Luminescent Lanthanide Coordination Polymers Research Articles

Highly Efficient and Thermally Durable Luminescence of 1D Eu3+ Coordination Polymers with Arsenic Bridging Ligands.

In this work, bisarsine oxides were evaluated as novel bridging ligands, aiming to develop practical and efficient luminescent lanthanide coordination polymers. We have synthesized one-dimensional (1D) Eu3+ coordination polymers that incorporate bisarsine oxide bridging ligands and hexafluoroacetylacetonate anions. These polymers exhibited a denser packing of chains compared to analogous polymers bridged with bisphosphine oxides. The coordination polymers demonstrated exceptional thermal stability and substantial emission quantum yields. Additionally, the bisarsine oxides induced a pronounced polarization effect, facilitating a sensitive electric dipole transition that yields considerably narrow band red emission. Remarkably, the Eu3+ coordination polymers with bisarsine oxides maintained intense emission even at 550 K. A distinctive feature of these polymers is their heating-induced emission enhancement observed when the temperature was increased from 300 K to 400 K.

Construction of Highly Luminescent Lanthanide Coordination Polymers and Their Visualization for Luminescence Sensing.

NaH2SIP was selected as an organic ligand (NaH2SIP = 5-sulfoisophthalic acid monosodium salt). We successfully constructed a new class of lanthanide coordination polymers Ln-HS ([Ln(SIP)(DMF)(H2O)4]DMF·H2O; Ln = Eu, Tb, Sm, and Dy) by a simple solvothermal synthesis method. They exhibited excellent photoluminescence properties for Ln3+ ions, where Eu-HS and Tb-HS exhibited high quantum yields of 13.70 and 42.38%, respectively. The codoped lanthanide coordination polymers obtained by doping with different ratios of Eu3+/Tb3+ serve as excellent ratiometric thermometers with high sensitivities in the physiological temperature range, with values of 16.8, 7.0, and 14.5%·K-1, respectively. The luminescent colors of Tb0.95Eu0.05-HS and Tb0.94Eu0.06-HS exhibit variations from green to yellow to orange, achieving visualized luminescence in a narrow temperature range. The composite film material Tb0.94Eu0.06-HS@PMMA demonstrates this color variation. Next, Tb0.5Sm0.5-HS obtained by Tb3+/Sm3+ codoping was investigated. The difference in the luminescence colors visible to the naked eye at different excitation wavelengths and the change in luminescence colors occur in a very narrow temperature range. All of them show the great value of the visualized luminescence in practical anticounterfeiting, with double anticounterfeiting function and high security.

A multicenter lanthanide coordination polymer for ratiometric pesticide monitoring

Due to the increasing environmental and public health issues, efficient recognition and detection approaches for pesticides has attracted concerns worldwide. Herein, luminescent lanthanide coordination polymers (Ln-CPs) with tunable emissive centers are synthesized by simultaneously doping controlled amounts of Eu3+, Tb3+ and Gd3+ into the same framework. An optimized version of the multicenter Ln-CP (Eu0.048Tb0.052Gd0.9-CPBA) is prepared for 2D fingerprint recognizing pesticides. Additionally, the special “turn-on” response of ligand-based emission and “turn-off” response of Eu3+/Tb3+-based emission toward glyphosate (GPS) endow Eu0.048Tb0.052Gd0.9-CPBA with highly selective ratiometric sensing capability. The rapid, sensitive, selective and recyclable sensor for GPS provides a facile and adjustable synthetic approach for the development of multicenter ratiometric sensors. The real-time monitoring platform not only improves the sensitivity and selectivity but also holds great environmental significance.

Single molecule magnet features in luminescent lanthanide coordination polymers with heptacoordinate Dy/Yb(III) ions as nodes.

Two sets of 1D/2D lanthanide coordination polymers with formulas of Ln(oqa)3·2H2O [Hoqa = 2-(4-oxoquinolin-1(4H)-yl) acetic acid, Ln = Dy (1), Yb (2)] and Ln(oaa)2(HCOO)(H2O) [Hoaa = 2-(9-oxoacridin-10(9H)-yl) acetic acid, Ln = Dy (3), Yb (4)] have been synthesized and their physical properties were investigated. All four complexes are constructed from seven-coordinate lanthanide ions and corresponding organic linkers. The lanthanide ions in 1 and 2 adopt a pentagonal bipyramid coordination geometry, whereas the coordination geometry of lanthanide ions in 3 and 4 can be described as a capped octahedron. Slow magnetic relaxation behaviors were observed in these four products at a zero/non-zero static magnetic field. Complexes 1, 2 and 4 exhibit the characteristic emission of Ln(III) ions, whereas complex 3 shows ligand-based emission. Bright yellow light emission was also observed when a voltage was applied, demonstrating the potential of 1 for application in light-emitting diodes (LEDs). Compounds 3 and 4 are the first examples of lanthanide complexes based on Hoaa ligands.

