Hydrothermal synthesis and characterization of two 2-D lanthanide-2,2′-bipyridine-3,3′-dicarboxylate coordination polymers based on zigzag chains

Two lanthanide coordination polymers, {[La₂(bpdc)₃(H₂O)₄]·(H₂O)₄}_n (1) and {[Sm₂(bpdc)₃(H₂O)₂]·(H₂O)₅}_n (2) (H₂bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid) have been obtained by hydrothermal synthesis. Single-crystal X-ray diffraction shows that 1 and 2 are two-dimensional network structures based on the zigzag chains which are linked by bpdc ligands, forming the first examples of binary lanthanide polymers with bpdc. It is unprecedented that the adjacent zigzag chains are symmetrical in mirror images with the arraying form of ?ABAB?. In 1 and 2, lanthanide ion are all nine-coordinate and bpdc ligands exhibit different kinds of coordination modes. The 1-D infinite water chain in 1 and pentameric water ring in 2 have been found between lattice water molecules. Thermo-gravimetric analyses of 1 and 2 display considerable thermal stability. Photoluminescent properties of 1 and 2 are discussed.     

First examples of ternary lanthanide 2,2′-bipyridine-3,3′-dicarboxylate coordination polymers with zigzag chains structures assembled from lanthanide ions, 2,2′-bipyridine-3,3′-dicarboxylate and 1,10-phenanthroline

Four lanthanide coordination polymers, [{Ln₂(bpdc)₃(phen)₂(H₂O)₂} · (H₂O)₆]_n (Ln = Sm (1); Eu (2); Gd (3), Tb (4)), were self-assembled from 2,2′-bipyridine-3,3′-dicarboxylic acid (H₂bpdc),1,10-phenanthroline(phen) and corresponding lanthanide oxides by hydrothermal synthesis. Compounds 1-4 are found to be isomorphous and isostructural. Single-crystal X-ray diffraction studies show that compounds 1-4 are all of one-dimensional zigzag chain structures and extend to two-dimensional networks through π-π interactions and hydrogen bonds. The pyridyl nitrogen atoms of the 2,2′-bipyridyl unit in the bpdc ligand are uncoordinated in an anti-conformation along the central C-C bond of the ligand. Thermogravimetric analysis of 1-4 showed an obvious thermal stability indicating that the coordination habit of the metal ions with bpdc and phen has an effect on the overall framework. Photoluminescence measurement indicates that compound 2 and compound 4 are strong red and green emitters, respectively.     

A reusable zigzag copper(II) coordination polymer with bio-essential constituents as a facile DNA scission agent

A copper(II) coordination polymer has been synthesized in the form of an infinite zigzag chain where each metal is bonded to one glycine, two adenine, one nitrate anion and a water molecule giving a distorted octahedral coordination geometry with N₃O₃ donor set. Each chain is hydrogen-bonded through C-H?O and N-H?O interactions on both sides leading to an overall polymeric structure. This compound not only shows facile chemical nuclease activity for pBR322 supercoiled DNA but also can be reused keeping its scission activity unchanged.     

Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers

Three new copper complexes, [Cu^IICu^I(ip)(ipH)(4,4′-bipy)_3/2]_n (1), [Cu(ip)(4,4′-bipy)]_n · 3nH₂O (2), and [Cu(ipH)₂(4,4′-bipy)]_n (3), have been hydrothermally synthesized by the reaction of Cu(NO₃)₂ · 3H₂O with isophthalic acid (ipH₂) and 4,4′-bipyridine (4,4′-bipy) under different reaction conditions. Complex 1, a mixed-valence copper(I,II) complex, exhibits a 2-D interpenetrating grid framework, in which five-coordinated Cu^II and three-coordinated Cu^I environments are established. The oxidation states of center Cu atoms have been confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectra (EPR). Complex 2 features a 2-D box-like bilayer architecture, in which Cu^II atoms are linked by ip ligands to form a 1-D double-chain and the resulting chains are further strutted by the 4,4′-bipy ligands. In complex 3, two bridging 4,4′-bipy ligands and two terminal ipH ligands confine the Cu^II center in a square plane coordination geometry. The whole molecule of 3 was arranged into a 1-D linear chain structure. Additionally, the thermogravimetric analyses (TGA) for complexes 1-3 are also discussed in this paper.     

