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.     

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.     

3D pillar-layered 4d–4f heterometallic coordination polymers based on pyridine-3,5-dicaboxylate and oxalate mixed ligands

Three 4d–4f heterometallic polymers, Ln₂Ag₂(Hpydc)₂(pydc)₂(ox) · 4H₂O (Ln = Nd (1), Eu (2) and Er (3); H₂Pydc = pyridine-3,5-dicarboxylic acid, H₂ox = oxalic acid), have been successfully synthesized under hydrothermal condition and structurally characterized. Single-crystal X-ray diffraction analyses reveal that three compounds are isomorphous and exhibit 3D pillar-layered coordination frameworks constructed from two-dimensional lanthanide-carboxylate layers and [Ag(pydc)]^? pillars. Furthermore, the luminescent property of compound 2 was 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.     

One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses,crystal structures and magnetic properties

Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H₂O)}Ln(MeOH)(H₂O)₂{(μ-CN)₂Fe(CN)₄}]·2H₂O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)₆]^3? ions (H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)₆]^3? ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form.     

Synthesis,crystal structures and photoluminescent properties of the complexes of a new coumarin derivative with lanthanide ions

A new coumarin-based podand-type ligand (L) and its five complexes [Ln(NO₃)₃L] (Ln = Pr (1), Eu (2), Gd (3), Tb (4) and Er (5)) were synthesized. The X-ray single-crystal diffraction analyses indicate that these complexes are isomorphous and lanthanide ions are ten-coordinated. The tetradentate ligand forms a half-ring coordination structure with its oxygen atoms and the distances of its two chelate chains vary regularly with the ionic radii. The photoluminescence properties were also investigated by phosphorescence, quantum yields and lifetime.     

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.     

Syntheses,structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H₂N(CH₃)₂]₈H₃[LnNa(H₂O)₄(OH)WO(H₂O) (B-α-AsW₉ O₃₃)₂]·8H₂O [Ln = La^III (1), Ce^III (2), Pr^III (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na₂WO₄·2H₂O, C₂H₇N·HCl, NaAsO₂ and Ln(NO₃)₃·6H₂O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H₂O)₄(OH) WO(H₂O)(B-α-AsW₉O₃₃)₂]^11 − polyanion consists of two trivacant Keggin [B-α-AsW₉O₃₃]^9 − moieties linked by one [WO(H₂O)]^4 + group and a dimeric [LnNa(H₂O)₄(OH)]^3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.     

Template-assisted assembly of porous lanthanide coordination polymers with 2-aminoterephthalic acid

Porous lanthanide coordination polymers, {[Ln₂(atpt)₃(H₂O)₂] · 0.5(4,4′-bpy)(H₂O)}_n [Ln = Eu(1), Gd(2), Yb(3), H₂atpt = 2-aminoterephthalic acid, 4,4′-bpy = 4,4′-bipyridine] were obtained by hydro-solvothermal reaction, in which 4,4′-bpy acts as template. For the first time the nitrogen atom of an atpt ligand coordinates to metal ions in 1–3. The photophysical properties and thermal stability of 1 were investigated.     

Construction of three-dimensional Ln–Ag (Ln = Eu; Tm) coordination polymers based on isonicotinate and oxalate ligands

Hexanuclear 4d–4f heterometallic coordination polymers, [Ln₂Ag₄(IN)₅(ox)₂(NO₃)(H₂O)₂ · 3H₂O] [Ln = Eu (1), Tm (2); IN = isonicotinate and ox = oxalate], have been synthesized by hydrothermal reaction of mixed organic ligands and metal salts. Both structures display the same unusual 3D heterometallic coordination frameworks based on rare zigzag lanthanide–oxalate–silver chains, Ag₂(IN)₃ units and IN linkers. The photoluminescent properties of complex 2 were studied.     