Two luminescent lanthanide coordination polymers incorporating free pyridyl sites as the multi-responsive sensors for hazardous ions

The fast and effective detection of hazardous ions is very necessary owing to their serious effects on the ecological environment and human health. In this work, π-conjugated 1,10-phenanthroline (phen) chromophore has been utilized in combination with 2,2′-bipyridine-3,3′-dicarboxylate (H2bpdc) as a double-pyridyl-functionalized spacer to create two luminescent lanthanide coordination polymers [Ln2(phen)2(bpdc)3(H2O)2]n·6nH2O {Ln = Eu (1) and Tb (2)}, which were characterized by elemental analysis, thermogravimetric analyses, PXRD, single-crystal X-ray diffraction, IR and UV/Vis spectroscopy. 1 and 2 consist of free H2O molecules and 1-D polymeric chains [Ln2(phen)2(bpdc)3(H2O)2]n constructed by the linkages of [Ln(phen)(H2O)]3+ groups and bpdc2− ligands. Owing to the existence of free Lewis basic pyridyl sites as the receptor, 1 and 2 exhibit fast response (approximate 20–50 s) and high efficiency for detecting various hazardous ions (Pb2+, Fe3+, Co2+, Cu2+, Al3+, CrO42− and Cr2O72−) in aqueous solution, which have the higher Ksv values of 1.80 × 104–9.78 × 104 M−1 and the lower detection limits of 0.939–6.826 ppm. Intriguingly, most of the reported luminescent lanthanide coordination polymers can be served as either separate- or dual-responsive sensors for the detection of hazardous ions to date, however, reports on the multi-responsive sensors of a multiplicity of hazardous ions in aqueous media are relatively scarce. Therefore, 1 and 2 can be regarded as a new type of the multi-responsive sensor for fast and effectively detecting a variety of hazardous ions in water.

Doped Luminescent Lanthanide Coordination Polymers Exhibiting both White-Light Emission and Thermal Sensitivity.

Multifunctional lanthanide coordination polymers (CPs) have the advantages of acting in two or more fields simultaneously. Herein, two single lanthanide CPs, formulated as LnL(D/L-Hlac)(H2O)2·0.5H2O (Ln = Eu (1), Tb (2); H2L = 4,4'-(pyridine-3,5-diyl)dibenzoic acid) and their doped lanthanide analogue Tb0.9373Eu0.0627L(D/L-Hlac)(H2O)2·0.5H2O (3) were prepared through hydrothermal methods. Luminescence measurements reveal that 1 displays red photoluminescence and its Commission International ed'Eclairage (CIE) coordinates are almost invariant in the temperature range from 80 to 300 K, while the emission color of 2 changes from yellow to green and its CIE coordinates change from (0.36132, 0.56365) at 80 K to (0.30448, 0.45566) at 300 K. Significantly, 3 not only displays white-light emission with CIE coordinates of (0.32999, 0.33406) but also exhibits a thermal sensitivity of 2.27% K-1 at 230-300 K. The obviously larger thermal sensitivity in 3 in comparison to that of 1.07% K-1 for 2 demonstrates that lanthanide CPs with both a heat-sensitive fluorescent thermometer and high-efficiency white-light emission can be expected by doping Eu(III) ions into Tb(III)-based CPs.

