The assembly of POM-induced inorganic–organic hybrids based on copper ions and mixed ligands

Three inorganic–organic hybrid materials based on Keggin-type polyoxometalates (POMs), [Cu^II₂(phen)₂(4,4′-bipy)(H4,4′-bipy)₂(H₂O)₂][PMo₁₂O₄₀]₂·2H₂O (1), [Cu^II(phen)₂(H4,4′bipy)][PW₁₂O₄₀]·H₂O (2), and [Cu^II₂(phen)₂(4,4′-bipy)(BW₁₂O₄₀)(H₂O)₂](H₂4,4′-bipy)_0.5·3H₂O (3) (phen = 1,10-phenanthroline, 4,4′-bipy = 4,4′-bipyridine), were synthesized using different POMs in the hydrothermal conditions. Compounds 1–3 were characterized by single-crystal X-ray diffraction, IR spectra, elemental analyses, powder X-ray diffraction analyses, and thermogravimetric analyses. Compound 1 presents a two-dimensional (2-D) network containing the Keggin-type [PMo₁₂O₄₀]^3? anion and dinuclear metal–organic units [Cu^II₂(phen)₂(4,4′-bipy)(H4,4′-bipy)₂(H₂O)₂]³⁺. Compound 2 is a 2-D architecture constructed from a [PW₁₂O₄₀]^3? and mononuclear metal–organic units [Cu^II(phen)₂(H4,4′-bipy)]³⁺. In 3, the [BW₁₂O₄₀]^5? anions link [Cu^II₂(phen)₂(4,4′-bipy)] units to form a one-dimensional (1-D) chain [Cu^II₂(phen)₂(4,4′-bipy)(BW₁₂O₄₀)(H₂O)₂]; the 1-D chain connects with protonated 4,4′-bipy ligands and lattice waters, yielding a 2-D layer. Fluorescence spectra, UV–vis spectra, and electrochemical properties of 1–3 have been investigated.     

Syntheses,structures, and properties of four coordination compounds constructed from asymmetric semi-rigid V-shaped multicarboxylate ligand

Four new compounds, [Mn(HL)(phen)₂(H₂O)] (1), [Ni(HL)(phen)₂(H₂O)] (2), [Zn(HL)(4,4′-bipy)_1.5(H₂O)] _n ?·?2nH₂O (3) and [Zn₂(HL)₂(H₂O)₆] (4), have been synthesized from an asymmetric semi-rigid V-shaped multicarboxylate 4-(4-carboxy-phenoxy)-phthalic acid (H₃L) with 1,10-phenanthroline (phen), or 4,4′-bipyridine (4,4′-bipy) as auxiliary ligands. Single-crystal X-ray diffraction analysis reveals that 1, 2 and 4 have 0-D structures with 3-D supramolecular frameworks formed by intermolecular hydrogen bonds. Compound 3 shows a 1-D infinite ribbon bridged by 4,4′-bipy, which further forms a 3-D supramolecular architecture by π–π stacking interactions and hydrogen bonds. Thermal stabilities of 1–4 and luminescence properties of 3 and 4 have also been investigated.     

Metal–organic Coordination Polymers Assembled from Divalent Transition Salts with a Flexible Spacer Ligand: Hydrothermal Syntheses,Crystal Structures,and Luminescent and Magnetic Properties

Seven new metal-organic coordination polymers, [M(tzda)(H₂O)₄] _n [M = Co(1), Ni (2) and Zn(3)], [Zn(tzda)(4,4′-bipy)] _n (4), [Cd(tzda)(4,4′-bipy)_0.5(H₂O)] _n (5) and [M(tzda)(4,4′-bipy)(H₂O)] _n [M = Co(6), Ni(7)] [H₂tzda = (1,3,4-thiadiazole-2,5-diyldithio)diacetic acid, 4,4′-bipy = 4,4′-bipyridine] have been hydrothermally synthesized and structurally characterized by X-ray single crystal diffraction. Compounds 1–3 display similar 1D zigzag chain structure. Compound 4 possesses a 2D-layered architecture generated from [Zn(tzda)] _n moiety with double-chain structure cross-linking 4,4′-bipy spacers, while compound 5 consists of –Cd–OCO–Cd–OCO– chains cross-linked through –CH₂SC₂N₂SSCH₂– spacers of tzda anions and 4,4′-bipy, also showing a 2D-layered structure. The structures of 6 and 7 seem more complicated, in which the [M(tzda)] _n layered subunits are extended to unique 3D framework by the bridging 4,4′-bipy ligand. Photoluminescence investigations reveal that 4 and 5 both display strong blue emissions in the solid state at room temperature, which could be significant in the field of luminescent materials. The magnetic studies of 6 and 7 show both display the characteristics of a weak antiferromagnetic coupling between metal ions in the system mediated by carboxylate bridges.     