Two novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu2Ln2(ox)(SiW11)2} dimers and [Cu(en)(ox)]/[Cu(en)2] linkers

Two novel 2-D organic–inorganic hybrid silicotungstates [H₂en][Cu(en)₂(H₂O)]₂{[Cu(en)₂]₃[Cu(en)(ox)]₂[Ln₂(ox)(α-SiW₁₁O₃₉)₂]}·nH₂O (Ln = Er^III, n = 10 for 1, Ln = Sm^III, n = 8 for 2) with mixed organic ligands of ox and en (ox = oxalate, en = ethylenediamine) have been hydrothermally synthesized and characterized by IR spectrum, thermogravimetric analysis (TGA), power X-ray diffraction (PXRD) and X-ray single-crystal diffraction, respectively. Notably, 1 and 2 are isomorphic and exhibit the first novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu₂Ln₂(ox)(SiW₁₁)₂} dimers and [Cu(en)(ox)]/[Cu(en)₂] linkers. Furthermore, the TG curve of 1 and 2 display three steps of weight loss in the range of 25–1000 °C.     

Syntheses,structures and properties of chiral Ln(III) coordination polymers based on (R)-4-(4-(1-carboxyethoxy)phenoxy)-3-fluorobenzoic acid

Two isomorphic chiral lanthanide coordination polymers (CCPs), namely, [Ln₂(cpfa)₃]_n {Ln = Yb Xu et al. (2011) and Lu Zheng et al. (2015) } {H₂cpfa = (R)-4-(4-(1-carboxyethoxy)phenoxy)-3-fluorobenzoic acid, have been synthesized under hydro(solvo)thermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), powder X-ray diffraction (PXRD), elemental analyses, thermogravimetric (TG) analyses and circular dichroism spectra (CD). Structure analysis reveals that CCPs 1 and 2 are isomorphic, crystallizing in Orthorhombic space group P2₁2₁2₁ and giving 3D rhombic framework. Further, CCP 1 show the strong NIR luminescence of Yb(III) ions, suggesting that [cpfa]^2 − is able to sensitize the luminescence of lanthanide ions efficiently. The two polymers also exhibit modest SHG efficiency indicating their potential application as optical materials. Thermogravimetric analyses show the remarkable thermal stabilities of the two lanthanide 3D frameworks up to 420 °C.     

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.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Synthesis,structural characterization and properties of a novel 1D helical chain arsenomolybdate {[Cu(en)2][Cu(en)(H2O)][(Cu(en)2(H2O)] [AsIIIAsVMo9O34)]} · 2H2O

An organic–inorganic hybrid 1D helical chain arsenomolybdate {[Cu(en)₂][Cu(en)(H₂O)][(Cu(en)₂(H₂O)] [As^IIIAs^VMo₉O₃₄)]} · 2H₂O (1) (en = ethylenediamine) has been hydrothermally synthesized and characterized by elemental analyses, IR, UV and CD spectrum, powder X-ray diffraction, TG-DTA and single-crystal X-ray diffraction. The asymmetric unit of 1 consists of a monocapped trivacant Keggin [As^IIIAs^VMo₉O₃₄]^6 − subunit, a pendant [Cu(en)₂(H₂O)]^2 + cation, a pendant [Cu(en)(H₂O)]^2 + cation, one bridging [Cu(en)₂]^2 + cation and two lattice water molecules. It should be noted that 1 illustrates a one-dimensional (1D) helical chain assembled by {[Cu(en)(H₂O)][(Cu(en)₂(H₂O)][As^IIIAs^VMo₉O₃₄)]}^2 − clusters and [Cu(en)₂]^2 + linkers.     