Structural diversity and near-infrared luminescence of lanthanide coordination polymers with different flexibility and coordination orientation based on bipyridyl carboxylate and dicarboxylate ligands

Three series of new lanthanide coordination polymers, [Ln(bpdc)(suc)0.5(H2O)]n.nH2O (Ln ​= ​La (1), Ce (2), Pr (3), Nd (4)), [Ln2(bpdc)2(1,3-bdc)(H2O)]n·2nH2O (Ln ​= ​Ce (5), Pr (6), Nd (7)), [Ln4(bpdc)4(1,4-bdc)2(H2O)3]n.3nH2O (Ln ​= ​Ce (8), Pr (9), Nd (10)) (H2bpdc ​= ​2,2′-bipyridine-6,6′-dicarboxylic acid, H2suc ​= ​succinic acid, H2(1,3-bdc) ​= ​benzene-1,3-dicarboxylic acid and H2(1,4-bdc) ​= ​benzene-1,4-dicarboxylic acid) have been synthesized by hydrothermal reaction with aliphatic and aromatic auxiliary ligands. Compounds 1–4 possess 2D layers with the hxl topological net. Compounds 5–7 present 2D layers with the sql topological net. Compounds 8–10 display 3D frameworks with the hex topological net. Meanwhile, the influence of coordination orientation of the auxiliary ligands on the final structures are investigated. Compounds 1–10 have good thermal stabilities and compounds 7, 9 and 10 show typical near-infrared luminescence.

Synthesis, structure and luminescence of lanthanide coordination polymers based on the 1,3-Bis(carboxymethyl) imidazolium salt

The 1,3-bis(carboxymethyl)imidazolium salt (zwitterion) (HBCI) was reacted, under solvothermal conditions, with rare earth chlorides to provide a series of new two-dimensional (2D) coordination polymers, namely [LnBCI) (HCOO) (H2O)2Cl]n [Ln = Sm (1); Eu (2); Gd (3); Tb (4); Dy (5)]. The complexes were characterized by X-ray single crystal diffraction, powder X-ray diffraction, infrared spectroscopy, elemental analysis and thermogravimetric analysis. Compounds of 1, 2, 4 and 5 exhibit the characteristic luminescence of the corresponding lanthanide ions, due to the 4fn-4fn transition. Furthermore, the fluorescence lifetime of 2 and the phosphorescence spectrum of 5 at 77k are discussed.

Novel hybrid materials of lanthanide coordination polymers ion exchanged Mg-Al layered double hydroxide: Multi-color photoluminescence and white color thin film

In the context, pillared layered hybrid materials Ln(PDA)33—LDH are prepared through ion exchange assembly of luminescent lanthanide coordination polymers [H2NMe2]3[Ln(DPA)3] (Ln = Eu, Tb, Sm, Dy, Nd; [H2NMe2]+ = dimethyl amino cation; H2DPA = 2,6-dipicolinic acid) and pillared layered double hydroxide (Mg6Al2(OH)16CO3·4H2O). Among Mg-Al LDH interacts with [H2NMe2]3[Ln(DPA)3] through anion exchange ([Ln(PDA)3]3-) and electrostatic effect to form [Ln(PDA)3]3--LDH. All these hybrids display the typical Ln3+ emission. By controlling the composition of different Ln3+ cations in hybrid systems, the luminescent color can be tuned and the white light output can be realized. Furthermore, with careful adjustment of the excitation wavelength, the color of the luminescence can be modulated. Moreover, the white light emissive thin film based on the [Dy/Eu(PDA)3]3--LDH are prepared in order to extend their potential application, which displays desirable white light.

A General Model of Sensitized Luminescence in Lanthanide-Based Coordination Polymers and Metal-Organic Framework Materials.

Luminescent lanthanides containing coordination polymers and metal-organic frameworks hold great potential in many applications due to their distinctive spectroscopic properties. While the ability to design coordination polymers for specific functions is often mentioned as a major benefit bestowed on these compounds, the lack of a meaningful understanding of the luminescence in lanthanide coordination polymers remains a significant challenge toward functional design. Currently, the study of these compounds is based on the antenna effect as derived from molecular systems, where organic antennae are used to facilitate lanthanide-centered luminescence. This molecular-based approach does not take into account the unique features of extended network solids, particularly the formation of band structure. While guidelines for the antenna effect are well established, they require modification before being applied to coordination polymers. A series of nine coordination polymers with varying topologies and organic linkers were studied to investigate the accuracy of the antenna effect in coordination polymer systems. By comparing a molecular-based approach to a band-based one, it was determined that the band structure that occurs in aggregated organic solids needs to be considered when evaluating the luminescence of lanthanide coordination polymers.

Automated long-term monitoring of extracellular acidification and changes in impedance of living cells

Luminescent lanthanide coordination polymers [H2NMe2]3[Ln(DPA)3] (Ln = Eu, Tb, Sm, Dy; [H2NMe2]+ = dimethyl amino cation; H2DPA = 2,6-dipicolinic acid) are synthesized, whose multi-color can be tuned and even white color luminescence can be integrated. Besides, the fluorescent sensing property of the [H2NMe2]3[Tb(DPA)3] system is checked, which shows selective fluorescent quenching effect for Fe3 +.

