The synthesis and structure of a novel 1D copper(II) weak coordination polymer with 2,6-pyridinedicarboxylic acid

A novel copper complex, [Cu(dipic)(H₂O)₂] _n (H₂dipic?=?2,6-pyridinedicarboxylic acid), was synthesized and its crystal structure determined by X-ray diffraction. The complex has a polymeric structure of infinite one-dimensional (1D) zigzag chains, consisting of six-coordinate Cu(II) units. Each copper(II) ion is in a distorted octahedral environment with a CuNO₅ core: two oxygen atoms and one nitrogen atom from one dipic anion, one oxygen atom from an adjacent dipic ligand and two oxygen atoms from coordinated water. Each dipic anion connects two copper ions via a μ₂-oxygen atom. The zigzag 1D-chains are linked by extensive hydrogen bonds to form 2D infinite sheets.     

Spacer-dependent structural and physicochemical diversity in copper(II) complexes with salicyloyl hydrazones: a monomer and soluble polymers

Complexation of copper(II) with a series of heterodonor chelating Schiff bases (LL) of salicylic acid hydrazide and aliphatic or cycloaliphatic ketones affords soluble one-dimensional (1D) metallopolymers containing Schiff bases as bridging ligands. Single-crystal X-ray diffraction results reveal nanometer-sized metallopolymeric wires [Cu(μ-LL)(2)](n) with off-axis linkers and a zigzag geometry. Octahedrally coordinated copper centers, exhibiting a Jahn-Teller distortion, are doubly bridged by two Schiff-base molecules in the μ(2)-η(1),η(2) coordination mode. The use of dibutylketone with long alkyl chains as a component for Schiff base formation leads to a distorted square planar monomeric copper(II) complex [Cu(LL)(2)], as evidenced by its X-ray crystal structure. The compounds are characterized by elemental analyses and IR and UV-vis spectroscopy, as well as magnetic susceptibility and cyclic voltammetry measurements. Electrochemical studies on the complexes reveal an existence of polymeric and monomeric forms in solution and the dependence of Cu(II)/Cu(I) reduction potentials on alkyl groups of salicyloyl hydrazone ligands. Polymeric complexes form conducting films on Pt electrodes upon multicycle potential sweeps.     

Syntheses and Crystal Structures of Two One-dimensional Coordination Polymers Constructed from a Flexible Hinge-like Ligand

By using the flexible hinge-like ligand 2,2＇-bis（3-hydroxy-l,4-naphthoquinone） （H2bhnq）, two isomorphous one-dimensional zigzag chain coordination polymers have been obtained. Single-crystal X-ray analyses revealed that the metal centers in these two complexes are distorted octahedra involving four oxygen atoms of two bhnq2 anions, and two oxygen atoms of two DMF molecules situated in trans positions to one another. Crystal data for [Mn（bhnq）（DMF）2]n 1： C26H22MnN2O8, Mr = 545.40, monoclinic, space group C2/c, a = 14.936（3）, b = 10.362（2）, c = 15.901（3）A., β = 99.86（3）°, V = 2424.7（8）A3, Z = 4, Dc = 1.494 g/cm^3, F（000） = 1124,μ = 0.599 mm^-1, final GOOF = 1.025, R = 0.0654 and wR = 0.1537. Crystal data for [Cd（bhnq）（DMF）2]n 2： C26H22CdN2O8, Mr = 602.86, monoclinic, space group C2/c, a = 14.839（3）, b = 10.493（2）, c = 16.034（3）A, β = 99.40（3）°, V = 2463.1（9）A^3, Z = 4, Dc = 1.626 g/cm^3, F（000） = 1216,μ = 0.941 mm^-1, final GOOF = 1.069, R = 0.0358 and wR = 0.0944.     

Stepwise guest adsorption with large hysteresis in a coordination polymer {[Cu(bhnq)(THF)2](THF)}n constructed from a flexible hingelike ligand

Reversible vapochromic behavior of a porous copper(II) coordination polymer {[Cu(bhnq)(THF)2](THF)}n (1; THF = tetrahydrofuran) constructed from a flexible hingelike ligand H2bhnq [2,2'-bis(3-hydroxy-1,4-naphthoquinone)] has been investigated by adsorption measurements. The isotherms show large hysteretic and stepwise profiles, suggesting the occurrence of the guest-induced framework transformation. The dynamic coil-like behavior of 1 can be controlled through the change of the hydrogen-bonding interactions caused by the reversible and selective incorporation of guest molecules.     

