Lanthanide Coordination Polymers Research Articles

Multi-Color Luminescence and Sensing of Rare Earth Hybrids by Ionic Exchange Modification.

Luminescent rare earth coordination polymers [H2NMe2]3[Y(DPA)3] ([H2NMe2](+)=dimethyl amino cation; H2DPA=2,6-dipicolinic acid) are synthesized and is further modified by the ionic exchange reaction of [H2NMe2](+) cation with rare earth ions, which is named as RE(3+)⊂[Y(DPA)3] (RE=Eu, Tb, Sm, Dy) hybrid systems. The multi-color can be tuned for these functionalized hybrid systems and even white color luminescence can be integrated for Sm(3+)⊂[Y(DPA)3]. Besides, the fluorescent sensing property of Tb(3+)⊂[Y(DPA)3] system is checked, which shows high selectivity towards Cr(3+) with the concentration of 10(-5)mol⋅L(-1).

Understanding the Structure of Reversible Coordination Polymers Based on Europium in Electrostatic Assemblies Using Time-Resolved Luminescence.

In situ characterization of the structure of reversible coordination polymers remains a challenge because of their dynamic and concentration-responsive nature. It is especially difficult to determine these structures in their self-assemblies where their degree of polymerization responds to the local concentration. In this paper, we report on the structure of reversible lanthanide coordination polymers in electrostatic assemblies using time-resolved luminescence (TRL) measurement. The reversible coordinating system is composed of the bifunctional ligand 1,11-bis(2,6-dicarboxypyridin-4-yloxy)-3,6,9-trioxaundecane (L2EO4) and europium ion Eu(3+). Upon mixing with the positively charged diblock copolymer poly(2-vinylpyridine)-b-poly(ethylene oxide) (P2VP41-b-PEO205), electrostatic polyion micelles are formed and the negatively charged L2EO4-Eu coordination complex simultaneously transforms into coordination "polymers" in the micellar core. By virtue of the water-sensitive luminescence of Eu(3+), we are able to obtain the structural information of the L2EO4-Eu coordination polymers before and after the formation of polyion micelles. Upon analyzing the fluorescence decay curves of Eu(3+) before and after micellization, the fraction of Eu(3+) fully coordinated with L2EO4 is found to increase from 32 to 83%, which verifies the occurrence of chain extension of the L2EO4-Eu coordination polymers in the micellar core. Our work provides a qualitative picture for the structure change of reversible coordination polymers, which allows us to look into these "invisible" structures.

Lanthanide Coordination Polymer Nanoparticles as an Excellent Artificial Peroxidase for Hydrogen Peroxide Detection

Lanthanide coordination polymer nanoparticles (Ln-CPNs) have been recently demonstrated as excellent platforms for biomolecule detection. In this work, we synthesized novel cerium coordination polymer nanoparticles ATP-Ce-Tris CPNs in a simple and quick way using ATP molecules as the biocompatible ligands to Ce(3+) ions in tris(hydroxymethyl)aminomethane hydrochloric (Tris-HCl) solution. In view of the excellent free radical scavenging property of cerium compounds, which is ascribed to the mixed valence state (Ce(3+), Ce(4+)) and the reversible switch from Ce(3+) to Ce(4+), the synthesized ATP-Ce-Tris CPNs was used as artificial peroxidase to selectively and sensitively detect H2O2. The sensing mechanism depends on the oxidation of the fluorescent ATP-Ce(III)-Tris CPNs to nonfluorescent ATP-Ce(IV)-Tris CPNs by H2O2. Compared with those inorganic cerium oxide sensors, this kind of fluoresence ATP-Ce-Tris CPNs sensor needs no additional organic redox dye, such as ABTS (2,20-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid), TMB (3,3,5,5-tetramethylbenzidine), or fluorescein as signal molecules. Moreover, such ATP-Ce-Tris CPNs sensor exhibited a more sensitive response to H2O2 with a detection limit down to 0.6 nM, which is 2 orders of magnitude lower than those of cerium oxide sensors. This sensing platform was further extended to the detection of glucose in combination with the specific catalytic effect of glucose oxidase (GOx) for the oxidation of glucose and formation of H2O2.