Rethinking Sensitized Luminescence in Lanthanide Coordination Polymers and MOFs: Band Sensitization and Water Enhanced Eu Luminescence in [Ln(C15H9O5)3(H2O)3]n (Ln = Eu, Tb).

A coordination polymer [Ln(C15H9O9)3(H2O)3]n (1-Ln = Eu(III), Tb(III)) assembled from benzophenonedicarboxylate was synthesized and characterized. The organic component is shown to sensitize lanthanide-based emission in both compounds, with quantum yields of 36% (Eu) and 6% (Tb). Luminescence of lanthanide coordination polymers is currently described from a molecular approach. This methodology fails to explain the luminescence of this system. It was found that the band structure of the organic component rather than the molecular triplet state was able to explain the observed luminescence. Deuterated (Ln(C15H9O9)3(D2O)3) and dehydrated (Ln(C15H9O9)3) analogues were also studied. When bound H2O was replaced by D2O, lifetime and emission increased as expected. Upon dehydration, lifetimes increased again, but emission of 1-Eu unexpectedly decreased. This reduction is reasoned through an unprecedented enhancement effect of the compound's luminescence by the OH/OD oscillators in the organic-to-Eu(III) energy transfer process.

Luminescent Eu(III) coordination polymer cross-linked with Zn(II) complexes

A structural design of new luminescent lanthanide coordination polymers composed of Eu3+ complex and Zn2+ complexes are introduced. The Eu3+ coordination polymer [Eu(hfa)3(dppy)2ZnCl2]n (Eu–Zn) (hfa: hexafluoroacetylacetonato, dppy: 4-pyridyldiphenylphosphane oxide) were synthesized by the complexation of Eu(hfa)3(H2O)2 with ZnCl2(dppy)2. The structure was characterized using XRD and TG-DTA. The photophysical properties were estimated using the emission spectra, the emission lifetimes, and the emission quantum yields. The emission quantum yields are larger then that of precursor Eu(hfa)3(H2O)2. The emission quantum yield of Eu–Zn was found to be 59%. The preparations, structures and photophysical properties of Eu–Zn are demonstrated as a new luminescent Eu3+ coordination polymer for the first time.

Lanthanide coordination polymers for multi-color luminescence and sensing of Fe3 +

Luminescent lanthanide coordination polymers [H2NMe2]3[Ln(DPA)3] (Ln=Eu, Tb, Sm, Dy; [H2NMe2]+=dimethyl amino cation; H2DPA=2,6-dipicolinic acid) are synthesized, whose multi-color can be tuned and even white color luminescence can be integrated. Besides, the fluorescent sensing property of the [H2NMe2]3[Tb(DPA)3] system is checked, which shows selective fluorescent quenching effect for Fe3+.

Luminescent lanthanide coordination polymers synthesized via in-situ hydrolysis of dimethyl-3,4-furandicarboxylate

Dimethyl-3,4-furandicarboxylate undergoes hydrolysis under hydrothermal conditions with lanthanide (Ln) ions to form two-dimensional coordination polymers, [Ln(C6H2O5)(C6H3O5)(H2O)]n (Ln=Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). The resulting materials exhibit luminescent properties with quantum yields and lifetimes for the Eu(III) and Tb(III) compounds of 1.1±0.3% and 0.387±0.0001ms, and 3.3±0.8% and 0.769±0.006ms, respectively. Energy values for the singlet and triplet states were determined for dimethyl-3,4-furandicarboxylate and 3,4-furandicarboxylic acid. Excited state dynamics and structural features are examined to explicate the reported quantum yields. A series of other FDC structures is briefly presented.

