Mixed-ligand Coordination Polymers Research Articles

Mechanochemical and Conventional Synthesis of Zn(II)/Cd(II) Luminescent Coordination Polymers: Dual Sensing Probe for Selective Detection of Chromate Anions and TNP in Aqueous Phase.

Isostructural Zn(II)/Cd(II) mixed ligand coordination polymers (CPs) {[M(IPA)(L)]}n (CP1 and CP2) built from isophthalic acid (H2IPA) and 3-pyridylcarboxaldehyde nicotinoylhydrazone (L) were prepared using versatile synthetic routes: viz., diffusion of precursor solutions, conventional reflux methods, and green mechanochemical (grinding) reactions. Both robust CPs synthesized by different routes were characterized by various analytical methods, and their thermal and chemical stability as well as the phase purity was established. Crystallographic studies revealed that CP1 and CP2 are isostructural frameworks and feature a double-lined two-dimensional network composed of Zn2+/Cd2+ nodes connected through IPA and pillared by the Schiff base ligand L with a double-walled edge. The photoluminescent (PL) properties of CP1 and CP2 have been exploited as dual detection fluorosensors for hexavalent chromate anions (CrO42-/Cr2O72-) and 2,4,6-trinitrophenol (TNP) because it was observed that the emission intensity of aqueous suspensions of CPs selectively quenches by chromate anions or TNP among large pools of different anions or nitro compounds, respectively. Competitive experiments in the presence of interfering anions/other nitro compounds also revealed no major effect in the quenching efficiency, suggesting the selective detection of hexavalent chromate anions as well as TNP by the LCPs. The limits of detection by CP1 for CrO42-/Cr2O72- and TNP are 4 ppm/4 ppm and 28 ppb, respectively, whereas the limits of detection by CP2 for the same analytes are 1 ppm/1 ppm and 14 ppb, respectively. A probable mechanism for the quenching phenomena is also discussed.

Mixed ligand coordination polymer based on 4,4′-sulfonyldibenzoic acid and 1,3-bis(2-methyl-1-imidazolyl)benzene: Synthesis, characterization, luminescent and proton conducting properties

A new proton-conductive Zn(II) coordination polymer, namely, [Zn(SDBA)(1,3-BMIB)·H2O]n (1) (1,3-BMIB = 1,3-bis(2-methyl-1-imidazolyl)benzene, H2SDBA = 4,4'-sulfonyldibenzoic acid)) has been synthesized under hydrothermal condition and characterized by elemental analysis, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction study reveals that complex 1 features 2D (4, 4) grid layer. Complex 1 exhibits strong fluorescent emissions in the solid state at room temperature. Moreover, complex 1 also exhibits a proton conductivity of over 10−5 S cm−1 at 328 K and 99% relative humidity.

Sulfonic Group Functionalized Mixed Ligand Coordination Polymers: Synthesis, Characterization, Water Sorption, and Proton Conduction Studies.

Five sulfonic acid group functionalized mixed ligand coordination polymers (CPs), namely, {[Zn(bpeH)(5-sip)(H2O)]·(H2O)}n (1), {[Cu(pyz)(5-Hsip)(H2O)2]·(H2O)2}n (2), {[Cu(bpee)0.5(5-sip)(H2O)2]·(H2O)4(bpeeH2)0.5}n (3), {[Cu(bpy)(5-Hsip)(H2O)]·(H2O)2}n (4), and {[Cu(bpy)2(5-H2sip)2]·(H2O)6}n (5) [where sip3- = 5-sulfoisophthalate; bpe = 4,4'-bispyridylethane; pyz = pyrazine; bpee = 4,4'-bispyridylethylene; bpy = 4,4'-bipyridine], have been synthesized with varying different N,N'-donor linkers using slow diffusion techniques at room temperature. The CPs possess guest water filled 1D channels and noncoordinating sulfonic acid or coordinated sulfonate groups, which are interconnected by means of extended intermolecular H-bonding interaction, which supports the humidity dependent proton conductivity of the samples. Under 95% relative humidity (% RH), the CPs exhibit the temperature dependent proton conductivity which is maximum up to in the range of ∼10-5-10-6 S cm-1 at 65 °C. In most of the cases, the framework shows activation energies with the value ranging from 0.35 to 0.54 eV, suggesting mostly the contribution of the Grotthuss mechanism of the proton conductivity.

