Monodentate Mode Research Articles

Poly[[[μ-3,3′-(dimethylsilanediyl)dibenzoato][μ-1,1′-(1,4-phenylene)di-1H-imidazole]zinc] monohydrate

The asymmetric unit of the title compound, {[Zn(C16H16O4Si)(C12H10N4)]·H2O}n, consists of one ZnII ion, two half 3,3′-(dimethyl­silanedi­yl)dibenzoate ligands and two half 1,1′-(1,4-phenyl­ene)di-1H-imidazole ligands. The ZnII ion is four-coordinated by two O atoms from two carboxlate ligands, two N atoms from two imidazole ligands. Two ZnII ions are bridged by two carboxyl­ate groups in chelating mode, generating a binuclear secondary building unit (SBU), which is further coordinated by two N atoms from two imidazole ligands in monodentate mode. Thus, the binuclear SBUs are further bridged by imidazole ligands in two different directions, giving rise to a chain. The water solvent mol­ecules are hydrogen bonded within the chain along the c axis.

Self-assembly of triorganotin(IV) moieties with 1,2,4,5-benzenetetracarboxylic acid: Syntheses, characterizations and influence of solvent on the molecular structure

A series of triorganotin carboxylates based on 1,2,4,5-benzenetetracarboxylic acid (H4btec): [(Ph3Sn)8(btec)2(CH2CH3OH)2]n·2n(CH3CH2OH) (1), [(Ph3Sn)4(btec)(DMF)4] (2), and [(Cy3Sn)4(btec)(DMF)4] (3) were synthesized and characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy and X-ray crystallography diffraction analyses. In 1–3, all four carboxyl groups of H4btec coordinate with tin atoms in monodentate mode. The molecular structure of complex 1 is 1D infinite chains further linked by hydrogen bonds forming a 2D supramolecular network. Complexes 2 and 3 are symmetric monomers connected via hydrogen bonds. It is found that coordinating solvent molecules can change their molecular structures.

Efficient Photocatalytic Decomposition of Perfluorooctanoic Acid by Indium Oxide and Its Mechanism

Perfluorooctanoic acid (C(7)F(15)COOH, PFOA) has increasingly attracted worldwide concerns due to its global occurrence and resistance to most conventional treatment processes. Though TiO(2)-based photocatalysis is strong enough to decompose most organics, it is not effective for PFOA decomposition. We first find that indium oxide (In(2)O(3)) possesses significant activity for PFOA decomposition under UV irradiation, with the rate constant about 8.4 times higher than that by TiO(2). The major intermediates of PFOA were C(2)-C(7) shorter-chain perfluorocarboxylic acids, implying that the reaction proceeded in a stepwise manner. By using diffuse reflectance infrared Fourier transform spectroscopy, (19)F magic angle spinning nuclear magnetic resonance, and electron spin resonance, we demonstrate that the terminal carboxylate group of PFOA molecule tightly coordinates to the In(2)O(3) surface in a bidentate or bridging configuration, which is beneficial for PFOA to be directly decomposed by photogenerated holes of In(2)O(3) under UV irradiation, while PFOA coordinates to TiO(2) in a monodentate mode, and photogenerated holes of TiO(2) preferentially transform to hydroxyl radicals, which are inert to react with PFOA. PFOA decomposition in wastewater was inhibited by bicarbonate and other organic matters; however, their adverse impacts can be mostly avoided via pH adjustment and ozone addition.

Synthesis and Characterization of Highly Crystalline MgO Nanopowders via a Modified Chemical-Precipitation Process

A modified chemical-precipitation method is proposed to synthesize MgO nanopowders with high crystallinity at a low temperature of 400 degrees C using acetic acid as a modifier. The as-obtained intermediates and final products were investigated by Fourier-transformed infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and transmission electron microscopy, respectively. The influence of acetic acid in the MgO preparation process was also investigated by a comparison of the samples without acetic acid, and the mechanism of acetic acid modification is also proposed. The carboxyl group of acetic acid could coordinate with Mg atom in a monodentate mode to form a new organic ligand intermediate Mg(OH)(OCOCH3), which facilitates the thermal decomposition of the intermediate at low temperature and enhances the crystallization of MgO.

