Comparison of the pH‐dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility‐mass spectrometry

The analog methanobactin (amb) peptide with the sequence ac‐His₁‐Cys₂‐Gly₃‐Pro₄‐Tyr₅‐His₆‐Cys₇ (amb_5A) will bind the metal ions of zinc, nickel, and copper. To further understand how amb_5A binds these metals, we have undertaken a series of studies of structurally related heptapeptides where one or two of the potential His or Cys binding sites have been replaced by Gly, or the C‐terminus has been blocked by amidation. The studies were designed to compare how these metals bind to these sequences in different pH solutions of pH 4.2 to 10 and utilized native electrospray ionization (ESI) with ion mobility‐mass spectrometry (IM‐MS) which allows for the quantitative analysis of the charged species produced during the reactions. The native ESI conditions were chosen to conserve as much of the solution‐phase behavior of the amb peptides as possible and an analysis of how the IM‐MS results compare with the expected solution‐phase behavior is discussed. The oligopeptides studied here have applications for tag‐based protein purification methods, as therapeutics for diseases caused by elevated metal ion levels or as inhibitors for metal‐protein enzymes such as matrix metalloproteinases.     

Redox activity and multiple copper(I) coordination of 2His–2Cys oligopeptide

Copper binding motifs with their molecular mechanisms of selective copper(I) recognition are essential molecules for acquiring copper ions, trafficking copper to specific locations and controlling the potentially damaging redox activities of copper in biochemical processes. The redox activity and multiple Cu(I) binding of an analog methanobactin peptide‐2 (amb₂) with the sequence acetyl–His₁–Cys₂–Tyr₃–Pro₄–His₅–Cys₆ was investigated using ion mobility–mass spectrometry (IM‐MS) and UV–Vis spectrophotometry analyses. The Cu(II) titration of amb₂ showed oxidation of amb₂ via the formation of intra‐ and intermolecular Cys–Cys disulfide bridges and the multiple Cu(I) coordination by unoxidized amb₂ or the partially oxidized dimer and trimer of amb₂. The principal product of these reactions was [amb₂ + 3Cu(I)]⁺ which probably coordinates the three Cu(I) ions via two bridging thiolate groups of Cys₂ and Cys₆ and the δN₆ of the imidazole groups of His_6, as determined by geometry optimized structures at the B3LYP/LanL2DZ level of theory. The products observed by IM‐MS showed direct correlation to spectral changes associated with disulfide bond formation in the UV–Vis spectrophotometric study. The results show that IM‐MS analysis is a powerful technique for unambiguously determining the major ion species produced during the redox and metal binding chemistry of oligopeptides. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis,spectral and antibacterial activity of Co(II), Ni(II) and Zn(II) complexes with 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H‐naphthalen‐1‐ylidene)‐hydrazide

A bioactive Schiff base HL i.e. 2‐hydroxy‐benzoic acid(3,4‐dihydro‐2H ‐naphthalen‐1‐ylidene)‐hydrazide was synthesized by reacting equimolar amount of salicylic acid hydrazide and 1‐tetralone. Co(II), Ni(II) and Zn(II) complexes of ligand HL was synthesized in 1:1 and 1:2 molar ratio of metal to ligand. The structure of the synthesized ligand and metal complexes was established by elemental analysis, molar conductance, magnetic susceptibility measurements, electronic, IR and EPR spectral techniques. For determining the thermal stability the TGA has been done. In DFT studies the geometries of Schiff bases and metal complexes were fully optimized with respect to the energy using the 6–31 + g(d,p) basis set. Spectral data reveal that ligand behave uninegative tridentate in ML complexes and uninegative bidentate in ML₂ complexes. On the basis of characterization octahedral geometry has been assigned for Co(II) and Ni(II) complexes, while tetrahedral for Zn(II) complexes. Antibacterial activity of the synthesized compounds were evaluated against Staphylococcus aureus , Bacillus subtilis, Escherichia coli , Xanthomonas campestris and Pseudomonas aeruginosa and the results revealed that metal complexes show enhanced activity in comparison to free ligand.     

