Two new coordination polymers constructed by angular tripyridyl ligand: syntheses,structures, and properties

U-shaped tripyridyl ligand 2,6-bis(pyridine-4-carboxamido)pyridine (L) was synthesized and used to assemble metal complexes. The resulting new complexes [Mn(L)₃(SCN)₂] _n (1) and [Co(L)₃(SCN)₂] _n (2) are isostructural, crystallizing in the monoclinic C2/c space group. In compounds 1 and 2, each metal is in a slightly distorted octahedron ligated by six nitrogens from four L and two SCN^?. Complexes 1 and 2 possess infinite 1-D zigzag polymeric chain structures where L adopts bridge and terminal coordination. These 1-D coordination polymers assemble into 3-D supermolecules of compounds 1 and 2 through hydrogen bonds. Fluorescence measurements and thermal analysis show that 1 emits strong fluorescence with a single broad band centered at 410?nm upon excitation at 357?nm and the polymeric chain structure is stable up to 340°C.     

Two cobalt coordination polymers based on an asymmetric dicarboxylate: structural diversity tuned by auxiliary ligands

Two 1-D cobalt coordination polymers, [Co(mbtx)(hpht)(H₂O)] _n (1) and [Co(mbix)(hpht)] _n (2) (mbtx?=?1,3-bis(1,2,4-triazol-1-ylmethyl)benzene, mbix?=?1,3-bis(imidazol-1-ylmethyl)benzene, H₂hpht?=?homophthalic acid), were synthesized by hydrothermal reactions and characterized by elemental analyzes, IR spectroscopy, thermogravimetry, and single-crystal X-ray diffraction. Complex 1 is a 1-D heterostranded double-helical chain as a result of bridging hpht and mbtx, and the 1-D chains are further self-assembled into a 2-D layer structure through hydrogen bonds. Complex 2 shows a 1-D molecular ladder structure, linked through C–H···π interactions to give a 2-D layer structure, which is further linked through C–H?O hydrogen bonds to form a 3-D framework. The mbtx adopts cis-conformation in 1, while for 2, mbix has trans-conformation. Factors causing the differences between 1 and 2 are discussed.     

Syntheses, structures and properties of five copper coordination polymers constructed by the triazole ligand

Reactions of different metal salts with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) gave rise to five new complexes, namely [Cu₄(CN)₄(3-abpt)₂]_n (1), [CuBr(3-abpt)]_n (2), [CuI(3-abpt)]_n (3), [Cu₃I₃(3-abpt)]_n (4) and [Cu(3-abpt)(SO₄)(H₂O)]_n (5). Compounds 1, 3, 4 and 5 are all 2D structures. Compound 1 is a double-layered polymer with an uncommon 3-nodal 3-connected (10³)(10².4)₄ network, 3 shows a 2D square layered structure, 4 is also a double-layered polymer with 2-nodal 4-connected (3.4.5.6².7)₂(3.4².5².7) network and 5 is a 2D structure which is ultimately stacked with an ABAB repeat pattern. Compound 2 is a 1D coordination polymer which exhibits a ladder-like network. The photoluminescence of 1-2 has also been investigated. The long emission lifetimes of 1-2 could be assigned to metal-to-ligand charge transfer triple excited states [MLCT].     

Alkyl group dependence on structure and magnetic properties in layered cobalt coordination polymers containing substituted glutarate ligands and 4,4′-bipyridine