Facile Preparation of a Nanostructured Silver Oxide from a Mixed Ligand Coordination Polymer: Characterization and Biological Activity

Facile Preparation of a Nanostructured Silver Oxide from a Mixed Ligand Coordination Polymer: Characterization and Biological Activity

Three-dimensional nickel(II) and cobalt(II) coordination polymers constructed from 2,5-dichloroterephthalic acid and bis(imidazole) ligands

Two ternary mixed-ligand coordination polymers (CPs), namely [Ni(L)2(DCTP)] n (1) and [Co(L)(DCTP)] n (2), have been hydrothermally synthesized by reacting different transition metal salts with 2,5-dichloroterephthalic acid (H2DCTP) and 4,4′-[bis(imidazol-1-ylmethylene)]biphenyl (L) as ligands. Both CPs 1 and 2 were characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction; CP 1 exhibits a non-interpenetrated six-connected α-Po (or pcu net) framework structure, with the point symbol {412·63}. CP 2 shows a fivefold-interpenetrating four-connected sqc6 topology with the point symbol {66}. The thermal stabilities, luminescence and catalytic properties of both CPs for the degradation of methyl orange in a Fenton-like process have been investigated.

Synthesis, characterization and X-ray crystal structures of two non-molecular coordination polymers of manganese(II) and copper(II) with N-(2-pyridylmethyl)-l-alanine and isothiocyanato ligands

The reduced Schiff base, N-(2-pyridylmethyl)-l-alanine (Pyala), has been prepared and used as a ligand for the synthesis of two new non-centrosymmetrical isothiocyanate mixed-ligand coordination polymers, [MnPyalaSCN] n and [CuPyalaSCN] n . Pyala and the metal complexes were characterized by physico-chemical and spectroscopic methods. The single-crystal X-ray structures of the complexes reveal both compounds to be non-molecular coordination polymers which crystallize in the orthorhombic system. The ligand acts as a bridge between two metal centres in both compounds, forming two six-membered rings around each Mn atom and two five-membered rings around each Cu centre. The 1D chains are assembled via N–H⋯O, N–H⋯S hydrogen bonds and S–S interactions building 3D helical supramolecular networks in both compounds. Packing of the polymers of both compounds along the b-axis gives chiral channels.

Construction of two mixed-ligand coordination polymers presenting unusual polyrotaxane-like entanglements

Two novel polyrotaxane-like coordination polymers, [Ni4(L)4(H2O)3(bpp)4]·3H2O (1) and [Cd4(L)4(bpp)3]·3H2O (2) (H2L=Me2Si(p-C6H4COOH)2, bpp=1,3-bis(4-pyridyl)propane), have been synthesized and structurally characterized. Compound 1 features a 2D→3D polyrotaxane array by the interlock of bilayer networks. Compound 2 exhibits an unusual 3D polyrotaxane-like self-threading framework. In addition, compound 2 shows an emission at 485nm when it was excitated at 400nm.

Syntheses, crystal structures, and DNA binding and catalytic properties of two transition metal coordination polymers constructed from 5-aminoisophthalic acid and bis-benzimidazole ligands

Two mixed-ligand transition metal coordination polymers, {[Co(aip)(bbp)]·(H2O)} n (1) and {[Ni2(aip)(Hbbop)2]·(H2O)2} n (2) (H2aip = 5-aminoisophthalic acid, bbp = 1,3-bis(benzoimidazol-2-yl)propane, H2bbop = 1,3-bis(benzimidazol-2-yl)-2-oxapropane), were synthesized and characterized by elemental analyses, IR spectra, single-crystal X-ray diffraction, and thermogravimetric analyses. Complex 1 has a 1D chain structure, while 2 has a 3-connected 2D network with (63) topology. Both structures are further connected by hydrogen bonds and π–π stacking interactions to form the 3D supramolecular architectures. DNA binding and catalytic properties of the two complexes were investigated.

