Synthesis,structure and properties of a one-dimensional coordination polymer containing both dicyanamide and ethylenediamine

The nickel(II) complex [Ni(en)₂{N(CN)₂}]ClO₄ 1 (en?=?ethylenediamine) has been synthesized and its structure determined. The complex forms a one-dimensional chain structure via the bidentate bridging ligand dicyanamide. A two-dimensional network is formed via interchain hydrogen-bond interactions. The magnetic properties of the compound (5–300?K) show the existence of weak antiferromagnetic exchange interactions between paramagnetic centers along chains.     

A hexanuclear discrete assembly and a two dimensional coordination polymer constructed from heterotrinuclear [(CuL)2Zn]2+ nodes and dicyanamide spacer (H2L = salen type Schiff base ligands)

Two new Cu(II)–Zn(II) complexes as a discrete hexanuclear cluster [{(CuL¹)₂Zn}₂(μ_1,5-N(CN)₂)₂](ClO₄)₂ (1) and a two dimensional (2D) coordination polymer [(CuL²)₂Zn(μ_1,5-N(CN)₂)₂]_n (2) have been isolated by mixing two similar tetradentate Schiff bases H₂L¹ (N,N′-bis(ɑ-ethylsalicylidene)-1,3-propanediamine) and H₂L² (N,N′-bis(salicylidene)-1,3-pentanediamine) separately with Cu(ClO₄)₂·6H₂O, Zn(ClO₄)₂·6H₂O and NaN(CN)₂ ?at same reaction condition. The heterometallic complexes have been structurally characterized by single crystal X-ray analyses showing that both are formed by angular trinuclear nodes and μ_1,5-dicyanamide spacers. The trinuclear nodes ([(CuL¹)₂Zn]²⁺ in 1 and [(CuL²)₂Zn]²⁺ in 2 are produced in situ from their corresponding reactants. The two Schiff base ligands coordinating the Cu(II) ions through the N₂O₂ donor set are additionally bonded to a Zn(II) ion with the four phenoxido oxygen atoms that act as bridging atoms. The zinc ion completes its coordination geometry with two terminal nitrogen atoms of two different dicyanamide spacers. The orientation of spacers from zinc ion are convergent in 1 whereas divergent in 2. Thus, two [(CuL¹)₂Zn]²⁺ nodes are interconnected by double μ_1,5-dicyanamide bridges via Zn(II) centres to form discrete hexanuclear assembly of complex 1. On the other hand, [(CuL²)₂Zn]²⁺ nodes in 2 are joined by μ_l,5-dicyanamide that bridge Zn(II) to Cu(II) centres of symmetry related units in order to construct a 2D coordination polymer. Consequently, the final coordination environment around Zn(II) is octahedral in both complexes whereas that around Cu(II) are square planar and square pyramidal in 1 and 2 respectively.     

Synthesis,structure and electrochemical properties of a zinc(II) coordination polymer based on ferrocenyl-substituted carboxylate and bis (benzimidazolyl)pentane ligands

By reaction of two ligands, Na(o-OOCC₆H₄COFc) (Fc?=?(η⁵–C₅H₅)Fe(η⁵–C₅H₄)) and 1,1′–(1,5–pentamethylene)bis-1H-benzimidazole (pbbm), with Zn(OAc)₂?·?2H₂O in methanol solution, we have synthesized a zinc(II) coordination polymer [Zn(o-OOCC₆H₄COFc)₂(pbbm)] _n . The polymer was characterized by X-ray single crystal diffraction, IR spectroscopy, and elemental analysis. Each Zn atom was connected by two pbbm ligands, leading to an infinite one-dimensional chain. Two monodentate o-FcCOC₆H₄COO^? anions completed the coordination sphere of the central Zn(II) ion. The polymer's electrochemical properties were investigated in DMF solution.     

