Comparison of zinc complexation properties of dissolved organic matter from surface waters and wastewater treatment plant effluents

Unlike natural organic matter(NOM), wastewater organic matter(WWOM) from wastewater treatment plant effluents has not been extensively studied with respect to complexation reactions with heavy metals such as copper or zinc. In this study, organic matter from surface waters and a wastewater treatment plant effluent were concentrated by reverse osmosis(RO) method. The samples were treated in the laboratory to remove trace metals and major cations. The zinc complexing properties of both NOM and the WWOM were studied by square wave anodic stripping voltammetry(SWASV). Experimental data were compared to predictions using the Windermere Humic Aqueous Model(WHAM) Version VI. We found that the zinc binding of WWOM was much stronger than that of NOM and not well predicted by WHAM. This suggests that in natural water bodies that receive wastewater treatment plant effluents the ratio of WWOM to NOM must be taken into account in order to accurately predict free zinc activities.

Hydrothermal Synthesis and Crystal Structure of a Zinc Complex:[Zn_(2.5)(phen)(BDC)_2(OH)] (phen = 1,10-Phenanthroline, BDC = Benzene-1,4-dicarboxylic Acid)

A metal-organic coordination polymer [ZnE.s（phen）（BDC）2（OH）]2 （phen = 1,10- phenanthroline, BDC = benzene-1,4-dicarboxylic acid） 1 has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analyses and IR spectroscopy. The complex crystallizes in the triclinic system, space group PI with a = 11.199（2）, b = 11.593（2）, c = 11.865（3）/A, α= 99.330（1）, β = 111.506（1）, γ = 104.804（1）^o, V= 1328.4（5）A^3, Dc= 1.722 g/cm^3, Z = 1, Mr = 1377.82, F（000） = 692,μ（MoKa） = 2.306 mm^-1, S = 1.093, R= 0.0281 and wR = 0.0756 for 4179 observed reflections （I 〉 2σ（/））. The coordination polyhedron around Zn（II） can be described as a tetrahedron, trigonal bipyramid and octahedron. It is worth noting that the crystal structure of 1 is composed of tetranuclear zinc clusters linked by {ZnO6} units.

Synthesis and Crystal Structure of Zinc(II) Complex with Isonicotinate Containing a Three-dimensional Hydrogen-bond Network

A zinc complex, [Zn(iso)_2(H_2O)_4](iso=C_6H_4NO_2^-), was synthesized and characterized by elemental analysis, thermal analysis and IR spectrum studies. The crystal structure of the complex was determined by X-ray diffraction. The crystal crystallizes in the triclinic system, molecular formula ZnC12H16N2O8, Mr=381.64, space group P with a = 6.338(1), b =6.919(1), c=9.277(1), α=96.28(1), β=104.91(1), γ=112.85(1)°, V=352.12(9)?3, Z=1, Dc=1.80g?cm-3 and F(000)=196, μ =1.791mm-1. The crystal structure was solved by direct methods for final R=0.0204 and Rw=0.0542 for 1258 observed reflections with [Fo>4σ(Fo)]. The crystal structure reveals that zinc ion is trans-octahedral with two pyridyl nitrogens and two aque oxygens at the equational positions and two aqua oxygens at the axial positions. The complex forms a three-dimensional network through intermolecular hydrogen bonds.

Synthesis and Crystal Structure of Complex of Zinc(Ⅱ) with Schiff Base {Zn[CH_3O(O)-C_6H_3CH_3=NN=C(S)NH_2](DMF)}_2

The title complex is a new binuclear Zn(Ⅱ) with chelate ligand of Schiff base containing S and N atom.The complex crystallizes in the orthorhombicspace group Pccn,with a=12.338(9),b=16.666(8),c=17.503(6),V=3599(6),Mr=723.52,Z=4,Dx=1.34 g/cm3,μ=15.22 cm-1,F(000)=1488.The structure was solved by direct methods and the final R=0.078.The crystal consists of discrete molecules with symmetric center at the center of the fourmembered ring consisting of two Zn atoms and two O atoms.