Lanthanide‐Coordination Polymers with Pyridinedicarboxylic Acids: Syntheses, Structures, and Luminescent Properties

AbstractFive lanthanide coordination polymers (Ln‐CPs) based on pyridine‐dicarboxylate and lanthanide metal ions were synthesized and characterized, namely [Sm(pydc)(Hpydc)(H2O)5]·4H2O (1) (H2pydc = 2, 5‐pyridine‐dicarboxylic acid), [Ho(pydc)(Hpydc)(H2O)3]n·4nH2O (2), [Ce(pydc)(bdc)(H2O)]n (3) (H2bdc = 1, 4‐benzenedicarboxylic acid), [Nd2(dipic)3(H2O)3]n (4), and [Pr2Ag2(dipic)4(H2O)5]n·5nH2O (5) (H2dipic = 3, 5‐pyridine‐dicarboxylic acid). Complexes 1 and 2 display mononuclear structure and 1D zigzag chains, respectively. In complex 3, the CeIII ions are connected through pydc2– and bdc2– ligands to generate an intricate 3D architecture. Complex 4 is constructed through dinuclear {Nd2} SBUs and oxygen bridging from carboxyl groups of dipic2– to generate a 3D framework. In 5, PrIII ions and AgI ions are assembled into a 2D heterometallic layer, in which the rare Ag···Ag weak interactions are observed. Furthermore, the solid state luminescent properties of 1–4 were measured and discussed.

Synthesis, Structure, and Luminescent Properties of Lanthanide Coordination Polymers Based on 5‐Hydroxyisophthalate and Phen Ligands

AbstractThree lanthanide coordination polymers incorporating 5‐hydroxyisophthalate (L) and phen ligands, [Eu(L)(phen)]n (1) and [Ln(L)(phen)2]n [Ln = Sm (2) and Pr (3)], were synthesized. X‐ray structural analysis reveals that 1 features a (3,6)‐connected 3D rtl topology. Complexes 2 and 3 are isostructural and have 2D sheets with 63 topology. Comparison of the structural differences between 1 and 2 (or 3) suggests that the different metal sources play an important role in the formation of such coordination networks. Compounds 1 and 2 show photoluminescence and their emission properties are closely related to their corresponding central LnIII atoms.

Self-Assembly Syntheses, Structural Characterization, and Luminescent Properties of Lanthanide Coordination Polymers Constructed by Three Triazole-Carboxylate Ligands

Herein, 15 lanthanide coordination complexes based on three di-, tri-, and tetra-carboxylic ligands with imidazolyl groups have been solvothermally designed, synthesized, and characterized. All the complexes exhibit high thermal stabilities and can remain stable in the open air more than 7 days. Luminescent spectra of Eu3+ and Tb3+ complexes at room temperature indicate that the three carboxylic ligands H2L1, H3L2, and H4L3 are promising potential light sensitizers for lanthanide ions based on their suitable triplet energy levels. Luminescent lifetimes and quantum yields of these compounds were further measured and compared. The correlations between their structural features and photophysical properties are discussed in detail.

Visible and near-infrared luminescence of polycatenated cationic pyridinone lanthanide networks

A series of isomorphic lanthanide coordination polymers [Ln(III)(MBP)2(NO3)2(Br)·2C3H6O] [Ln=Eu, Tb, Er, Yb, and Gd; MBP=N,N′-methylene-bis(pyridin-4-one)] featuring polycatenated sql cationic network and incorporated bromide counter ion were prepared. Their visible and near-infrared (NIR) luminescence properties were characterized by steady-state excitation and emission spectra, as well as luminescence lifetimes and quantum yields. The D 2d dodecahedron coordination geometry causes visible light excitations and strongly monochromatic emissions. The external heavy-atom environment induces remarkable enhancement on the NIR emissions. The sensitization processes are revealed by analyzing the electronic properties of MBP ligand.

