Synthesis, structures, and luminescence properties of lanthanide complexes with structurally related new tetrapodal ligands featuring salicylamide pendant arms

To explore the relationships between the structures of ligands and their complexes, we have synthesized and characterized a series of lanthanide complexes with two structurally related ligands, 1,1,1,1-tetrakis{[(2'-(2-benzylaminoformyl))phenoxyl]methyl}methane (L(I)) and 1,1,1,1-tetrakis{[(2'-(2-picolyaminoformyl))phenoxyl]methyl}methane (L(II)). A series of zero- to three-dimensional lanthanide coordination complexes have been obtained by changing the substituents on the Pentaerythritol. Our results revealed that, complexes of the L(I) ligand, {Ln(4)L(I)(3)(NO(3))(12).nC(4)H(10)O}(infinity) (Ln = Nd, Eu, Tb, Er, n = 3 or 6)] show the binodal 3,4-connected three-dimensional interpenetration coordination polymers with topology of a (8(3))(4)(8(6))(3) notation. Compared to L(I), complexes of L(II) present a cage-like homodinuclear [Ln(2)L(II)(2)(NO(3))(6).2H(2)O].nH(2)O (Ln = Nd, Tb, Dy, n = 0 or 1) or a helical one-dimensional coordination {[ErL(II)(NO(3))(3).H(2)O].H(2)O}(infinity) polymer. The luminescence properties of the resulting complexes formed with ions used in fluoroimmunoassays (Ln = Eu, Tb) are also studied in detail. It is noteworthy that subtle variation of the terminal group from benzene to pyridine not only sensibly affects the overall molecular structures but also the luminescence properties as well.     

Structure variation and luminescence properties of lanthanide complexes with 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane

Using 1,9-salicylamide bissubstituted oxadecane ligand, 1,9-bis [2-(2′-picolylaminoformyl)-1,4,7,9-tetraoxadecane (L), two novel lanthanide complexes have been prepared and well characterized by means of elemental analysis, IR spectroscopy, UV-vis spectroscopy, TGA analysis and single-crystal X-ray diffraction. {[PrL(NO₃)₃(H₂O)₂]·CH₃OH}_n is a 1D zigzag polymer with three-dimensional supramolecular structure formed by hydrogen bonds, while [EuL(NO₃)₃(H₂O)]_n is a linear coordination polymer and present an interesting supramolecular double chain, which are very different from the structure of terbium complex reported before. The result reported herein demonstrated that steric crowding associated with the decreasing lanthanide ion radius causes changes of the conformation of the ligand as well as structures. Luminescence studies for the Eu(III) complexes demonstrated that the salicylamide ligand also exhibits a good antennae effect for the Eu(III) ion due to efficient intersystem crossing and ligand-to-metal energy transfer and the Eu(III) ion is well shielded from the surrounding environment.     

Hydrothermal syntheses and characterization of four 2-D lanthanide coordination polymers with glutarate and 1,10-phenanthroline

Four 2-D coordination polymers Ln₂(phen)₂(C₅H₆O₄)₃ [Ln?=?Pr(1), Eu(2), Er(3), Yb(4), phen?=?1,10-phenanthroline] were obtained via hydrothermal reactions and determined by X-ray diffraction analysis. The crystal structure data reveal that these complexes are isostructural. In the asymmetric unit, the two Ln(III) ions are nine-coordinate and have similar coordination environments. The Ln(III) ions are built into 2-D layers by three different coordination modes of glutarate. The resulting 2-D layer forms 3-D supramolecular architecture by two types of π···π stacking interactions. All the complexes were characterized by IR spectra and thermogravimetric analysis, and the emission spectrum shows that Eu₂(phen)₂(C₅H₆O₄)₃ possesses strong luminescence.     