Synthesis and Crystal Structure of an Azide Bridged Binuclear Zinc(Ⅱ) Dimer Containing Taurine Schiff Base [Zn_2(C_8H_9N_2O_3S)_2·(N_3)_2·(H_2O)_2]_2·_2H_2O

The title complex [Zn2L2（N3）2（H2O）2]·2H2O （L = N-（2-pyridylmethylidene） taurine） has been synthesized in a methanol-water solution. The crystal belongs to monoclinic, space group P2 1/C with a = 15.8064（10）, b = 10.5015（5）, c = 17.3193（11） ,A, β= 111.314（2）°, V = 2678.2 （3） ,A ^3 C16H26N10O10S2Zn2, Mr = 713.33, Z = 4, DC = 1.769 g/cm^3, μ = 2.017 mm^-1 and F（000） = 1456. The asymmetric unit consists of two half-molecules of the complex and two water molecules. Four N and two O atoms form the coordination environment of each Zn atom, resulting in a distorted octahedral configuration. The two halves of each independent dimer are related by a crystallographic inversion centre, which lies at the centre of the ring formed by two Zn atoms and the coordinating atoms of the two azide anions. The average separation of Zn（Ⅱ）...Zn（Ⅱ） is 3.322 A. The molecules are linked by O-H...O hydrogen bonds, generating an interesting zigzag infinite chain structure in the ac plane.

Synthesis and Crystal Structure of a Zinc(II) Complex with 2-(4′-Chlorine-benzoyl)-benzoic Acid and 1,10-Phenanthroline

A new metal-organic complex Zn2（cbba）4（phen）2 （Hcbba = 2-（4＇chlorine-ben- zoyl）benzoic acid, phen = 1,10-phenanthroline） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, fluorescence spectrum and single-crystal X-ray diffraction. The compound crystallizes in orthorhombic, space group Pbcn with a = 12.0821（II）, b = 18.3140（17）, c = 30.961（3） A, V= 6850.7（11） A^3, C80H48C14N4O12Zn2, Mr= 1529.76, Dc = 1.483 g/cm^3,μ（MoKa） = 0.925 mm^-1, F（000） = 3120, Z = 4, the final R = 0.0559 and wR = 0.1146 for 3963 observed reflections （I〉 2σ（I））. In the crystal structure, the zinc atom is five-coordinated with three carboxylate oxygen atoms from three different cbba ligands and two nitrogen atoms from the phen ligand, showing a distorted square-pyramidal geometry. Furthermore, it exhibits a 3D supramolecular network through π-π interactions and shows yellow photoluminescent property at room temperature.

Synthesis and Crystal Structure of a Zinc(II) Complex Salt with the Schiff Base of Picolinaldehyde N-oxide and Semicarbazone

The title zinc（Ⅱ） complex salt [Zn（H2O）6]（ClO4）2-（PNOS）4, where PNOS is derived from picolinaldehyde N-oxide with semicarbazone, has been prepared and structurally characterized by X-ray single-crystal analysis. It crystallizes in triclinic, space group PI with a = 7.529（3）, b = 10.206（4）, c = 14.678（6）A, a = 86.293（6）, β= 87.686（7）, γ= 81.382（6）°, C28H44Cl2N16O22Zn, Mr = 1093.06, V = 1112.3（8） ,A^3 Z = 1, Dc = 1.632 g/cm^3, S = 1.089, μ（MoKa） = 0.773 mm^-1, F（000） = 564, the final R = 0.0438 and wR = 0.1076 for 3888 independent reflections with Rint = 0.0224. The crystal structure possesses a [Zn（H2O）6]^2＋ cation, two ClO4^- anions and four PNOSs. In the crystal structure, Zn^2＋ cation is located at the symcenter and coordinated by six water molecules. In [Zn（H2O）6]^2＋, an elongate octahedral complex cation, the average Zn-O bond length is 2.087（2） A. There exist a lot of H bonds in the structure, linking the cation [Zn（H2O）6]^2＋, anion ClO4^- and PNOS to form a 3D network.

Syntheses, Characterizations, Crystal Structures and Antibacterial Activities of Two Zinc(II) Complexes with a Schiff Base Derived from o-Vanillin and p-Toluidine

Two new zinc（Ⅱ） complexes, [Zn2L2Ch].2[ZnL（CH3OH）Cl2] 1 and [ZnL2（NO3）2] 2, were synthesized by reacting ZnX2.nH2O （X = Cl^-, NO3^-） and a Schiff base ligand 2-[（4-methylphenylimino）methyl]-6-methoxyphenol （C15HIsNO2, L） which was obtained by the condensation of o-vanillin （2-hydroxy-3-methoxybenzaldehyde） with p-toluidine. Both 1 and 2 were characterized by single-crystal X-ray diffraction technique, elemental analysis, molar conductance, FT-IR, UV-Vis, IH-NMR spectra and thermogravimetrie analysis. The Schiff base ligand and its zinc（Ⅱ） complexes have been tested in vitro to evaluate their antibacterial activity against bacteria, viz., Escherichia Coli, Staphylococcus aureus and Bacillus Subtilis. The results show that these complexes have higher activity than the corresponding free Schiff base ligand against the same bacteria.

