Homochiral coordination polymer with infinite double-stranded helices

Hydrothermal reaction of 4,4-trimethylenedipyridine (tmdp) with ZnI2 under 175 degrees C yields a novel compound, {[Zn2I4(tmdp)2]n.[Zn2I4(tmdp)2]n}, which has a chiral infinite double-stranded helical structure consisting of two single-stranded helices of the same handedness.     

Porous coordination polymer hybrid device with quartz oscillator: effect of crystal size on sorption kinetics

A new strategy to synthesize monodispersed porous coordination polymer (PCP) nanocrystals at room temperature was developed and utilized for the formation of PCP thin films on gold substrates with fine control over the crystal sizes using the coordination modulation method. Hybridization of these PCP thin films with an environment-controlled quartz crystal microbalance system allowed determining the adsorption properties for organic vapors (methanol and hexane). In the case of high sensitivity (at the low-concentration dosing of analytes), the sensor response depended on the crystal size but not on the type of analyte. In contrast, at the high-concentration dosing, a clear dependence of the sorption kinetics on the analyte was observed due to significant sorbate-sorbate interaction.     

An organouranium coordination polymer containing infinite metal oxide chains

The title compound, catena‐poly[[[dioxouranium(VI)]‐bis(μ‐2‐hydroxybenzohydroxamato)] dihydrate], {[U(C₇H₆NO₃)₂O₂]·2H₂O}_n, is a uranyl coordination polymer based on the salicylhydroxamate ligand. The ligand acts both as a chelate, forming five‐membered rings, and as a bridge between two U atoms. The coordination around each U atom is a distorted hexagonal bipyramid. Infinite chains running along [001] are formed via bridging salicylhydroxamate O atoms. The chains have C₂ symmetry, with U atoms in special positions on twofold axes. The water molecules are not coordinated to the metal but crosslink, through hydrogen bonding, adjacent coordination polymer chains in the [110] and [10] directions.     

Measurement of sorption in polymer membranes with a quartz crystal microbalance

An application of the oscillating quartz crystal microbalance (QCM) in the measurements of sorption rates and equilibria in polymer—vapor systems is presented. The sorption isotherms of methanol, ethanol and n-heptane in cellulose acetate and poly(hexamethylene adipamide) were measured with the QCM at 298K. The results agree reasonably with the Flory model except at low absorbate activities where appreciable deviations due to localized absorption were observed, as verified with IR spectroscopy. The diffusion coefficient of methanol in cellulose acetate was also calculated from the sorption rate data measured with the QCM. The values obtained at different methanol concentrations correlate well with the published diffusion coefficients.     

A new layered Ca–succinate coordination polymer

A new layered Ca–succinate coordination polymer, poly[μ₃‐succinato‐calcium(II)], [Ca(C₄H₅O₄)]_n, was synthesized by reaction of CaCl₂·2H₂O and succinic acid in an aqueous medium under hydrothermal microwave conditions. The structure contains infinite layers of edge‐sharing calcium pentagonal–bipyramidal polyhedra forming six‐membered rings connected through succinate ligands. Such an assembly of inorganic building units is unique for calcium metal–organic framework‐type structures. Adjacent layers are packed into a final pseudo‐three‐dimensional structure through weak C—H...O hydrogen bonds.     

Functional colloidal particles stabilized by layered silicate with hydrophilic face and hydrophobic polymer brushes

In this study, we describe a new strategy for producing narrowly dispersed functional colloidal particles stabilized by a nanocomposite with hydrophilic clay faces and hydrophobic polystyrene (PS) brushes on the edges. This method involves preparation of polymer brushes on the edges of clay layers and Pickering suspension polymerization of styrene in the presence of the nanocomposites. PS brushes on the edges of clay layers were prepared by atom transfer radical polymerization. X‐ray diffraction and thermogravimetric analysis results indicated that PS chains were grafted to the edges of clay platelets. Transmission electron microscope results showed that different morphologies of clay‐PS particles could be obtained in different solvents. In water, clay‐PS particles aggregated together, in which PS chains collapsed forming nanosized hydrophobic domains and hydrophilic clay faces stayed in aqueous phase. In toluene, clay‐PS particles formed face‐to‐face structure. Narrowly dispersed PS colloidal particles stabilized by clay‐PS were prepared by suspension polymerization. Because of the negatively charged clay particles on the surface, the zeta potential of the PS colloidal particles was negative. Positively charged poly(2‐vinyl pyridine) (P2VP) chains were adsorbed to the surface of PS colloidal particles in aqueous solution at a low pH value, and gold nanoparticles were prepared in P2VP brushes. Such colloidal particles may find important applications in a variety of fields including waterborne adhesives, paints, catalysis of chemical reactions, and protein separation. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1535–1543, 2009     