Porous coordination polymer of copper(II) assembled from mixed organic ligands pyridine-2,4-dicarboxylic acid and trans-1,2-bis(4-pyridyl)ethylene: Synthesis, crystal structure and magnetic study

A 3-D porous coordination polymer of Cu(II) has been synthesized using two different organic bridging ligands, pyridine-2,4-dicarboxylate (pydc) and trans-1,2-bis(4-pyridyl)ethylene (bpe). Here, pydc and bpe connect two adjacent Cu(II) centers, resulting in a rectangular grid-like 2-D sheet with grid dimensions 10.058 × 15.258 Å. The channels are formed when 2-D networks running along the b-axis which are filled by solvent water molecules. The stability of porous networks, after removal of guest water molecules is confirmed by thermogravimetric analysis and X-ray powder diffraction technique. The low temperature magnetic study has been carried out, which indicates the presence of weak antiferromagnetic coupling with J = −0.59 cm⁻¹.     

Hydrothermal synthesis, crystal structure and magnetic characterization of two 4f-3d heterometallic coordination polymers

Two new 4f-3d heterometallic coordination polymers [Gd₂Co(L₁)₃(ox)(H₂O)₄]·2.5H₂O (1, L₁ = pyridine-2,5-dicarboxylate anion, ox = oxalate dianion) and [GdNi(L₂)₂(ox)_0.5(H₂O)₃]·3H₂O (2, L₂ = pyridine-2,3-dicarboxylate anion) were successfully synthesized under hydrothermal conditions. In compound 1, one dimensional heterometallic and lanthanide infinite sheets were constructed with sole L₁ spacers and L₁-ox mixed bridges, respectively. While similar one dimensional heterometallic infinite sheet and normal lanthanide infinite zigzag chain were formed based on sole L₂ and L₂-ox mixed bridges, respectively in compound 2. Both of the two compounds exhibited new and interesting three dimensional topologies. In addition, the magnetic properties of the two compounds were analyzed via solid-state dc magnetic susceptibility measurements.     

Hydrothermal synthesis and structure of a Cu(I) bromide coordination polymer, [(tpyprz)3Cu10Br10] (tpyprz = tetra-2-pyridylpyrazine)

The hydrothermal reaction of CuBr₂ and tpyprz in the presence of NH₄VO₃ and HF for 72 h at 170 °C provided [(tpyprz)₃Cu₁₀Br₁₀] (1) in 20% yield. The two-dimensional structure of 1 may be described as Cu(I)-tpyprz chains, linked through {Cu₄Br₅}⁻ clusters in the ac-plane and decorated with {Cu₃Br₅}²⁻ clusters projecting from one face of the layer in the b-direction. The Cu(I) sites exhibit distorted trigonal coordination {CuBr₃} and distorted tetrahedral geometries, {CuBr₂N₂} and {CuN₄}. Crystal data for 1: monoclinic space group C2, a = 12.7561(8) Å, b = 19.359(1) Å, c = 15.860(1) Å, β = 97.178(1)°, V = 3885.8(4) Å³, Z = 2, D_calc = 2.222 g cm⁻³, μ(Mo Kα) = 78.75 cm⁻¹.     

In situ alkylation of 4,4′-bipyridine in hydrothermal synthesis of one-dimensional copper(I) bromide compounds

Hydrothermal reaction of CuBr₂, 4,4′-bipyridine and ethanol/methanol generated two copper (I) bromide complexes with in situ alkylated 4,4′-bipyridium, namely [C₁₄H₁₈N₂][Cu₅Br₇] (1) and [C₁₂H₁₄N₂][Cu₄Br₆] (2). The structure of 1 consists of chains and N,N′-diethyl-4,4′-bipyridinium. The underlying structural motif in of 1 is the Cu₅Br capped square pyramid, which is different from the Cu₅Br₂ pentagonal bipyramidal structural motif in various documented anions. The in 1 contains untypical μ₅-bromide, with which five copper atoms forms a capped square pyramid rather than a pentagonal pyramid as predicted by Subramanian and Hoffmann. Compound 2 is isostructural with [C₁₂H₁₄N₂][Cu₄Cl₆] reported by Willett, and consists of chains and N,N′-dimethyl-4,4′-bipyridinium. The chain is composed of alternating Cu₆Br₆ and Cu₂Br₆ units.     