Synthesis and structural characterization of a new vapochromic Pt(II) complex based on the 1-terpyridyl-2,3,4,5,6-pentaphenylbenzene (TPPPB) ligand

A novel terpyridine ligand containing a pentaphenylphenyl moiety linked to the terpyridyl core (1-terpyridyl-2,3,4,5,6-pentaphenyl-benzene (TPPPB)) has been synthesized in good yield and reacted with Pt(DMSO)2Cl2, to produce the cationic complex [Pt(TPPPB)Cl]Cl (5). 5 was studied structurally and spectroscopically. It is observed to be brightly luminescent in the solid state at room temperature and at 77 K, with no change in lambdaem(max). The complex exhibits reversible vapochromic behavior upon exposure to methylene chloride vapors, changing color from red (5-R) to green (5-G). The shift to higher energy in the emission maximum from 654 to 514 nm is the largest vapochromic shift (140 nm) yet reported. The [Pt(TPPPB)Cl]Cl complex exhibits high selectivity for certain volatile organic compounds (VOCs) including methylene chloride, ethanol, ethyl acetate, and acetonitrile. The crystal structures of both the green and red forms have been determined by single-crystal X-ray diffraction. In both forms, the cationic Pt(II) complex possesses the anticipated square-planar coordination geometry that is distorted as a consequence of constraints from the terpyridyl binding. Analysis of the crystal packing of the green form (5-G) reveals the presence of non-interacting Pt...Pt separations with distances of 3.9092(9) and 4.5483(11) A and a zigzag arrangement between neighboring Pt(II) ions. The red form (5-R) contains complexes that are stacked with Pt...Pt separations of 3.2981(14) and 3.3427(14) A, indicative of metallophilic interaction. The change in the emitting state, as a consequence of the effect of the volatile organic compounds, results from a disruption of the d8-d8 metallophilic interactions in the red form and its metal-metal-to-ligand charge transfer (MMLCT) excited state to a more-localized Pt(dpi)-to-tpy(pi*) metal-to-ligand charge transfer (MLCT) excited state in the green form.     

Counterions influence reactivity of metal ions with cysteinyldopa model compounds

Cysteinyldopas are naturally occurring conjugates of cysteine and dopa (3,4-dihydroxy-l-phenylalanine) that are precursors to red pheomelanin pigments. Metal ions are known to influence pheomelanogenesis in vitro and may be regulatory factors in vivo. Cydo (3-[(2-amino-ethyl)sulfanyl]-4,6-di-tert-butylbenzene-1,2-diol) and CarboxyCydo (2-amino-3-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)-propionic acid) are model compounds of cysteinyldopa that retain its metal-binding functionalities but cannot polymerize due to the presence of blocking tert-butyl groups. Cydo reacts readily with zinc(II) acetate or nickel(II) acetate to form a cyclized 1,4-benzothiazine (zine) intermediate that undergoes ring contraction to form benzothiazole (zole) unless it is stabilized by coordination to a metal ion. The crystal structure of [Ni(zine)2] is reported. The acetate counteranion is required for the zinc-promoted reactivity, as neither zinc(II) sulfate nor zinc(II) chloride alone promotes the transformation. The counterion is less important for redox-active copper and iron, which both readily promote the oxidation of Cydo to zine and zole species; Cu(II) complexes of both zine and zole have been characterized by X-ray crystallography. In the case of CarboxyCydo, a 3-carboxy-1,4-benzothiazine intermediate decarboxylates to form [Cu(zine)2] under basic conditions, but in the absence of base forms a mixture of products that includes the carboxylated dimer 2,2'-bibenzothiazine (bi-zine). These products are consistent with species implicated in the pheomelanogenesis biosynthetic pathway and emphasize how metal ions, their counteranions, and reaction conditions can alter pheomelanin product distribution.     

One-dimensional azido-bridged chiral metal complexes with ferromagnetic or antiferromagnetic interactions: syntheses, structures, and magnetic studies

