Benzene Ligands Research Articles

A Uranyl Metal Organic Framework Arising from the Coordination of a Partially Hydrolyzed Tetrauranyl Node with the Tautomerically Diverse 1,4-(Diamidoximyl)benzene Ligand

We report a unique uranium-based metal organic framework afforded from the spontaneous reaction of 1,4-(diamidoximyl)benzene (1,4-(DAO)Bz) with uranyl chloride. The structure is the first reported ...

Catalytic Assessment of Copper(I) Complexes and a Polymer Analog towards the One‐Pot Synthesis of Imines and Quinoxalines

Three copper(I) complexes, [CuCl(L)(PPh3)2] [L = FL (1), BL (2) or TL (3)] were prepared from [(PPh3)2Cu(µ‐Cl)2Cu(PPh3)] and N‐carbamothioylfuran‐2‐carboxamide (FL), N‐carbamothioylbenzamide (BL) or N‐carbamothioylthiophene‐2‐carboxamide (TL) ligands in benzene and four‐coordinated tetrahedral copper complexes were well characterized by various spectroscopic techniques (UV/Vis, FT‐IR, 1H NMR, 13C NMR and 31P NMR). The molecular structure of the ligands (FL and BL) and complexes was established from single‐crystal X‐ray diffraction studies. Copper complexes have been shown to catalyse the one‐pot synthesis of imines and quinoxalines. Heterogenized catalyst (4) was prepared by reacting more active complex 3 with polystyrene supported triphenylphosphane, and characterized by elemental analyses, and DRS‐UV, FT‐IR, ICP‐OES, and solid‐state NMR techniques. Catalytic activity of the complexes (3 and 4) was tested in the formation of imines from alcohols and amines, and quinoxalines from hydroxy ketones and diamines. Heterogeneity and reusability of catalyst 4 were evaluated, and the catalyst can be reused for four runs without any loss in activity.

Two CoII coordination polymers of biphenyl-2,2′,5,5′-tetracarboxylic acid with flexible N-donor ligands: syntheses, structures and magnetic properties

Two CoII-based coordination polymers, namely poly[(μ4-biphenyl-2,2',5,5'-tetracarboxylato){μ2-1,3-bis[(1H-imidazol-1-yl)methyl]benzene}dicobalt(II)], [Co2(C16H6O8)(C14H14N4)2]n or [Co2(o,m-bpta)(1,3-bimb)2]n (I), and poly[[aqua(μ4-biphenyl-2,2',5,5'-tetracarboxylato){1,4-bis[(1H-imidazol-1-yl)methyl]benzene}dicobalt(II)] dihydrate], {[Co2(C16H6O8)(C14H14N4)2(H2O)2]·4H2O}n or {[Co2(o,m-bpta)(1,4-bimb)2(H2O)2]·4H2O}n (II), were synthesized from a mixture of biphenyl-2,2',5,5'-tetracarboxylic acid, i.e. [H4(o,m-bpta)], CoCl2·6H2O and N-donor ligands under solvothermal conditions. The complexes were characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction and powder X-ray diffraction analysis. The bridging (o,m-bpta)4- ligands combine with CoII ions in different μ4-coordination modes, leading to the formation of one-dimensional chains. The central CoII atoms display tetrahedral [CoN2O2] and octahedral [CoN2O4] geometries in I and II, respectively. The bis[(1H-imidazol-1-yl)methyl]benzene (bimb) ligands adopt trans or cis conformations to connect CoII ions, thus forming two three-dimensional (3D) networks. Complex I shows a (2,4)-connected 3D network with left- and right-handed helical chains constructed by (o,m-bpta)4- ligands. Complex II is a (4,4)-connected 3D novel network with ribbon-like chains formed by (o,m-bpta)4- linkers. Magnetic studies indicate an orbital contribution to the magnetic moment of I and II due to the longer Co...Co distances. An attempt has been made to fit the χMT results to the magnetic formulae for mononuclear CoII complexes, the fitting indicating the presence of weak antiferromagnetic interactions between the CoII ions.