Crystal structure, magnetism and spectroscopy of bis(tetraphenylphosphonium)tetrakis(dicyanamido)cobaltate(II) with bridging and pendant dicyanamide ligands

The synthesis, structure and magnetic properties of the cobalt(II) complex, (Ph₄P)₂[Co(NCNCN)₄] (1) is reported. The compound crystallises in the monoclinic system, space group C2/c, with cell constants: β=105.65(2)°, Z=4 and The structure of 1 consists of octahedral CoN₆ chromophores with uni- and bidentate N(CN)₂ ligands. Cobalt atoms are doubly bridged by bidentate NCNCN groups forming infinite ribbons along the crystallographic b-axis. As first representative of an anionic dicyanamide complex 1 behaves as a weak ferromagnet at low temperatures.     

Syntheses,structures, and magnetic properties of two 1-D dicyanamide manganese(III) complexes with Schiff-base ligands

Two new 1-D manganese(III) Schiff-base complexes bridged by dicyanamide (dca), [Mn(III)(5-Brsalen)(dca)] ? CH₃OH (1) and [Mn(III)(3,5-Brsalen)(dca)] · CH₃OH · CH₃CN (2) (5-Brsalen = N,N′-ethylenebis(5-bromo salicylaldiminato) dianion; 3,5-Brsalen = N,N′-ethylenebis(3,5-dibromosalicylal diminato) dianion), have been synthesized and characterized. X-ray diffraction analyses reveal that the two complexes have 1-D chain structures constructed by μ _1,5-dca bridge. Magnetic susceptibility measurements exhibit weak antiferromagnetic exchange coupling in the complexes.     

Synthesis,structure and luminescent properties of a new two-dimensional (4,4) network cadmium coordination polymer with dicyanamide and benzimidazole ligands

The new cadmium coordination polymer [Cd(bim)₂(dca)₂]_n (1), (bim?=?benzimidazole, dca?= dicyanamide) was synthesized and characterized by IR, thermogravimetric analysis and luminescent properties. The coordination geometry of cadmium atom is distorted octahedral, coordinated equatorially by four nitrogen atoms from four dicyanamide ligands, and axially by two nitrogen atoms from two benzoimidazoles. Each dca ligand links two cadmium(II) atoms and 1 forms a two-dimensional (4,4) network.     

Synthesis,structure, cytotoxic activities,and DNA-binding of 1-D copper(II) and zinc(II) coordination polymers

Two 1-D coordination polymers have been synthesized and identified as [Zn(ox)(en)] _n (H₂O)_{2 n} (1) and [Cu₂(dmeo)(N₃)₂] _n (2), where en represents diaminoethane, ox and dmeo stand for dianions of oxalic acid and N,N′-bis[2-(dimethylamino)ethyl]oxamide, respectively. Polymer 1 was characterized by elemental analysis, molar conductance measurement, IR and electronic spectra, and single-crystal X-ray diffraction. Polymer 1 consists of 1-D chains bridged by oxalate. The Zn^II can be described as a distorted octahedral environment and the Zn^II···Zn^II separation through the μ-oxalato-bridge is 5.5420(9)?Å. Hydrogen bonds assemble the coordination polymers to a 3-D supermolecular structure. The crystal structure of 2 has been reported previously. However, the bioactivities were not studied. The DNA-binding properties and cytotoxic activities of the two coordination polymers are investigated. The results suggest that the two polymers interact with HS-DNA in groove binding with binding affinity following the order of 1?>?2, which is consistent with their anticancer activities.     

Synthesis and characterization of Cu(II), Co(II) and Ni(II) coordination polymers containing bis(imidazolyl) ligands