Alkali metal halogenides coordination compounds with hexamethylenetetramine

Six coordination compounds: [Li(H2O)4]+·hmta·Cl−, [Li(H2O)4]+·hmta·I−, [Na(H2O)4(hmta)] 2 2+ ·2H2O·2Br−, [Na(H2O)4(hmta)] 2 2+ ·2H2O·2I−, [K(H2O)(hmta)I] n and [Rb(H2O)(hmta)I] n , have been synthesized and characterised by IR spectroscopy, thermogravimetry coupled with differential thermal analysis, elemental analysis and X-ray crystallography. Both the sodium compounds are isostructural in a solid state, an isostructurality is also observed between compounds containing potassium and rubidium iodides. The sodium compounds exist as dimers (dinuclear core of the complex ion is created by two sodium cations and two water molecules). The molecules of potassium and rubidium compounds are assembled to the two dimensional hybrid nets. The each potentially multifunctional ligand (the hmta) exists in the outer coordination sphere in lithium compounds, acts in a monodentate mode in sodium compounds and in bidentate-bridging modes in potassium and rubidium compounds. The lithium ions are four coordinated, and the sodium, potassium and rubidium ions are six coordinated. Thermal analyses show that the investigated compounds decompose gradually with the formation of alkali metal halides which, during the further heating, are totally removed or they undergo partial decomposition to oxides.

Anatase TiO2 Surface Functionalization by Alkylphosphonic Acid: A DFT+D Study

We report on a DFT study of the adsorption of n-butylphosphonic acid [CH3(CH2)3PO(OH)2] on the anatase (101) TiO2 model surface. The pure GGA (PBE and rPBE) approach is compared to a hybrid functional (B3LYP). Dispersion forces are taken into account in the Grimme framework correcting both energies and gradients. The surface coverage is varied from 0.25 ML (one phosphonic unit every four surface Ti5c) to 1 ML (one phosphonic unit/Ti5c). The overall picture resulting from these three approaches is qualitatively the same, although quantitative details are different. At low coverage, the alkylphosphonic acid adsorbs in a monodissociated bidentate mode, forming two P═O–Ti5c bonds with one additional OH–Os bond, where Ti5c and Os refer to surface titanium and oxygen atoms. At full coverage, the molecules adsorb in a monodentate mode and reorient in order to minimize lateral repulsion and maximize H-bonds. The contribution of dispersion forces to the adsorption energy increases with the coverage. The 0.75 and 1 ML coverages, which are the most favored, correspond nicely to the reported experimental coverages. The results suggest that for entropic reasons the surface could be rather disordered, with coexisting domains of different coverages 0.75 and 1 ML. No additional states in the band gap of the semiconductors are formed for this hybrid organic–inorganic system. The workfunction decreases by 0.7 eV when a full self-assembled monolayer is supported on the surface.

O-Tolyl/benzyl dithiocarbonates of phosphorus(III) and (V): syntheses and characterization

O-Tolyl/benzyl dithiocarbonates, ROCS2Na (R = o-, m-, or p-CH3C6H4–, and –CH2C6H5), were synthesized and characterized. These new ligands reacted with PCl3/POCl3 in refluxing toluene which resulted in the formation of phosphorus(III) and phosphorus(V) tolyl/benzyl dithiocarbonates corresponding to [(ROCS2) n PCl3−n ] and [(ROCS2) n POCl3−n ] (R = o-, m-, or p-CH3C6H4–, and –CH2C6H5; n = 1, 2, 3). These pale yellow liquid compounds were characterized by IR, mass, and NMR (1H, 13C, and 31P) spectral studies, which suggest the dithiocarbonate ligands bind in a monodentate mode leading to P–S–C linkages in these derivatives.