Architectural diversity of six coordination compounds based on (S)-(+)-mandelic acid and different N-donor auxiliary ligands: syntheses,structures, and luminescent properties

Six transition metal coordination compounds with H₂mand and different N-donor ligands, [Co(Hmand)₂(2,2′-bipy)]·H₂O (1), [Ni(Hmand)₂(2,2′-bipy)]·H₂O (2), [Ni(Hmand)₂(bpe)] (3), [Zn(Hmand)₂(2,4′-bipy)(H₂O)]·2H₂O (4), [Zn(Hmand)(bpe)(H₂O)]_n[(ClO₄)]_n·nH₂O (5), and [Zn(Hmand)(4,4′-bipy)(H₂O)]_n[(ClO₄)]_n (6), were synthesized under different conditions (H₂mand = (S)-(+)-mandelic acid, bpe = 1,2-di(4-pyridyl)ethane, 4,4′-bipy = 4,4′-bipyridine, 2,4′-bipy = 2,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine). Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectra, thermogravimetric analysis, powder X-ray diffraction, and circular dichroism. Compounds 1 and 2 are isostructural (0-D structures), which are extended to supramolecular 1-D chains by hydrogen bonding. Compound 3 exhibits 1-D straight chain structures, which are further linked via hydrogen bond interactions to generate a 3-D supramolecular architecture. Compound 4 displays a discrete molecular unit. Neighboring units are further linked by hydrogen bonds and π–π interactions to form a 3-D supramolecular architecture. Compound 5 displays a 2-D undulated network, further extended into a 3-D supramolecular architecture through hydrogen bond interactions. Compound 6 possesses a 2-D sheet structure. Auxiliary ligands and counteranions play an important role in the formation of final frameworks, and the hydrogen-bonding interactions and π–π stacking interactions contributed to the formation of the diverse supramolecular architectures. Compounds 1, 2, 4, 5, and 6 crystallize in chiral space groups, with the circular dichroism spectra exhibiting positive cotton effects. Furthermore, the luminescent properties of 4–6 have been examined in the solid state at room temperature, and the different crystal structures influence emission spectra significantly.     

Syntheses,crystal structures and antibacterial activities of M(II) benzene-1,2,3-triyltris(oxy)triacetic acid complexes

Four metal(II) complexes with benzene-1,2,3-triyltris(oxy)triacetic acid (H₃L), {[Co_1.5(L)(H₂O)₆]·6H₂O}_n (1), {[Co_1.5(L)(4,4′-bipy)_1.5(H₂O)₄]·4H₂O}_n (2), {[Co(HL)(2,2′-bipy)(H₂O)₂]·1.5H₂O}_n (3), and {[Cu(HL)(phen)(H₂O)₂]·H₂O}_n (4) (4,4′-bipy = 4,4′-bipyridine; 2,2′-bipy = 2,2′-bipyridine; phen = phenanthroline), were prepared and structurally characterized. Complex 2 displays a 1-D structure, while 1, 3, and 4 reveal 0-D structures, which further extend to 3-D supramolecular networks by hydrogen bonding interactions, of which 1 and 4 contain double-helical chains, 2 includes meso-helices, and 3 comprises single-helices. Furthermore, the thermal stabilities and antibacterial activities of the complexes were studied.     

Zinc(II) and manganese(II) coordination polymers constructed by 2-naphthyl imidazole dicarboxylate: syntheses,structures and properties

Three coordination polymers [Zn(μ₃-HNIDC)(CH₃OH)]_n (H₃NIDC = 2-(2-naphthyl)-1H-imidazole-4,5-dicarboxylic acid) (1), [Mn(μ₂-HNIDC)(4,4′-bipy)]_n (4,4′-bipy = 4,4′-bipyridine) (2) and [Mn₂(μ₂-HNIDC)₂(phen)₂]_n (phen = 1,10-phenanthroline) (3) have been solvothermally synthesised and structurally characterised by single-crystal X-ray diffraction, elemental analyses, thermal analyses and IR spectra. Polymer 1 displays a three-dimensional open architecture with one-dimensional (1D) channels. Polymer 2 exhibits a sheet structure containing infinite rectangles. Polymer 3 presents a 1D wave chain structure. The solid-state photoluminescence of 1 has been investigated as well.     

