Syntheses,structures and properties of two copper-2-picolinic-acid germanomolybdate hybrids with mixed organic components

Two inorganic–organic hybrids based on saturated α-Keggin-type germanomolybdates with mixed organic components [H₂DAP]₂[Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (1) and [NH₄]₂[H₈L] [Cu(PA)₂][α-GeMo₁₂O₄₀]·8H₂O (2) (DAP = 1.2-diaminopropane, HPA = 2-picolinic acid, H₆L = 1,3-bis[tris(hydroxymethyl)methylamino]propane) have been obtained via the conventional aqueous solution method and structurally characterized by elemental analysis, IR spectra, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. 1 stands for an one-dimensional linear organic–inorganic hybrid germanomolybdate chain constructed from classical Keggin [α-GeMo₁₂O₄₀]^4 − units supported by [Cu(PA)₂] linkers, whereas 2 represents the first hybrid germanomolybdate containing the H₆L component and consists of a saturated α-Keggin polyanion [α-GeMo₁₂O₄₀]^4 −, a diprotonated [H₈L]^2 + cation, a copper coordination complex [Cu(PA)₂], two ammonium cations [NH₄]⁺ and eight lattice water molecules. Furthermore, the electrochemical and electrocatalytic properties of 1 and 2 have also been investigated in detail.     

Four novel lanthanide(III) coordination polymers with 3D network structures containing 2-fold interpenetration

Four novel lanthanide(III) coordination polymers [Ln(L)_1.5(H₂O)₂]·5H₂O [Ln = Sm (1), Eu (2), Tb (3), Dy (4)] have been hydrothermally synthesized by the reaction of 1,2-bis[4-amino-5-carboxylmethylthio-(1,2,4-triazol-3-yl)]ethane (H₂L) with lanthanide(III) salts, and structurally characterized by single crystal X-ray diffraction. Polymers 1–4 are isostructural, in which all the Ln^III atoms are nine-coordinated and the carboxylate groups adopt three different coordination modes (bidentate chelate, bidentate bridging, bidentate chelate bridging) to connect Ln^III atoms. These polymers exhibit 3D network structures with 2-fold interpenetration, in which intriguing 1D channels are observed. Besides, the spectra properties of the title polymers are investigated, the strong luminescence characteristics of 2–3 are found.     

Effect of coordination environment on the magnetic relaxation of mononuclear DyIII field-induced single molecule magnets

Two mononuclear Dy^III complexes [Dy(H₂TEG)(NO₃)₃]·[18-crown-6] (H₂TEG = triethylene glycol) (1) and [Dy(H₂TEG)Cl₃]·[18-crown-6] (2) have been prepared using H₂TEG as ligands. Magnetic studies revealed that both complexes show field-induced double magnetic relaxation behavior with energy barriers of 28 K and 54 K. Distinct magnetic dynamic properties observed in 1 and 2 are mostly attributed to the dissimilar coordination environments around Dy^III centers in these two complexes.     

An unprecedented 3D honeycomb-shaped cobalt phosphonate containing sixfold helical chains: Synthesis,crystal structure and thermal stability

A new cobalt(II) phosphonate, [Co(aepa)(4,4′-bpy)(H₂O)₂]·2H₂O 1 (H₂aepa = 2-aminoethylphosphonic acid) has been hydrothermally synthesized and characterized by IR, elemental analysis, TGA and single crystal X-ray diffraction analysis. Compound 1 features a 3D alveolate network structure originating from the intertwist of the rare sixfold 1D helical chains, which are assembled from the coordination of the aepa^2? ligands to the cobalt atoms.     

Two Mn(II)–Au(I) supramolecular assemblies bonded by coordination,aurophilicity and hydrogen-bonding, π–π interactions and their magnetic properties

Two Mn(II)–Au(I) supramolecular assemblies {{Mn[Au(CN)₂]₂(H₂O)₄} [Au(CN)₂]₂(H₂bpy) · H₂O}(bpy = 4,4′-bipyridine) 1 and {Mn(4,4′-dmbpy) [Au(CN)₂]₂(CH₃OH)} (4,4′-dmbpy = 4,4′-dimethyl-bipyridine) 2 have been synthesized and magnetic properties have been investigated The interplay of aurophilicity, coordination, hydrogen-bonding and π–π interactions in two complexes result in three-dimensional network.     