Synthesis, crystal structure and biological properties of Cd and Zn coordination polymers based on a flexible tripodal ligand.

Two new coordination polymers, namely poly[[hexathiocyanatotetrakis{μ3-2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene}tricadmium(II)] 3.5-hydrate], {[Cd3(SCN)6(C18H21N9)4]·3.5H2O}n (1), and poly[[hexathiocyanatotetrakis{μ3-2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene}trizinc(II)] 3.5-hydrate], {[Zn3(SCN)6(C18H21N9)4]·3.5H2O}n (2), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction analysis. From the X-ray analysis, it is noteworthy that polymers 1 and 2 are isostructural, with their three-dimensional structures composed of three kinds of four-connection metal ions and two kinds of three-connection 2,4,6-trimethyl-1,3,5-tris[(triazol-1-yl)methyl]benzene (TTTMB) ligand nodes. Each metal ion is six-coordinated in a slightly distorted octahedral geometry. The antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) and the antidiabetic activity against α-amylase of the synthesized compounds were evaluated in vitro. The results of the DPPH free-radical scavenging assay showed that polymers 1 and 2 exhibited strong antioxidant effects, with IC50 values of 3.81 and 2.56 mg ml-1, respectively. The IC50 value in the antidiabetic studies of polymer 1 was 3.94 mg ml-1, while polymer 2 exhibited no antidiabetic activity. Polymers 1 and 2 revealed different inhibitory activities on DPPH and α-amylase, which indicated that the metal ions play important roles in the biological activity of coordination polymers. In addition, the solid-state photoluminescence properties and thermal stability of 1 and 2 have been investigated.

Ethylene polymerization by binuclear chromium complex with tetrakis(pyrazolyl-methyl)benzene ligand

The reaction of one equivalent of 1,2,4,5-tetrakis(pyrazolyl-methyl)benzene ligand (L) with two equivalents of Cr(THF)3Cl3 in tetrahydrofuran has produced a binuclear neutral complex of general formula [Cr2L(THF)2Cl6] (1). It was characterized by mass spectrometry, Fourier-transformed infrared, X-ray photoelectron spectroscopy, and magnetic susceptibility. Theoretical calculations supported the formation of binuclear complex (1) with each hexacoordinate metal center. This complex was active in ethylene polymerization employing methylaluminoxane as cocatalyst, with moderate activities (5.7–20.8 kg polymer/(mol precat.) (bar) (h)). The reaction parameters such as temperature, monomer pressure, and Al/Cr ratio were studied. An increase of reaction temperature produced a decreasing of catalytic activity. However, an increase in the monomer pressure did not produce a significant increase in catalytic activity. The Al/Cr ratios used to activate this complex are smaller than those reported for the tris(pyrazolyl)borate chromium complex. This system produced high-density polyethylenes with wide molecular weight, Mw, distributions between 42,280 and 74,346 and polydispersity index from 2.3 to 6.6.

Copper-Catalyzed Electrophilic Amination of gem-Diborylalkanes with Hydroxylamines Providing α-Aminoboronic Acid Derivatives.

A copper-catalyzed electrophilic amination of gem-diborylalkanes with hydroxylamines has been developed. The key to its success is the use of the Me3Si-modified 1,2-bis(diphenylphosphino)benzene ligand. Additionally, the reactivity of neopentylglycol derivatives compared to that of commonly used pinacol-derived ones is found to be higher, particularly in the case of relatively sterically congested substrates. The copper catalysis presented here enables the first successful catalytic carbon-heteroatom bond forming reaction of gem-diborylalkanes to form the corresponding α-aminoboronic acid derivatives, which are of great interest in medicinal and pharmaceutical chemistry.

Cadmium(II) three-dimensional coordination polymers constructed from 1,3,5-tris(4-carboxyphenoxy)benzene: synthesis, crystal structure, fluorescence and I2 sorption characterization.