五-和六配位的三核锌配合物{[ZnL(OAc)]2Zn}∙CH3COCH3的合成，晶体结构及荧光性质

合成并结构表征了一种新型的线性三核锌(II)配合物,{[ZnL(OAc)]2Zn}∙CH3COCH3（H2L：乙二氧双(5-溴-2-羟基苯亚甲基胺)）。X-射线结构表明配合物中三个锌(II)离子配位到了两个四齿的L2-单元和两个桥联的的乙酸根基团。围绕两端的Zn(1) 或 Zn(1)#1原子形成了扭曲的四方锥配位几何体,围绕中心Zn(2) 原子构成了一个稍微扭曲的八面体配位结构。同时,观察到锌(II)配合物能发出蓝绿色荧光,其最大发射波长为464 nm。     

Ring‐opening polymerization of rac‐lactide catalyzed by Al(III) and Zn(II) complexes incorporating Schiff base ligands derived from pyrrole‐2‐carboxaldehyde

A series of Al(III) chloride [LAl‐Cl]; Al(III) alkoxide [LAl‐OR]₂; and Zn(II) [LZn]₂ complexes with Schiff base ligands were obtained. ¹H NMR and X‐ray diffraction studies indicate that [LAl‐Cl] complexes have C_s symmetry and the Al center is penta‐coordinated. The Al(III) alkoxide complex [L⁵Al‐OⁱPr]₂ is a dimer bridged by OⁱPr^? with the Al center in a distorted octahedral environment. Zn complexes [LZn]₂ are double helix dimers with tetra‐coordinated Zn centers. The catalytic activity for the ring‐opening polymerization of rac‐lactide was evaluated. The best activity in this series is shown by the aluminium chloride complex with a flexible three‐carbon bridge; more flexible four‐carbon bridges lower the activity.     

Entrapment of amino acids in gas phase surfactant assemblies: The case of tryptophan confined in positively charged (1R,2S)‐dodecyl (2‐hydroxy‐1‐methyl‐2‐phenylethyl) dimethylammonium bromide aggregates

The ability of positively charged aggregates of the surfactant (1R ,2S )‐dodecyl(2‐hydroxy‐1‐methyl‐2‐phenylethyl)dimethylammonium bromide (DMEB) to incorporate D‐tryptophan or L‐tryptophan in the gas phase has been investigated by electrospray ion mobility mass spectrometry (ESI‐IM‐MS). Strongly impacted by the pH of the electrosprayed solutions, both protonated (T⁺) and deprotonated (T⁻) tryptophan are effectively included into the aggregates, whereas, tryptophan in zwitterionic (T⁰) form is practically absent in singly charged DMEB aggregates but can be found in multiply charged ones. The ability to incorporate tryptophan increases with the aggregation number and charge state of aggregates. More than 1 tryptophan species can be entrapped (aggregates including up to 5 tryptophan are observed). Collision induced dissociation experiments performed on the positively singly charged DMEB hexamer containing 1 T⁻ show that at low collision energies the loss of a DMEB molecule is preferred with respect to the loss of the DMEB cation plus T⁻ species which, in turn, is preferred with respect to the loss of mere tryptophan, suggesting that the deprotonated amino acid is preferentially located in proximity of a DMEB head group and with the ionic moiety pointing towards the core of the aggregate. The analysis of the collision cross sections (CCS) of bare and tryptophan containing aggregates allowed evaluating the contributions of tryptophan and bromide ions to the total aggregate CCS. No significant discrimination between D‐tryptophan and L‐tryptophan by the chiral DMEB aggregates has been evidenced by mass spectra data, CID experiments, and CCS values.     

Crystal structure,characterization and catalytic activities of Cu(II) coordination complexes with 8‐hydroxyquinoline and pyrazine‐2‐carboxylic acid

Green and blue crystals of the coordination complexes [Cu(8‐hquin)₂(H₂O)₂], 1 and [Cu(pyzca)₂(H₂O)₂], 2 were obtained by the reaction of copper chloride with 8‐hydroxyquinoline (8‐hquinH) or pyrazine‐2‐carboxylic acid (pyzcaH) as ligands. The structures of 1 and 2 were characterized by elemental analyses, electronic absorption, Infrared (IR) and thermal studies. The luminescent behavior complexes 1 and 2 was also discussed. The coordination environment of copper(II) center displays distorted octahedral coordination geometry. The structure of the complexes 1 and 2 is constructed by an infinite number of discrete mononuclear molecules extending along the a‐axis to form a 1D‐chain via H‐bonds. The extensive hydrogen bonds and short contacts develop the structures of 1 and 2 to 3D‐network. The catalytic behavior of the complexes 1 and 2 was utilized for degradation of methylene blue dye (MB). The kinetic data indicated that the complexes 1 and 2 are effective catalysts for degradation of MB dye. Photoluminescence probing technology was used as a sensitive probe for detecting ^?OH radicals.     