Hydrothermal synthesis, crystal structure and luminescence of four novel metal-organic frameworks

Using the principle of crystal engineering, four novel metal-organic coordination polymers, {[Cd₁(nic)2(H₂O)]2[Cd₂(nic)2(H₂O)2]}_n (1), [Cd₂(fma)2(phen)2]_n (2), [Cd(fma)(bipy)(H₂O)]_n (3) and [Zn(mal)(bipy)·3H₂O]_n (4) (nic=nicotinate, fma=fumarate, mal=malate, phen=phenanthroline, bipy=2,2′-bipyridine) have been synthesized by hydrothermal reaction of M(CH₃COO)2·2H₂O (M=Zn, Cd) with nicotinic acid, fumaric acid and cooperative L (L=phen, bipy), respectively. X-ray analysis reveals that complex 1 possesses an unprecedented two-dimensional topology structure constructed from three-ply-like layers, complex 2 is an infinite 2D undulating network, complex 3 is a 1D zigzag chain and complex 4 belongs to a 1D chain. The results indicate a transformation of fumarate into malate during the course of hydrothermal treatment of complex 4. The photophysical properties have been investigated with luminescent excitation and emission spectra.     

Synthesis,structure and luminescence properties of two novel lanthanide complexes with 2-fluorobenzoic acid and 1,10-phenanthroline

Two lanthanide complexes with 2-fluorobenzoate (2-FBA) and 1,10-phenanthroline (phen) were synthesized and characterized by X-ray diffraction. The structure of each complex contains two non-equivalent binuclear molecules, [Ln(2-FBA)₃?·?phen?·?CH₃CH₂OH]₂ and [Ln(2-FBA)₃?·?phen]₂ (Ln?=?Eu (1) and Sm (2)). In [Ln(2-FBA)₃?·?phen?·?CH₃CH₂OH]₂, the Ln³⁺ is surrounded by eight atoms, five O atoms from five 2-FBA groups, one O atom from ethanol and two N atoms from phen ligand; 2-FBA groups coordinate Ln³⁺ with monodentate and bridging coordination modes. The polyhedron around Ln³⁺ is a distorted square-antiprism. In [Ln(2-FBA)₃?·?phen]₂, the Ln³⁺ is coordinated by nine atoms, seven O atoms from five 2-FBA groups and two N atoms of phen ligand; 2-FBA groups coordinate Ln³⁺ ion with chelating, bridging and chelating-bridging three coordination modes. The polyhedron around Ln³⁺ ion is a distorted, monocapped square-antiprism. The europium complex exhibits strong red fluorescence from ⁵D₀?→?⁷F _j ( j?=?1–4) transition emission of Eu³⁺.     

Hydrothermal synthesis and crystal structure of two new lanthanide coordination polymers with 1,2-phenylenediacetate

Two new compounds {[Ln₂(1,2-pda)₃(H₂O)₂]·?2H₂O} _n (1,2-H₂pda?=?1,2-phenylenediacetic acid, Ln?=?Tb, 1; Ho, 2) were prepared by hydrothermal reaction and characterized by X-ray crystallography. The Ln³⁺ is nine-coordinate by eight oxygen atoms of six 1,2-pda ligands and one oxygen of water. Ln³⁺ ions are bridged by 1,2-pda ligands via bridging/chelating-bridging pentadentate and chelating-bridging/chelating-bridging hexadentate coordination to form 3-D framework structures. Complex 1 emits strong green fluorescence corresponding to ⁵D₄???⁷F_j (j?=?6–3) transitions of the Tb³⁺.     

Three new lanthanide compounds based on nitronyl nitroxide radical: Crystal structure,magnetic properties,and luminescence properties

Three new lanthanide compounds were obtained using 2-(3-methylthiophene)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) (NIT-3Methien). These compounds, [Gd(hfac)₃(NIT-3Methien)₂]?0.5CH₃(CH₂)₅CH₃ (1: Half n-heptane trihexafluoroacetylacetonate-di-2-(3-methylthiophene)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide gadolinium(III)), [Tb(hfac)₃(NIT-3Methien)₂]?0.5H₂O (2: Half Hydrate trihexafluoroacetylacetonate-di-2-(3-methylthiophene)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide terbium(III)), and [Dy(hfac)₃(NIT-3Methien)₂]?0.5H₂O (3: Half Hydrate trihexafluoroacetylacetonate-di-2-(3-methylthiophene)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide dysprosium(III)), (CH₃(CH₂)₅CH₃ = n-heptane), (hfac = hexafluoroacetylacetonate), were characterized structurally and magnetically. The three compounds crystallize in the triclinic space group P1( - ). Ln(III) ion was eight-coordinate by six oxygens from three hfac ligands and two oxygens from two radicals. In 1, direct current (DC) magnetic studies reveal ferromagnetic interactions between the Gd(III) ion and radicals with J₁ = 0.94 cm^?1. In 2 and 3, there are antiferromagnetic interactions between the Tb(III), or Dy(III) ions and radicals. The luminescence characterizations show that 2 exhibits highly selective luminescent sensing of Cr₂O₇^2? ions.     