Two three-dimensional (3D) CdII coordination polymers, namely poly[[di-μ-aqua-diaquabis{μ5-4,4',4''-[benzene-1,3,5-triyltris(oxy)]tribenzoato}tricadmium(II)] dihydrate], {[Cd3(C27H15O9)2(H2O)4]·2H2O}n, (I), and poly[[aqua{μ6-4,4',4''-[benzene-1,3,5-triyltris(oxy)]tribenzoato}(μ-formato)[μ-1,1'-(1,4-phenylene)bis(1H-imidazole)]dicadmium(II)] dihydrate], {[Cd2(C27H15O9)(C12H10N4)(HCOO)(H2O)]·2H2O}n, (II), have been hydrothermally synthesized from the reaction system containing Cd(NO3)2·4H2O and the flexible tripodal ligand 1,3,5-tris(4-carboxyphenoxy)benzene (H3tcpb) via tuning of the auxiliary ligand. Both complexes have been characterized by single-crystal X-ray diffraction analysis, elemental analysis, IR spectra, powder X-ray diffraction and thermogravimetric analysis. Complex (I) is a 3D framework constructed from trinuclear structural units and tcpb3- ligands in a μ5-coordination mode. The central CdII atom of the trinuclear unit is located on a crystallographic inversion centre and adopts an octahedral geometry. The metal atoms are bridged by four syn-syn carboxylate groups and two μ2-water molecules to form trinuclear [Cd3(COO)4(μ2-H2O)2] secondary building units (SBUs). These SBUs are incorporated into clusters by bridging carboxylate groups to produce pillars along the c axis. The one-dimensional inorganic pillars are connected by tcpb3- linkers in a μ5-coordination mode, thus forming a 3D network; its topology corresponds to the point symbol (42.62.82)(44.62)2(45.66.84)2. In contrast to (I), complex (II) is characterized by a 3D framework based on dinuclear cadmium SBUs, i.e. [Cd2(COO)3]. The two symmetry-independent CdII ions display different coordinated geometries, namely octahedral [CdN2O4] and monocapped octahedral [CdO7]. The dinuclear SBUs are incorporated into clusters by bridging formate groups to produce pillars along the c axis. These pillars are further bridged either by tcpb3- ligands into sheets or by 1,4-bis(imidazol-1-yl)benzene ligands into undulating layers, and finally these two-dimensional surfaces interweave, forming a 3D structure with the point symbol (4.62)(47.614). Compound (II) exhibits reversible I2 uptake of 56.8 mg g-1 with apparent changes in the visible colour and the UV-Vis and fluorescence spectra, and therefore may be regarded as a potential reagent for the capture and release of I2.

Two coordination polymers based on mixed 1,4-bis(benzimidazo-1-yl)benzene and O-donor linker ligands: syntheses, crystal structures and properties

Two coordination polymers based on 1,4-bis(benzimidazo-1-ly)benzene (L) and O-donor linking co-ligands, namely {[ZnL(mipa)(H2O)]}n (1) and {[Cd2L2(sdba)Cl2]}n (2) (H2mipa = 5-methylisophthalic acid, H2sdba = 4,4′-sulfonyldibenzoic acid), have been synthesized under solvothermal conditions and structurally characterized by X-ray single-crystal diffraction. Compound 1 has a 1D chain structure, forming 2D layers by hydrogen bonds. Adjacent layers stack over each other in an ABCD manner along the c-axis to further pack into a 3D supramolecular structure supported by π–π interactions. Compound 2 possesses an intriguing 3D architecture, which is constructed from dinuclear [Cd2L4Cl2] secondary building units and V-shaped sdba2− linkers. Both compounds show strong photoluminescence at room temperature with peaks at 362 and 356 nm, respectively, assigned to intraligand and/or ligand-to-ligand charge transfer transitions. Compound 2 can be used as a highly selective probe for Hg2+ detection in aqueous solution based on luminescence quenching. The activity of compound 2 as a photocatalyst for the degradation of methylene blue under UV irradiation has been explored.