Hydrothermal syntheses and characterization of a series of mixed-ligand luminescent CdII frameworks with novel 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate ligand and benzenedicarboxylate isomers

Under similar hydrothermal synthetic conditions using a novel flexible ligand 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetonitrile (PPAN), benzenedicarboxylate isomers (H₂pa = phthalate, H₂ip = isophthalate, and H₂tp = terephthalate) and Cadmium(II) acetate, three novel mixed-ligand Cd(II) coordination polymers {[Cd₂(PPAA)₂(μ-pa)(H₂O)]·2H₂O}_n (1), {[Cd₄(PPAA)₄ (μ₄-ip)₂]·2H₂O}_n (2) and {[Cd₂(PPAA)₂(μ-tp)]·2H₂O}_n (3) (PPAA⁻ = 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl) acetate) have been isolated, in 1–3 PPAN, and are also hydrolyzed into a novel PPAA⁻ ligand. Complex 1 is a 1D coordination polymer in which the tetra-nuclear [Cd₄(PPAA)₄]^4 + structural units are extended by tri-dentate μ-pa^2 − ligands. Complex 2 contains binuclear [Cd₂(PPAA)₂]^4 + structural units, which are extended by four tetra-dentate μ₄-ip^2 − ligands to link eight neighboring binuclear [Cd₂(PPAA)₂]^4 + units ultimately forming a 2D layered framework, while complex 3 contains 1D double chain containing [Cd(PPAA)]_n cation structural units, which are further extended by tetradentate μ-tp^2 − ligands to form a new 2D layered framework. All the complexes have been investigated by elemental analysis, FT-IR, thermal analysis and fluorescence characterization. The flexible coordination modes of PPAA⁻ are also briefly analyzed. The flexible coordination modes of PPAA⁻ and benzenedicarboxylate isomers also reveal great potential in the construction of these novel mixed-ligand luminescent frameworks with diverse structural motifs and unique functional properties.     

Syntheses, structures, and photoluminescence of two Cd(II) coordination polymers constructed from analogue (pyridyl)imidazole derivative and polycarboxylate acid

Two novel Cd(II) coordination frameworks based on a semirigid asymmetric ligand L and aromatic multi-carboxylate ligands, {[Cd₂L(btc)(H₂O)₂]·5H₂O}_n (1) and [Cd₂L₂(bdc)]_n (2) (L = (4-((2-(pyridine-2-yl)-1H-imidazol-1-yl)methyl)benzoic acid, H₃btc = 1,3,5-benzenetricarboxylic acid, H₂bdc = 1,3-benzenedicarboxylic acid), have been hydrothermally synthesized, and structurally characterized by elemental analysis, IR spectroscopy, single-crystal X-ray crystallography. Due to various coordination modes and conformations of the semirigid asymmetric ligand, and carboxylate containing co-ligands, therefore, the two complexes exhibit structural and dimensional diversity. Complex 1 exhibits a novel 2D (3, 5)-connected network structure with (3·5²)(3²·5³·6⁴·7) topology. Complex 2 exhibits a novel 3D CdSO₄ topology, which is formed from different dinuclear cadmium units. In addition, the photoluminescence properties of the free ligand L, and complexes 1 and 2 were studied in the solid state at room temperature.     

A functionalized polyoxometalate by hexanuclear copper–amino acid coordination complexes

A new functionalized polyoxometalate by transition metal–amino acid coordination complexes, H₄[Na(H₂O)₂][Cu₆Na(gly)₈(H₂O)₂][BW₁₂O₄₀]₂ · 13H₂O (1) (gly = glycine) has been synthesized and characterized by elemental analysis, IR spectroscopy, TG analysis, and single crystal X-ray diffraction. Compound 1 possesses a 3D framework, which is built up of [BW₁₂O₄₀]⁵⁻ building blocks, hexanuclear [Cu₆Na(gly)₈] coordination clusters and Na⁺ ions. Furthermore, magnetic measurements show ferromagnetic interactions for compound 1.     