Two structurally related flexible imidazolyl ligands, bis(N-imidazolyl)methane (L₁) and 1,4-bis(N-imidazolyl)butane (L₂), were reacted with Cu(II), Co(II) and Ni(II) salts of aliphatic/aromatic dicarboxylic acids resulting in the formation of a number of novel metal–organic coordination architectures, [CuB₂(ox)₂(L₁)₂(H₂O)₂] · 4H₂O (1) (ox = oxalate), [Cu(pdc)(L₂)_1.5] · 4H₂O (2, pdc = pyridine-2,6-dicarboxylate), [Co(L)₂(H₂O)₂](tp) · 4H₂O (3, tp = terephthalate), [Ni(L₁)₂(H₂O)₂](ip) · 5H₂O (4, ip = isophthalate), [Cu₂(L₁)₄(H₂O)₄](tp)₂ · 7H₂O (5), [Co(mal)(L₁)(H₂O)] · 0.5MeOH (6, mal = malonate), [Co(pdc)(L₁)(H₂O)] (7). All the complexes have been structurally characterized by X-ray diffraction analysis. The different coordination modes of the dicarboxylate anions, due to their chain length, rigidity and diimidazolyl functionality, lead to a wide range of different coordination structures. The coordination polymers exhibit 1D single chain, ladder, 2D sheet and 2D network structures. The aliphatic and aromatic dicarboxylates can adopt chelating μ₂ and chelating-bridging μ₃ coordination modes, or act as uncoordinated counter anions. The central metal ions are coordinated in N₂O₄, N₄O₂, N₂O₃ and N₃O₃ fashions, depending on the ancillary ligands. The topology of 1 gives rise to macrocycles which are connected through hydrogen bonds to form 1D chains, whereas compound 2 exhibits a 1D polymeric ladder in which the carboxylate acts as a pincer ligand. Compounds 3–5 show doubly bridged 1D chains, and the dicarboxylate groups are not coordinated but form 2D corrugated sheets with water molecules intercalated between the cationic layers. Compound 6 has a 2D network sheet structure in which each metal ion links three neighboring Co atoms by the bis(N-imidazolyl)methane ligand. The cobalt compound 7, with a 2D polymeric double sheet structure, is built from pincer carboxylate (pdc) and 1,4-bis(N-imidazolyl)methane ligands.     

Chelating resin containing s-bonded dithizonefor the separation of copper(II), nickel(II) and zinc(II)

Analytical and physicochemical properties of a crosslinked poly (vinyl pyridine) based resin containing dithizone were examined. The resin was further used for the preconcentration of copper, nickel and zinc at batch and column level. Various conditions such as pH, equilibration time, temperature were optimised for the maximum loading of copper, nickel and zinc. The loading capacities of the resin for copper, nickel and zinc were observed to be 0.51, 0.59 and 0.65 mmol g⁻¹ of dry resin respectively. Elution of loaded copper, nickel and zinc from the resin was done by using 0.1 M HCl, 0.1 M H₂SO₄ and 0.1 M HNO₃ respectively. Separation of copper, nickel and zinc in binary and ternary mixtures was achieved without any cross contamination.     

Syntheses, crystal structures and properties of novel zinc(II) complexes obtained by reactions of zinc(II) malonate with flexible multidentate ligands

Complex [Zn₂(bimb)₂(mal)₂(H₂O)₂]·4H₂O (1) (mal=⁻OCOCH₂COO⁻) was obtained by reaction of bidentate ligand 4,4′-bis(imidazole-1-ylmethyl)biphenyl (bimb) with zinc(II) salt of malonate, while the reaction of the same metal salt with 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) gives another novel complex [Zn₂(titmb)₂(mal)][mal]·12H₂O (2). The structures of these complexes were determined by X-ray crystallography. The results revealed that 1 is a cyclic dinuclear complex in which the malonate groups act as terminators and prevent further aggregation, while 2 is a 2D honeycomb network in which each independent 2D sheet contains two sub-layers bridged by the malonate groups and complex 2 also contains free malonate as a counteranion connected to the 2D layer by C-H?O hydrogen bonds. The entirely different structure and topology of complexes 1 and 2, on the one hand, indicates that the nature of organic ligands affected the structures of assemblies greatly, and on the other, reveals the versatility of the malonate which can act as a bridging and/or blocking ligand.     