Different crystal structure and photophysical properties of lanthanide complexes with 5-bromonicotinic acid

Five novel lanthanide (Eu³⁺ (1), Tb³⁺ (2), Sm³⁺ (3), Dy³⁺ (4) and Gd³⁺ (5)) complexes with 5-Bromonicotinic acid (5-Brnic) were synthesized and two of them (Tb³⁺, Sm³⁺) were characterized by X-ray diffraction. The results reveal that {[Tb(5-Brnic)₃(H₂O)₃]·H₂O}_n (2) and [Sm(5-Brnic)₃(H₂O)₂·H₂O]₂ (3) exhibit different coordination geometries and crystal structures. Complex 2 has a one-dimensional chain-like polymeric structure through the bridged 5-Brnic anions which links up two neighboring terbium ions, while Complex 3 forms a dimeric molecular structure. The lowest triplet state energy of 5-Brnic was determined to be 24 330 cm⁻¹ corresponded to the 0-0 transition in the phosphorescence spectrum of its gadolinium complex at 411 nm. The strong luminescent emission intensities of these complexes indicated that the triplet state energy of 5-Brnic is suitable for the sensitization of luminescence of Eu³⁺, Tb³⁺, Sm³⁺ and Dy³⁺, especially for that of Tb³⁺ and Dy³⁺.     

Dinuclear rare-earth picrate complexes based on a multidentate amide ligand: syntheses,crystal structures,and luminescence properties

A new amide-based multidentate ligand, N,N′-1,2-ethanediyl-bis{2-[(N,N-diethylcarbamoyl)methoxy]benzamide} (L) reacts with M(Pic)₃?·?6H₂O to give rare-earth picrate complexes [M₂L₂(Pic)₄(H₂O)₂](Pic)₂ (M = La (1), Nd (2), Eu (3), Gd (4), Tb (5), Dy (6), Yb (7), Y (8)). X-ray single-crystal diffraction analyses indicate that dinuclear complexes 3?·?2C₄H₈O₂, 6?·?2C₄H₈O₂, and 8?·?2CH₃CN are isomorphous. Each metal is nine-coordinate by four oxygen atoms of two ligands, four oxygen atoms of two bidentate picrates, and one water molecule with a distorted monocapped square antiprism. With hydrogen bonds between the free picrate anions and the coordination cations the complexes exhibit 2-D layers. The luminescent properties of 3 [Eu₂L₂(Pic)₄(H₂O)₂](Pic)₂ are described and factors that influence luminescent intensities are also discussed.     

A 1-D chain praseodymium complex with chelidamic acid: synthesis,structure, and optical properties

The title compound [Pr(C₇H₃NO₅)(C₇H₄NO₅)(H₂O)₂] _n · 1.25nH₂O (1) or [Pr(HChel)(H₂Chel)(H₂O)₂] _n · 1.25nH₂O, where H₃Chel is 4-hydroxypyridine-2,6-dicarboxylic (chelidamic) acid, was synthesized by reaction of chelidamic acid, PrCl₃ · 6H₂O and H₂O under hydrothermal conditions, and characterized by X-ray single-crystal diffraction. The crystal structure of 1 reveals that Pr is nine-coordinate with distorted tricapped trigonal prismatic coordination. Coordination polyhedra are interlinked into a 1-D chain, further linked by hydrogen bonds into a 3-D network. Fluorescence spectra exhibit strong green luminescence with maximum emission at 530 nm when excited with λ _ex = 475 nm, originating from π–π* of the ligand.     