Nested [Na6(H2O)]6+ encapsulation of nickel(II) coordination framework assembled from pyridyl-2,6-dicarboxylic acid

Hydrothermal reactions of pyridyl-2,6-dicarboxylic acid (H₂PDC) and NiCl₂ · 6H₂O in the presence of NaOH and KOH, respectively afforded the products, {[Ni(PDC)(Cl)](Na)(H₂O)/3}_n (1) and K₂[Ni(PDC)₂] · 7H₂O (2), of which 1 was characterized consisting of 3-D porous framework and [Na₆(H₂O)]⁶⁺ inclusions, and 2 was a mononuclear complex with potassium hydrate as counterion.     

Three unprecedented high-connected 3D lanthanide–organic frameworks based on benzene-1,2,4,5-tetracarboxylic acid

Three unprecedented high-connected 3D lanthanide coordination polymers based on benzene-1,2,4,5-tetracarboxylic acid (H₄bta), {[Ln₂(bta)_1.5(H₂O)₄] · 3H₂O}_n (Ln = La (1) and Ce (2)) and [Pr(bta)_0.5(H₂bta)_0.5(H₂O)]_n (3), have been synthesized under hydrothermal conditions. Complexes 1 and 2 show trinodal (4,4,10)-connected 3D network structures consisting of tetranuclear metal clusters bridged by bta^4 − ligands, and a chair conformation hexamer water cluster can be found within the cage enclosed by eight neighboring tetranuclear metal clusters in the two complexes. While 3 consists of 2D {Pr(bta)_0.5}_n layers linked by H₂bta^2 − ligands, resulting in an unprecedented trinodal (4,6,10)-connected 3D topological network. The organic ligand exhibits five kinds of coordination modes, in which one of them is reported for the first time. Moreover, the luminescent properties of 1–3 have also been investigated.     

A novel polyoxometalate-based metal-organic compound constructed from an unprecedented [Ag8(Hpyttz)4(H2pyttz)2] cluster and an in-situ [VW12O40]3 − anion

A novel polyoxometalate (POM)-based metal-organic compound constructed from a multinuclear Ag^I cluster and Keggin-type [VW₁₂O₄₀]^3 − anion, [Ag₄(Hpyttz)₂(H₂pyttz)][HVW₁₂O₄₀]·3H₂O (1) (H₂pyttz = 5′-(pyridin-4-yl)-1H,2′H-3,3′-bi(1,2,4-triazole), was hydrothermally synthesized and characterized by IR spectroscopy, TG analysis, powder and single-crystal X-ray diffraction. In compound 1, [VW₁₂O₄₀]^3 − (VW₁₂) was in-situ transformed from [SiW₁₂O₄₀]^4 − anion. Eight Ag^I ions were connected by six Hpyttz/H₂pyttz ligands with three coordination modes forming an unprecedented [Ag₈(Hpyttz)₄(H₂pyttz)₂] cluster, which connected with six VW₁₂ anions to construct a 2-D double-layer (3,6)-connected network with {4³}₂{4⁶.6⁶.8³} topology. Moreover, the photocatalytic activity of 1 has been investigated.     

Ionothermal synthesis of a new cobalt metal-organic framework based on tetranuclear cobalt clusters

A new metal-organic network (EMIM)[Co₂(hip)₂(μ₃-OH)]·H₂O (1), (H₂hip = 5-hydroxyisophthalic acid and EMIM = 1-ethly-3-methylimidazolium), has been synthesized by the ionothermal reaction of cobalt nitrate, H₂hip and [EMIM]Br ionic liquid. Single-crystal X-ray diffraction analysis reveals that 1 exhibits a two-dimensional (2D) bilayer constructed from tetranuclear [Co₄(μ₃-OH)₂] building units and hip²⁻ linkers. There are square cavities with the dimension of 10.161 × 10.868 Å. The [EMIM]⁺ cations are located in the cavities, which have the hydrogen bonding interactions with the bilayer. Further more, the strong hydrogen bonds between the carboxylate and hydroxyl oxygen atoms of hip²⁻ ligands and lattice water molecules extend the 2D layer into a 3D supramolecular network. The magnetic properties of 1 have been investigated by variable-temperature magnetic susceptibility and magnetization measurements, and the results reveal that there exist antiferromagnetic interactions.     