Zinc(II) and Cadmium(II) Metal Complexes with Bis(tetrazole) Ligands: Synthesis and Crystal Structures

Two new metal complexes [Zn( L¹ )]_n ( 1 ) and [Cd₃( L² )₂Cl₂(H2O)6]_n ( 2 ) (H₂ L¹ = 1,5‐bis(tetrazol‐5‐yl)‐3‐oxapentane, H₂ L² = bis(tetrazol‐5‐yl)methane) have been synthesized and characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction analysis. Complex 1 was a 2‐D sheet constructed by L¹ and Zn(II) center, further assembled to form a three‐dimensional (3‐D) supramolecular networks through weak hydrogen‐bonding interactions. In the complex 2 , there were two unequivalent Cd(II) centers, and some of ligands L² adopted chelate coordination mode, and others adopted bridge coordination mode linking the Cd1 center and simultaneously bridging the Cd2 center, the Cl^‐ anions adopted μ₂ bridging mode, ligands L² and the Cl^‐ anions linked the Cd(II) centers to form a 3‐D supramolecular networks.     

Construction of 1D and 2D Zinc Coordination Polymers Based on Organic Carboxylate Anions and Flexible Imidazole‐Containing Ligand

Two novel zinc coordination polymers {[Zn(PhCOO)₂(bmix)]}_n 1 and {[Zn(ada)(bmix)]·(H₂O)₂}_n 2 (bmix = 1,4‐bis(2‐methylimidazole‐1‐ylmethyl)benzene, H₂ada = adipic acid), were obtained by the hydrothermal reactions of bmix and zinc acetate with two carboxylate anions, respectively. Structural analyses show that complex 1 possess a one‐dimensional helix chain structure, 2 takes two‐dimensional corrugated (4,4) layer motif. The structural differences of two complexes indicate that organic carboxylate anions play important roles in the formation of such zinc(II) coordination architectures.     

The enhanced biological activities of three Zn (II) complexes based on different 1,2,4‐triazole fungicides

In order to screen effective fungicides, three Zn (II) complexes, [Zn L ¹ ₄ (NO₃)₂]·2H₂O·2EtOH ( 1 ), [Zn L ² ₄ (NO₃)₂] ( 2 ), and [Zn L ³ ₄ (DMF)₂](NO₃)₂ ( 3 ), ( L ¹  = paclobutrazol, L ²  = diniconazole, and L ³  = hexaconazole), were synthesized and characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal XRD. The antifungal activities of these complexes were then evaluated against four selected fungi using the mycelial growth rate method. The resulting data indicate that all the complexes show the enhanced antifungal activities than the corresponding ligand and mixtures. And, the interactions between the metal salt and ligands in the three complexes seem to be synergistic. According to the study of the influence of the structures on the activity, complex 2 with C=C linkage and 2,4‐dichlorophenyl moieties enhances the bioactivity significantly, especially against Wheat gibberellic ( II ). Density functional theory (DFT) calculations were carried out to help explain the enhanced bioactivity of the Zn (II) complexes. Meanwhile, all complexes are excellent grow‐regulators, especially complex 3 . The resulting data show that the complexes based on triazole fungicides have the potential applications in agriculture.     

一种新型含三苯胺的喹啉衍生物及其金属配合物的合成与表征

A new 8-hydroxyquinoline derivative(5)was synthesized and characterized by ESI-MS,~1H NMR spectroscopy,elemental analysis and IR spectroscopy.The photophysical properties of compounds 5,6 and 7 were also deteminedby UV-vis and FL spectroscopy.The vibrational frequency of ligand 5 predicted by using B3LYP method is in goodagreement with experimentally determined values.The compositions of the corresponding copper(Ⅱ)and zinc(Ⅱ)complexes were confirmed to be Cu(C_(29)H_(21)N_2O)_2·H_2O(6)and Zn(C_(29)H_(21)N_2O)_2·H_2O(7)by elementary analysis,thermogravimetry analysis and IR spectroscopy.     