Copper(II) PMDTA and copper(II) TMEDA complexes: precursors for the synthesis of dinuclear dicationic copper(II) complexes

Copper(II) cations coordinated with PMDTA (pentamethyldiethylenetriamine) and TMEDA (tetramethylethylenediamine) possess a high synthetic potential. The synthesis of these cations was carried out by metathesis reactions with silver salts. The cationic copper(II) complexes, [Cu(PMDTA)(Me₂CO)Cl]⁺, [Cu(PMDTA)(H₂O)Cl]⁺, [Cu(PMDTA)(DMF)]⁺, [Cu(PMDTA)Cl]⁺, [Cu(PMDTA)OAc]⁺, [Cu(PMDTA)(MeCN)₂]²⁺, [Cu₂(TMEDA)₂Cl₃]⁺ and [Cu(TMEDA)(MeCN)₃]²⁺ were synthesised as PF₆ salts, crystallised and characterised by single-crystal X-ray diffraction.     

A MLCT-switched photochromic copper(II) coordination polymer with 1,2-bis(2′-methyl-5′-(4″-pyridyl)-3′-thienyl)perfluorocyclopentene in crystalline phase

A novel Cu(II) coordination polymer with photochromic 1,2-bis(2′-methyl-5′-(4″-pyridyl)-3′-thienyl)perfluorocyclopentene (BM-4-PTP) was prepared and crystallographically characterized. Its photochromic behavior as well as magnetic property was investigated in crystalline phase. In complex [Cu(BM-4-PTP)Br₂(DMF)₂] (1), each copper atom is bridged by two N atoms of BM-4-PTP, two Br atoms from anions and two O atoms of DMF in an slightly distorted octahedral geometry. The basal planar center is in turn linked by bidentate ligand forming a 1-D polymeric chain. Free ligand showed typical spectral changes upon appropriate optical excitation, indicating the reversible photochromism in crystalline phase. Complex 1 occurred reversible photoisomerization not only through the π-π^∗ transition but also the MLCT transition in crystalline phase. On the other hand, the magnetic property of complex 1 has been investigated by means of ESR. The spectra slightly and reversibly changed in response to UV and visible light supporting the normal photoreactivity in crystalline phase.     

Synthesis, crystal structure and magnetic properties of a chain coordination polymer {[Cu4L2(H2O)] · H2O}n

A chain coordination polymer with the chemical formula {[Cu₄L₂(H₂O)] · H₂O}_n, has been synthesized by the assembly reaction of K₂CuL · 1.5H₂O and Cu(OAC)₂ · H₂O with a 1:1 mole ratio in methanol, where H₄L = 2-hydroxy-3-[(E)-({2-[(2-hydroxybenzoyl)imino]ethyl}imino)methyl] benzoic acid, OAC⁻ = CH₃COO⁻. The crystal structure was determined by single-crystal X-ray diffraction analysis, the compound has chain molecular structure formed by dissymmetrical tetranuclear units. The magnetic measurements showed that Cu-Cu of the complex exhibit antiferromagnetic interactions, and satisfactory fittings to the observed magnetic susceptibility data were obtained by assuming a binuclear system, and further using molecular field approximation to deal with magnetic exchange interactions between binuclear systems.     

Structural variations and spectroscopic properties of copper(I) complexes with bis(schiff base) ligands

Six copper(I) complexes {[Cu₂(L1)(PPh₃)₂I₂] · 2CH₂Cl₂}_n (1), {[Cu₂(L2)(PPh₃)₂]BF₄}_n (2), [Cu₂(L3)(PPh₃)₄I₂] · 2CH₂Cl₂ (3), [Cu₂(L4)(PPh₃)₄I₂] (4), [Cu₂(L5)(PPh₃)₂I₂] (5) and [Cu₂(L6)(PPh₃)₂I₂] (6) have been prepared by reactions of bis(schiff base) ligands: pyridine-4-carbaldehyde azine (L1), 1,2-bis(4′-pyridylmethyleneamino)ethane (L2), pyridine-3-carbaldehyde azine (L3), 1,2-bis(3′-pyridylmethyleneamino)ethane (L4), pyridine-2-carbaldehyde azine (L5), 1,2-bis(2′-pyridylmethyleneamino)ethane (L6) with PPh₃ and copper(I) salt, respectively. Ligand L1 or L2 links (PPh₃)₂Cu₂(μ-I)₂ units to form an infinite coordination polymer chain. Ligand 3 or 4 acts as a monodentate ligand to coordinate two copper(I) atoms yielding a dimer. Ligand 5 or 6 chelates two copper(I) atoms using pyridyl nitrogen and imine nitrogen to form a dimer. Complexes 1-4 exhibit photoluminescence in the solid state at room temperature. The emission has been attributed to be intraligand π-π* transition mixed with MLCT characters.     