Dynamic porous coordination polymer based on 2D stacked layers exhibiting high sorption selectivity for CO2

A new dynamic porous coordination polymer (PCP) [Ni(dcpy)(bipy)(0.5)(H(2)O)]·1.5H(2)O (1) was synthesized by assembly of 3-(2',5'-dicarboxylphenyl)pyridine (dcpy), 4,4'-bipyridine (bipy) and NiSO(4)via solvothermal, hydrothermal and microwave methods, displaying a wavelike 2D stacked layer framework. Gas adsorption studies for 1 shows a high selective adsorption of CO(2) over other gases (N(2), CH(4) and CO). The adsorption capacity for N(2) can be moderately altered by different activation temperatures demonstrating the framework flexibility of 1.     

Synthesis,crystal structure,and fluorescence of a 2-D coordination polymer

A 2-D coordination polymer with mixed ligands, [Zn₂(BDC)(4,4′-bipy) (HCOO)₂] (1) (BDC, 1,4-benzenedicarboxylate; 4,4′-bipy, 4,4′-bipyridine), has been synthesized by solvothermal reaction. Compound 1 provides the first coordination polymer structure constructed by bridging BDC, 4,4′-bipy, and formate. Both BDC and 4,4′-bipy link zincs alternatively, resulting in a zigzag coordination chain; adjacent chains are further linked by formates to form an infinite extended 2-D folding screen layer. The synthesis mechanism and fluorescence property are discussed.     

Unprecedented NaI-CuII-LnIII heterometallic coordination polymers based on 3,5-pyrazoledicarboxylate with both infinite cationic and anionic chains

The self-assembly of 3,5-pyrazoledicarboxylic acid (H3pdc) and metal salts under hydrothermal conditions leads to the formation of a series of novel NaI-CuII-LnIII heterometallic coordination polymers, [[Na(H2O)4]2[Cu(pdc)2Ln(H2O)5]2 x 3H2O]n [Ln = La (1); Sm (2); Pr (3); Nd (4) and pdc3- = 3,5-pyrazoledicarboxylate]. X-Ray structure analyses show that these complexes all exhibit pairs of infinite, unexpected, cationic and anionic chains. It is the first successful attempt to construct unprecedented NaI-CuII-LnIII heterometallic coordination polymers with both infinite cationic and anionic chains. These four complexes show homologous thermal stabilities. The different magnetic properties of are also been reported in this paper.     

Synthesis,crystal structure and magnetic properties of 2D bi-layered coordination polymer

A new coordination polymer, [Ni(pydc)(H₂O)₂]?·?H₂O (1) (H₂pydc?=?pyridine-3,4-dicarboxylic acid), have been synthesized by treating Ni(II) nitrate with 3,4-pyridinedicarboxylic acid under hydrothermal conditions. The single-crystal X-ray structure reveals that 1 is a 2D bi-layered coordination polymer. Single-crystals are triclinic, space group P 1 , with a?=?7.065(3), b?=?7.812(4), c?=?9.031(4)?Å, α?=?75.568(8), β?=?68.970(8), γ?=?75.927(8)°, V?=?444.0(3)?ų, Z?=?2. Variable temperature magnetic susceptibility measurements demonstrate a ferromagnetic interaction in 1.     