One-dimensional chiral copper(II) and manganese(II) coordination polymers with single asymmetric end-to-end (EE) azide bridges, [Cu(R-L)2(N3)]n(ClO4)n (1), [Cu(S-L)2 (N3)]n(ClO4)n (2), [Mn(R-L)2(N3)]n(ClO4)n (3), and [Mn(S-L)2(N3)]n(ClO4)n (4) (R-L or S-L = R- or S-pyridine-2-carbaldehyde-imine), have been synthesized, using azide ions as bridging groups and chiral Schiff bases as auxiliary ligands, and characterized. The crystal structure determination of complexes 1 and 2 reveals the formation of one-dimensional chiral chains, in which the central Cu(II) ion is six-coordinate in the form of an elongated octahedron. Complex 3 consists of chiral helical polymeric chains, in which the central Mn(II) has a slightly distorted octahedral geometry. They all crystallize in the chiral space group P2(1). Complexes 1 and 2 are rare examples that exhibit ferromagnetic interaction between copper(II) ions through the single end-to-end azido bridge. Fitting the susceptibility data for 1 using a 1D uniform chain model led to the parameters J = 0.70(3) cm(-1), g = 2.06(2), and zj' = 0.07(2) cm(-1). The magnetic studies on 3 and 4 show that there is weak antiferromagnetic coupling between the manganese(II) ions.     

Synthesis, crystal structure, magnetic properties and theoretical studies on a one-dimensional polynuclear copper(II) complex [Cu2(mu1,3-SCN)2(mu'1,3-SCN)2(MPyO)2]n

A new one-dimensional polynuclear copper(II) complex [Cu(2)(mu(1,3)-SCN)(2)(mu'(1,3)-SCN)(2)(MPyO)(2)](n)(where MPyO = 4-methylpyridine N-oxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex there exist two kinds of bridging coordination modes, namely, mu(1,3)-SCN(-) equatorial-equatorial (EE) bridging ligand and micro'(1,3)-SCN(-) equatorial-axial (EA) bridging ligand. Two micro(1,3)-SCN(-) EE bridging ligands coordinate two copper(II) ions in a binuclear unit, and the S atoms from the micro'(1,3)-SCN(-) EA bridging ligands as axial coordinated atoms link the binuclear units into one-dimensional chains. The ESR spectra have been investigated, and variable temperature (4-300 K) magnetic measurements were analyzed using a binuclear Cu(ii) magnetic interaction formula and indicate the existence of strong antiferromagnetic coupling with 2J=- 216.00 cm(-1) between bridged copper(II) ions. Density functional calculations have been carried out on this binuclear unit, yielding a similar singlet-triplet splitting. The mechanism of strong antiferromangetic interaction is revealed according to the calculations.     

A novel one-dimensional copper(II) imino nitroxide polymer

A copper(II) complex [Cu(im2-py)(4,4′-bipy)(NO₃)](NO₃)·1.5H₂O (im2-py?=?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl; 4,4′-bipy?=?4,4′-bipyridyl) has been synthesized by reaction of Cu(NO₃)·3H₂O with im2py and 4,4-bipyridyl in methanol solution. Its crystal structure has been determined by X-ray diffraction. The structure shows that each copper ion is coordinated by a bidentate imino nitroxide radical, two 4,4′-bipyridyl ligands and a nitrate group to form a distorted square pyramidal environment. The crystal structure consists of chains of copper ions linked by 4,4′-bipyridyl.     

Stability of Cu(II) and Zn(II) Complexes with Pyridinecarbohydrazones of Pyridoxal-5-phosphate in Aqueous Solution

Composition of coordination compounds formed by copper(II) or zinc(II) ions and pyridine-2-, -3-, and -4-carbohydrazones of pyridoxal-5-phosphate in aqueous solution at 298.2 K, рН 7.4, I 0.25 has been studied by means of spectrophotometry. Conditional constants of the complexes stability have been determined. Cu(II) ions formed more stable ML₂ coordination compounds in comparison with Zn(II), zinc(II) ions are efficiently bound to the derivative of picolinic acid hydrazide to form the ML complex.     

Synthesis and structure of complexes of some d metals with 10-(2-benzothiazolylazo)-9-phenanthrole (HL). Crystal and molecular structures of [CdL2] · DMF

The coordination compounds of cadmium(II), zinc(II), nickel(II), cobalt(II), and copper(II) with 10-(2-benzothiazolylazo)-9-phenanthrole (HL) were isolated in the crystalline state and studied. The crystal structure of the cadmium complex [CdL₂] · DMF was determined by X-ray diffraction. The ligand is attached to cadmium in the form of anion functioning as an O,N,N-tridentate chelating ligand; this is accompanied by a change in its isomer form. The Cd configuration is a distorted octahedron.     