One-dimensional nickel and cobalt phthalate coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine: Hydrothermal synthesis, structural characterization and thermal properties

Hydrothermal synthesis has afforded a family of three structurally related metal phthalate (pht) 1-D coordination polymers incorporating the kinked dipodal organodiimine 4,4′-dipyridylamine (dpa), with a general formulation of [L₂M(dpa)₂M(H₂O)₄] · H₂O (L = pht, M = Co, 1, M = Ni, 2; L = 4-methylphthalate (4-mpht), M = Co, 3). Single crystal X-ray diffraction of 1 and 2 revealed the presence of one-dimensional (1-D) polymeric chains consisting of [M(H₂O)₄]²⁺ and [M(pht)₂]²⁻ subunits linked through dpa tethers. These chains in turn conjoin into pseudo 2-D layers and 3-D networks via extensive supramolecular hydrogen bonding pathways. An extremely similar structure is observed for 3 despite the presence of the bulkier methyl group substituent. 1-3 were further characterized via infrared spectroscopy and elemental and thermogravimetric analysis. 1-3 represent the first dicarboxylate coordination polymers incorporating dpa tethering ligands.     

Hydrothermal synthesis and crystal structure of one-dimensional organic/inorganic hybrid material: [Mo4O12(2,2′-bpy)3]n

A new polyoxomolybdenum compound [Mo₄O₁₂(2,2′-bpy)₃]_n (1) (2,2′-bpy = 2,2′-bipyridine) has been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single crystal X-ray diffraction. The solid state structure is a 1D chain with a repeat unit of three corner-sharing {MoO₄N₂} octahedra and one {MoO₄} tetrahedron.     

Two forms of a copper(II) complex of 3-phenyl-5-(2-pyridyl)-4-(4-pyridyl)-4H-1,2,4-triazole: a six-coordinate monomer versus a five-coordinate polymer

The reaction of the new bidirectional ligand 3-phenyl-5-(2-pyridyl)-4-(4-pyridyl)-4H-1,2,4-triazole (pyppt) with Cu(ClO₄)₂ · 6H₂O in a 2:1 molar ratio in EtOH affords the complex [Cu^II(pyppt)₂(ClO₄)₂] · H₂O (1) as a microcrystalline turquoise solid. Recrystallisation of complex 1 from MeCN by vapour diffusion of Et₂O gives blue crystals of the monomeric octahedral complex [Cu^II(pyppt)₂(ClO₄)₂] · MeCN (2). In contrast, addition of EtOH to a solution of complex 1 in MeCN followed by slow evaporation yields blue crystals of the five-coordinate polymeric complex {[Cu^II(pyppt)₂](ClO₄)₂ · EtOH}_∞ (3). The structures of both complexes have been determined by single crystal X-ray diffraction.     

Structural aspects of some 2:1 dipyridylamine complexes of some copper(II) salts: An interesting new polymorph of the binuclear carbonate/perchlorate tetrahydrate adduct

Recent work has described the structural characterization of the complexes :dpyam:H₂O (1:4:4), X′ = ClO₄, BF₄, ‘dpyam’ = dipyridylamine, as a pair of triclinic Z = 1 isomorphs, the cations being modelled in terms of pairs of copper atoms bridged by a carbonate ion disordered about a crystallographic inversion centre. This work has been revisited in the course of describing a new polymorph of the perchlorate in a triclinic cell of twice the size, in which the carbonate unit, now non-disordered, bridges a pair of crystallographically independent copper atoms which display distinctly different coordination environments, one close to the square-pyramidal norm, the other not. Studies of adducts of the form [(dpyam)₂CuX]X′(·nH₂O) are also recorded. The X/X′ = propionate/iodide adduct is found to be isomorphous with its acetate/BF₄ but, interestingly, not its propionate/Cl counterpart. ‘Low’-temperature redeterminations of the NCO/Cl · 4H₂O and nitrite/ClO₄ adducts are also recorded, enabling definition of the hydrogen-bonding scheme in the former.     