Lanthanide coordination polymers constructed from 5-(4-pyridyl)-isophthalic acid: Synthesis,structure and photoluminescent properties

Nine lanthanide coordination polymers [Ln₂(pyip)₃(H₂O)₄·DMF·3H₂O]_n (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) based on the pyip^2 − ligand {H₂pyip = 5-(4-pyridyl)-isophthalic acid} have been synthesized under solvothermal conditions. X-ray crystallographic studies reveal that 1–9 are isostructural and crystallize in the triclinic system, space group P2₁/c, and exhibit a 3D framework. Topological analysis reveals that the 3D framework can be simplified to a uninodal 6-connected pcu alpha-Po primitive cubic type structure. Meanwhile, the luminescent properties of these nine coordination polymers in the solid state are also investigated. Especially the Eu and Tb compounds show bright red and green luminescence with luminescence lifetimes of 0.39 and 0.80 ms, respectively.     

Synthesis,structure, and characterization of polymeric lanthanide 2-aminoterephthalate frameworks [Ln2(atp)3(H2O)2]·dmf·4H2O

X-ray crystallography reveals four isostructural lanthanide polymeric solids, [Ln₂(atp)₃(H₂O)₂]·dmf·4H₂O (atp = 2-aminoterephthalate; dmf = N,N′-dimethylformamide; Ln = La (1), Ce (2), Pr (3) and Nd (4), respectively) that are obtained from the solvothermal synthesis which are crystallized in an interesting 3D polymeric framework with a (4,4,6)-linked {4²·8⁴}{4⁴·6²}₂{4⁸·6⁶·8}₂ fsy net topology. Upon excitation at 350 nm, they all show the solid state ligand-centered luminescences but both 2 and 3 also exhibit the weak lanthanide-based characteristic emissions in the visible region at room temperature. The cyclic voltammetric investigation indicates that 2 exhibits appreciable electrochemical activity for formaldehyde.     

A series of lanthanide (III) coordination polymers derived via in situ hydrothermal decarboxylation of quinoline-2,3-dicarboxylic acid

A series of one-dimensional coordination polymers assembled from LnNO₃ · 6H₂O (Ln = Sm(1), Eu(2), Tb(3), La(4), Ce(5), Pr(6), Nd(7), Dy(8)), quinoline-2,3-dicarboxylic acid (2,3-H₂qldc) and 1,10-phenanthroline (phen) formulated as [Ln(2,3-qldc)(3-qlc)(phen)]_n (3-Hqlc = quinoline-3-carboxylic acid) were obtained under hydrothermal conditions. It is remarkable that in situ hydrothermal decarboxylation was observed during preparing these polymers. Complexes 1–8 were characterized by elemental analyses, IR spectroscopy and single crystal X-ray diffraction analyses. The thermal stabilities and photoluminescence properties of these complexes have been investigated.     

1D chain lanthanide coordination polymers with 6-hydroxynicotinic acid: Crystal structures and luminescent properties

Four new lanthanide coordination polymers {[Ln(HL)₂(H₂O)₅] · HL ·  H₂O}_n (Ln = Sm for 1, Eu for 2, Tb for 3 and Dy for 4) (H₂L = 6-hydroxynicotinic acid) have been synthesized and characterized by elemental analysis, FT-IR spectra and X-ray single-crystal diffraction. They all exhibit 1D chain structure, which are further linked via hydrogen bonds to form 3D supramolecular architecture. Luminescent properties of these lanthanide coordination polymers are studied.     

Synthesis and characterization of decanuclear Ln(III) cluster of mixed calix[8]arene-phosphonate ligands (Ln = Pr,Nd)

Two novel decanuclear Ln(III) compounds (Ln = Pr for 1, Nd for 2) have been solvothermally obtained by using p-tert-butylcalix[8]arene (H₈TBC8A) and phenylphosphonate (PhPO₃H₂) as ligands. Single crystal X-ray diffraction studies reveal that both compounds are stacked by dumbbell-like Ln₁₀ clusters, which are capped by two TBC8A^8 − supports and linked by four complementary PhPO₃^2 − ligands as well as other bridging anions. In addition, the self-assembly behavior of both compounds is interesting: the cationic Ln₁₀ cluster layers are separated by the layers of H₆TBC8A^2 − ligands. Moreover, the luminescent and magnetic properties of both compounds were examined.