Smart lanthanide coordination polymer fluorescence probe for mercury(II) determination

Lanthanide coordination polymers (LCPs) have recently emerged as attractive biosensor materials due to their flexible components, high tailorable properties and unique luminescence features. In this work, we designed a smart LCP probe of Tb-CIP/AMP {(CIP, ciprofloxacin) (AMP, adenosine monophosphate)} for Hg2+ detection by using lanthanide ions as metal nodes, CIP as ligand molecule, and AMP as bridging linker and recognition unit. Tb-CIP/AMP emits strong green luminescence due to the inclusion of AMP, which withdraws the coordinated water molecules and shields Tb3+ from the quenching effect of O–H vibration in water molecules. The subsequent addition of Hg2+ into Tb-CIP/AMP can strongly quench the fluorescence because of the specific coordination interaction between AMP and Hg2+. As a kind of Hg2+ nanosensor, the probe exhibited excellent selectivity for Hg2+ and high sensitivity with detection limit of 0.16 nM. In addition, the probe has long fluorescence lifetime up to millisecond and has been applied to detect Hg2+ in drinking water and human urine samples with satisfactory results. We envision that our strategy, in the future, could be extended to the designation of other LCP-based hypersensitive time-gated luminescence assays in biological media and biomedical imaging.

Magnetic Properties and Photoluminescence of Lanthanide Coordination Polymers Constructed with Conformation-Flexible Cyclohexane-Tetracarboxylate Ligands

To investigate the effects on the physical properties of complexes with different conformations of flexible ligands, four lanthanide (Ln) coordination polymers with flexible ligand cyclohexane-1e,2a,4a,5e-tetracarboxylic acid (H4LI), [Ln(HLII)(H2O)2]·1.5H2O (Ln = Dy, 1; Tb, 2) and [Ln2(H2LIV)(LIV)(H2O)4]·1.5H2O (Ln = Dy, 3; Tb, 4), have been synthesized and characterized. Complexes 1 and 2 are 2D layers composed of LII ligands and [Ln2O2] dinuclear units whereas complexes 3 and 4 are 3D coordination frameworks constructed with LIV ligands and two kinds of dinuclear units, [Ln2O2] and [Ln2(COO)2]. Notably, the conformations of ligands in two structures, which were different and changed from the original LI conformation to LII (e,a,e,e) and LIV (e,e,e,e) conformations, impact the construction of different structures and the magnetic properties. Complex 1 shows antiferromagnetic interactions whereas complex 3 exhibits weak ferromagnetic interactions and slow magnetic relaxation properties. Additionally, the photoluminescence of complexes 2 and 4 have been investigated.

A new series of trivalent lanthanide (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy) coordination polymers with a 1,2-cyclohexanedicarboxylate ligand: synthesis, crystal structure, luminescence and catalytic properties

Eight lanthanide coordination polymers (Ln(1,2-chdc)(form)(H2O)) have been solvothermally synthesized from the reaction of 1,2-cyclohexane dicarboxylic acid (denoted as 1,2-chdcH2) with trivalent metallic cations (Ce3+ (1), Pr3+ (2), Nd3+ (3), Sm3+ (4), Eu3+ (5), Gd3+ (6), Tb3+ (7) and Dy3+ (8); from a nitrate or chloride source) in a mixed H2O/N,N-dimethylformamide solvent (DMF) at T = 100–150 °C (form = formate ligand). Their crystal structures are similar and built up from nine-fold coordinated lanthanide cations (LnO9 – tricapped trigonal prism), linked to each other through three Ln–O–Ln bonds (face sharing connection mode of LnO9 polyhedra) in order to generate infinite ribbons. The coordination sphere of the lanthanide center is ensured by oxygen atoms from the 1,2-chdcH2 ligand and formate groups. The latter come from the partial solvothermal decomposition of DMF solvent. The resulting compounds exhibit a layered structure with infinite chains of LnO9, connected to each other via the ditopic 1,2-chdc linker. Luminescence studies (steady-state excitation, emission and time-resolved decay measurements) have been performed on the compounds bearing Ce3+, Nd3+, Sm3+, Eu3+, Tb3+, and Dy3+ cations. The Nd compound (3) was found to be efficient for isoprene (methyl-2-butadiene, CH2CH–C(Me)CH2) polymerization despite the presence of water in its molecular structure, affording a highly cis stereo-regular polymer.