Nanocrystalline hybrid inorganic–organic one-dimensional chain systems tailored with 2- and 3-phenyl ring monocarboxylic acids

Two novel nanosized hybrid inorganic–organic frameworks, VO(C14H9COO)2, and VO(C10H7COO)2 have been solvothermally synthesized and their structures elucidated using a combination of powder XRD and DFT geometry optimization. They contain one-dimensional chains of corner-sharing tetrahedra in the case of VO(C10H7COO)2, and corner-sharing octahedra for VO(C14H9COO)2 oriented along orthorhombic/monoclinic c-axis, respectively. While VO(C14H9COO)2 exhibits bidentate bridging binding of organic moiety to the metal center, VO(C10H7COO)2 shows a monodentate mode as evidenced from DFT and infrared spectroscopy. Both hybrids exhibit fiber-like morphology, consisting of smaller individual single crystals aligned in parallel to the growth direction along the c-axis. They are thermally stable up to 350 °C having even more stable impurities containing vanadium in its highest oxidation state. The magnetic properties have also been investigated and indicate antiferromagnetic ordering along the chains characterized by rather low spin exchange parameters.

Interplay between the structural and magnetic probes in the elucidation of the structure of a novel 2D layered [V4O4(OH)2(O2CC6H4CO2)4]·DMF

The title compound has been synthesized under solvothermal conditions by reacting vanadium(V) oxytriisopropoxide with terephthalic acid in N,N-dimethylformamide. A combination of synchrotron powder diffraction, infrared spectroscopy, scanning and transmission electron microscopy, and thermal and chemical analysis elucidated the chemical, structural and microstructural features of a new 2D layered inorganic-organic framework. Due to the low-crystallinity of the final material, its crystal structure has been solved from synchrotron X-ray powder diffraction data using a direct space global optimization technique and subsequent constraint Rietveld refinement. [V(4)O(4)(OH)(2)(O(2)CC(6)H(4)CO(2))(4)]·DMF crystallizes in the monoclinic system (space group P2/m (No. 10)); cell parameters: a = 20.923(4) Å, b = 5.963(4) Å, c = 20.425(1) Å, β = 123.70(6)°, V = 2120.1(9) Å(3), Z = 2. The overall structure can be described as an array of parallel 2D layers running along [-101] direction, consisting of two types of vanadium oxidation states and coordination polyhedra: face-shared trigonal prisms (V(4+)) and distorted corner-shared square pyramids (V(5+)). Both configurations form independent parallel chains oriented along the 2-fold symmetry crystallographic b-axis mutually interlinked with terephthalate ligands in a monodentate mode perpendicular to it. The morphology of the compound exhibits long nanofibers, with the growth direction along the layered [-101] axis. The magnetic susceptibility measurements show that the magnetic properties of [V(4)O(4)(OH)(2)(O(2)CC(6)H(4)CO(2))(4)]·DMF can be described by a linear antiferromagnetic chain model, with the isotropic exchange interaction of J = -75 K between the nearest V(4+) neighbours of S = 1/2.

Three copper(II) complexes connected through tetradentate carboxylate linkers and bidentate N-heterocyclic ligands: From 3-D MOF to 1-D chain

Three copper coordination polymers [Cu2(bbtc)(bbi)2]·3H2O (1) [bbi = 1,1-(1,4-butanediyl)bis(imidazole), bbtc = 3,3′,4,4′-benzophenonetetracarboxylate], [Cu3(Hbbtc)2(3-bpfp)3(H2O)2]·10H2O (2) [3-bpfp = bis(3-pyridylformyl)piperazine], and [Cu(H2bbtc)(4-bpfp)(H2O)]·H2O (3) [4-bpfp = bis(4-pyridylformyl)piperazine] have been hydrothermally synthesized by self-assembly of aromatic tetracarboxylate ligand bbtcd [bbtcd = 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride], and bidentate N-heterocyclic ligands bbi, 3-bpfp or 4-bpfp. X-ray diffraction analysis reveals that compound 1 is a novel three-dimensional (3-D) metal-organic framework with a binodal (4,4)-connected {62.84}{64.82}2 topology. Compound 2 possesses a two-dimensional (2-D) layered structure, in which a trinodal (3,4,4)-connected network with novel {3.62}2{3.63.72}2{32.62.72} topology can be found. Compound 3 displays a one-dimensional (1-D) ribbon polymer chain based on 4-bpfp ligands and H2bbtc2- anions. The adjacent layers for 2 and the adjacent chains for 3 are further linked by hydrogen bonding and π–π stacking interactions to form 3-D supramolecular networks. Importantly, bbtcd with different protonation extent displays three different coordination modes in compounds 1–3: the four carboxyl groups of bbtc4- anions combine with CuII ions by tetra(monodentate) mode in 1, three carboxyl groups of Hbbtc3− anions show tri(monodentate) coordination mode and the fourth carboxyl group is protonated in 2, whereas for 3 only two carboxyl groups H2bbtc2− anions adopt bis(monodentate) coordination mode and the other two are protonated. N-heterocyclic ligands play important roles in the construction of title complexes with different dimensionality. In addition, the electrochemical properties of the three copper compounds bulk-modified carbon paste electrodes have been reported.