Syntheses and characterization of different zinc(II) oxide nano-structures from direct thermal decomposition of 1D coordination polymers

Three zinc(II) nitrite coordination polymers, [Zn(4-bpdb)(NO₂)₂]_n (1), {[Zn(3-bpdb)(NO₂)]·0.5H₂O}_n (2) and [Zn(3-bpdh)(NO₂)₂]_n (3), 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene} were prepared and characterized by elemental analyses and IR spectroscopy. Compound 3 was structurally characterized by single-crystal X-ray diffraction and is one-dimensional polymer with coordination environments of distorted octahedral, ZnN₂O₄. The thermal stabilities of compounds 1–3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Direct calcination of the compounds 1–3 at 600 °C under air atmospheres yields different morphologies of nano-sized ZnO.     

New Cu(II) compounds with ligands synthesized through nucleophilic addition of pyrazoles to dicyanamide. Synthesis,crystal structures and spectroscopy

Three newly synthesized ligands, i.e. (pyrazolecarbimido)-cyanoamine (abbreviated as Hdcapz), (3-methylpyrazolecarbimido)cyanoamine (abbreviated as Hdcampz) and (3,5-dimethylpyrazolecarbimido)cyanoamine (abbreviated as Hdcadmpz) are presented in this study, including the X-ray crystal structures for two of them, as well as their coordination behaviour with respect to Cu(II).     

Studies on mononuclear chelates derived from substituted Schiff-base ligands (part 6): synthesis and characterization of a new 3-ethoxysalicyliden- p -aminoacetophenoneoxime and its complexes with cobalt(II), nickel(II), copper(II) and zinc(II)

Schiff-base complexes of cobalt(II), nickel(II), copper(II) and, zinc(II) with 3-ethoxysalicyliden-p-aminoacetophenoneoxime (HL) were prepared and characterized on the basis of elemental analyses, IR, ¹H- and ¹³C-NMR, electronic spectra, magnetic susceptibility measurements, molar conductivity and thermogravimetric analyses (TGA). A tetrahedral geometry has been assigned to the complexes.     

Nanoparticles of a new zinc(II) coordination polymer: synthesis,characterization, thermal,and structural studies

Nanoparticles of a Zn(II) coordination polymer {[Zn(DADMBTZ)(CH₃COO)₂] _n , DADMBTZ?=?2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole} were synthesized by reaction of Zn(NO₃)₂?·?4H₂O, CH₃COONH₄ and DADMBTZ by a sonochemical method. The nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. [Zn(DADMBTZ)(CH₃COO)₂] _n was structurally characterized by single-crystal X-ray diffraction. In this four-coordinate compound with nearly C₂ symmetry, DADMBTZ is bidentate. The metal lies in a pseudo-tetrahedral environment and is ligated by the two bithiazole ring nitrogen atoms and an oxygen from each of the two monodentate acetates; 2-D networks are formed via N–H···O hydrogen bonds. Thermal stability of [Zn(DADMBTZ)(CH₃COO)₂] _n was studied by thermal gravimetric and differential thermal analyses. A ZnO nanostructure was obtained by direct thermolyses at 500°C under air. The ZnO nanostructure was characterized by SEM, XRD, and FT-IR spectroscopy.     

Palladium(II) and platinum(II) saccharinate complexes containing pyridine and 3-acetylpyridine: Synthesis, crystal structures, fluorescence and thermal properties

New palladium(II) and platinum(II) complexes of saccharinate (sac), trans-[Pd(py)₂(sac)₂] (1), cis-[Pt(py)₂(sac)₂] (2), trans-[Pd(3-acpy)₂(sac)₂] (3) and cis-[Pt(3-acpy)₂(sac)₂] (4) (py = pyridine and 3-acpy = 3-acetylpyridine) have been synthesized. Elemental analysis, UV-Vis, IR, NMR and TG/DTA characterizations have been carried out. The structures of 1-4 were determined by X-ray diffraction. The palladium(II) and platinum(II) ions are coordinated by two N-bonded sac ligands, and two nitrogen atoms of py or 3-acpy, forming a distorted square-planar geometry. The palladium(II) complexes (1 and 3) are trans isomers, while the platinum(II) complexes (2 and 4) are cis isomers. The mononuclear species in the solid state are connected by weak intermolecular C-H?O hydrogen bonds, C-H?π and π?π stacking interactions. The platinum(II) complexes show significant fluorescence at the room temperature.     