Enhanced antifungal activities of four Zn(II) complexes based on uniconazole

Four Zn(II) complexes, [Zn L ₂(SO₄)]_n ( 1 ), [Zn L ₄(H₂O)₂]?2(NO₃)?4EtOH ( 2 ), [Zn L ₂Cl₂]? L ( 3 ), and [Zn L ₂Br₂]? L ( 4 ) ( L  = uniconazole), were synthesized using a hydrothermal method and characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal XRD. Complex 1 formed a one‐dimensional polymer chain. However, complexes 2 ‐ 4 were obtained as zero‐dimensional mononuclear coordination compounds. The antifungal activities of these complexes were then evaluated against four selected fungi using the mycelial growth rate method. The resulting data indicate that all complexes show better antifungal activities than their ligands and mixtures. In addition, the interactions between the metal salts of complexes 1 ‐ 4 and uniconazole seem to be synergistic. Furthermore, the polymer chain structure of complex 1 significantly enhanced the bioactivity, especially against Botryosphaeria ribis ( I ). Density functional theory (DFT) calculations were carried out to help explain the enhanced bioactivity after the formation of Zn(II) complexes. The resulting data show that the HOMO–LUMO energy gaps of complexes 1 ‐ 4 (0.0578, 0.0946, 0.1053, and 0.1245 eV) are smaller than that of the free ligand (0.1247 eV) and correlate with the antifungal activity of the zinc complexes.     

Pseudohalide‐directed Assembly of Two Zinc(II) Coordination Polymers with a 3,4‐Bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole Tecton

The zinc(II) pseudohalide complexes {[Zn(L³³⁴)(SCN)₂(H₂O)](H₂O)₂}_n ( 1 ) and [Zn(L³³⁴)(dca)₂]_n ( 2 ) were synthesized and characterized using the ligand 3,4‐bis(3‐pyridyl)‐5‐(4‐pyridyl)‐1,2,4‐triazole (L³³⁴) and ZnCl₂ in presence of thiocyanate (SCN^–) and dicynamide [dca, N(CN)₂^–] respectively. Single‐crystal X‐ray structural analysis revealed that the central Zn^II atoms in both complexes have similar octahedral arrangement. Compound 1 has a 2D sheet structure bridged by bidentate L³³⁴ and double μ_N,S‐thiocyanate anions, whereas complex 2 , incorporating with two monodentate dicynamide anions, displays a two‐dimensional coordination framework bridged by tetradentate L³³⁴ ligand. Structural analysis demonstrated that the influence of pseudohalide anions plays an important role in determining the resultant structure. Both complexes were characterized by IR spectroscopy, microanalysis, and powder X‐ray diffraction techniques. In addition, the solid fluorescence and thermal stability properties of both complexes were investigated.     

Structurally characterized dinuclear zinc(II) bis(salamo)‐type tetraoxime complex possessing square pyramidal and trigonal bipyramidal geometries

A novel dinuclear Zn(II) complex with the chemical formula [Zn₂(L)(OCH₃)] has been synthesized by a bis(salamo)‐type tetraoxime ligand based on 3‐bromo‐5‐chlorosalicylicaldehyde, and characterized by elemental analyses, IR, UV–vis, and fluorescent spectra, and single‐crystal X‐ray diffraction analysis. All the Zn(II) atoms are pentacoordinated by N₂O₂ donor atoms from the (L)³⁻ unit and one oxygen atom from one μ₂‐methoxyl group. The Zn(II) (Zn1 and Zn4) atoms have distorted square pyramidal geometries (τ₁ = 0.458, τ₄ = 0.388), whereas the Zn2 and Zn3 atoms adopt trigonal bipyramidal (τ₂ = 0.675, τ₃ = 0.550) geometries. The Zn(II) complex is self‐assembled by intermolecular C H···O interactions to form an infinite three‐dimensional supramolecular structure. Interestingly, the intermolecular C H···π interactions in the Zn(II) complex is involved not in the formation of three‐dimensional structures but rather in the formation of the 0D dimer structure. Meanwhile, the optical properties of the Zn(II) complex were also measured and are discussed.     

Supramolecular architectures in CoII and CuII complexes with thiophene‐2‐carboxylate and 2‐amino‐4,6‐dimethoxypyrimidine ligands

