A new 2D network constructed by polymeric anions and lanthanides. Synthesis,structure and magnetic property of two new compounds

Two new compounds based on [H₂W₁₂O₄₀]^6? (W₁₂) clusters and Ln-organic complexes, [Ln₃(Hdipic)(dipic)(H₂O)₁₃(H₂W₁₂O₄₀)]·13H₂O Ln = Sm (1), Gd (2), (dipic = pyridine-2,6-dicarboxylate anion) have been synthesized and characterized by element analysis, IR spectrometry and thermogravimetric analysis. Single-crystal X-ray diffraction analyses reveal that compounds 1 and 2 are isostructural. In 1 and 2 four Ln³⁺ ions lie in a plane and form a centrosymmetric regular rhomblike ring {Ln₄(dipic)₂(Hdipic)₂(H₂O)₁₂}⁶⁺(Sm₄-ring) through the ligands. The covalent combination of W₁₂ subunits as a tetradentate ligand to Ln₄-rings from two sides creates a polymeric anion, {[H₂W₁₂O₄₀]₂[Ln₄(dipic)₂(Hdipic)₂(H₂O)₁₂]}^6?, and then Ln1 ions connect these anions leading to the 2D layers. The magnetic measurements indicate that in 1 and 2 there exist very weak antiferromagnetic interactions.     

A new 3D supramolecular compound containing 1D chains and 1D water chains

The first crystal structure involving the discrete unsubstituted 1,2,4-triazolate anion is reported. In the title compound, [Na₂(H₂O)₈]_n(trz)_2n [trz = 1,2,4-triazolate] (1), each sodium(I) ion is coordinated by six water molecules with a slight distorted octahedron geometry. Each Na(I) are bridged by two μ₂-aqua ligands and arranged in an alternating fashion to construct a 1D zigzag {[Na₂(H₂O)₈]²⁺}_n chain. The 3D supermolecular framework is formed with 1D {[Na₂(H₂O)₈]²⁺}_n chain as the assembly units, by 1D water chain and 1,2,4-triazolate anion as the hydrogen bonding spacers.     

Synthesis, crystal structures and photoluminescence of Zn–Ln heterometallic polymers based on pyridine-2,3-dicarboxylic acid

Three new two-dimensional 3d–4f isostructural heterometallic coordination polymers, namely [Ln₂Zn(2,3-pydc)₄(H₂O)₄·4H₂O]_n (Ln = Sm (1), Eu (2), Gd (3), 2,3-pydcH₂ = pyridine-2,3-dicarboxylic acid) have been successfully synthesized by the hydrothermal reactions of Ln₂O₃, Zn(NO₃)₂·6H₂O, H₂pydc and H₂O. X-ray diffraction analyses reveal that they possess a 2D heterometallic framework containing 1D lanthanide chains based on dimeric [Ln(2,3-pydc)₂(H₂O)₂]₂ unit. The Zn(II) ion, which is six-coordinated by four oxygen and two nitrogen atoms from four 2,3-pydc²⁻ ligands, as a bridge, links the lanthanide chains to make the 1D chains further extend into 2D layer framework. Furthermore, the neighboring layers are assembled into three-dimensional supramolecular network through inter-layer O–HO and C–HO hydrogen-bond interactions. In addition, the solid-state luminescent property of complex 2 was investigated.     

Decorated rutile net built on the six-connected Ln2 SBUs (secondary building units) and three-connected organic spacers

Three new three-dimensional Lanthanide coordination polymers, namely [Ln₂(Ac)₂(ip)₂(H₂O)₄ · H₂O]_n [LnGd(1), Sm(2), Nd(3)], where Ac = acetate, ip = isophthalate, have been synthesized in hydrothermal method and characterized by single-crystal X-ray diffraction. Compounds 1–3 are isostructural and crystallize in the monoclinic system, space group P2(1)/C. Thermogravimetry, infrared spectra, elemental analysis have also been used to characterize 1. From topological view, the compounds present the second lanthanide-based, non-interpenetrating, decorated rutile net with the (4 × 6²)(4² × 6¹⁰ × 8³)₂ topology notation. Notably, within them, (H₂O)₆ cluster formed by free and coordinated water molecules via H-bonds is observed; and based on the consideration of the average OO distance and IR spectrums, it is similar to those of liquid water.     