A one-dimensional chain of polyoxometalate polymer bridged by dinuclear copper coordination units with 4-(5-phenylpyridin-2-yl)pyridine

A new Keggin polyoxometalate-based polymer, formulated as (Hppy)₂Cu₂(ppy)₄[SiMo₁₂O₄₀] (1) ppy = 4-(5-phenylpyridin-2-yl)pyridine, had been synthesized under hydrothermal conditions. Complex 1 exhibits a one-dimensional polyoxometalate-based chain constructed from Keggin anions of [SiMo₁₂O₄₀]^4? weakly connected by dinuclear [Cu(ppy)₂] groups. This complex crystallizes in the triclinic space group P-1, a = 12.621(3) Å, b = 13.168(3) Å, c = 17.467(4) Å, α = 86.09(3)°, β = 85.35(3)°, γ = 64.10(3)°, V = 2601.1(9) Å³, Z = 1. The elemental analyses, FT-IR, TG-DTA for this compound were also determined.     

Self-assembly of organic-inorganic hybrid materials constructed from eight-connected coordination polymer hosts with nanotube channels and polyoxometalate guests as templates

Two polyoxometalate-templated organic-inorganic hybrid porous frameworks, namely, [Cu2(H2O)2(bpp)2Cl][PM12O40].approximately 20H2O (for 1, M = W; for 2, M = Mo; bpp = 1,3-bis(4-pyridyl)propane), were self-assembly obtained and structurally determined by elemental analyses, inductively coupled plasma analyses, infrared spectroscopy, and single-crystal X-ray diffraction analyses. Single-crystal X-ray analysis of these crystals revealed that both of the structures are constructed from eight-connected three-dimensional coordination polymer hosts [Cu2(H2O)2(bpp)2Cl]n(3n+) and ball-shaped Keggin-type guests [PM12O40]n(3n-) as templates. The polymer hosts resulted from a bcc-type framework with nanotubes, and the nanotubes can be regarded as a tetra-stranded helix structure. Furthermore, compounds 1 and 2 exhibit photoluminescent properties at ambient temperature, and the compound 2 bulk-modified carbon paste electrode ( 2-CPE) displays good electrocatalytic activity toward the reduction of nitrite.     

Metal dicyanamide layered coordination polymers with cyanopyridine co-ligands: Synthesis, crystal structures and magnetism

A series of metal dicyanamide (dca) coordination polymers combined with cyanopyridine (cypy) terminal co-ligands, namely, [Co₂(dca)₄(4-cypy)₄]_n (1), [Cd(dca)₂(4-cypy)₂]_n (2), [Fe(dca)₂(3-cypy)₂]_n (3) and [Co(dca)₂(3-cypy)₂]_n (4), have been synthesized at the ambient conditions. X-ray single crystal diffraction reveals that complexes 1-4 have similar metal-dca coordination layers in which the octahedral metal centers are connected by μ_1,5-dca linkers. Notably, three types of 3-D packing lattices are observed for these layered arrays. The thermal stabilities of such new crystalline materials have been studied by thermogravimetric analysis of mass loss. The magnetic properties of the Co^II and Fe^II complexes have been investigated and discussed in detail. A discrete mononuclear molecule [Cd(dca)₂(pyom)₂] (5) is also described, in which the chelated ligand O-methyl picolinimidate (pyom) arises from the addition of methanol solvent across the CN bond of 2-cypy.     

A chiral layered Co(II) coordination polymer with helical chains from achiral materials

A layered coordination polymer Co(PDC)(H2O)2.H2O containing two helical chains was synthesized, and the resultant crystals were not racemic as evidenced by the observation of strong signals in vibrational circular dichroism (VCD) spectra.     

Compaction of TiO2 suspension utilizing hydrophilic/hydrophobic transition of cationic thermosensitive polymers

Compaction of TiO2 suspended particles utilizing the hydrophilic/hydrophobic transition of a cationic thermosensitive copolymer of N-isopropylacrylamide (NIPAM) and N-dimethylaminopropylacrylamide (DMAPAA) was examined. The surface of suspended TiO2 particles were sufficiently covered with the adsorbed polymer molecules at room temperature, and the suspension was subsequently heated above the transition temperature of the polymer. The thrusting motion of a plunger was used in order to provide an adequate mechanical force to compact the TiO2 suspended particles. The transition temperature was dependent on the DMAPAA content in the copolymer and the pH of the suspension. The transition temperature increased with increasing DMAPAA content and decreased with increasing pH. While suspended TiO2 particles were not compacted with poly(NIPAM), hard compacted sludge was readily obtained for cationic copolymer even if the content of DMAPAA groups was as low as 0.23 mol%. Furthermore, residual polymer molecules in the supernatant were not detected even if the polymer dosage was increased. These findings were attributed to the hydrophobic interaction of thermosensitive copolymer molecules adsorbed on TiO2 particles.     