Poly[[tetraaqua-μ4-fumarato-di-μ3-fumarato-dineodymium(III)] trihydrate

The title coordination polymer, {[Nd2(C4H2O4)3(H2O)4]·3H2O}, was synthesized by the reaction of neodymium(III) nitrate hexa­hydrate with fumaric acid in a water–methanol (7:3) solution. The asymmetric unit comprises two Nd3+ cations, three fumarate dianions (L 2−), four aqua ligands and three uncoordinated water mol­ecules. The carboxyl­ate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxyl­ate groups chelate two Nd3+ cations, while one of the O atoms is coordinated to another Nd3+ cation. Another fumarate dianion bridges three Nd3+ cations: one of the carboxyl­ate groups chelates one Nd3+ cation, while the other carboxyl­ate group bridges two Nd3+ cations in a monodentate mode. The third fumarate dianion bridges four Nd3+ cations, where one of the carboxyl­ate groups chelates one Nd3+ cation and coordinates in a monodentate mode to a second Nd3+, while the second carboxyl­ate groups bridges two Nd3+ cations in a monodentate mode and one O atom is coordinated to one Nd3+ cation. The Nd3+ cations are in a distorted tricapped–trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water mol­ecules. The Nd3+ cations are linked by two carboxyl­ate O atoms and two carboxyl­ate groups, generating infinite Nd–O chains to form a three-dimensional framework. There are O—H⋯O and C—H⋯O hydrogen-bonding interactions between the coordin­ated and uncoordinated water mol­ecules and carboxyl­ate O atoms.

Synthesis and Characterization of a New Metal-Organic Framework Constructed by Flexible Co-Ligands

Solvothermal reaction of Co(II) nitrate and the V-shaped ligand 1,2-bis(4-carboxy-phenoxy)ethane in the presence of the N-donor ligand of bi (1,1-(1,4-butanediyl)bis(imidazole) afforded a new complex, [Co(bce)(bi)0.5]n (H2bce = 1,2-bis(4-carboxy-phenoxy)ethane) (1), which was synthesized and characterized. The bce ligand adopting bis(monodentate) mode connects metal centers into a macrometallocycle subunit, which is further linked by a bi organic ligand into a two-dimensional (2D) layer. Moreover, the thermal stability of the compound is presented.

Syntheses, Structures and Luminescent Properties of Three new Zinc(II) Complexes Constructed from Dicarboxylate and N-donor Coligands

Three new metal coordination polymers, [Zn(oba)(bim)]n (1), [Zn(oba)(2,2′-bipy)]n (2) and [Zn(oba)(pbim)]n (3) [H2oba = 2-(4-carboxyphenoxy)benzoic acid, bim = benzimidazole,2,2′-bipy = 2,2′-bipyridine and pbim = 2-(4-Pyridyl)benzimidazole], were synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Compound 1 is a two-dimensional supramolecular framework, which is connected by one-dimensional chains through hydrogen bonding interactions. In compound 2, an alternate arrangement of the right- and left-handed helical chains through interchained π-π stacking interactions, formed a two-dimensional supramolecular framework. Compound 3 exhibited a 2D → 3D interdigital architecture with side arms. In compounds 1, 2 and 3, the oba2− ligands act as bridging ligands exhibiting three coordination modes to link metal ions; i.e., bis-monodentate, bidentate chelating and monodentate modes. The luminescent properties of 1, 2 and 3, were also investigated.