Two new Pb(II) coordination polymers, [Pb2(μ-4,4′-bipy) (μ-2-sb)2(DMF)] n and {[Pb2(μ-4,4′-bipy) (μ-2-sb)2(H2O)2] · H2O} n (4,4′-bipy = 4,4′-bipyridine and 2-H2sb = 2-sufobenzoic acid)

Two new 2D Pb₂(μ-4,4′-bipy)(μ-2-sb)₂ coordination polymers, [Pb₂(μ-4,4′-bipy)(μ-2-sb)₂(DMF)] _n (1) and {[Pb₂(μ-4,4′-bipy)(μ-2-sb)₂(H₂O)₂] · H₂O} _n (2), have been synthesized, characterized and studied by X-ray crystallography. The structural studies show the Pb atoms to have seven- and eight-coordinate holodirected geometries.     

Syntheses,structures, and properties of supramolecular complexes with bipyridine and amino-Schiff-base derived from salicylaldehyde with glycine

The reactions of stoichiometric amounts of Cu(CH₃COO)₂ · 2H₂O or Ni(CH₃COO)₂ · 2H₂O with KHL (potassium salt of salicylideneglycine) and 4,4′-bipy or 2,2′-bipy ethanol afforded [Cu₂(L)₂(μ-4,4′-bipy)(4,4′-bipy)₂] · 2H₂O (1) (L = salicylideneglycine) and Ni(OAc)₂(2,2′-bipy) (H₂O)₂ (2), respectively. The structure of 1 contains two Cu(II)'s, bridged by 4,4′-bipy; each copper is square pyramidal. Complex 2 contains a Ni(II) in highly distorted octahedral geometry. The two complexes were constructed into 3-D interwoven networks by typical H-bonding (i.e., O?H ··· O and N?H ··· O) and some other intra- or intermolecular weak interactions (i.e., C?H ··· O).     

The construction of two lanthanide coordination polymers based on 5-hydroxyisophthalate and bipyridine

Two lanthanide coordination polymers, [Tm₂·(5-IPA)₄·(2,2′-Hbipy)₂]·3H₂O (1, 5-H₂IPA?=?5-hydroxyisophthalic acid, 2,2′-bipy?=?2,2′-bipyridine) and [Er·(5-HIPA)₃·(4,4′-bipy)₃·(H₂O)₂]·3H₂O (2, 4,4′-bipy?=?4,4′-bipyridine), have formed by hydrothermal synthesis. Complex 1 exhibits a 2-D coordination network containing parallelepiped-shaped voids occupied by guest 2′2-bipy molecules. Complex 2 possesses a 1-D linear chain structure. The 1-D chains are linked by 4,4′-bipy molecules to form a 3-D supramolecular framework. IR spectroscopy, elemental analysis, and thermogravimetric analysis were also investigated.     

Synthesis and crystal structures of 3D supramolecular compounds: [ M (4,4′-bipy)2(H2O)4] · (4,4′-bipy)2 · (3,5-daba)2 · 8H2O ( M =Zn,Mn)

Two new supramolecular compounds [M(4,4′-bipy)₂ (H₂O)₄] ·?(4,4′-bipy)₂ ·?(3,5-daba)₂ ·?8H₂O (M=Zn(1) or Mn(2), 4,4′-bipy =?4,4′-bipyridine, 3,5-daba =?3,5-diaminobenzoic acid anion) were synthesized and characterized by elemental analysis and X-ray crystal diffraction. In [M(4,4′-bipy)₂(H₂O)₄]²⁺, the M(II) is coordinated by two nitrogen atoms from two 4,4′-bipy molecules and four oxygen atoms from four waters to form an octahedral configuration. There exist uncoordinated 4,4′-bipy molecules, 3,5-diaminobenzolate counterions and water guests in the compounds. The 3D structures of the title supramolecular compounds are constructed by rich hydrogen bonds among [M(4,4′-bipy)₂(H₂O)₄]²⁺, uncoordinated 4,4′-bipy molecules, water molecules and 3,5-daba, containing a diverting hexa-member water ring.     

Design,synthesis and magnetic properties of a ladderlike complex constructed by secondary building units

A secondary building unit (SBU), [Ni(2,2′-bipy)(5-npa)(H₂O)] _n [where 2,2′-bipy = 2,2′-bipyridine, 5-npa = 5-nitroisophthalic dianion], was synthesized as starting material of a polystep reaction. A ladderlike complex (LLC) Ni(II) coordination polymer, {[Ni(2,2′-bipy)(5-npa)(4,4′bipy)_0.5]·(H₂O)} _n , was constructed by polystep reaction using this SBU. In LLC, two SBUs were cross-linked by 4,4′-bipy [where 4,4′-bipy = 4,4′-bipyridine] forming a 1-D ladderlike structure. The magnetic properties of the LLC and SBU are discussed.     