Synthesis, Crystal Structure and Calculated β Value of a Tetrahedral Zinc (II) Complex——Zn(2-NH_2py)_2Br_2

A new zinc(II) complex, Zn(2-NH2py)2Br2 (py=pyridine), has been synthesized, and its molecular structure has been confirmed by IR, elemental analysis and -ray crystal structure analysis. Its space group is P21/n with Mr=413.43 (C10H12Br2N4Zn), a=7.435(2), b=12.865(3), c=14.186(4)? b=94.08(2)? V=1353.5(5) 3, Z=4, Dc=2.029 g/cm3, F(000)=328, ?2.378mm－1, R=0.0283, wR=0.0501. The total observed reflections with I≥2?I) were 5314, of which the independent reflections were 3106. The complex structure contains a distorted tetrahedron formed by four atoms coordinated to zinc atom, namely two bromide atoms and two nitrogen atoms. The two ZnBr bond lengths within one molecule, 2.3763(6) and 2.4002(5)? respectively, are not equal; and so are the two ZnN bond lengths, which are 2.031(2) and 2.044(2)?respectively. The calculation results using PM3 method through MOPAC software package in Chem 3D show that its first molecular hyperpolarizability b value is 5.210－30esu, which is comparable with that of p-nitroaniline. No bulk SHG effect has been detected due to the centrosymmetric space group.

Design and Self-assembly of a Novel Tetranuclear Zinc(Ⅱ) Complex via Reaction of 1,3-Thiazolidine-2-thione(tzdtH) with Zn(NO_ 3)_ 2

The self-assembly of clusters in inorganic systems is an interesting subject. The self-assembly of big molecules has been well established in biological systems. In addition, the coordination chemistry of metal-sulfur-nitrogen cluster complexes has been a very active and attracting field for many years as a result of the novelty and versatility of the crystal structures and reactivities of such clusters, as well as their potential applications as the models for the active sites in non-heme proteins. At the same time, there is currently considerable interest in the formation of metal complexes with heterocyclic ligands because of the diverse characteristics of ligands and their consequential wide range of applications.

Synthesis and Crystal Structure of a Tetranuclear Carboxylate-bridged Lanthanum(III)-Zinc(II) Complex [La_2Zn_2(m-CNC_6H_4COO)_(10)(Py)_2(C_2H_5OH)_2]

The title complex was prepared from self-assembly reaction of La（NO3）3(6H2O, Zn（NO3）2(6H2O, m-cyanobenzoic acid （m-CNC6H4COOH） and pyridine （Py） in refluxing ethanol and its structure was determined by single-crystal X-ray diffraction. Crystallographic data: C94H62N12La2O22Zn2, Mr = 2120.12, triclinic space group P, a = 13.2219（5）, b = 13.2713（5）, c = 14.1987（6） ?, (???69.156（1）, ( = 84.034（1）, ( = 89.400（1） (, V = 2314.9（2） ?3, Z = 1, Dc = 1.521 g/cm3, F（000） = 1060, ( (MoK（） = 14.94 cm－1, the final R = 0.043 and wR = 0.117 for 6381 unique reflections with I > 2(（I）. Crystal structure determination shows that the neighboring lanthanum（III） and zinc（II） ions are bridged by three bidentate m-cyanobenzonate ligands in the syn-syn fashion to form a pair of dinuclear [LaZn（m-CNC6H4COO）3（Py）（C2H5OH）] subunits, being linked together by two bidentate and two tridentate m-cyanobenzonate groups in the syn-syn and syn-anti modes, respectively, to construct a tetranuclear La-Zn complex [La2Zn2（m-CNC6H4COO）10（Py）2（C2H5OH）2].