Coordination preference of 1,2-bis((1H-imidazole-1-yl)methyl)benzene and different carboxylate ligands with transition metal ions directed by weak interactions

Three novel metal-organic complexes, formulated as [Cu2(2-HBA)2(bimb)4] (1), {[Cd(CEDA)(bimb)]·H2O}n (2), and {[Ag2(bimb)2]·(1,4-CDA)·13H2O} (3) (bimb = 1,2-bis((1H-imidazole-1-yl)methyl)benzene; 2-HBA = 2-hydroxybenzoic acid; CEDA = cyclohex-4-ene-1,2-dicarboxylic acid; 1,4-CDA = cyclohexane-1,4-dicarboxylic acid), were synthesized by self-assembly of mixed ligands with Cu(II), Cd(II), and Ag(I) under hydrothermal conditions and characterized by means of single-crystal X-ray diffraction, X-ray powder diffraction, infrared spectra, thermogravimetric analysis, fluorescence spectra and UV–vis absorption spectra. 1 is shown as a 0D structure, which is formed by Cu2+, 2-HBA ligands and bimb ligands. 2 displays a 1D ladder structure, which is built by Cd2+, CEDA ligands and bimb ligands, and it is assembled into 2D structure by hydrogen bonding. 3 possesses a 0D [Ag(bimb)]2 dimer which is assembled into 3D structure by the AgO weak interaction and hydrogen bonding. Interestingly, a rare 13-core water cluster participates in forming the network of 3. The UV–vis spectrum and luminescence properties were also studied and discussed.

A triangular palladium(II) supramolecular coordination complex based on 1,4-bis(1H-imidazol-1-yl)benzene and (2,2'-bipyridyl)palladium(II) nitrate: synthesis and crystal structure.

The self-assembly of ditopic bis(1H-imidazol-1-yl)benzene ligands (LH) and the complex (2,2'-bipyridyl-κ2N,N')bis(nitrato-κO)palladium(II) affords the supramolecular coordination complex tris[μ-bis(1H-imidazol-1-yl)benzene-κ2N3:N3']-triangulo-tris[(2,2'-bipyridyl-κ2N,N')palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd3(C10H8N2)3(C12H10N4)3](PF6)6·7CH3CN, 2. The structure of 2 was characterized in acetonitrile-d3 by 1H/13C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI-MS) and confirmed in the solid state by X-ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF6- counter-ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter- and intramolecular C-H...N and C-H...F interactions. Interestingly, the crystal structure displays two distinct conformations for the LH ligand (i.e. syn and anti), with an all-syn-[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti-LH and syn/anti-[Pd] are a priori possible and expected to be in rapid equilibrium.

Co(II) and Cd(II) metal-organic frameworks with a linear 1,4-di(1H-imidazol-1-yl) benzene and V-shaped polycarboxylate acid ligands: Synthesis, magnetic property and discriminating Fe3 + ion in aqueous solution

Reactions of polycarboxylic acid ligands (H3cpa = 3-(4-carboxy-2-methoxyphenoxy) phthalic acid, H3cmp = 4-(4-carboxy-2-methoxyphenoxy) phthalic acid), N-containing ligand (bimp = 1,4-di(1H-imidazol-1-yl) benzene), with cobalt and cadmium salts under diverse reaction conditions have afforded two novel metal-organic frameworks: [Co3(cpa)2(bimp)2]n (1), [Cd2(cmp)(bimp)2]n (2). The V-shape organic polycarboxylic acid ligands play vital roles in determining the final structure and properties of the complexes. Complex 1 has a 3D structure constructed via bimp ligand connecting adjacent 2D layers and complex 2 has a 3D network with right-handed screw. Magnetic susceptibility measurements (χM) for complex 1 has been performed, and revealed predominant antiferromagnetic behavior. Complex 2 has been employed as a type of fluorescent probe to monitor different metal ions, and showed the obviously selective response to Fe3+ ion through luminescence quenching.