Construction of Three New Coordination Polymers Based on Dicarboxylate and Different Organic N-Donor Ligands

Three new metal coordination polymers, {[Ni2(L1)2(bip)2]·H2O} n (1), [Zn2(L2)2(bih)0.5] n (2) and [Cd(L2)(bih)0.5] n (3) [H2L1 = 2-(3-carboxyphenoxy)benzoic acid, H2L2 = 2-(4-carboxyphenoxy) benzoic acid, bip = 4,4′-bis(2-imidazol-1-ylmethyl) biphenyl and bih = 1,6-bis(2-methylimidazol-1-yl) hexane], have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Compound 1 is a one-dimensional ladder-like chain structure. Compound 2 is a two-dimensional layer structure. In compound 3, the alternate arrangement of the right- and left-handed helical chains through bih ligands interactions, which lead to form a two-dimensional framework. In compound 1, 2 and 3, the L1 and L2 ligands act as bridging ligands, exhibiting three coordination modes to link metal ions: bis-monodentate, bidentate chelating and monodentate modes. Moreover, the luminescent properties of compound 2 and 3 were also investigated in this work.

Crystal structure and thermal decomposition mechanism of a 5-aminotetrazole copper(II) complex

A novel 5-aminotetrazole mixed ligands complex of formula [Cu(PTS)2(ATZ)2(H2O)2] (C16H24CuN10O8S2, PTS = p-toluenesulfonate, ATZ = 5-aminotetrazole) has been obtained by the reaction of 5-aminotetrazole with copper acetate and p-toluenesulfonic acid on heating in water. It was characterized by elemental analysis, FT-IR spectroscopy, and X-ray single crystal diffraction. The compound crystallizes in monoclinic system, space group P21/c, Z = 2, a = 14.079(4) A, b = 6.088(3) A, c = 14.632(4) A, β = 105.268(4)°, V = 1209.8(5) A3. The central copper(II) cation is coordinated by two N atoms and four O atoms from two ATZ ligands, two water molecules and two p-toluenesulfonate ions to form a six-coordinated and distorted octahedral structure. Neutral ATZ is coordinated in the monodentate mode by the N(4) atom. The sulfonate group of the PTS ligand remains weak-coordinated modes and forms a number of hydrogen bonds with water molecule ligands and ATZ ligands. A supramolecular framework is connected by electrostatic interaction, weak coordinated bonding, hydrogen-bonding, and π–π interaction. The thermal decomposition mechanism of the title compound was predicted based on DSC, TG-DTG, and FT-IR analyses. Thermolysis of ATZ and its several derivatives is compared.

Structural, optical and electrical properties of europium picrate tetraethylene glycol complex as emissive material for OLED

A new europium complex [Eu(Pic) 2(H 2O)(EO4)](Pic)·0.75H 2O was synthesized and used as the emission material for the single layer device structure of ITO/EO4–Eu–Pic/Al, using a spin-coating technique. Study on the optical properties of the [Eu(Pic) 2(H 2O)(EO4)](Pic)·0.75H 2O complex where EO4=tetraethylene glycol and Pic=picrate anion, had to be undertaken before being applicable to the study of an organic light emitting diode (OLED). The electrical property of an OLED using current–voltage ( I– V) measurement was also studied. In complex, the Eu(III) ion was coordinated with the EO4 ligand as a pentadentate mode, one water molecule, and with two Pic anions as bidentate and monodentate modes, forming a nine-coordination number. The photoluminescence (PL) spectra of the crystalline complex in the solid state and its thin film showed a hypersensitive peak at 613.5–614.9 nm that assigned to the 5D 0→ 7F 2 transition. A narrow band emission from the thin film EO4–Eu–Pic was obtained. The typical semiconductor I– V curve of device ITO/EO4–Eu–Pic/Al showed the threshold and turn on voltages at 1.08 and 4.6 V, respectively. The energy transfer process from the ligand to the Eu(III) ion was discussed by investigating the excitation and PL characteristics. Effect of the picrate anion on the device performance was also studied.