Five two-dimensional divalent cobalt coordination polymers containing 4,4′-bipyridine (bpy) and substituted or unsubstituted glutarate ligands have been prepared hydrothermally and structurally characterized by single-crystal X-ray diffraction. [Co(mg)(bpy)]_n (1, mg=3-methylglutarate) forms a (4,4) rhomboid grid structure based on the connection of {Co₂(CO₂)₂} dimeric units. Using the more sterically encumbered ligands 3,3-dimethylglutarate (dmg) and 3-ethyl, 3-methylglutarate (emg) generated {[Co(dmg)(bpy)(H₂O)]·2H₂O}_n (2) and {[Co(emg)(bpy)(H₂O)]·H₂O}_n (3), respectively. These complexes manifest {Co(CO₂)}_n chains linked into 2-D by aliphatic dicarboxylate and bpy ligands. The “tied-back” substituted glutarate ligand 1,1-cyclopentanediacetate (cda) afforded [Co(cda)(bpy)]_n (4), and the unsubstituted glutarate (glu) generated [Co(glu)(bpy)]_n (5), both of which exhibit a topology similar to that of 1. The magnetic properties of complexes 1-4 were analyzed successfully with a recently developed phenomenological chain model accounting for both magnetic coupling (J) and zero-field splitting effects (D), even though 1 and 4 contain isolated, discrete {Co₂(CO₂)₂} dimers. The D parameter in this series varied between 21.8(8) and 48.0(9) cm⁻¹. However weak antiferromagnetic coupling was observed in 1 (J=-2.43(4) cm⁻¹) and 4 (J=−0.89(2) cm⁻¹), while weak ferromagnetic coupling appears to be operative in both 2 (J=0.324(5) cm⁻¹) and 3 (J=0.24(1) cm⁻¹).     

Ligand-controlled assembly of Cd(II) coordination polymers based on mixed ligands of naphthalene-dicarboxylate and dipyrido[3,2-d:2′,3′-f]quinoxaline: From 0D+1D cocrystal, 2D rectangular network (4,4), to 3D PtS-type architecture

Three novel Cd(II) coordination polymers, namely, [Cd(Dpq)(1,8-NDC)(H₂O)₂][Cd(Dpq)(1,8-NDC)]·2H₂O (1), [Cd(Dpq)(1,4-NDC)(H₂O)] (2), and [Cd(Dpq)(2,6-NDC)] (3) have been obtained from hydrothermal reactions of cadmium(II) nitrate with the mixed ligands dipyrido [3,2-d:2′,3′-f]quinoxaline (Dpq) and three structurally related naphthalene-dicarboxylate ligands [1,8-naphthalene-dicarboxylic acid (1,8-H₂NDC), 1,4-naphthalene-dicarboxylic acid (1,4-H₂NDC), and 2,6-naphthalene-dicarboxylic acid (2,6-H₂NDC)]. Single-crystal X-ray diffraction analysis reveals that the three polymers exhibit novel structures due to different naphthalene-dicarboxylic acid. Compound 1 is a novel cocrystal of left- and right-handed helical chains and binuclear complexes and ultimately packed into a 3D supramolecular structure through hydrogen bonds and π-π stacking interactions. Compound 2 shows a 2D rectangular network (4,4) bridged by 1,4-NDC with two kinds of coordination modes and ultimately packed into a 3D supramolecular structure through inter-layer π-π stacking interactions. Compound 3 is a new 3D coordination polymer with distorted PtS-type network. In addition, the title compounds exhibit blue/green emission in solid state at room temperature.     

Syntheses and characterizations of three coordination polymers based on dipyridylbenzoates and 1,4-bezenedicarboxylate

Three coordination polymers, namely [Ni(3,4-pmb)(bdc)_0.5] (1), [Co(3,5-pmb)(bdc)_0.5] (2) and [Cd(3,5-pmb)(bdc)_0.5] (3) (3,4-pmb = 3,4-bis[4-pyridylmethyleneoxyl]benzoate, 3,5-pmb = 3,5-bis[4-pyridylmethyleneoxyl]benzoate and bdc = 1,4-benzenedicarboxylate), have been synthesized by the hydrothermal method and structurally characterized. The X-ray structural analysis reveals that the three complexes possess different structural motifs. Complex 1 has a three-dimensional (3D) threefold interpenetrated diamondiod architecture and crystallizes in the monoclinic C2/c space group, in which each Ni(II) atom is connected to four other Ni(II) centers, resulting in the formation of a (4,4) diamondoid network. Complex 2 is a (3D) fourfold interpenetrated polyrotaxane and crystallizes in the monoclinic P2(1)/c space group. It is constructed by four equivalent independent 3D units and entangled by each other give a 3D fourfold structure. Complex 3 is a 2D network in which two Cd(II) centers are bridged equivalently by four carboxylate groups of different pmb and bdc ligands, forming a paddle wheel secondary building unit (SBU) (CdO₄N), and the five coordinating atoms in the CdO₄N unit occupy the vertices of square-pyramidal structure. Moreover, complex 3 exhibits strong photoluminescence at room temperature.     