Synthesis, Characterization and CO2 Adsorption of Cr(III)-Based Metal-Organic Framework

Chromium(III)-based metal-organic framework was prepared by using a tritopic bridging 1,3,5-Tris(4-carboxyphenyl) benzene ligand as a linker and chromium as metal that forms a secondary building unit, by solvothermal method. Continuous weight loss of Cr-MOF sample in the entire temperature range was related to loss of desorption of adsorbed gases from pores and cavities, removal of guest molecules such as N,N-dimethyl formamide, and framework disintegration. Specific surface area was found to be 420 m2/g and significant steep raise in the isotherm at partial pressure >0.2 indicates microporous character of the sample. The CO2 adsorption capacity of Cr-MOF sample measured at 298 K and partial pressure of 0.9 atm was found to be 3.5 wt.%. Temperature elevation from 298 to 343 K decreases adsorption capacity according to the Le-Chatelier's Principle. The CO2 adsorption increases linearly as the pressure increases from 0 to 0.9 atm is due to relatively weak adsorption sites and homogeneity.

Synthesis and characterization of two Cd (II) complexes constructed with tricarboxylic acids and as a fluorescent probe of iron ions

Tricarboxylic acid 3,5-bis(-carboxy-phenoxy) benzoic acid (H3BCPBA) 1,5-bis(imidazol-l-yl)-benzene(bib) ligands and cadmium nitrate were used to synthesize two new metal–organic frameworks with different structure under the hydrothermal and solvent thermal conditions, namely [Cd(HBCPBA)(bip)]n (1) and [Cd2(HBCPBA)2(bip)0.5]n (2). We determined the structure of two metal-organic frameworks by XRD, and characterized their structures by TG and powder X-ray diffraction (PXRD). Also we tested the fluorescence properties of the two coordination polymers at room temperature. The results showed the Complex 1 crystallizes in the Hexagonal space group P65, with tentacle structure. Complex 2 crystallizes in the Monoclinic space group P21/c, with a layer of three interdigitated structure. Fluorescence test results show that these two complexes can be used as fluorescent probes to selectively detect and identify Fe3+ ions in water.

Preparation, Characterization, and Electrochemical Activation of a Model [Cp*Rh] Hydride.

Monomeric half-sandwich rhodium hydride complexes are often proposed as intermediates in catalytic cycles, but relatively few such compounds have been isolated and studied, limiting understanding of their properties. Here, we report preparation and isolation of a monomeric rhodium(III) hydride complex bearing the pentamethylcyclopentadienyl (Cp*) and bis(diphenylphosphino)benzene (dppb) ligands. The hydride complex is formed rapidly upon addition of weak acid to a reduced precursor complex, Cp*Rh(dppb). Single-crystal X-ray diffraction data for the [Cp*Rh] hydride, which were previously unavailable for this class of compounds, provide evidence of the direct Rh-H interaction. Complementary infrared spectra show the Rh-H stretching frequency at 1986 cm-1. In contrast to results with other [Cp*Rh] complexes bearing diimine ligands, treatment of the isolated hydride with strong acid does not result in H2 evolution. Electrochemical studies reveal that the hydride complex can be reduced only at very negative potentials (ca. -2.5 V vs ferrocenium/ferrocene), resulting in Rh-H bond cleavage and H2 generation. These results are discussed in the context of catalytic H2 generation, and development of design rules for improved catalysts bearing the [Cp*] ligand.

A 2D Co(II) coordination polymer based on 1,3,5-tris(1H-imidazol-1-yl)benzene: photocatalytic properties and theoretical analysis

A new 2D Co(II) based coordination polymer (CP), {[Co2(tib)2(NO3)3(H2O)2·NO3]n (1), has been synthesized using 1,3,5-tris(1-imidazolyl)benzene (tib) ligand. The single crystal X-ray diffraction study indicates that 1 possesses an infinite 2D layer, which is further extended into a 3D supramolecular network via O–H···O hydrogen bonding interactions. Additionally, the thermogravimetric analysis (TGA) of CP indicates its decomposition temperature was about 268 °C. The UV/Vis diffuse-reflection spectrum of 1 indicates its semiconducting nature on the basis of which the photocatalytic properties of 1 against photodecomposition of organic dyes have been studied. The possible mechanism associated with the photocatalytic activity of 1 against organic dyes is addressed using density of states (DOS) calculations.

A New Highly Thermally Stable Co(II)-coordination polymer with Semi-flexible Bis(Imidazole) Directed Secondary Building Unit: Solvothermal Syntheses and Structures

A new thermally highly stable 2D coordination polymer, formulated as [Co(μ6-aO2btc)0.5(μ-obix)]n (ao2btc = dioxygenated form of 3,3′,5,5′-azobenzenetetracarboxylate) synthesized using the semi-flexible 1,2-bis(imidazole-1-ylmethyl)benzene (obix) ligand in solvothermal conditions and characterized by single-crystal diffraction, FT-IR and photoluminescence spectroscopy and thermogravimetric/differential thermal analysis. Crystallographic studies of complex 1 reveal that two Co(II) ions are bridged by carboxylate groups of ao2btc ligand to form paddle-wheel SBU. These SBUs are stabilized by the coordination of obix ligand. The Co(II) ions are µ6-bridged by hexadentate aO2btc ligand to generate 2D polymer chains with 3,4-connected binodal net (point symbol {4.62}2{42.62.82}) and topological type is 3,4L13. Thermal analysis shows that complex 1 thermally stable up to 401 °C.

Indenyl Rhodium Complexes with Arene Ligands: Synthesis and Application for Reductive Amination

An efficient protocol for synthesis of indenyl rhodium complexes with arene ligands has been developed. The hexafluoroantimonate salts [(η5-indenyl)Rh(arene)](SbF6)2 (arene = benzene (2a), o-xylene (2b), mesitylene (2c), durene (2d), hexamethylbenzene (2e), and [2.2]paracyclophane (2g)) were obtained by iodide abstraction from [(η5-indenyl)RhI2]n (1) with AgSbF6 in the presence of benzene and its derivatives. The procedure is also suitable for the synthesis of the dirhodium arene complex [(μ-η:η′-1,3-dimesitylpropane){Rh(η5-indenyl)}2](SbF6)4 (3) starting from 1,3-dimesitylpropane. The structures of [2e](SbF6)2, [2g](SbF6)2, and [3](SbF6)4 were determined by X-ray diffraction. The last species has a sterically unfavorable conformation, in which the bridgehead carbon atoms of the indenyl ligand are arranged close to the propane linker between two mesitylene moieties. Experimental and DFT calculation data revealed that the benzene ligand in 2a is more labile than that in the related cyclopentadienyl complex...

Synthesis, Structure, and Properties of Coordination Polymers Based on 1,4-Bis((2-methyl-1H-imidazol-1-yl)methyl)benzene and Different Carboxylate Ligands