From 1D to 3D lanthanide coordination polymers constructed with pyridine-3,5-dicarboxylic acid: synthesis, crystal structures, and catalytic properties

Three series of lanthanide coordination polymers have been synthesized. The structural difference may be derived from the lanthanide contraction. Moreover, we also discussed the size-selective catalytic activity towards cyanosilylation of aldehydes.

Hybrid materials based on novel 2D lanthanide coordination polymers covalently bonded to amine-modified SBA-15 and MCM-41: assembly, characterization, structural features, thermal and luminescence properties.

Three novel 2D coordination polymers [Tb2(μ4-L)2(μ-HL)(μ-HCOO)(DEF)]n (Tb-L), [Eu(μ4-L)(L)(H2O)2]n (Eu-L), and [Nd(μ4-L)(L)(H2O)2]n (Nd-L) were assembled from the corresponding lanthanide(iii) nitrates and 5 methoxy-(4-benzaldehyde)-1,3-benzenedicarboxylic acid (H2L) as a main multifunctional building block bearing carboxylate and aldehyde functional groups, using H2O/DEF {DEF = N,N-diethylformamide} as a reaction medium. The obtained coordination polymers were isolated as stable microcrystalline solids and fully characterized by elemental analysis, FT-IR spectroscopy, TGA, BET, PXRD, and single-crystal X-ray diffraction methods. Their structures feature intricate 2D metal-organic networks, which were topologically classified as underlying layers with the 4,6L26 (for Tb-L) or sql (for Eu-L and Nd-L) topologies. Besides, a novel series of mesoporous hybrid materials wherein the Tb-L, Eu-L, or Nd-L coordination polymers are covalently grafted into the amine-functionalized SBA-15-NH2 or MCM-41-NH2 matrices (via the formation of Schiff-base groups) was also synthesized and fully characterized. These hybrid materials show high thermal and photoluminescence stability, as well as remarkable chemical resistance to boiling water, and acidic or alkaline medium. Luminescent properties of the parent coordination polymers and derived hybrid materials are investigated in detail, showing that the latter combine the luminescent characteristics (intense green or red emissions and excellent stability) of lanthanide coordination polymers and structural features of ordered mesoporous silica molecular sieves. Moreover, light emitting devices were assembled, by coating the hybrid materials onto the surface of UV-LED bulbs, and showed excellent light emitting properties.

Lanthanide Coordination Polymer Nanosheet Aggregates: Solvothermal Synthesis and Downconversion Luminescence

A lanthanide coordination polymers (CPs) nanostructure (1) has been synthesized via a facile template-free solvothermal strategy using DMF as solvent and 2-methyl benzoic acid (2-MeBAH) as ligands. The products are characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), elemental analyses (EA), and downward luminescence. Product1built from Tb3+and 2-MeBAH has one-dimensional structure which is connected by trinuclear second building units (SBUs). Downward luminescence shows that sample1exhibits characteristic transitions of the Tb3+ion at 489, 544, 583, and 621 nm, and the strongest peak is at 544 nm ascribed to the transition ofD45→F57of Tb3+.

