Ag(Hbtc)-L¹–Ag(Hbtc)-L¹–chain. The packing diagram shows a 2D criss-cross supramolecular structure, with?π?···?π?and C–H ···?π?interactions stabilizing the framework. Compound 4 contains a [Ag₂(L²)₂]²⁺ dimer with hydrogen-bonding,?π?··· π, and Ag ··· O interactions forming a 3D supramolecular framework. The luminescent properties for these compounds in the solid state are discussed.     

Syntheses and structures of three Mn(II) coordination polymers assembled from a dithiocarboxylic acid and N-donor ligands

Three new complexes, {[Mn(dtb)(bpe)·2H₂O]·H₂O} _n (1), {[Mn(dtb)(bpa)·2H₂O]·H₂O} _n (2), and {[Mn(dtb)(phen)]} _n (3) [H₂dtb?=?5,5′-dithiobis(2-nitrobenzoic acid), bpe?=?1,2-bis(4-pyridyl)ethene, bpa?=?1,2-bi(4-pyridyl)ethane, phen?=?1,10-phenanthroline], have been synthesized under hydrothermal conditions with Mn(OAc)₂·4H₂O, dtb, and different N-donor ligands. X-ray structure analyses of 1 and 2 reveal analogous structures with 1D helical chains and 2D 4⁴ chiral layers. The structure of 3 shows a 1D chain which is outwardly decorated with phen ligands. These neutral polymeric complexes exhibit structural diversity due to the different coordination modes of the flexible dtb ligand and the N-donor ligands. The thermogravimetric analyses and X-ray powder diffractions of 1–3 are also presented.     

Assembly,crystal structures,and luminescent properties of three new thiocyanate-bridging mercury(II) coordination polymers

Two ligands, 2-{5,5-dimethyl-3-[2-(pyridin-3-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L1) and 2-{5,5-dimethyl-3-[2-(pyridin-2-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L2), were synthesized. By reaction of mercury thiocyanate with L1 and L2, respectively, coordination polymers [Hg(L1)(μ_1,3-SCN)₂]_n (1), [Hg(L1)₂(μ_1,3-SCN)₂]_n (2), and [Hg(L2)(μ_1,3-SCN)(SCN)]_n (3) with different structures and topologies were obtained. In 1, the thiocyanate shows μ_1,3-SCN bridging coordination, and adjacent Hg(II) ions are bridged by two μ_1,3-SCN ions to form an infinite chain with the remaining position of five-coordinate Hg(II) occupied by L1. In 2, the thiocyanate has the same coordination as 1. However, Hg(II) has octahedral coordination with two L1 involved in coordination. An unusual feature of 3 is the presence of two types of thiocyanates, one has a S-terminal ligand and the other has a μ_1,3-SCN bridge. The mercury(II) in 3 is four-coordinated by L2 and three thiocyanates. Luminescent properties and thermal stabilities of 1–3 were studied.     

Coordination polymers of cadmium with (4-carbomethoxy-naphthalen-1-yloxy) acetic acid derivatives

Three cadmium coordination polymers derived from the dianions of (4-carboxymethoxy-naphthalen-1-yloxy) acetic acid (LH₂) and (4-carboxymethoxy-2,3-bis-arylsulfanyl naphthalene-1-yloxy) acetic acid (L₁H₂), in which the dianions of the corresponding acids act as a spacer to cadmium nodes, have been prepared and characterized. The coordination polymer of the dianion of (4-carboxy-methoxy-2,3-bis-arylsulfanylnaphthalene-1-yloxy) acetic acid with cadmium is a 3-D coordination polymer, whereas the dimensionality of the coordination polymer of the dianion of (4-carboxymethoxy-naphthalen-1-yloxy) acetic acid is dependent on the ancillary ligand. The presence of the chelating ligand 1,10-phenanthroline gave a 1-D polymer of the dicarboxylate anion L, but in the absence of a chelating ligand a 2-D coordination polymer encapsulating hexa–aquacadmium(II) ions was obtained. The latter two coordination polymers show fluorescence emission in the solid state.     

Synthesis,structure and luminescent properties of a new two-dimensional (4,4) network cadmium coordination polymer with dicyanamide and benzimidazole ligands

The new cadmium coordination polymer [Cd(bim)₂(dca)₂]_n (1), (bim?=?benzimidazole, dca?= dicyanamide) was synthesized and characterized by IR, thermogravimetric analysis and luminescent properties. The coordination geometry of cadmium atom is distorted octahedral, coordinated equatorially by four nitrogen atoms from four dicyanamide ligands, and axially by two nitrogen atoms from two benzoimidazoles. Each dca ligand links two cadmium(II) atoms and 1 forms a two-dimensional (4,4) network.