Homochiral zinc benzene-1,3,5-tricarboxylate coordination networks with a chiral nitrogen ligand or template: Spontaneous resolution of a twofold interpenetrated 2D sql (4,4) network and formation of enantiopure 3D sra (SrAl2) networks

A pair of homochiral enantiomorphic two-fold interpenetrated, mixed-ligand coordination polymers (CPs), 2D-{[Zn(μ-Hbtc)(μ-R-btrip)]·H2O}n1 and 2D-{[Zn(μ-Hbtc)(μ-S-btrip)]·H2O}n2, were found in a racemic conglomerate in space group P212121 with enantiomorphous crystals by spontaneous resolution (H3btc=benzene-1,3,5-tricarboxylic acid, trimesic acid). The racemic ligand 1,2-bis(1,2,4-triazol-4-yl)propane (rac- or R,S-btrip) spontaneously resolves upon coordination to Zn(II) and crystallization from Zn(NO3)2·6H2O for 1 or ZnBr2 for 2, in presence of the trimesic acid (H3btc) under hydrothermal conditions. Single-crystal analysis of 1 and 2 revealed a chiral two-dimensional sql (4,4) network based on the interconnection of {Zn(Hbtc)} and {Zn(btrip)} chains at the Zn atom. Each 2D sql network is 2-fold interpenetrated by a symmetry related net. The interpenetration appears controlled by triazole–C–H⋯N hydrogen bonds. When the enantiopure Schiff base 2-((E)-(1-(4-methoxyphenyl)ethylamino)methyl)phenol (N-(1-(4-methoxyphenyl)ethyl)salicylaldimine) was reacted with ZnSO4 and H3btc in water/methanol the imine CN bond hydrolyzed retro-synthetically to the aldehyde and the amine which was protonated to the ammonium cation. The in-situ formed enantiopure (R) or (S)-1-(4-methoxyphenyl)ethylammonium cation was incorporated as a template in the crystallization of the anionic 3D-network {bis(benzene-1,3,5-tricarboxylato-κ4O:O′:O″:O‴′)dizinc(II)}, {[Zn2(μ4-btc)2]2−}n in the chiral compounds {[(R)- or (S)-4-CH3OC6H4CH(CH3)NH3]2[Zn2(μ4-btc)2]·2H2O}n (3 or 4, respectively). The 3D-network exhibited sra (SrAl2, zeolite ABW) topology. The ammonium cations are positioned by charge-assisted N–H(+)⋯(−)O (carboxylato) H-bonds and charge-assisted π-stacking in the anionic framework.

Sonochemical synthesis of two new nano lead(II) coordination polymers: Evaluation of structural transformation via mechanochemical approach

Two new lead(II) mixed-ligand coordination polymers, [Pb(PNO)(SCN)]n (1) and [Pb(PNO)(N3)]n (2), (HPNO=picolinic acid N-oxide) were synthesized by a sonochemical method and characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Compounds 1 and 2 were structurally characterized by single crystal X-ray diffraction. The thermal behavior of 1 and 2 were studied by thermal gravimetric analysis. Structural transformations of compounds 1 and 2 were evaluated through anion-replacement processes by mechanochemical method. Moreover, the effect of sonication conditions including time, concentrations of initial reagents and power of irradiation were evaluated on size and morphology of compounds 1 and 2.

Crystal structures, topological analysis and luminescence properties of three coordination polymers based on a semi-rigid ligand and N-donor ligand linkers

Three new mixed-ligand coordination polymers have been synthesized based on 3,3′-(anthracene-9,10-diyl)diacrylate acid and different N-donor ligands. Complex 2 displays rapid and selective sensing of Fe3+.

Synthesis, crystal structure and luminescent properties of three new zinc/cadmium coordination polymers containing cyanoacetate and 1,2-di(4-pyridyl)ethylene

Three mixed-ligand coordination polymers based on cyanoacetate (cna) and 1,2-di(4-pyridyl)ethylene (dpe), namely [M(cna)2(dpe)]n (M=ZnII (1), (2), and CdII (3)) were synthesised and structurally characterized. Compound 1 exhibits a 1D zigzag polymeric chain, while compounds 2 and 3 are isostructural exhibiting 1D-ladder chain structures built from double-μ2-dpe connecting between [M2(μ1,3-cna)2(cna)2] secondary building units. The adjacent polymeric chains of 1–3 are linked by various intermolecular weak hydrogen bonds and N⋯π and/or C–H⋯π interactions through cyanoacetate and dpe ligands, stabilizing overall 3D supramolecular networks. Furthermore, the divergence of structural motifs between 1 and isostructures 2 and 3 strongly influences on their solid-state photoluminescent properties at room temperature. Compound 1 exhibits intense photoluminescence, whereas this is quenched in compounds 2 and 3.