Assembly of one 2D layer and two 3D pillared-layer structures derived from metal ions and 5-(pyridin-4-yl)isophthalic acid with or without pillars

Three new coordination polymers, [Mn(L)(H₂O)₂]₂·5H₂O (1), [Cu(L)(4,4′-bipy)]₂·H₂O (2) and [Pb(L)(4,4′-bipy)_0.5] (3) (H₂L = 5-(pyridin-4-yl)isophthalic acid; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by IR, thermogravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. Complex 1 shows a 2D layer structure which stacks with the other ones to form 1D channels to hold 1D water chains. Complex 2 displays a 3D + 3D → 3D polycatenation network. 3 shows a unique 2D + 2D → 3D polycatenation net in which each Pb center has a hemidirected coordination geometry due to the existence of “inert pair effect”. The thermal and luminescent properties of 1–3 were also examined.     

Two octamolybdate-based hybrids functionalized by 1,3-bis[tris(hydroxymethyl)methylamino]propane ligand

Two octamolybdate-based organic–inorganic hybrids functionalized by 1,3-bis[tris(hydroxymethyl)methylamino]propane (H₆bthmap) Na₂H₄[γ-Mo₈O₂₆(H₅bthmap)₂]·2H₂O (1) and [NH₄]₆{[Cu(H₃bthmap)]₂(β-Mo₈O₂₆)} (2) have been synthesized through the aqueous synthetic method and structurally characterized by elemental analyses, IR spectra, UV spectra, thermogravimetric (TG) analysis and single-crystal X-ray diffraction. X-ray crystallography reveals that 1 consists of a classic [γ-Mo₈O₂₆]^4 − polyoxoanion decorated by two flexible [H₅bthmap]⁻ ligands through two O atoms from two [H₅bthmap]⁻ ligands and 2 contains a [β-Mo₈O₂₆]^4 − polyoxoanion with bisupporting [Cu(H₃bthmap)]⁻ anions via two terminal O atoms from the [β-Mo₈O₂₆]^4 − polyoxoanion. As far as we know, 1 and 2 represent the first octamolybdate-based hybrids with 1,3-bis[tris(hydroxymethyl)methylamino]propane ligands. The TG curves of 1 and 2 indicate two steps of weight loss and three steps of weight between 25 and 980 °C, respectively. Furthermore, the electrochemical and electrocatalytic properties of 1 and 2 have been investigated.     

A three-dimensional organic–inorganic 3d–4f hybrid polymer constructed with organic pyridinedicarboxylic acid and inorganic lanthanide sulfate skeletons

One 3d–4f heterometallic polymer, namely, {[Eu₂Cu(PDC)₂(SO₄)₂(H₂O)₆]·2H₂O}_n (H₂PDC = pyridine-3,5-dicarboxylic acid), has been successfully synthesized under hydrothermal conditions and structurally characterized. Single-crystal X-ray diffraction analysis reveals that the polymer features an unusual three-dimensional network structure in which infinite lanthanide-carboxylate chains are linked by [Cu(SO₄)₂]²⁻ metalloligands to form a mixed-metal coordination network. Furthermore, luminescent property of the hybrid material has also been investigated at room temperature.     

Synthesis,crystal structure and photoluminescent properties of a 3D Zn(II) coordination polymer

A new 3D coordination polymer [NH₂(CH₃)₂]₂[Zn₇L₄(DMF)₂(H₂O)₃]·19H₂O (1) (L = 2,3′,5,5′-biphenyl tetracarboxylic acid) has been solvothermally synthesized and structurally characterized by IR, elemental analysis and single-crystal X-ray diffraction. Single-crystal X-ray diffraction studies indicate that 1 exhibits 3D framework with a one-dimensional (1D) channel. The luminescence properties have been studied, and the results showed that 1 displays strong fluorescent emissions both in the solid state and in methanol suspension at room temperature. More interesting, the addition of Fe^3 + causes the fluorescence intensity of 1 to be weakened, which implies that it may be used as luminescent probes of Fe^3 +.     