Hexanuclear 4d–4f complexes [Ln2Ag4(ina)8(H2O)10][NO3]2 · 4H2O (Ln = Sm, Eu, Dy): Syntheses, structures and photoluminescent properties

Hexanuclear 4d–4f heterometallic complexes, [Ln₂Ag₄(ina)₈(H₂O)₁₀][NO₃] ₂ · 4H₂O [Ln = Sm (1), Eu (2), Dy (3) and Hina = isonicotinic acid], have been synthesized by the hydrothermal reaction of lanthanide oxides, Ag^I, and isonicotinic acid at a suitable temperature. Single-crystal X-ray diffraction studies indicate that these 4d–4f complexes consist of extended 1D zigzag chains structure built upon [Sm₂Ag₄(ina)₈(H₂O)₁₀] subunits connected by Ag–Ag interactions. Furthermore, the photoluminescent properties of the complex 2 were studied.     

Preparation, crystal structure and properties of two novel metal-organic frameworks assembled from pyridine-3,5-dicarboxylic acid N-oxide

Two novel coordination polymers, [Cu(PDCO) · (H₂O)]_n (1) and [Cd(PDCO)(bipy) · (H₂O) · 5H₂O]_n (2), (H₂PDCO = pyridine-3,5-dicarboxylic acid N-oxide, bipy = 4,4′-bipyridine), have been synthesized under hydrothermal conditions, and their structures were determined by single-crystal X-ray diffraction studies. Polymer 1 features a three-dimensional (3D) network with nonequivalent nodes of (6³)₂(6⁹ · 8⁵ · 10) topology. Polymer 2 exhibits one-dimensional (1D) double-stranded chains. The magnetic character of 1 as well as the gas adsorption and luminescent properties of 2 have been investigated.     

1-D and 2-D lanthanide coordination polymers constructed from 4-sulfobenzoate and 1,10-phenanthroline

Two complexes {[Dy₂(4-SBA)₃(phen)₂(H₂O)₄] · 2H₂O}_n (1) and {[Eu₂(4-SBA)₃(phen)₂(H₂O)₂]}_n (2) (4-SBA = 4-sulfobenzoate, phen = 1,10-phenanthroline) were synthesized and their structures were determined by X-ray crystallography. The 1 has a 1-D chain structure by bidentate and tridentate 4-SBA ligands as linkages and 3-D network was formed by strong hydrogen bonds. The 2 has a 2-D network structure by tridentate and tetradentate 4-SBA ligands as linkages. The luminescence properties and thermal stability of the two complexes were investigated.     

Design and construction of two new polymers featuring macrocyclic subunits based on a rigid clamp-like ligand

Reaction of a rigid conjugated clamp-like ligand N,N′-bis(pyridin-3-yl)-2,6-pyridinedicarboxamide (bppdca) with ZnSO₄·7H₂O or CoSO₄·7H₂O resulted in the formation of two new polymers, namely, {[Zn₂(bppdca)(SO₄)₂(DMF)₂]·(DMF)}_n (1) and {[Co(bppdca)(SO₄)(CH₃OH)(DMF)]·H₂O}_n (2). Both 1 and 2 feature one-dimensional double-chain structures with macrocyclic subunits, and the chains further self-assemble into a higher-dimensional framework via the hydrogen-bonding and π–π stacking interactions. Fluorescence studies show that the free ligand displays a strong fluorescence emission in solid state at room temperature, but in 1 and 2, the complexation of the ligand with metal ions and weak intermolecular interactions make the fluorescence emission partial quenching.     

Three cobalt (II) complexes with triethylenetetraaminehexaacetic acid: From binuclear complex to 3d-4f coordination polymers

The cobalt(II)–lanthanide(III) heteronuclear complexes [Ln(H₂O)₄Co₂(TTHA)(SCN)₂]·H₃O⁺ (H₆TTHA = triethylenetetraaminehexaacetic acid, Ln = La(2), Ce(3)) have been synthesized based on a binuclear building block of [Co₂(H₂TTHA)(H₂O)₂] in [Co₂(H₂TTHA)(H₂O)₂]·4H₂O (1). Single-crystal structures show that complex 1 is a binuclear complex, containing the [Co₂(H₂TTHA)(H₂O)₂] unit as a useful building block. Adding the La^3 + and Ce^3 + ions to this synthesis system, two new 3d-4f mixed complexes 2 and 3 were obtained. Complexes 2 and 3 show 3D framework, comprising an infinite 1D (one-dimensional) chain based on heterometallic Ln₂Co₂ (Ln = La(2), Ce(3)). Further investigations such as IR spectra, UV–vis spectra, TGA, XRD and magnetic properties were studied.     