Mixed ligand coordination polymer based on 5-nitroisophthalic acid and 1-(4-nitrophenyl)-1,2,4-triazole: Synthesis, characterization, magnetic and photocatalytic properties

A new Cu(II) coordination polymer, namely, [Cu(NPT)2(NO2-BDC)]n (1) (NO2-H2BDC=5-nitro-1,3-benzenedicarboxylic acid, NPT=4-(4-nitrophenyl)-1,2,4-triazole) has been synthesized under hydrothermal condition and characterized by elemental analysis, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction study reveals that complex 1 features one-dimensional chain structure. The magnetic studies reveal that the antiferromagnetic interactions exist between the adjacent CuII ions. Moreover, complex 1 displays highly photocatalytic degradation activity for the degradation of rhodamine B, methylene blue and methyl orange.

Syntheses, structures, and luminescence of two Zn(II) coordination polymers based on 5-(4-imidazol-1-yl-phenyl)-2H-tetrazole and carboxylates

Reactions of Zn(II) salts, 5-(4-(1H-imidazol-1-yl)phenyl)-1H-tetrazolate (HIPT) and 2-mercaptobenzoic acid or 2-propyl-1H-imidazole-4,5-dicarboxylic acid (H3PrIDC), result in two mixed-ligand coordination polymers (CPs), [Zn2(IPT)(DSDB)(OH)]n (H2DSDB = 2,2′-disulfanediyldibenzoic acid, 1) and [Zn2(IPT)(PrIDC)(H2O)]n (H3PrIDC = 2-propyl-1H-imidazole-4,5-dicarboxylic acid, 2). Compound 1 possesses a 2-D structure built by 1-D [Zn(IPT)]n chains and DSDB2− connectors, in which the DSDB2− is generated via in situ reaction from 2-mercaptobenzoic acid. It displays a new intricate 4-nodal {3·4·6·7·8·9}{3·6·7·8·9·10}{3·8·9}{4·6·8} topology. Compound 2 displays a 3-D framework with new 3-connected topology with Schläfli symbol of (4·8·10) (8·122), in which the 1-D Zn-carboxylate chains were bridged by 3-connected IPT− ligands. The thermal stabilities and luminescence properties of 1 and 2 have also been studied. The compounds exhibit intense solid-state fluorescent emissions at room temperature.

A novel mixed-ligand coordination polymer with pillared-layer & ladder like structure: synthesis, crystal structure, properties study, and application as sorbent for acetaminophen extraction

The novel coordination polymer, [Cd (NO3) (P-2) (pzca)]n (1); [P-2=pillar ligand = 4, 4'-bipyridine; pzca = 2-pyrazinecarboxylate] has been synthesized by the branched tube method under heat gradient condition and characterized by elemental analysis, FT-IR spectroscopy and powder X-ray diffraction. Compound 1 was structurally characterized by single-crystal X-ray diffraction. X-ray analysis reveals that it forms an one-dimensional covalent ladder like structure by two different bridging ligands, 4, 4’-bipy and pzca, which further significantly extends into two-dimensional networks via hydrogen bonding and other weak interactions. This polymer consists of three parts: equatorial layers, the bpy ligands connect axially these layers as the pillar which result in coordination pillared-layer structure (CPL) and one dimensional pores. The application of compound 1 was studied as a sorbent for extraction of acetaminophen medicine. Acetaminophen was extracted by solid phase extraction method and monitored by UV-Vis spectrophotometer. Furthermore, the remarkable thermal stability of compound 1 has also been studied by thermal gravimetric analyses (TGA).