A pair of novel helical Zn(II) enantiomers constructed from l- and d-threonine Schiff bases: Synthesis,crystal structures and properties

Two novel homochiral helical Zn(II) coordination polymers, {[Zn₂(nap-l-thr)₂(H₂O)₂]·H₂O}_n (1) and {[Zn₂(nap-d-thr)₂(H₂O)₂]·H₂O}_n (2) (H₂nap-l-thr = N-(2-hydroxy-1-naphthylmethylidene)-l-threonine, H₂nap-d-thr = N-(2-hydroxy-1-naphthylmethylidene)-d-threonine) have been successfully synthesized and characterized by elemental analysis, IR, UV–visible and single-crystal X-ray diffraction. It is interesting to note that both complexes are a pair of enantiomers: 1 exhibits 1D right-handed helical chain of [Zn-COO⁻]_∞ and 2 is 1D left-handed helical chain of [Zn-COO⁻]_∞. There are various hydrogen bonds between the adjacent helical chains which result in a 2D homochiral supramolecular layer structure. Notably, under similar synthetic procedure by using the NO₃⁻, CH₃COO⁻, Cl⁻ salts of Zn^2 + ion as a starting reagent, and identical compounds were obtained. In addition, the chiral nature of complexes 1 and 2 are confirmed by the results of circular dichroism (CD) spectra measurements. Thermal stability and luminescence properties were also investigated.     

Coordination assemblies of CdII/ZnII/CoII with the 3-(pyridin-4-yl) benzoate tecton: Structural diversity and properties

Three novel coordination polymers{[CdL₂(HL)(H₂O)]·(H₂O)}_n (1), [Zn₂(OH)L₃]_n (2) and [CoL₂(H₂O)]_n (3) have been hydrothermally synthesized from M(NO₃)₂·nH₂O (M^II = Cd^II, Zn^II and Co^II) and an unsymmetrical tecton 3-(pyridin-4-yl) benzoic acid (HL). All complexes show interesting structural patterns, namely, unprecedented 1D double-stranded supramolecular clasp for 1, novel (3,5,6)-connected helical tubular double layer for 2, 2-fold interpenetrating cds network for 3. The fluorescent and thermal properties of complexes 1, 2 and/or 3 have also been investigated.     

Three new coordination polymers based on 4-oxo-1(4H)quinolineacetate: Synthesis,structures and luminescent properties

Reactions of 4-oxo-1(4H)-quinolineacetic acid (Hoqa) and varied metal salts of Zn(II), Cd(II) and Ag(I) resulted in the formation of three new coordination polymers, namely, [Zn(oqa)₂]·H₂O (1), [Cd(bpy)(oqa)₂(H₂O)₂]·4H₂O (2) and [Ag(bpy)(oqa)]·2H₂O (3) (bpy = 4,4′-bipyridine). Complex 1 has a three-dimensional (3D) polymeric network with diamondoid topology; compounds 2–3 exhibit one-dimensional (1D) chain structure characteristics, which are further assembled through π–π stacking attractions and hydrogen bonds, forming the 3D supramolecular frameworks. In addition, the solid-state luminescent properties of the ligand Hoqa and complexes 1–2 have been investigated at room temperature.     

Tuning structural topologies of two coordination polymers via alter N-donor auxiliary ligand

Based on the N-donor auxiliary ligand effect, two new Ni(II) coordination polymers [Ni₂(HL)₂(bpe)₂] (1) and [Ni(HL)(bipy)(H₂O)₂] (2) [H₃L = 2-(4′-carboxyphenyl)terephthalic acid; bpe = 1,2-bis(4-pyridyl)ethane; bipy = 4,4′-bipyridine] have been successfully synthesized and characterized by single-crystal X-ray diffraction study, elemental analysis, IR spectra, TGA and powder X-ray diffraction (PXRD). This work presents a comparative study on the tuning of structural topologies by using two N-donor ligands with different lengths as auxiliary ligands. The structural determination reveals that complex 1, incorporating bpe ligands, features a three-dimensional (3D) 4-connected 4-fold dia interpenetrating architecture with the point symbol of 6⁶, while 2, containing bipy ligands, exhibits a two-dimensional (2D) sql layer structure with a 4-connected (4⁴·6²) topology. Moreover, the magnetic properties for 1 and 2 were also measured and compared on account of their different structures.