Syntheses, crystal structures and properties of two 1-D cadmium(II) coordination polymers based on 1,1′-(1,3-propanediyl)bis-1H-benzimidazole

The combination of framework-builders 1,1′-(1,3-propanediyl)bis-1H-benzimidazole (pbbm), Cd(II) ion and framework-regulator ClO₄⁻ or SO₄²⁻ provides two new coordination polymers [Cd(pbbm)₂(ClO₄)₂]_n(1) and {[Cd(pbbm)SO₄(H₂O)₂]·CH₃OH}_n(2). Both of them display 1-D chain framework, but their detailed structures are clearly different from each other. 1 displays a 1-D ribbon of rings framework, 2 features an interesting infinite 1-D looped chain structure composed of two kinds of rings, the smaller 8-membered ring and the larger 20-membered ring. The antimicrobial activities of the two polymers were tested by the agar diffusion method and the results indicated that they exhibited antimicrobial activities against bacterial strands. The measurement of the non-isothermal kinetics of the thermal decomposition of 2 reveals that there are at least three steps that occur in its decomposition process.     

Synthesis and crystal structures of two new zigzag versus helical coordination polymers based on diphenic acid

Two new coordination polymers, [Mn(dpa)(2,2′-bipy)] _n (1) and [Ni(dpa)(2,2′-bipy)] _n (2) (H₂dpa = 3,4′-biphenyl-dicarboxylic acid, 2,2′-bipy = bipyridine), have been synthesized and structurally characterized by elemental analysis, IR, and X-ray diffraction. Single-crystal X-ray analyses revealed that 3,4′-diphenic acid acts as a bridging ligand, exhibiting rich coordination modes to link metal ions: μ ₂–η ¹: η ¹, μ ₁–η ¹: η ¹, and μ ₁ –η ¹: η ⁰. Compound 1 demonstrates a 1-D zigzag chain. Compound 2 is a 1-D helical chain. In 1 and 2, there exist intermolecular π–π stacking interactions and non-covalent interactions responsible for the stabilization of the supramolecular structure. In 1, the Mn(II) chains exhibit a weak antiferromagnetic interaction.     

Syntheses,structures and fluorescent properties of three copper cyanide coordination polymers based on N-heterocyclic ligands

Hydrothermal reactions of CuCN, K₃[Fe(CN)₆] with 2,2′-bipyridine, 1,10-phenanthroline or 2,6-bis(1,2,4-triazolyl)pyridine (btp) afford three coordination polymers, [Cu₇(CN)₇(bipy)₂] _n (1), [Cu₂(CN)₂(phen)] _n (2) and [Cu₃(CN)₃(btp)] _n (3). Complex 1 displays 1D polymeric ribbons which are assembled through Cu ··· Cu and π–π stacking interactions into a 3D framework. Complex 2 shows a 1D zigzag chain structure in which phen is a side ligand. In 3, the copper cyanide 2D polymeric networks are connected by tridentate btp to form a 3D metal-organic framework. These coordination polymers exhibit strong fluorescent emissions in the solid state.     

Syntheses and structures of three new coordination polymers with the flexible 1,2-bis(1,2,4-triazol-1-yl)ethane ligand

Three new coordination polymers {[Ni(bte)₂(NCO)₂](H₂O)} _n (1), {[Ni(bte)₂(N₃)₂](H₂O)} _n (2) and {[Ag(bte)₂](NO₃)} _n (3) (bte?=?1,2-bis(1,2,4-triazol-1-yl)ethane) were synthesized and characterized by X-ray crystallography, IR and thermogravimetric analysis. The coordination geometry of the Ni(II) atom is distorted octahedral, coordinated equatorially by four nitrogen atoms from four triazole rings of four symmetry-related bte ligands, and axially by two nitrogen atoms from two isocyanate anions in 1 and azide anions in 2, respectively. The structures of 1 and 2 are both polymeric, with 18-membered spiro-fused rings and each 18-membered ring involving two inversion-related bte molecules. The coordination geometry of the Ag(I) atom in 3 is distorted tetrahedral, formed by four nitrogen atoms from four triazole rings of four symmetry-related bte ligands. Each bte ligand links two Ag(I) atoms and forms a two-dimensional undulated (4,4) network in 3.     