The coordination chemistry of mixed‐ligand complexes continues to be an active area of research since these compounds have a wide range of applications. Many coordination polymers and metal–organic framworks are emerging as novel functional materials. Aminopyrimidine and its derivatives are flexible ligands with versatile binding and coordination modes which have been proven to be useful in the construction of organic–inorganic hybrid materials and coordination polymers. Thiophenecarboxylic acid, its derivatives and their complexes exhibit pharmacological properties. Cobalt(II) and copper(II) complexes of thiophenecarboxylate have many biological applications, for example, as antifungal and antitumor agents. Two new cobalt(II) and copper(II) complexes incorporating thiophene‐2‐carboxylate (2‐TPC) and 2‐amino‐4,6‐dimethoxypyrimidine (OMP) ligands have been synthesized and characterized by X‐ray diffraction studies, namely (2‐amino‐4,6‐dimethoxypyrimidine‐κN)aquachlorido(thiophene‐2‐carboxylato‐κO)cobalt(II) monohydrate, [Co(C₅H₃O₂S)Cl(C₆H₉N₃O₂)(H₂O)]·H₂O, (I), and catena‐poly[copper(II)‐tetrakis(μ‐thiophene‐2‐carboxylato‐κ²O:O′)‐copper(II)‐(μ‐2‐amino‐4,6‐dimethoxypyrimidine‐κ²N¹:N³)], [Cu₂(C₅H₃O₂S)₄(C₆H₉N₃O₂)]_n, (II). In (I), the Co^II ion has a distorted tetrahedral coordination environment involving one O atom from a monodentate 2‐TPC ligand, one N atom from an OMP ligand, one chloride ligand and one O atom of a water molecule. An additional water molecule is present in the asymmetric unit. The amino group of the coordinated OMP molecule and the coordinated carboxylate O atom of the 2‐TPC ligand form an interligand N—H…O hydrogen bond, generating an S(6) ring motif. The pyrimidine molecules also form a base pair [R₂²(8) motif] via a pair of N—H…N hydrogen bonds. These interactions, together with O—H…O and O—H…Cl hydrogen bonds and π–π stacking interactions, generate a three‐dimensional supramolecular architecture. The one‐dimensional coordination polymer (II) contains the classical paddle‐wheel [Cu₂(CH₃COO)₄(H₂O)₂] unit, where each carboxylate group of four 2‐TPC ligands bridges two square‐pyramidally coordinated Cu^II ions and the apically coordinated OMP ligands bridge the dinuclear copper units. Each dinuclear copper unit has a crystallographic inversion centre, whereas the bridging OMP ligand has crystallographic twofold symmetry. The one‐dimensional polymeric chains self‐assemble via N—H…O, π–π and C—H…π interactions, generating a three‐dimensional supramolecular architecture.     

Novel 13,14‐dimethyl‐5,8‐dioxa‐2,11,13,14‐tetraaza‐1,12‐diphosphabicyclo [10.1.1] tetradecane 1,12‐dioxide ligand and its Ni(II), Co(II), and Cu(II) complexes: Synthesis,characterization, antimicrobial,DNA cleavage,and computational studies

A novel diazadiphosphetidine ligand derived from the reaction of 2,4‐dichloro‐1,3‐dimethyl‐1,3,2,4‐diazadiphosphetidine‐2,4‐dioxide and 2,2′‐(ethane‐1,2‐diylbis[oxy])bis(ethan‐1‐amine) and its Ni(II), Cu(II), and Co(II) complexes have been synthesized, characterized by spectroscopic, elemental analyses, magnetic susceptibility, and conductivity methods, and screened for antimicrobial, DNA binding, and cleavage properties. Spectroscopic analysis and elemental analyses indicate the formula [M(H₂L)Cl₂] for the Cu(II), Co(II), Ni(II), and Zn(II) complexes and octahedral geometry for all the complexes. The non‐electrolytic nature of the complexes in dimethyl sulfoxide (DMSO) was confirmed by their molar conductance values, which are in the range 12.32–6.73 Ω^?1 cm² mol^?1. Computational studies have been carried out at the density functional theory (DFT)‐B3LYP/6‐31G(d) level of theory on the structural and spectroscopic properties of diazadiphosphetidine H₂L and its binuclear Cu(II), Co(II), Ni(II), and Zn(II) complexes. Six tautomers and geometrical isomers of the diazadiphosphetidine ligand were confirmed using semiempirical AM1 and DFT method from DMOL³ calculations. The copper complex had the best antibacterial activity against Staphylococcus aureus (ATCC 29213). DNA cleavage activities of the compounds, evaluated on pBR322 DNA by agarose gel electrophoresis in the presence and absence of an oxidant (H₂O₂) and a free‐radical scavenger (DMSO), indicated no activity for the ligand and moderate activity for the complexes, with the copper complex cleaving pBR322 DNA more efficiently in the presence of H₂O₂.     