Three types of lanthanide coordination polymers from 1D to 3D based on a tetracarboxylate ligand: synthesis, structural diversities and properties

Three types of lanthanide coordination polymers with the formulas [Ln(Habtc)(H2O)(DMA)]n (1–3) {Ln = Ho (1), Er (2), Tm (3)}, [Ln(Habtc)(H2O)2(DMF)]n (4–6) {Ln = Gd (4), Er (5), Tm (6)} and {[(CH3)2NH2][(H2abtc)2Ln(H2O)]·5H2O}n {Ln = Gd (7), Dy (8), Er (9), Tm (10)} were constructed under solvothermal conditions in the presence of 3,3′,5,5′-azobenzenetetracarboxylic acid (H4abtc). They have three structural types from 3D to 1D polymers. The structural features of the three types of Ln-CPs are as follows: 1–3 shows a three-dimensional (3D) framework with an sni-type topology. Compounds 4–6 form a 2D sheet-like extended structure and these sheets stack on each other to give a 3D supramolecular architecture. The structures of 7–10 can be described as 1D chains constructed from Ln3+ ions and H2abtc2− ligands. The versatile structures well exhibit the rich coordination chemistry of H4abtc and the coordination geometries of LnIII ions. In addition, the magnetic and luminescence properties of complex 8 were investigated. Luminescent selective and sensitive sensing of Cr3+ compared with other metal ions was investigated by using 8. Moreover, the 1D anionic lanthanide coordination polymer 10 presents highly selective adsorption of cationic dyes via ion-exchange processes. The results show that H4abtc is a good ligand for constructing CPs with varying structures and properties.

Photoluminescence enhancement induced by a halide anion encapsulation in a series of novel lanthanide(iii) coordination polymers

The halogen anions encapsulated in the tunnel of 2D Ln-CPs could enhance solid-state photoluminescence.

Excitation wavelength-induced color-tunable and white-light emissions in lanthanide(iii) coordination polymers constructed using an environment-dependent luminescent tetrazolate–dicarboxylate ligand

Color-tunable and white-light emitting lanthanide(iii) polymers with a selective light-emitting ligand have been constructed.

A visual and reversible assay for temperature using thioflavin T-doped lanthanide/nucleotide coordination polymers.

In this work, we prepared a type of thioflavin T (ThT)-doped lanthanide/nucleotide coordination polymer by the self-assembly of ThT, europium ions (Eu(3+)) and nucleotides (guanosine monophosphate, GMP) in aqueous solution (i.e. ThT/Eu/GMP). The Eu/GMP coordination polymers show excellent adaptive inclusion properties for ThT in a convenient one-step approach, which can readily enhance the fluorescence of ThT via the restricted effect. Moreover, the as-prepared hydrophilic ThT/Eu/GMP coordination polymers have the capability to act as a temperature-sensitive, visual and reversible sensor in aqueous solution under the irradiation of visible light. Our proposed design is cost-effective and simple to prepare without chemical modification or fluorescence labeling.

Crystal growth and structural remarks on malonate-based lanthanide coordination polymers

The synthesis, structural and thermal studies of several malonate-containing lanthanide(iii) complexes plus a structural overview of twenty-three known homometallic Ln(iii)-malonate systems are provided herein.

Hydrothermally Synthesis and Characterization of Lanthanide Coordination Polymers with (42.62.82)(43.63)2(46.67.82)(48.67) Topology {[Ln2(1,4-pda)3(H2O)]·2H2O}n (Ln = Pr, Nd, Dy)

Hydrothermally Synthesis and Characterization of Lanthanide Coordination Polymers with (42.62.82)(43.63)2(46.67.82)(48.67) Topology {[Ln2(1,4-pda)3(H2O)]·2H2O}n (Ln = Pr, Nd, Dy)

Turn-on fluorescence detection of ciprofloxacin in tablets based on lanthanide coordination polymer nanoparticles

Metal–organic coordination polymers (MOCPs) have emerged as a new family of functional nanomaterials.