Three novel coordination polymers, formulated as {[Zn(1,4-bmimb)(PhAA)2]·H2O}n (1), [Cu(1,4-bmimb)0.5(2,6-PyDC)]n (2), and {[Cu(1,4-bmimb)0.5(2-PAC)(HCOO)]·2H2O}n (3) (1,4-bmimb = 1,4-bis((2-methyl-1H-imidazol-1-yl)methyl)benzene; PhAA = phenylacetic acid; 2,6-PyDC = pyridine-2,6-dicarboxylic acid; 2-PAC = 2-pyrazinecarboxylic acid), were synthesized by the self-assembly of mixed ligands with Zn(II) and Cu(II) under solvothermal conditions and characterized by means of single-crystal X-ray diffraction, X-ray powder diffraction, infrared spectra, thermogravimetric analysis, fluorescence spectra and UV-vis absorption spectra. 1 is shown as a Z-shaped chain, which is formed by Zn2+, PhAA ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding and π···π interaction. Similarly, 2 displays a single chain, which is built by Cu2+, 2,6-PyDC ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding and π···π interaction. 3 possesses a 1D ladder structure, which is formed by Cu2+, 2,6-PyDC ligands, and 1,4-bmimb ligands, and is assembled into a 3D structure by hydrogen bonding. The luminescence properties (for 1) and UV-vis spectrum (for 2 and 3) were also studied and discussed.

Periodic mesoporous organosilica materials as sorbents for solid-phase extraction of drugs prior to simultaneous enantiomeric separation by capillary electrophoresis

Two novel periodic mesoporous organosilica materials were synthesized with a neutral phenylene-bridged ligand, 1,4-bis(trimethoxysilylethyl)benzene, one of them using tetraethyl orthosilicate as additional silica source (PMO-TMSEB-1 and PMO-TMSEB-2). A third material was also synthesized with 1,4-bis(triethoxysilyl)benzene ligand (PMO-TESB-1) which use has scarcely been reported. The three materials were evaluated as solid-phase extraction (SPE) sorbents for the off-line extraction of a mixture of seven drugs of different nature (duloxetine, terbutaline, econazole, propranolol, verapamil, metoprolol, and betaxolol) from water samples. Subsequent simultaneous enantiomeric analysis by CE, using sulfated-β-cyclodextrin (2% w/v) dissolved in a 25 mM phosphate buffer (pH 3.0) and a voltage of −20 kV (negative polarity) was carried out. Enantiomeric resolutions ranging from 2.4 to 8.5 were obtained in an analysis time of 16 min. After optimization of SPE parameters, it was shown that using just 100 mg of PMO-TESB-1 as sorbent, a preconcentration factor of 400 with 200 mL solution was achieved, allowing recoveries between 80.5 and 103.1% (except for terbutaline), with good repeatability (% RSD = 2–8 %, n = 5). Analytical characteristics of the method were evaluated in terms of precision, linearity and accuracy with method quantitation limits between 5.6 and 21.9 μg/L. The developed method was applied to the analysis of spiked wastewater samples collected in different treatment plants, with recoveries between 73.9 and 102.9% except for econazole with recovery values ranging between 58.5 and 72.4%.

Synthesis, crystal structure and characterization of new three-dimensional Cu(II) coordination polymer based on 1,3,5-tris(imidazol-1-ylmethyl)benzene

The title Cu(II) coordination polymer of 1,3,5-tris(imidazol-1-ylmethyl) benzene, namely {Cu(SO4)(C18H18N6)(C2H6O2)}n, was synthesized and characterized by elemental analysis, infrared spectra (IR), thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Single crystal structure analysis shows that the title complex possesses a three-dimensional (3D) architecture with a very rare (3,4,6)-connected (4.62)2(42.68.83.102)(64.82) topology . There are two kinds of crystallographically independent CuII centres, each lying on a centrosymmetric position and having a similar six-coordinated octahedral structure. One is coordinated by four N atoms from four 1,3,5-tris(-imidazol-1-yl)methyl benzene (timb) ligands and two O atoms from two different bridging sulfate anions. The second is surrounded by two timb N atoms and four O atoms, two from sulfate anions and two from two ethane-1,2-diol ligands. The tripodal timb ligand bridges neighbouring CuII centres to generate a two-dimensional layered structure. Adjacent layers are further bridged by sulfate anions, resulting in a three-dimensional structure. X-ray powder diffraction studies of the title complex confirm that there is no impurity phase in the bulk material since experimental diffraction patterns match well with the simulated ones. In addition, their thermal stabilities have also been investigated.