Hydrothermal Synthesis, Crystal Structure and Photoluminescent Property of a Zinc(II) Complex with 2,2′-Diphenic Acid and 2,2′-Bipyridine Ligands

A new dinuclear complex [Zn（dpa）（bipy）（H2O）]2 （dpa = 2,2＇-diphenic acid, bipy = 2,2＇-bipyridine） 1 has been hydrothermally synthesized and structurally characterized by elemental analysis, IR, fluorescence spectrum and single-crystal X-ray diffraction. The complex crystallizes in monoclinic, space group P21/c with a = 10.960（2）, b = 9.4841（18）, c = 20.599（4）, β = 104.452（3）o, V = 2073.4（7）3, C48H36N4O10Zn2, Mr = 959.55, Dc = 1.537 g/cm3, μ（MoKα） = 1.225 mm-1, F（000） = 984, Z = 2, the final R = 0.0364 and wR = 0.0843 for 2788 observed reflections （I 〉 2σ（I））. In the crystal structure, the zinc atom is five-coordinated with two carboxylate oxygen atoms from different dpas, one coordinated water molecule and two nitrogen atoms from bipy ligands, showing a slightly distorted triangular bipyramidal geometry. Furthermore, it exhibits a zero-dimensional network structure with a sixteen-membered ring and shows yellow photoluminescent property at room temperature.

Synthesis,Crystal Structure and Fluorescent and Thermal Stability Properties of the Zinc(Ⅱ) Complex [Zn(C_(15)H_(11)O_3)_2(C_(12)H_8N_2)_2]·5H_2O

A new complex has been synthesized with o-methylbenzoyl-benzoic acid（HL） and 1,10-phenanthroline（phen） in the mixture of water and ethanol. It crystallizes in monoclinic, space group C2/c with a = 13.6328（18）, b = 17.7876（18）, c = 19.998（2）, β = 104.720（4）o, C54H48N4O11Zn, Mr = 994.33, V = 4690.2（9）3, Dc = 1.408 g/cm3, Z = 4, F（000） = 2072, μ（MoKα） = 0.59 mm-1, R = 0.0736 and wR = 0.2029. The crystal structure shows that the zinc ions are coordinated with two oxygen atoms from two HL molecules and four nitrogen atoms from two phen molecules, forming distorted octahedral coordination geometry. The fluorescent and thermal stability properties of the complex are studied. The result shows that it has one fluorescent emission band at around 412 nm. In addition, the complex is stable under 210 ℃.

Synthesis,Structure,and Luminescent Property of a 3-D Zinc Complex {[Zn_8^(II)(4-APha)_8(CH_3COO)_8](CH_3CH_2OH)_2}_n

The title complex [ZN8II（4-APha）8（CH3COO）8（CH3CH2OH）2]n （1, 4-APha = 4-ami- nophenylhydroxamic acid） has been prepared under solvothermal conditions. It has been characterized by X-ray single-crystal diffraction, IR and elemental analysis. The crystal belongs to the monoclinic system, space group C2/c with a = 39.074（4）, b = 9.9645（8）, c=38.846（3） A, β = 136.438°, V= 10423.1（14） A3, C84H118N16O39Zn8, Mr = 2498.90, Z = 4, Dc = 1.592 g/cm3,μ= 1.900 mm-1, F（000） = 5144, the final R = 0.1036 and wR = 0.2953. This complex possesses a 3-D structure which is constructed from 1-D chain motifs linked by the 4-APha＂ ligands. The luminescent property of the title complex has been investigated.

Synthesis and Characterization of Two Binuclear Macrocyclic Zinc(Ⅱ) Complexes by Anion Exchange

Two macrocyclic zinc（Ⅱ） complexes {[ZnL（VO3）2]·0.33H2O}n（1） and [ZnL（H2O）2][Ni（CN）4]（2）（L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane） have been obtained from the reactions of [ZnL]（ClO4）2 with NH4VO3 and K2[Ni（CN）4], respectively, and structurally characterized by elemental analysis, IR, XRPD, TG and X-ray diffraction. Single-crystal X-ray diffraction analyses indicated that the Zn（Ⅱ） atom lies on an inversion center and is octahedrally coordinated by four nitrogen atoms of the tetradentate macrocyclic ligand in the equatorial plane and two oxygen atoms of [VO4] tetrahedra in the axial positions in 1, and two oxygen atoms of two water molecules in 2. Complex 1 shows a three-dimensional structure, which is constructed by the links of [VO3]nn- chains with [ZnL]2＋, forming one-dimensional channels occupied by guest water molecules. The monomers of [ZnL（H2O）2]2＋ and [Ni（CN）4]2- are connected through the intermolecular hydrogen bonds to form a two-dimensional sheet in complex 2.