Synthesis,crystal structures and NIR luminescence properties of binuclear lanthanide Schiff Base complexes

Three binuclear lanthanide complexes [Nd₂(L¹)₃(MeOH)]·MeOH·H₂O (1) and [Ln₂(H₂L²)₂(OAc)₄]·2(CF₃SO₃)·MeOH·EtOH (Ln = Nd (2) and Ho (3)) were prepared using two Schiff base ligands. Interestingly, 1 has a triple-decker structure with two lanthanide ions enclosed by three rigid conjugated Schiff base ligands (H₂L¹), while 2 and 3 show nanoscale ring structures (8 × 12 × 12 Å) formed by flexible long-chain Schiff base ligands (H₂L², ~ 23 Å) with the lanthanide ions located in the center. Upon excitation of the ligand-centered absorption bands, 1–2 and 3 show typical NIR emission spectra for Nd^3 + and Ho^3 + ions, respectively. In 1, the Nd(III) centers are shielded within the decker-like structure and surrounded by chromogenic Schiff base ligands (energy transfer donors). Luminescence studies show that the NIR emission lifetime of 1 is longer than that of 2 in solution.     

Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

First dicadmium(II) complex of tripodal amide ligand with one edge-sharing monocapped octahedral geometry

A new dicadmium(II) complex [Cd₂(L)₂(H₂O)₂](NO₃)₄ · 8H₂O (1) with the tripodal amide ligand L (tris[3-aza-2-oxo-4-(2-pyridyl)butyl]amine) was synthesized and structurally characterized. Complex 1 is revealed as a dinuclear 2:2 (Cd:L) complex, in which each cadmium(II) ion is hepta-coordinated with the coordination surrounding of distorted monocapped octahedral geometry. Two cadmium(II) ions are dibridged by two carbonyl μ-O atoms forming a Cd₂(μ-O)₂ parallelogram-type moiety. Interestingly, the dinuclear coordination sphere can be seen as resulting from the fusion of two distorted monocapped octahedral [Cd(L)(H₂O)]²⁺ units through sharing one edge originated from the two carbonyl μ-O atoms as a first example. Comparative NMR, IR and FAB-mass data of 1 are also discussed.     

A novel lamella 2D Ag(I) coordination polymer of graphite-like structure featuring short interlayer distance

The reaction of Ag₂O with a mixture of benzene-1,3,5-tricarboxylic acid (H₃BTC) and 2-aminopyrazine (APYZ) under the ammoniacal conditions gives rise to a novel metal–organic coordination polymer Ag₆(BTC)₂(APYZ)₆·9H₂O (1). The structure of 1 possesses a high ordered lamella 2D structure with an interesting graphite-like 6³ net which is comprised of Ag₄ and Ag₆ fused hexagonal rings respectively. 1 exhibits photoluminescence maximized at 416 nm upon 330 nm excitation at room temperature, which may be mainly ascribed to ligand-to-ligand charge transfer (LLCT). Semiconducting behavior was also measured at ambient temperature with σ values of 5.56 × 10⁻⁷ S cm⁻¹ based on the π–π stacking and Ag(I)–π interactions.     

Novel Hg and Mn supramolecular complexes with a versatile building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiolate involving in situ ligand formation

Reaction of potassium N′-(pyridine-4-carbonyl)-hydrazinecarbodithioate ([K⁺(H₂L)⁻]) with Hg^II or Mn^II inorganic salt in the presence of 1,10-phenanthroline (phen) or 4,4′-bipyridine (bipy), yields complexes [Hg(pyt)₂(phen)] (1) and {[Mn(pyt)₂(H₂O)₂]·(bipy)·(H₂O)₂}_n (2), in which the pyt ligand (Hpyt = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thiol) is obtained by in situ ligand formation from the acyclic precursor [K⁺(H₂L)⁻]. Single crystal X-ray diffraction suggests that the pyt anionic ligands in 1 and 2 behave as thiolate and thione isomers, respectively, and display S- and μ-N_pyridyl, N_oxadiazole-binding fashions. Complex 1 shows a 1-D fishbone-like supramolecular array via strong aromatic stacking interactions between the discrete mononuclear coordination motifs, whereas 2 has a 2-D layered host coordination framework with the inclusion of bipy and water guests in the cavities.     

Novel lanthanide coordination polymers with Eu-compound exhibits warm white light emission: Synthesis,structure, and magnetic properties

Five two-dimensional lanthanide coordination polymers: [Ln₂(TDA)₃(bipy)₂(H₂O)₂]·bipy·2H₂O (Ln = Nd (1), Sm (2), Eu (3), Tb (4), Yb (5), TDA = thiophene-2,5-dicarboxylic acid anion, bipy = 2,2′-bipyridine) were fabricated and structurally characterized. Compounds 1–5 are isostructural belonging to the triclinic system with space group P-1. Luminescence analyses were performed on coordination polymers containing Eu^3 + and Tb^3 +, and compound 3 shows a warm white light emission upon excitation.     