Syntheses, crystal structures and magnetic properties of Ni(II)–2,4-pyridine-dicarboxylates

Two new complexes [Ni(pydc)(H₂O)₂]_n (1) and [Ni₂(pydc)₂(H₂O)₅]_n (2) (H₂pydc = 2,4-pyridinedicarboxylic acid) have been obtained by hydrothermal synthetic method and characterized by single crystal X-ray analysis. In 1 six-coordinate Ni(II) ions are coordinated by pydc ligands to form 2-D layer structures; while in 2 six-coordinate Ni(II) ions are only connected into 1-D zigzag chains constructed by dinuclear nickel units. Although the coordination geometries around Ni(II) centers in both complexes are similar, their structure topologies are greatly tuned by coordination modes of pydc. Variable temperature magnetic susceptibility studies have shown that both compounds 1 and 2 may display antiferromagnetic coupling between paramagnetic metal centers mediated by bridging carboxylate groups.     

One-, two- and three-dimensional Cu(II) complexes built via new oligopyrazinediamine ligands: from antiferromagnetic to ferromagnetic coupling

Six new pyrazine-modulated N,N'-bis(alpha-pyridyl)-2,6-diaminopyridine ligands (PMN5) were synthesized and their complexes studied. Reaction of copper(II) with the ligand that contained one pyrazine ring in its terminal position led to formation of a one-dimensional zigzag complex whereas copper(II) reactions with ligands containing three pyrazine rings or one pyrazine ring in its middle position yielded straight one-dimensional complexes. A 2-D complex was produced from the ligand with two pyrazine rings at both terminals. When nickel(II) was introduced, a 3-D network was obtained from the three-pyrazine-modulated ligand. Researches on variable-temperature magnetic susceptibility measurements revealed excellent Heisenberg chains with weak antiferromagnetic interaction of J values from -2 to -3 cm(-1)viasigma and pi pathways in straight one-dimensional complexes between the Cu(II) centers separated by 6.8-6.9 A. The zigzag one-dimensional complex showed very poor magnetic coupling. The two-dimensional compound showed significant ferromagnetic interaction in spite of the Cu-Cu distance of 7.2 A. Ferromagnetic coupling was discussed and attributed to the unusual coordination mode of in-plane and out-of-plane linkage of bridging pyrazine rings. The three-dimensional heterometal Cu(II)-Ni(II) compound showed weak antiferromagnetic interaction, which was satisfactorily fitted with J=-2.4 cm(-1) following a one-dimensional theoretical model including MFA.     

Novel inorganic-organic hybrids constructed from multinuclear copper cluster and Keggin polyanions: from 1D wave-like chain to 2D network

Two novel inorganic-organic hybrids constructed from Keggin-type polyanions and multinuclear copper clusters based on 1-H-1,2,3-benzotriazole (HBTA), [Cu(I)(8)(BTA)(4)(HBTA)(8)(SiMo(12)O(40))]·2H(2)O (1) and [Cu(II)(6)(OH)(4)(BTA)(4)(SiW(12)O(40))(H(2)O)(6)]·6H(2)O (2), have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction, elemental analyses, IR spectra and thermogravimetric (TG) analyses. In compound 1, eight Cu(I) ions were linked by twelve HBTA/BTA ligands to form an octanuclear Cu(I) cluster, which is connected by SiMo(12)O(40)(4-) anion with two bridging O atoms and two terminal O atoms to construct a one-dimensional (1D) wave-like chain. The octanuclear copper unit represents the maximum subunit linked just by amine ligands in the POMs system. In 2, four BTA ligands linked five Cu(II) ions constructing a pentanuclear "porphyrin-like" subunit, which is connected by another Cu(II) ion to form a 1D metal-organic band. The SiW(12)O(40)(4-) polyanions as tetradentate inorganic linkages extend the 1D band into a two-dimensional (2D) network with (8(3))(2)(8(5)·10) topology. To the best of our knowledge, compounds 1 and 2 represent the first examples of inorganic-organic hybrids based on metal-HBTA multinuclear subunits and polyoxometalates. The photocatalysis and electrochemical properties have been investigated in this paper.     

Transition metal coordination compounds of an antiobesity serotoninergic ligand: spectroscopic characterization and adipogenesis activity

Coordination compounds of cobalt(II), nickel(II), copper(II) and zinc(II) with L-5-hydroxytryptophan (L-5-HTP) were synthesized and characterized by elemental analysis, IR and UV–Vis-NIR spectroscopy, mass spectrometry and thermogravimetric analysis. The X-ray structure of the pure enantiomer ligand (L-5-HTP) was obtained. The ligand coordinates to the metal ions in an unidentate mode, where the donor atom is the oxygen from the carboxylic group. The intramolecular H-bond, N1H···O2, observed in the X-ray crystal structure of the free L-5-HTP, remains as a stabilization factor in all of the coordination compounds. Two types of geometries were adopted by the metal centers: tetrahedral and octahedral. In vitro antiadipogenic studies of the coordination compounds showed that the tetrahedral cobalt(II) and copper(II) complexes presented potential antiobesity properties.     

A New 2D Zinc(Ⅱ)Coordination Polymer Constructed by Imidazole-4,5-dicarboxylic Acid(H3IDC)and 1,4-Bis(imidazol-l-ylmethyl)-benzene(bix)

T A new 2D Zn(Ⅱ)coordination polymer[Zn(HIDC)(bix)0.5]n(1)was obtained by the hydrothermal reaction of ZnCI2,imidazole-4,5-dicarboxylic acid(H3IDC)and 1,4-bis(imidazol-1-ylmethyl)-benzene(bix)with a 2:2:1 mole ratio.X-ray diffraction crystal structural analysis reveals it crystallizes in monoclinic,space group P21/n with α=12.125(3),b=10.541(3),c=684,μ(MoKα)=1.730 mm-1,the final R=0.0439 and wR=0.0888 for 2101 observed reflections with Ⅰ＞2σ(Ⅰ).In 1,each zinc(Ⅱ)ion is five-coordinated with a slightly distorted trigonal bipyramidal coordination geometry,and each μ2-HIDC2-acts as a bridge to bond two neighboring Zn(Ⅱ)ions,leading to a 1D zigzag chain architecture.The adjacent zigzag chains are further linked by μ2-bix to form an infinite 2D network structure.The fluorescence spectrum of 1 exhibits intense emission at 466 nm when excited at 397 nm in solid state at room temperature.     

Synthesis, structure and heterogeneous catalytic activities of Cu-containing polymeric compounds: anion effect and comparison of homogeneous vs. heterogeneous catalytic activity

The structures of new polymeric compounds containing Cu(II) ions and btp (2,6-bis(N'-1,2,4-triazolyl)pyridine) ligands have been determined. The btp ligands bridge Cu(II) ions to form double zigzag chains, [Cu(ClO4)2(btp)2] 3 with perchlorate anions, and form single zigzag chains, [Cu(btp)(H2O)4](SO4).2H2O 4 with sulfate anions. The polymeric compound 3 was found to effectively catalyze the epoxide ring-opening reaction with methanol, while polymeric compound 4 was almost inactive with epoxides under the same conditions. The polymeric compound 3 showed an efficient catalytic activity and regioselective reactivity in the ring opening of epoxides and allowed reuse without a significant loss of activity through three runs with epoxides.     

One and Two-dimensional Structures of a New Oxamido Copper(II) Complex with Phthalato Bridged

1 INTRODUCTION Coordination polymers are a family of materials composed of 1D chains, 2D sheets, and 3D networks of metal-organic building blocks connected via co- valent and hydrogen bonds. Recently, they have re- ceived increasing attention for their fascinating struc- tures and topological features[1～4]. The complex as ligands approach is one of the best strategies to de- sign and synthesize polynuclear species, and a good example of ‘complex ligand’ is represented by mono- nuclear…     

Structure and magnetic properties of a copper(II) compound with syn–anti carboxylato- and linear Cu–Cl–Cu chloro-bridges

The copper(II) polymer Cu(2-qic)Cl (2-qic = quinoline-2-carboxylate) was synthesized and then characterized by X-ray crystal structure determination, spectroscopic and magnetic studies. The crystal structure consists of copper(II) ions with two different chromophores: four-coordinated in a square-planar geometry and five-coordinated in an environment between square-pyramidal and trigonal-bipyramidal. The copper ions are bridged sequentially through the carboxylate groups in a syn–anti conformation, forming an infinite one-dimensional zigzag chain with two alternating non-equivalent copper(II) chromophores. The chloride atom acts as a single chloro-bridge link to adjacent chains, forming a ribbon type structure (1D). The variable-temperature (1.8–300 K) magnetic susceptibility data of the complex were interpreted with the dimer law using the molecular field approximation. The results obtained indicate a very weak ferromagnetic (J₂ = 0.37 cm⁻¹) interchain interaction through the syn–anti carboxylate bridge. A relatively strong antiferromagnetic interaction, transmitted through the chloro-bridge with an exchange coupling of J₁ = −57.0 cm⁻¹, dominates the magnetic properties of this complex. The magnitude and the nature of the exchange coupling are explained on the basis of the structural results.