Hydrothermal synthesis and characterization of a new 1-D polymeric lanthanum ethylenediaminetetraacetate with less metal-aqua coordination: {[La(EDTA)(H2O)]2}n

A new lanthanum ethylenediaminetetraacetate (EDTA) coordination polymer, {[La(EDTA)(H₂O)]₂}_n (EDTA³⁻ = [(CH₂N)₂(CH₂COOH)(CH₂COO⁻)₃]), was hydrothermally prepared from LaCl₃ solution and ethylenediaminetetracetic acid at 448 K. The compound was characterized by elemental analysis, FTIR, TG-DTA, and X-ray crystallography. The structure consists of ladder-like chains of [La(EDTA)(H₂O)]₂ dimers bridged by O-C-O groups. Hydrothermal method successfully reduced the high number of La-aqua coordinations in known lanthanum EDTA to one giving rise to relatively compact structure. It has high thermal stability up to 550 K. Every EDTA ligand with COOH group is involved in eight La-O(N) bonds to three nine-coordinated La centers.     

Communication of metal ions in the dinuclear ruthenium complexes containing 4,4′-bipyridine, 1,4-diisocyanobenzene, and pyrazine bridging ligands: Synthesis, characterization and structure determination

Reaction of [Ru(2,2′-bipyridine)(2,2′:6′,2″-terpyridine)Cl]PF₆ (abbreviated to [Ru(bipy)(terpy)Cl]PF₆) with 0.5 equiv of the bidentate ligand L produces the dinuclear complexes [{Ru(bipy)(terpy)}₂(μ-L)](PF₆)₄ (L = 4,4′-bipyridine 1, 1,4-diisocyanobenzene 2 and pyrazine 3) in moderate yields. Treating [Ru(bipy)(terpy)Cl]PF₆ with equal molar of 1,4-diisocyanobenzene affords [Ru(bipy)(terpy)(CNC₆H₄NC)](PF₆)₂ (2a). These new complexes have been characterized by mass, NMR, and UV-Vis spectroscopy, and the structures of 1-3 determined by an X-ray diffraction study. Cyclic voltammetric studies suggest that metal communication between the two ruthenium ions increases from 1 to 2 to 3.     

Sonochemical synthesis of nano-sized metal-organic lead(II) polymer: A precursor for the preparation of nano-structured lead(II) iodide and lead(II) oxide

Nanoparticles of a new Pb^II metal-organic polymer, [Pb(μ-pyr)(μ-I)₂]_n (1), with a net-like morphology have been synthesized by the reaction of pyrazine with Pb(NO₃)₂ and NaI via sonochemical irradiation. Nano-structured PbI₂ and PbO were synthesized from compound 1 by calcination at argon and air atmospheres, respectively. The structure of 1 was determined by single crystal X-ray crystallography and the nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The thermal stability of nano-sized and single crystalline samples of 1 were studied and compared.     

Syntheses and structures of two copper-molybdate complexes: The 3-D [Cu(4,4′-bpy)(MoO4)] and 1-D [Cu2(HDABCO)2(H2Mo8O27)] · 4H2O

Hydrothermal reaction of molybdenum oxide and copper(II) source in the presence of 4,4′-bipyridine (4,4′-bpy) afforded three-dimensional covalent framework [Cu^II(4,4′-bpy)(MoO₄)] (1), while reaction with 1,4-diazoniabicyclo[2,2,2]octane (DABCO) in place of 4,4′-bpy and addition of metal molybdenum resulted in one-dimensional chain-like compound . The copper in 1 is divalent and approximately shows trigonal bipyramidal geometry, while in 2 is monovalent and approximately shows T-shaped geometry. The structure of 1 has a three-dimensional pillar-layered framework constructed from bimetallic {CuMoO₄} layers bridged by bifunctional ligand 4,4′-bpy. Interestingly, the {CuMoO₄} layer in 1 consists of 16-membered {Cu₄Mo₄O₈} rings and 8-membered {Cu₂Mo₂O₄} rings, different from other reported {CuMoO₄} layers. The structure of 2 consists a one-dimensional chain that is attached by peripheral {Cu(HDABCO)}²⁺ units. The chain is constructed from octamolybdates through common corners.