Hydrothermal syntheses,crystal structures and luminescence properties of two lanthanide dinuclear complexes with hexafluoroglutarate

Two complexes [Ln₂(hfga)₂(phen)₄(H₂O)₆] · hfga · 2H₂O (H₂hfga = hexafluoroglutaric acid, phen = 1, 10-phenanthroline, Ln=Tb, 1; Eu, 2) were synthesized under hydrothermal conditions and their structures determined by X-ray crystallography. The complexes consist of dinuclear units with an inversion center. Each Ln(III) is nine-coordinate with two carboxylate oxygens from two hfga ligands, three oxygens from water and four nitrogens from two phen molecules. Two carboxylate groups of one hfga adopt monodentate coordination to Ln(III) as a long bidentate bridge linking two Ln(III) ions to form a dimer. Ln(III) ··· Ln(III) distances of 9.027(3) Å for 1 and 9.043(3) Å for 2 were observed. Both complexes emit strong fluorescence and show characteristic emission of Tb(III) and Eu(III) ions, respectively.     

Synthesis,crystal structure,and characterization of two lanthanide coordination polymers based on isonicotinate ligand

Two new europium complexes [Eu(inic)₃(H₂O)] (1) and [Eu(inic)₃] (2) [inic = isonicotinate] have been structurally determined by single-crystal X-ray diffraction and characterized by elemental analysis, infrared spectroscopy, fluorescence, and thermogravimetric analysis. In the two complexes, bifunctional isonicotinate ligands interlink europium metal ions to construct 2-D (for 1) and 3-D (for 2) coordination polymeric networks.     

Synthesis, crystal structure, and chirality of divalent lanthanide reagents containing tri- and tetraglyme

Six new divalent lanthanide complexes using triglyme (trigly) and tetraglyme (tetgly) as achiral ligands have been prepared, using a facile synthetic method, in search for enantioselective solid-state reagents. The crystal structures of cis-[SmI₂(trigly)thf] (1), trans-[YbI₂(trigly)thf] (2), trans-[SmI₂(trigly)dme] (3), trans-[YbI₂(tetgly)] (4), trans-[EuI₂(tetgly)thf] (5), and [Sm(tetgly)₂][SmI₃(tetgly)]I (6) have been determined. All complexes, except 5, are chiral. The 10-coordinate cation in 6 displays a helical chirality since the two tetraglyme ligands are wrapped around the samarium ion. Since trans-[YbI₂(tetgly)] (4), which has a chiral arrangement of terminal methyl groups, crystallizes as a conglomerate, preferential crystallization and consequent enantioselective reduction of acetophenone was attempted, but resulted in racemic products, possibly on account of racemic twinning in 4.     

Pyridine solvated dioxouranium complex with salen ligand: Synthesis,characterization and luminescence properties

A new derivative of dioxouranium(VI) salen complex, [UO2(L)(pyridine)], where [L = N,N′-Bis(2-hydroxybenzylidene)-2,2-dimethyl-1,3-propanediamine] is synthesized and characterized by elemental analysis (C, H, N), FT-IR, ESI-MS spectrometry, UV/Vis, fluorescence, ¹H and ¹³C NMR spectroscopy and thermal gravimetric (TG) study. Furthermore, the single crystal X-ray diffraction measurements of the complex were carried out at 100 and 273 K. The crystal structure measurements revealed that the complex has distorted pentagonal bipyramidal geometry with uranium atom located at the centre and bonded to two phenoxy oxygen and two azomethine nitrogen in tetradenate fashion and one nitrogen from pyridine making it seven coordinated. In addition, the photoluminescence property of the complex was also recorded.     

三维开放骨架镧系金属有机配位聚合物Tm(BTC)(DMF)(DMSO)的合成、结构和性质

以稀土元素铥(Tm) 作为金属中心, 均苯三甲酸(H3BTC)作为有机配体制备了一个新型的三维配位聚合物 Tm(BTC)(DMF)(DMSO), 并通过X射线单晶衍射、元素分析、热重分析、吸附测试等手段对其进行了表征.     

Crystal structure,thermodynamic behavior,and luminescence properties of a new series of lanthanide halogenated aromatic carboxylic acid complexes

Five lanthanide complexes with polydentate coordination were successfully synthesized by volatilization of 2,4-difluorobenzoate and o-phenanthroline ligands. The structure general formula is [Ln(2,4-DFBA)₃(phen)]₂, (Ln = La(1), Gd(2), Tb(3), Dy(4), Ho(5); 2,4-DFBA = 2,4-difluorobenzoate, phen = o-phenanthroline). The crystal structures of five complexes were determined, and supramolecular structures were probed. Characterization was performed by elemental analysis, IR, Raman spectroscopy and XRD, followed by an examination of the fluorescence and heat capacity properties. The molar heat capacities of complexes 4 and 5 were determined in detail by the DSC apparatus, and the thermodynamic functions were calculated. Finally, the fluorescence properties of complexes 3 and 4 were investigated. Using DFT, the HOMO, LUMO energy levels of the ligands and their single and triplet state energy levels were calculated at the level of the valence layer cleavage 6-311G(d,p) basis group, and the fluorescence enhancement mechanism was explained from the energy transfer perspective.     