Hybridization of layered niobates with cationic dyes

The hybridization of two different types of organic polycations, 1,1’-dimethyl-4,4’-bipyridinium dications (methyl viologen, MV²⁺) and 5,10,15,20-tetrakis(N-methyl-pyridinium-4-yl)-21H,23H-porphine tetracations (TMPyP⁴⁺), into layered niobates was investigated to construct an efficient dye-modified semiconductor for solar conversion and storage. Two different methods were employed for the direct intercalation of the cationic species, i.e., conventional ion-exchange with K₄Nb₆O₁₇ · 3H₂O as the starting host and a novel acid-base neutralization method with H₄Nb₆O₁₇ as the starting host. These two methods showed totally different behavior and the characteristic features of both will be discussed in relation to the structure of the hybrid formed, the amount of absorption observed for the guest molecules and the intercalation rates. An analysis of the photo-induced electron-transfer reactions will also be discussed to show how control of the intercalation of guest molecules affects the photofunctionality of these unique hybrids.     

Hydrothermal synthesis and crystal structure of a layered coordination polymer: [Zn2(C2O4)2(C3N2H4)2] n

A new metal-organic coordination polymer [Zn₂(C₂O₄)₂(C₃N₂H₄)₂] _n (1) has been hydrothermally synthesized with ZnCl₂·2H₂O, oxalic acid and imidazole. The compound has a 2D network, consisting of infinite zinc(II) oxalate chains connected to each other by three-coordinate oxygen atoms. Within the chains, the zinc atoms are each octahedrally coordinated by one nitrogen atom from imidazole and five oxygen atoms from oxalate groups. Furthermore, there are two coordination modes of oxalate to zinc ions: chelate bis-bidentate and chelate/bridging bis-bidentate in compound 1, and the latter is rare among related compounds. Crystal data: monoclinic, P2(1)/c, a?=?8.4310(17), b?=?9.4060(19), c?=?8.2790(17)?Å, β?=?93.15(3)°, V?=?655.5(2)?ų, Z?=?2, R ₁?=?0.0322, wR ₂?=?0.0850.     

Crystal structure and fluorescence of a new 2D layered cadmium(II) malate coordination polymer

A new two-dimensional layered cadmium coordination polymer [Cd(D,L-mal)H₂O] _n (H₂mal = malic acid) is solvothermally synthesized and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. Each Cd(II) centre is surrounded by seven oxygen atoms from three different malate ligands and one coordinated water molecular forming a pentagonal bipyramidal configuration. Furthermore, complex 1 exhibits blue intense photoluminescence property at room temperature.     

Three-dimensional porous coordination polymer functionalized with amide groups based on tridentate ligand: selective sorption and catalysis

To create a functionalized porous compound, amide group is used in porous framework to produce attractive interactions with guest molecules. To avoid hydrogen-bond formation between these amide groups our strategy was to build a three-dimensional (3D) coordination network using a tridentate amide ligand as the three-connector part. From Cd(NO3)2.4H2O and a three-connector ligand with amide groups a 3D porous coordination polymer (PCP) based on octahedral Cd(II) centers, {[Cd(4-btapa)2(NO3)2].6H2O.2DMF}n (1a), was obtained (4-btapa = 1,3,5-benzene tricarboxylic acid tris[N-(4-pyridyl)amide]). The amide groups, which act as guest interaction sites, occur on the surfaces of channels with dimensions of 4.7 x 7.3 A2. X-ray powder diffraction measurements showed that the desolvated compound (1b) selectively includes guests with a concurrent flexible structural (amorphous-to-crystalline) transformation. The highly ordered amide groups in the channels play an important role in the interaction with the guest molecules, which was confirmed by thermogravimetric analysis, adsorption/desorption measurements, and X-ray crystallography. We also performed a Knoevenagel condensation reaction catalyzed by 1a to demonstrate its selective heterogeneous base catalytic properties, which depend on the sizes of the reactants. The solid catalyst 1a maintains its crystalline framework after the reaction and is easily recycled.