Synthesis,structural characterization,and photocatalytic study of transition metal coordination polymers constructed from mixed ligands

Three 3-D coordination polymers, [Cu(cca)(4,4′-bipy)]_n (1), [Co₃(pda)₃(1,10′-phen)₂]_n (2), and [Co(pda)(1,10′-phen)]_n (3), have been synthesized from 4-carboxycinnamic acid (cca), 1,4′-phenylenediacrylic acid (pda), 4,4′-bipyridine (4,4′-bipy), 1,10′-phenanthroline (1,10′-phen), and Cu and Co salts under different conditions. The X-ray crystal structures of these three complexes are presented. Complex 1 exhibits a threefold 3-D α-Po interpenetration network. Complex 2 with a 3-D framework with six-connected single α-Po framework constructed from Co₃ unit has been synthesized and characterized. Complex 3 shows a 3-D framework with bcu topology composed of 1-D rod-shaped secondary building units. Furthermore, the photocatalytic properties of 2 were studied. When excited by UV light, 2 exhibits photocatalytic activity, in 300?min, about 71% Rhodamine B decomposes.     

Five metal imidazole dicarboxylate-based compounds comprising M3(MIDC)2 entities (M = Zn2+, Co2+, Mn2+): syntheses,structures and properties

Five metal imidazole dicarboxylate-based compounds, {[Zn₃(MIDC)₂(4,4′-bipy)₃](4,4′-bipy)·8H₂O}_n (1), {[Co₃(MIDC)₂(4,4′-bipy)₃](4,4′-bipy)·6H₂O}_n (2), {[Co₃(MIDC)₂(py)₂(H₂O)₂]}_n (3), {[Mn₆(MIDC)₄(py)₅(H₂O)₄]}_n (4), and {[Mn₃(MIDC)₂(Phen)₃(H₂O)₂]}_n (5) (H₃MIDC = 2-methyl-1H-imidazole-4,5-dicarboxylic acid; 4,4′-bipy = 4,4′-bipyridine; py = pyridine; Phen = 1,10-phenanthroline), have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray diffraction. We control the coordination modes of H₃MIDC via hydrazine and obtained a series of coordination compounds containing honeycomb-like [M₃(MIDC)₂]_n layers. We also investigated the effects of different neutral terminal or bridging ligands on [M₃(MIDC)₂]_n layers. Coplanar [M₃(MIDC)₂]_n layers and 4,4-bipy were used to construct 3-D frameworks of 1 and 2. Puckered [M₃(MIDC)₂]_n layers were found in 3–5; 4 is the first [M₃(L)₂]_n layer structure with two crests and troughs during each period (L = imidazole-4,5-dicarboxylic acid or its analog). Compound 5 is the first puckered [M₃(L)₂]_n layer structure decorated by chelating neutral ligands. Compound 1 exhibits weak blue photoluminescence in the solid state at room temperature. Variable-temperature magnetic susceptibility measurements of 2–5 indicate strong antiferromagnetic interactions.     

Ligand concentration-dependent supramolecular complexes with uncoordinated carbonyl groups based on a new pyrazole carboxylic acid ligand

One new pyrazole-based ligand, 1-carboxymethyl-3,5-dimethyl-1H-pyrazole-4-carboxylic acid (H₂cmdpca), has been synthesized and characterized. Structural analysis reveals that H₂cmdpca crystallizes in the monoclinic system and adopts a 3-D supramolecular network via the interaction of intermolecular hydrogen bonds. The reactions of Cd(II) ions with H₂cmdpca and 4,4′-bipyridine (4,4′-bpy) afforded three metal complexes, [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)₃]·H₂O (1), [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)]·3H₂O (2), and [Cd(4,4′-bpy)(Hcmdpca)₂(H₂O)] (3). Structural analyses reveal that these complexes are all monoclinic and 1, 2, and 3 exhibit mononuclear, 1-D chain, and 1-D with binuclear loop structures, respectively, which are further assembled into 3-D supramolecular frameworks through non-covalent interactions. 1 and 2 are true supramolecular isomers, while 2 and 3 are “pseudo-supramolecular” isomers. In addition, the thermal stability and luminescent properties of the complexes are also investigated.     