pH Dependent formations of dinuclear molybdenum(V) and incomplete cubane molybdenum(IV) complexes with nitrilotriacetate

Nitrilotriacetato oxomolybdenum(V) dinuclear complex (NH₄)₄[cis-Mo₂O₄(nta)₂] · 7H₂O (1) (H₃nta = nitrilotriacetic acid) and its incomplete cubane-type trinuclear molybdenum(IV) complex [Mo₃O(OH)₃(Hnta)₃] · Cl · 3H₂O (2) are isolated in a weak acidic and an acidic solutions, respectively (pH 4.5 and 1.0). The nitrilotriacetate ligand in the anion 1 or the cation 2 displays tridentate mode through the nitrogen atom and the oxygen atoms of β-carboxy groups. Unusual protonations of bridged oxygen atoms in 2 have not effect on the skeleton of molybdenum(IV) cap Mo₃O unit. There are obvious dissociations of molybdenum(V) complexes based on ¹³C NMR observations in solution.     

Structure and magnetic properties of a copper malonate/dipyridylamine layered coordination polymer with both syn–anti and anti–anti copper carboxylate chains

The novel 2-D copper metal–organic layered coordination polymer {[Cu₂(malonate)₂(dpa)(H₂O)₂] · H₂O} (1, dpa = 4,4′-dipyridylamine) has been prepared and characterized by single-crystal X-ray diffraction, IR and thermogravimetric analysis. The structure of compound 1 consists of alternating syn–anti and anti–anti copper malonate 1-D chains linked into a (6,3) herringbone layer motif through tethering dpa ligands. Variable temperature magnetic studies indicate weak ferromagnetic coupling through the 1-D copper malonate chains with J = 0.64(1) cm⁻¹ and g = 2.033(4).     

Microporous rare-earth coordination polymers constructed by 1,4-cyclohexanedicarboxylate

In this paper, three novel microporous materials of 1, 4-cyclohexanedicarboxylate Ln[(C₈H₁₀O₄)_1.5(H₂O)] · 0.5(H₂O) (Ln = Eu for 1, Nd for 2, Sm for 3) are synthesized by the hydrothermal method. The powder X-ray diffraction patterns demonstrate three complexes are isomorphism. The crystal structure of the coordination polymer 1 reveals that the Eu³⁺ ion center is located in the nine-coordinated environment and the carboxyl groups chelate Eu³⁺ ions to form 1-D channels through c-axis in μ_1, μ₂ and μ₃ fashion. The properties of the microporous materials are all characterized by the adsorption and desorption of the nitrogen gas and show tremendous difference. TGA illustrate the open frameworks are stable to about 450 °C and they are retained upon removal of water molecules in channels.     

Near-infrared (NIR) luminescent homoleptic linear tetranuclear [Ln4((OH)2-Salophen)4] (Ln = Nd or Yb) complexes self-assembled from the dihydroxylated Salophen ligand

Through self-assembly of the (OH)₂-Salophen H₄L (H₄L = N, N′-bis(3-hydroxyl salicylidene)benzene-1,2-diamine) with LnCl₃·6H₂O (Ln = La, Nd, Yb, Er or Gd), series of [Ln₄((OH)₂-Salophen)₄]-arrayed complexes [Ln₄(H₂L)₂(L)₂(EtOH)₂] (Ln = La, 1; Ln = Nd, 2; Ln = Yb, 3; Ln = Er, 4 or Ln = Gd, 5) were obtained, respectively. The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 2–3 with emissive lifetimes in microsecond ranges is observed, and the sensitization arises from the excited state (¹LC) of the (OH)₂-Salophen ligand despite the luminescent quenching with OH-oscillators around the Ln^3 + ions.     

Syntheses,crystal structures and luminescence properties of lanthanide coordination polymers involving in situ C–S bond cleavage of (4-pyridylthio)acetic acid

Lanthanide coordination polymers with the formula [Ln₂(C₂O₄)₃(H₂O)₆]_n (1) (Ln = Nd, 1) and [Ln₂(C₂O₄)₃(pythioH)₂(H₂O)₂]_n (Ln = Eu 2; Dy 3; Er 4) pythio = 4-pyridinethiolate) were synthesized by treating Ln^III nitrates with (4-pyridylthio)acetic acid under hydrothermal conditions. Single-crystal X-ray diffraction studies indicate that these lanthanide coordination polymers consist of extended oxalate-bridged two-dimensional layer structure. Interestingly, in situ C–S bond cleavage occurred and (4-pyridylthio)acetic acid was transformed into 4-pyridinethiolate and oxalate. The complexes 2 and 3 display strong fluorescent emission in the solid state at room temperature.