A series of novel metal-ferrocenedicarboxylate coordination polymers: crystal structures, magnetic and luminescence properties

Novel two-dimensional layered lanthanide(III)-ferrocenedicarboxylate coordination polymers {[M(η²-O₂CFcCO₂-η²)(μ₂-η²-O₂CFcCO₂-η²-μ₂)_0.5(H₂O)₂]·mH₂O}_n (Fc=(η⁵-C₅H₄)Fe(η⁵-C₅H₄), M=Tb³⁺, m=2, 1; M=Eu³⁺, m=2, 2; M=Y³⁺, m=1, 3) with trapezium-shaped units and one-dimensional wave-shaped Cd(II)-ferrocenedicarboxylate polymer {[Cd(η²-O₂CFcCO₂-η²)(H₂O)₃]·4H₂O}_n (4) have been prepared and structurally characterized by single crystal diffraction. In polymers 1-3, each central metal ion (Tb(III), or Eu(III) or Y(III)) is located in a pseudo-capped-tetragonal prism coordination geometry, and ferrocenedicarboxylate anion ligands have two coordination modes (bidentate-chelating mode and tridentate-bridging mode). The magnetic behaviors for 1 and 2 are studied in the temperature range of 5.0-300 K. The results show that the paramagnetic behavior of 2 is mainly due to the effective spin-orbital coupling between the ground and excited states through the Zeeman perturbation, and the weak magnetic interaction between Eu³⁺ centers can be observed. In addition, compared with sodium ferrocenedicarboxylate, the fluorescent intensities of the polymers 1-4 are enhanced in the solid state.     

Synthesis,structure and luminescent properties of a new two-dimensional (4,4) network cadmium coordination polymer with dicyanamide and benzimidazole ligands

The new cadmium coordination polymer [Cd(bim)₂(dca)₂]_n (1), (bim?=?benzimidazole, dca?= dicyanamide) was synthesized and characterized by IR, thermogravimetric analysis and luminescent properties. The coordination geometry of cadmium atom is distorted octahedral, coordinated equatorially by four nitrogen atoms from four dicyanamide ligands, and axially by two nitrogen atoms from two benzoimidazoles. Each dca ligand links two cadmium(II) atoms and 1 forms a two-dimensional (4,4) network.     

Influence of secondary ligand on structures and topologies of lanthanide coordination polymers with 1,3,5-triazine-2,4,6-triamine hexaacetic acid

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln₄(TTHA)₂(pzac)(H₃O)₂(H₂O)]·5H₂O (Ln = Pr (1a) and Nd (1b)), [Sm₈(TTHA)₄(pzac)_0.5(H₃O)(H₂O)_7.5]·4H₂O (2), [Ln₄(HTTHA)₂(SO₄)(H₂O)₄]·5H₂O (Ln = Pr (3a) and Nd (3b)), where H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H₂pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H₆TTHA as the primary ligand and either the in situ generated pzac^2? or sulfate as the secondary ligands. The influence of the deprotonated H₆TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.     

Synthesis,structure, and photoluminescence of a series of lanthanide coordination polymers constructed from nitrogen containing organic ligands

We have synthesized four coordination polymers with two different nitrogen containing organic ligands and different lanthanide metal ions, under hydrothermal condition. [{Ln₂(bpdc)₃(H₂O)₂}] _n (Ln = Dy (1), Sm (2)) (bpdc = 2,2-bipyridine-3,3-dicarboxylic acid) are isostructural, with 2-D supramolecular layer structure composed from 1-D chains. Like 1 and 2, [{Ln(pzda)₂(H₂O)₂} · 4H₂O] _n (Ln = Dy (3), Nd (4)) (pzda = pyrazine-2,6-dicarboxylic acid) are also isostructural with 1-D chain-like structures. The photoluminescence of 2 is studied.