Influence of secondary ligand on structures and topologies of lanthanide coordination polymers with 1,3,5-triazine-2,4,6-triamine hexaacetic acid

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln₄(TTHA)₂(pzac)(H₃O)₂(H₂O)]·5H₂O (Ln = Pr (1a) and Nd (1b)), [Sm₈(TTHA)₄(pzac)_0.5(H₃O)(H₂O)_7.5]·4H₂O (2), [Ln₄(HTTHA)₂(SO₄)(H₂O)₄]·5H₂O (Ln = Pr (3a) and Nd (3b)), where H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H₂pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H₆TTHA as the primary ligand and either the in situ generated pzac^2? or sulfate as the secondary ligands. The influence of the deprotonated H₆TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.     

Three isomeric copper(II) coordination polymers based on a bis-triazole-bis-amide ligand: Assembly,structures, and luminescent properties

Three copper(II) isomers, [Cu(dtcd)(DNBA)₂]_n (1–3) (HDNBA = 3,5-dinitrobenzoic acid, dtcd = N,N-di(4H-1,2,4-triazole)cyclohexane-1,4-dicarboxamide), were synthesized in a one-pot reaction, and structurally characterized. Polymer 1 shows a 1-D single chain in which dtcd connect adjacent Cu²⁺ ions, while DNBA^? is monodentate. In 2, every two Cu²⁺ ions are linked by carboxylate of a DNBA^? in a chelate-bridging mode into a binuclear unit, which is further connected by dtcd ligands into a 1-D double chain. In 3, dtcd connect Cu²⁺ ions via triazole nitrogens to generate 1-D single chains, which are further extended into a 2-D network by the amide oxygens of a dtcb from an adjacent chain. The pH plays an important role in product distribution of 1–3. The coordination behaviors of dtcd and DNBA^? also influence the final structures. Luminescent properties of 1–3 have been investigated.     

Reaction of 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene with [Re2(CO)8(CH3CN)2]: Novel coordination modes of the 1,1′-diphosphaferrocene ligand

Reaction of 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene (1) with [Re₂(CO)₈(CH₃CN)₂] afforded two trimetallic complexes in which the heterometallocene is ligated across the Re-Re bond. The structure of the complex having 1 bridging the Re₂(CO)₈ moiety through two P atoms was determined by X-ray diffraction and compared with those of analogous complexes with organic bridging bis-phosphines. The second complex obtained in this reaction presumably contains 1 acting as a (P,Fe) bridging ligand.     

A two dimensional coordination polymer based on drug ligand enoxacin and transition metal ion

A two-dimensional coordination polymer, [Mn(Enox)₂]·4H₂O, 1 (H-Enox?=?1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-pierazinyl)-1,8-naphtyridine-3-carboxylic acid), has been rationally designed and synthesized under hydrothermal conditions. Compound 1 is self-assembled from bifunctional drug ligand enoxacin and transition metal ion Mn(II) through covalent coordination bonds and hydrogen bondings.     

Syntheses and characterizations of four metal coordination polymers constructed by the pyridine-3,5-dicarboxylate ligand

A series of metal-organic frameworks, namely [Ni(PDB)(H₂O)]_n (1), [Pb(PDB)(H₂O)] · (H₂O) (2), [Co₂(PDB)₂(bpy)₂(H₂O)₄] · 4H₂O (3) and [Co₂(PDB)₂(phen)₂]_n (4) (H₂PDB = pyridine-3,5-dicarboxylic acid, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been synthesized based on pyridine-3,5-dicarboxylate acid and two neutral chelate ligands, with different metal ions such as Ni^II, Co^II and Pb^II, under hydrothermal conditions. The framework structures of these polymeric complexes have been determined by the X-ray single crystal diffraction technique. In the four complexes, the pyridine-3,5-dicarboxylate acid ligand exhibits diverse coordination modes, which play an important role in the construction of metal-organic frameworks. The thermal analyses of these four complexes have been measured and discussed. In addition, complex 2 shows strong phosphorescent emission at room temperature and the magnetic measurement of the polymer of 4 reveals a typical antiferromagnetic exchange.     