Syntheses, structures and luminescence of lanthanide coordination polymers based on 5-(3-pyridylmethoxy)isophthalate ligand

Eight new lanthanide coordination polymers, {[LnL(Bdc)0.5(H2O)2]·H2O}n [Ln=Ce(1), Pr(2), Nd(3), Sm(4), Eu(5), Gd(6), Tb(7), Dy(8)] (H2L=5-(3-pyridylmethoxy)isophthalic acid, H2Bdc=terephthalic acid), have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, PXRD and single crystal X-ray diffraction. Complexes 1–8 display isostructural 3D metal-organic frameworks (MOFs) constructed from 2D [LnL(H2O)2]n networks pillared by Bdc2− spacers. Tetradentate 5-(3-pyridylmethoxy)isophthalate ligand coordinates four Ln(III) ions via two bridging carboxyl groups. The 3D MOFs can be simplified as a (4,5)-connected tcs topological network with the Schläfli notation of {44.62}{44.66}. Thermal stabilities (TG-DSC) of these complexes are determined. Eu(5) and Tb(7) complexes emitting strong red and green luminescences demonstrate that the ligand-to-lanthanide energy transfer is efficient.

Luminescent lanthanide coordination polymers for photonic applications

Luminescent lanthanide coordination polymers composed of lanthanide ions and organic joint ligands exhibit characteristic photophysical and thermostable properties that are different from typical organic dyes, luminescent metal complexes, and semiconductor nanoparticles.

Highly effective heterogeneous chemosensors of luminescent silica@coordination polymer core-shell micro-structures for metal ion sensing.

Heterogeneous solid sensors are regarded as promising next-generation sensor due to their excellent chemical stability, low contamination, and excellent recyclability, despite their low sensitivity and weak signal. The dispersity and signals specifically from the exterior of solid sensors are critical aspects which define the sensing sensitivity and selectivity. A novel strategy for the preparation of ideal heterogeneous sensors based upon luminescent lanthanide coordination polymers (LnCP) has been demonstrated. Ideal heterogeneous sensors are systematically achieved by producing the sensors in small, uniform, and thin core-shell particles (silica@LnCP, Ln = Eu, Tb). Eventually, we found that the extremely small amount of well-structured silica@LnCP microsphere, less than ca. 1/400 compared to the amount of several known coordination polymer-based sensors, was sufficient to achieve a reliable Cu2+ sensing with even much greater sensitivity (ca. 550% improvement).

Synthesis, crystal structure and luminescence properties of lanthanide coordination polymers with a new semirigid bridging thenylsalicylamide ligand

Two new lanthanide coordination polymers based on a semirigid bridging thenylsalicylamide ligand ([Ln{sub 2}L{sub 3}(NO{sub 3}){sub 6}]·(C{sub 4}H{sub 8}O{sub 2}){sub 2}){sub ∞} were obtained and characterized by elemental analysis, X-ray diffraction, IR and TGA measurements. The two compounds are isostructure and possess one dimensional trapezoid ladder-like chain built up from the connection of isolated LnO{sub 3}(NO{sub 3}){sub 3} polyhedra (distorted monocapped antisquare prism) through the ligand. The photoluminescence analysis suggest that there is an efficient ligand-to-Ln(III) energy transfer in Tb(III) complex and the ligand is an efficient “antenna” for Tb(III). From a more general perspective, the results demonstrated herein provide the possibility of controlling the formation of the desired lanthanide coordination structure to enrich the crystal engineering strategy and enlarge the arsenal for developing excellent luminescent lanthanide coordination polymers. - Graphical abstract: We present herein one dimensional lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display interesting structures but also possess strong luminescence properties. Display Omitted - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit interesting structures. • The luminescent properties of Tb(III) complexes are discussed in detail.

Hydrothermal synthesis and luminescence of lanthanide complexes sensitized with dpphen

Three new lanthanide complexes [Ln(dpphen)(L)(NO3)] (Ln=Tb(1), Eu(2), Nd(3), H2L=glutaric acid, dpphen=4,7-diphenyl-1,10-phenanthroline) have been synthesized hydrothermally by the reaction of H2L, dpphen and Ln(III) ions. The X-ray diffraction analysis reveals that three coordination polymers have similar structures. The Ln(III) ions are nine coordinated and glutarate ligands bridge Ln(III) to form 1D polymer chains. The solid-state luminescence of complexes 1 and 2 was investigated at room temperature. The complexes 1 and 2 exhibited strong green and red luminescence under ultraviolet light. The 5D4→7Fj (j=6, 5, 4 and 3) transition emissions of Tb(III) and the 5D0→7Fj (j=0–4) transition emissions of Eu(III) were observed in their emission spectra. The strong luminescence of complexes 1 and 2 demonstrates that luminescence of lanthanide coordination polymers is sensitized by an effective energy-transfer from dpphen ligand to Ln(III) ions. Moreover, the magnetic properties of complexes 1–3 were also investigated.