Synthesis and characterization of biologically active new Schiff bases containing 3‐functionalized 1,2,4‐triazoles and their zinc(II) complexes: crystal structure of 4‐bromo‐2‐[(E)‐(1H‐1,2,4‐triazol‐3‐ylimino)‐ methyl]phenol

Biologically active triazole Schiff bases ( L ¹  L ³ ) derived from the reaction of 3‐amino‐1,2,4‐triazole with chloro‐, bromo‐ and nitro‐ substituted salicylaldehydes and their Zn(II) complexes (1–3) have been synthesized and characterized by their physical, spectral and analytical data. Triazole Schiff bases potentially act as tridentate ligands and coordinate with the Zn(II) metal atom through salicylidene‐O, azomethine‐N and triazole‐N. The complexes have the general formula [M(L‐H)₂], where M = zinc(II) and L = ( L ¹ – L ³ ), and observe an octahedral geometry. The Schiff bases and their Zn(II) complexes have been screened for in‐vitro antibacterial, antifungal and brine shrimp bioassay. The biological activity data show the Zn(II) complexes to be more potent antibacterial and antifungal than the parent simple Schiff bases. Copyright © 2011 John Wiley & Sons, Ltd.     

Tetranuclear Zn(II) Complex Based on an Asymmetrical Salamo‐Type Chelating Ligand: Synthesis,Structural Characterization,and Fluorescence Property

A new tetranuclear Zn(II ) complex, [{Zn(L)(μ‐OAc )Zn(H₂O )}₂], based on an asymmetrical salamo‐type bisoxime chelating ligand H₃L (6‐hydroxy‐4′‐chloro‐2,2′‐[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) was synthesized and characterized by elemental analyses, differential thermal methods, single‐crystal X‐ray crystallography, and IR , UV –vis, and fluorescence spectra. The Zn(II ) complex crystallizes in the triclinic system, space group P ‐1 with cell parameters a = 9.0742(6) Å, b = 11.8225(5) Å, c = 12.4182(8) Å, Z = 2, V = 1212.56(12) ų , R ₁ = 0.0572, and wR ₂ = 0.1734. The environment of the tetranuclear Zn(II) complex is penta‐coordinated having a slightly distorted trigonal bipyramidal geometry. Moreover, a 1D chain supramolecular structure is formed along the c ‐axis by the intermolecular C1–H1B⋯O14 hydrogen bonds; in the same manner, C2–H2C⋯Cg2 functions in the formation of supramolecular structures along the a ‐axis of the 1D chain. A 2D supramolecular structure along the ac plane extends infinitely under the force of intermolecular hydrogen bonds. Differential scanning calorimetry‐thermogravimetry thermal analysis provides evidence of the coordination of Zn(II) atoms to the ligand H₃L. The Zn(II) complex shows intense photoluminescence with a maximum emission at ~453 nm upon excitation at 360 nm.     

Synthesis, Structure and Biological Activity of Zn（Ⅱ） Complex with Tris（benzimidazol-2-yl-methyl）amine Ligand

A new Zn(II) mononuclear complex with tris(benzimidazol‐2‐yl‐methyl)amine (NTB) was synthesized with stoichiometry of [Zn(NTB)NO₃]NO₃ · DIPY · DMF (DIPY : 4,4′‐dipyridyl). The complex was characterized by elemental analysis, UV and IR spectra. The crystal structure was determined by using X‐ray diffraction analysis. The crystal structure indicates that four N atoms and one O atom coordinate to zinc ion to construct a distorted trigonal‐dipyramid configuration. Three nonprotonated N atoms from imidazole groups are in the equatorial plane, one alkylamino N atom and one O atom from NO₃^?_‐ in the axial directions. The biological activity assay shows that this complex presents certain biological activity by means of pyrogallol autoxidation and it can be called a model compound of superoxide dismutase (SOD).     

基于顺丁烯二酸和N,N螯合配体构筑的两个新型三维氢键型超分子体系: 结构、磁性质与理论化学研究

通过调变辅助配体,设计合成了两个新的Cu(II)化合物Cu(mal)(tap)(H2O)]n(1) 和 [Cu2(mal)2(bpym)2(H2O)2]·2H2O(2) (其中H2mal =顺丁烯二酸, tap=1,4,5,8-四氮杂菲,bpym=2,2′-联嘧啶),并用X-射线单晶衍射技术对其进行了结构表征。化合物1是一维弓背状配位聚合链通过氢键和π–π 堆积作用拓展形成的三维超分子体系;化合物2 展现一个具有六连接α-Po(46)拓扑的3D→3D二重穿插结构。此外根据晶体结构,利用Gaussian 03W中的DFT方法对化合物1和2进行几何构型优化,同时,用DFT-BS方法研究了两个化合物的磁性,结果表明计算结果与实验结果吻合,它们均具有弱的反铁磁相互作用。