New nano-particle La(III) supramolecular compound as a precursor for preparation of lanthanum oxybromide-, hydroxide-, and oxide-nanostructures

Nano-particles of a new La(III) supramolecular compound [La(4,4′-bipy)(H₂O)₂(NO₃)_3.75Br_0.25] · (4,4′-Hbipy) (1), have been synthesized from reaction of 4,4′-bipy with La(NO₃)₃ and NaBr by the sonochemical method. For the first time LaOBr, La(OH)₃ and La₂O₃ nano-structures were prepared from [La(4,4′-bipy)(H₂O)₂(NO₃)_3.75Br_0.25] · (4,4′-Hbipy) (1) by calcination at 400, 500, and 700°C, respectively. The structure of 1 was determined by X-ray crystallography and the nano-structures were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Thermal stabilities of nano and crystal samples of 1 were studied and compared with each other.     

Pyridine effected tunable luminescence properties of a 1D cadmium(II) polymer with tetranuclear second building units

One novel 1D polymer, [Cd₂(m-BrPhHIDC)₂(4,4′-bipy)(H₂O)₂]_n (1) (m-BrPhH₃IDC = 2-(3-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid; 4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesised and characterised by single-crystal X-ray diffraction, elemental analysis, IR, powder X-ray diffraction (PXRD) and thermogravimetric analysis. Polymer 1 composed of tetranuclear square [Cd₂(m-BrPhHIDC)₂] second building units and 4,4′-bipy bridges shows the interesting tunable luminescence properties aroused by pyridine. A luminescence enhance mechanism has been proposed.     

Synthesis,crystal structure,and fluorescence of a 2-D coordination polymer

A 2-D coordination polymer with mixed ligands, [Zn₂(BDC)(4,4′-bipy) (HCOO)₂] (1) (BDC, 1,4-benzenedicarboxylate; 4,4′-bipy, 4,4′-bipyridine), has been synthesized by solvothermal reaction. Compound 1 provides the first coordination polymer structure constructed by bridging BDC, 4,4′-bipy, and formate. Both BDC and 4,4′-bipy link zincs alternatively, resulting in a zigzag coordination chain; adjacent chains are further linked by formates to form an infinite extended 2-D folding screen layer. The synthesis mechanism and fluorescence property are discussed.     

Formation of [FeW12O40]5− under hydrothermal conditions: syntheses,crystal structures,and characterization of [Fe(2,2′-bipy)3]2[HFeW12O40] · 5H2O and (4,4′-H2bipy)6(Hpy)2(H3O)[FeW12O40]3 · 11H2O

Two supramolecular compounds based on tungstoferrate [FeW₁₂O₄₀]^5?, [Fe^II(2,2′-bipy)₃]₂[HFeW₁₂O₄₀] · 5H₂O (1), and [Hpy]₂[4,4′-H₂bipy]₆(H₃O)[FeW₁₂O₄₀]₃ · 11H₂O (2) (py = pyridine, bipy = bipyridine) were synthesized hydrothermally and characterized structurally. The hydrogen bonds between polyoxoanions and water and the edge-to-face π–π interaction between [Fe^II(2,2′-bipy)₃]²⁺ with a shortest C–C distance of 3.513 Å are the main forces to construct the 3-D architecture of 1. In 2, a 3-D supramolecular architecture is assembled by the tungstoferrate anions, protonated 4,4′-bipy cations, and water through hydrogen bonding. The variable-temperature magnetic susceptibilities indicate that 1 is paramagnetic with μ _eff corresponding to one Fe(III) with spin-only contribution, showing that Fe in the coordination cations has a +II oxidation number and low spin state.     

Syntheses,structures, thermal stabilities and bacteriostatic activities of four lanthanide complexes

Four lanthanide complexes, [La₂(2,4-DClBA)₆(5,5′-DM-2,2′-bipy)₂(H₂O)₂]·2C₂H₅OH (1) and [Ln(2,4-DClBA)₃(5,5′-DM-2,2′-bipy)(C₂H₅OH)]₂ (Ln = Pr(2), Sm(3), Gd(4); 2,4-DClBA = 2,4-dichlorobenzoate; 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine), were synthesized and characterized via elemental analysis, infrared spectra and thermogravimetric analysis (TG). The crystal structures of 1 and 2–4 are different; Each La³⁺ is nine-coordinate adopting a distorted mono-capped square antiprism, while the Ln³⁺ ions of 2–4 are all eight-coordinate with a distorted square antiprismatic molecular geometry. There are subtle changes in the local coordination geometry of the lanthanide–5,5′-DM-2,2′-bipy complexes. Binuclear 1 complexes are stitched together via two kinds of hydrogen bonding interactions (OH?O and CH?O) to form 1-D chains along the y axis, while the units of 2–4 are stitched together via CH?O to form 1-D chains along the x axis. TG analysis revealed thermal decomposition processes and thermal stabilities of the complexes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli, and Staphylococcus aureus.