Tetraaquabis(2,6-dihydroxybenzoato-κO1)(2,6-dihydroxybenzoato-κ2O1,O1′)gadolinium(III) dihydrate

In the title compound, [Gd(C7H5O4)3(H2O)4]·2H2O, the GdIII ion shows a distorted square anti­prismatic coordination formed by four aqua ligands and four O atoms from the three 2,6-dihy­droxy­benzoate (L) ligands. Two L ligands coordinate the GdIII ion in a monodentate mode, while the third coordinates it in a bidentate–chelating coordination mode. An extensive three-dimensional O—H⋯O hydrogen-bonding network consolidates the crystal packing.

Samarium(III) picrate tetraethylene glycol complex: Photoluminescence study and active material in monolayer electroluminescent

A mononuclear Sm(III) complex involving Pic and EO4 (where Pic=picrate anion and EO4=tetraethylene glycol) has been studied. It shows a bright-orange emission when used as active material in a monolayer electroluminescent device of ITO/EO4–Sm–Pic/Al. The crystal structure of the complex consists of [Sm(Pic) 2(H 2O)(EO4)] + cation and [Pic] − anion. The Sm(III) ion is coordinated with nine oxygen atoms from one EO4 ligand in a pentadentate mode, two Pic anions each in bidentate and monodentate modes, and one water molecule. Both the terminal alcohol groups of the acyclic EO4 ligand were involved in the O–H…O hydrogen bonding by infinite one-dimensional (1D) chain within a symmetry direction [0 1 0]. The photoluminescence (PL) spectrum of the thin film shows the typical spectral features of the Sm(III) ion ( 4G 5/2→ 6H 7/2 transitions). The root-mean-square (rms) of the roughness of thin film is 30.605 nm and indicates that the formation of the monolayer electroluminescent device is not uniform and retains a high crystallinity. Typical semiconductor current–voltage ( I– V) property was also observed in this device with threshold and turn voltages of 2.8 and 6.2 V, respectively. The [Sm(Pic) 2(H 2O)(EO4)](Pic)·H 2O complex can be applied as a luminescent center in OLED for bright-orange emission.

Poly[[μ-aqua-bis(μ-4,4′-bipyridine-κ2N:N′)bis(μ-3-hydroxyadamantane-1-carboxylato-κ2O:O′)bis(3-hydroxyadamantane-1-carboxylato-κO)dicobalt(II)] heptahydrate

The title coordination compound, {[Co(C11H15O3)4(C10H8N2)2(H2O)]·7H2O}n, consists of a pair of CoII atoms, four 3-hy­droxy­adamantane-1-carboxyl­ate anions (L), one water mol­ecule, two bridging 4,4′-bipyridine (4,4′-bpy) ligands and seven uncoordinated water mol­ecules. Both of the CoII ions are coordinated in a distorted octa­hedral geometry. Four L ligands bind to each pair of CoII atoms in a plane, two of which bridge the two CoII atoms as bidentate groups while the other two coordinate to a single CoII atom in a monodentate mode. Two half-mol­ecules of 4,4′-bipyridine coordinate the CoII atoms from the upside and underside. The packing features extensice O—H⋯O hydrogen bonding.

Syntheses and Characterizations of Two One-Dimensional Coordination Polymers Assembled by Dicarboxylate and N-Donor Coligands

Two new coordination polymers [Mn(oba)(1,10-phen)] n (1) and [Zn(oba)(Pbim)2] n (2) [H2oba = 2-(3-carboxyphenoxy)benzoic acid, 1,10-phen = 1,10-phenanthro line and pbim = 2-(2-Pyridyl)benzimidazole] have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses revealed that 2,3′-oba ligand act as a bridging ligand, exhibiting three coordination modes to link metal ion: bis-monodentate, bidentate chelating and monodentate modes. Compound 1 and 2 all demonstrate a 1D chain. There exist intermolecular hydrogen bonds which further connect the 1D structure into 2D supramolecular structure in compound 1 and 2. In addition, the luminescent property for compound 2 is also investigated in the solid state at room temperature.