New Properties and Characteristics of Mixed Ligand Coordination Polymers Derived from Transition Metal Ions, 1,2,4,5-Benzenetetracarboxylate and Aromatic Diamines

Coordination polymers derived from 1,2,4,5-benzenetetracarboxylate (H2btec 2or btec ), Fe(II), Mn(II), Co(II), Ni(II), Cu(II), Cd(II) or UO2(II) metal ions, 1,10-phenanthroline(1,10-phen) or 2,2 ' bipyridine(2,2-bipy) were prepared. The polymers were characterized by elemental analysis, IR and electronic spectra, electrical conductance, magnetic susceptibility measurements and thermal behavior. The electronic spectra, magnetic susceptibility measurements and X-ray structure determination revealed octahedral and tetrahedral geometries around the metal ions. Kinetic and thermodynamic parameters of the thermal decomposition were computed from the thermal data using the Coats-Redfern equation. From the X-ray powder diffraction the particle sizes (6.4-25.4 nm) of the coordination polymers could be calculated using the Scherrers equation. Original Research Article Aly et al.; ACSj, 6(3): 144-157, 2015; Article no.ACSj.2015.046 145

Syntheses, structures, and properties of Co(II)/Zn(II) mixed-ligand coordination polymers based on 4-[(3,5-dinitrobenzoyl)amino]benzoic acid and 1,4-bis(1-imidazolyl) benzene

Two coordination polymers [Co(dnbab)2(bimb)](H2O)4 (1) and [Zn(dnbab)2(bimb)](H2O)5 (2) (Hdnbab=4-[(3,5-dinitrobenzoyl)amino]benzoic acid, bimb=1,4-bis(1-imidazolyl) benzene) have been solvothermally synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Complexes 1 and 2 are isostructures and each displays an one-dimensional (1D) zigzag chain, which further forms a 3D supramolecular architecture with 1-D channels via inter-chain π–π interactions and hydrogen bonds. Moreover, the magnetic properties of 1 and fluorescent properties of 2 have been investigated.

Controlled in situ reaction for the assembly of Cu(II) mixed-ligand coordination polymers: synthesis, structure, mechanistic insights, magnetism and catalysis.

It has been a challenge to decipher the in situ ligand reaction mechanism in assembly processes, involving metals and ligands. The present study shows two crystalline mixed-ligand Cu(II) coordination polymers isolated by controlled in situ ligand reactions under the same hydrothermal conditions. Two closely related examples provide a precious chance to access the in-depth mechanistic issues surrounding in situ reactions. The solid structure of 1 demonstrated that maleic acid was completely transformed to malic acid, whereas when fumaric acid was used in the same reaction conditions, an incomplete transformation from fumaric acid to malic acid was observed in the solid structure of 2. Compound 1 exhibits a 3D 6-connected sni network based on a binuclear copper(ii) secondary building unit, whereas the 3D network of 2 is classified to a (6,8)-connected topology network. The difference in steric hindrance between maleic acid and fumaric acid dictates the degree of the in situ nucleophilic addition reaction. The comparison of synthesis and final solid structures indicates that the one-step nucleophilic addition mechanism for in situ generated malic acid under the current reaction conditions of 1 is plausible. The magnetic sensitivity measurements of 1 demonstrated that overall antiferromagnetic coupling exists between Cu1 and Cu2 ions and between Cu3 and Cu4 ions. Furthermore, the obtained 1 can be an active catalyst for the solvent-free silylcyanation of aromatic aldehydes under mild conditions.

Synthesis, structures and physical properties of mixed-ligand coordination polymers based on a V-shaped dicarboxylic ligand

Four coordination polymers based on the V-shaped H2hfipbb ligand, (H2hfipbb = 4,4′-(hexafluoroisopropylidene)-bis(benzoic acid), and different auxiliary linear N-donor ligands have been constructed under solvothermal conditions and structurally characterized.

A series of mixed-ligand 2D and 3D coordination polymers assembled from a novel multifunctional pyridine-tricarboxylate building block: hydrothermal syntheses, structural and topological diversity, and magnetic and luminescent properties

4-(5-Carboxypyridin-2-yl)isophthalic acid (H3L) was applied as a new principal building block for the self-assembly generation of mixed-ligand coordination polymers.