Hydrothermal Synthesis, Crystal Structure and Fluorescence Properties of a Three-dimensional Triply-bridged Binuclear Zinc(Ⅱ) Complex [Zn_2(Mba)_3(Phen)_2EtOH)]·ClO_4

The novel complex [Zn2（Mba）3（Phen）2EtOH）]·ClO4 （Hrnba = methoxybenzoic acid, Phen = 1,10-phenanthroline, EtOH = ethanol） was synthesized by hydrothermal reactions, and its structure was determined by X-ray diffraction. The crystal belongs to the triclinic system, space group Pi with a = 1.15362（1）, b = 1.3655（3）, c = 1.61451（1） nm, α= 72.842（2）, β = 83.259（3）, y = 72.083（2）°, V = 2.3112（6） nm3, Z = 2,μ（MoKa） = 11.71 cm-1, F（000） = 1120, R = 0.0552 and wR = 0.1157 （I 〉 2σ（I））. The two centric zinc（H） ions in the complex locate in a distorted octahedral coordination geometry and a distorted trigonal bipyramid coordination geometry, respectively. Two bridging bidentate carboxyl groups and a μ2-O carboxyl group from three methoxybenzoic acids act as the bridge to link two Zn（Ⅱ） ions. The asymmetric units are connected by π-π packing interactions between aromatic rings to form a three-dimensional supramolecular network. The experimental results show a good fluorescence property for the complex.

Synthesis, Crystal Structure and Biological Properties of One Zinc(Ⅱ) Complex Based on 4-Acyl Pyrazolone Derivative

[Zn（L）（CH3OH）3]（H2L = N-（1-phenyl-3-methyl-4-propenylidene-5-pyrazolone）-salicylidene hydrazide） has been synthesized by the reaction of zinc nitrate and ligand H2 L. The complex crystallizes in orthorhombic system, space group Pbca with a = 5.888（15）, b = 14.564（14）, c = 22.20（2） , V = 5137（8） 3, Z = 8 and F（000） = 2184. The ligand serves as a negative bivalent tridentate chelating agent to coordinate with the central zinc（II） atom. DNA-binding was studied by UV-Vis spectral analysis and ethidium bromide（EB） displacement experiments. The results showed that the DNA-binding constant of the complex is 5.1×104 M–1. Antitumor activity of [Zn（L）（CH3OH）3] and the ligand have been investigated by MTT assay, which indicated that the complex has better cytotoxicity to Eca-109 and He La than free ligand.

Hydrothermal Syntheses,Crystal Structures,and Characterization of Two Zinc(Ⅱ)Complexes Containing Flexible Bis(benzimidazole)Ligands

Two zinc（II） complexes, namely, [Zn（L1）Cl2]2 （1） and {[Zn（L2）（tbta）]·3H2O}n （2） （L1 = 1,3-bis（2-methylbenzimidazol-1-ylmethyl）benzene, H2tbta = tetrabromoterephthalic acid, L2 = 1,3-bis（2-methylbenzimidazol-1-yl）-2-propanol） have been successfully obtained under hydrothermal conditions. Complex 1 displays binuclear structure which is further extended into a 1D supramolecular chain through π–π stacking. Complex 2 features 2D （4,4） network based on L2/tbta2– double linker. The thermal stability, fluorescence properties and catalytic activities of two complexes for degradation of Methyl orange in a Fenton-like process were discussed.

Synthesis, Crystal Structure and Kinetic Mechanism of Thermal Decomposition of a Zinc(II) Complex with N-Salicylidene-p-toluidine

The title complex, Zn（C24H13NO）2Cl21, has been synthesized by the reaction of zinc chloride with Schiff base ligand N-salicylidene-p-toluidine and its structure was determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group Cc with a = 14.896（3）, b = 12.506（2）, c = 15.352（3） A,β = 114.711 （4）°, V = 2598.0（8） A^3, C28H26ZnCl2N2O2, Mr = 558.80, Z = 4, Dc = 1 .429 g/cm^3,μ = 1.179 mm^-1, Flack parameter = 0.027（19）, F（000） = 1152, R = 0.0709 and wR = 0.1041 for 3117 observed reflections （Ⅰ 〉 2σ（Ⅰ））. In complex 1, the center Zn ion is four-coordinated by two O atoms from two Schiff base ligands and two Cl atoms in a distorted tetrahedral geometry. Additionally, the thermal decomposition of complex 1 as well as its kinetic mechanisms and equations is studied under the non-isothermal integral and differential methods in air by TG-DTG curves.