Construction of two new photoluminescent coordination polymers via 5-position substituted 1,3-benzenedicarboxylate

Two coordination polymers, [Cd(L1)(bib)] _n (1) and [Cd(L2)(bib)_0.5] _n (2) [H₂L1?=?5-hydroxyisophthalic acid, H₂L2?=?5-methylisophthalic acid and bib?=?1,4-bis(2-methyl-imidazol-1-yl)butane], have been synthesized and characterized by IR, elemental analysis, and X-ray diffraction. Compound 1 shows a 2-D layer structure and 2 is a two-fold interpenetrated 3-D pcu topology. The results suggest that the 5-position group affects the structure of coordination polymers. Luminescence properties of 1 and 2 are investigated.     

Syntheses,structures, and properties of two coordination polymers based on 5-methoxyisophthalate and flexible dipyridines

Hydrothermal reactions of 5-methoxyisophthalic acid (MeO-H₂ip), 1,3-di(4-pyridyl)propane (bpp) with Cd(NO₃)₂·4H₂O and Ni(NO₃)₂·6H₂O produced [Cd₂(MeO-ip)₂(bpp)₂]_n·nH₂O (1) and [Ni(MeO-ip)(bpp)(H2O)]_n·nH₂O (2), respectively. Complex 1 is a 2-D layer consisting of dinuclear Cd(II)-carboxylate units, two carboxylates of MeO-ip adopt μ₂,η²-bridging and chelating modes. MeO-ip bridges three Cd(II) ions to form a 1-D [Cd₂(MeO-ip)₂]_n chain, which is further extended into a 2-D layer by bpp in a trans,trans-conformation. However, two carboxylates of MeO-ip in 2 are monodentate and chelating to link Ni(II) into a 1-D [Ni(MeO-ip)]_n chain with bpp in a trans-gauche conformation connecting [Ni(MeO-ip)]_n chains into a two-fold interpenetrating 3-D network. Coordinated water and carboxylate oxygen from different MeO-ip form strong hydrogen bonds. The frameworks of 1 and 2 are stable below 250 and 300?°C, respectively. Luminescence indicates that 1 shows maximum emission at 375 and 450 nm upon excitation at 320 nm. Magnetic measurement of 2 suggests the presence of ferromagnetic interactions in 2.     

Two-dimensional metal-organic framework constructed from 4,4′-bipydine and 1,2,4-benzenetricarboxylate: Synthesis, structure and magnetic properties

Two new copper coordination polymers generated from mixed organic ligands 4,4′-bipydine and 1,2,4-benzenetricarboxylate [Cu₃(1,2,4-BTC)₂(4,4′-bipy)(H₂O)₄] 1 and [Cu(1,2,4-HBTC)(4,4′-bipy)] 2 (1,2,4-BTC=1,2,4-benzenetricarboxylate) have been prepared hydrothermally and characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the noncentrosymmetric space group Fdd2, with , , , , and Z=8. Its structure contains two different one-dimensional (1-D) chains for the Cu ions, namely and ; the carboxylate of 1,2,4-BTC ligands links the two different 1-D chains into an interesting steplike neutral framework. Compound 2 crystallizes in the monoclinic space group P2₁/n, with a=9.9806(8), b=16.5512(16), , β=99.375(5)°, , Z=4. Its structure contains novel paddle-wheel clusters Cu₂(CO₂)₄(4,4′-bipy)₂ as SBUs which are further linked by monoprotonated 1,2,4-BTC ligands into a 2-D neutral framework. The magnetic behaviors of both compounds have been studied.     

Topological diversification of two new Cd(II) photoluminescent coordination polymers via auxiliary N-donor ligands

Two new cadmium(II) coordination polymers, [Cd₂(nda)₂(L₁)] _n (1) and [Cd(nda)(L₂)_0.5] _n (2), were hydrothermally synthesized with 1,4-naphthalenedicarboxylic acid (H₂nda) and auxiliary N-donor coligands [L₁?=?1,5-bis(2-methyl-imidazol-1-yl)pentane and L₂?=?4,4′-bis(2-methyl-imidazol-1-ylmethyl)biphenyl]. Single-crystal X-ray diffraction analyses showed that the topological networks are different when the N-donor ligands are changed. Compound 1 showed a (4¹⁶.6⁵) topology and 2 showed a twofold interpenetrating pcu topology.