1D coordination polymers of silver(I) and copper(II) based on bis(N-heterocyclic carbene) ligands: Synthesis and structural studies

The alkyl chain-linked diimidazolium (or dibenzimidazolium) salts, 1,1′-diethyl-4,4′-tetramethylene-diimidazolium-diiodide (L¹H₂·I₂) and 1,1′-diethyl-3,3′-trimethylene-dibenzimidazolium-diiodide (L²H₂·I₂), and their silver(I) and copper(II) coordination polymers, [L¹AgI]_n (1) and [L²Cu₂I₄]_n (2), have been prepared and characterized. Complex 1 is a 1D helical polymer generated by bidentated carbene ligands (L¹) and Ag(I) atoms. The 1D polymer of 2 is formed by bidentated carbene ligands (L²) and coplanar quadrilateral Cu₂I₂ units. 3D supramolecular frameworks in the crystal packings of 1 and 2 are formed via intermolecular weak interactions, including C–H···π contacts, π–π interactions and C–H···I hydrogen bonds.     

Syntheses,crystal structures and luminescent properties of two new Zn(II) coordination polymers based on a dicarboxylate and different imidazole-containing ligands

To investigate the effect of different imidazole-containing ligands on the structure of coordination polymers, two new Zn(II) coordination polymers based on 1,4-cyclohexanedicarboxylic acid (H₂cda) and two different imidazole-containing ligands, [Zn(cda)(bib)_0.5]_n (1) and [Zn(cda)(bmib)_0.5]_n (2) (bib = 1,4-bis(imidazol-1-yl)benzene and bmib = 1,4-bis(2-methylimidazol-3-ium-yl)benzene), have been synthesized and characterized by single-crystal X-ray diffraction. Complex 1 shows a 3-D structure with point symbol (4.8².10³).(4.8²). Complex 2 displays a 2-D layer structure with an –AB– stacking sequence.     

Synthesis and structural characterization of novel zinc(II) and cadmium(II) complexes with pyridine-phosphine chalcogenide ligands

New pyridine-phosphine chalcogenide ligands, tris[2-(2-pyridyl)ethyl]phosphine sulfide 1a and tris[2-(2-pyridyl)ethyl]phosphine selenide 1b, react with zinc(II) and cadmium(II) chlorides in EtOH at room temperature to afford complexes of compositions 2ZnCl₂·2L (2, L = 1a) and 3CdCl₂·2L (3a,b, L = 1a,b) in high yields. The solid-state structure of complexes 2, 3 has been proved by X-ray analysis data. Complex 2 is a centrosymmetric dimer, where two atoms of zinc are bonded by two bridging pyridine-phosphine sulfide ligands through N atoms. Complexes 3a,b exist as polymeric chains with each bridging ligand acting as a chelate N,S- or N,Se-donor to one cadmium(II) center and as a pyridine N-donor to the next cadmium(II) center.     

Sonochemical syntheses of a straw-like nano-structure two-dimensional mixed-ligand zinc(II) coordination polymer as precursor for preparation of nano-sized ZnO

Straw-like nano-structure of a new mixed-ligand Zn(II) two-dimensional coordination polymer, {[Zn(μ-4,4′-bipy)(μ-3-bpdb)(H₂O)₂](ClO₄)₂·4,4′-bipy·3-bpdb·H₂O}_n (1) {4,4′-bipy = 4,4′-bipyridine and 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene}, was synthesized by a sonochemical method. The new nano-structure was characterised by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compound 1 was structurally characterised by single crystal X-ray diffraction and consists of two-dimensional polymeric units. ZnO nanoparticles were obtained by calcination of compound 1 at 500 °C under air atmosphere and were characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM).