Lanthanide Coordination Polymers Research Articles

Syntheses, Structures, and Ratiometric Fluorescent Sensing Properties of a Series of Lanthanide Coordination Polymers

The plentiful structural features and excellent fluorescence properties of lanthanide coordination polymers (Ln-CPs) have garnered much attention in recent years. Herein, 1,4-naphthalic acid (1,4-N...

High Proton Conduction in Two Highly Water-Stable Lanthanide Coordination Polymers from a Triazole Multicarboxylate Ligand.

Two lanthanide coordination polymers (CPs) {[Er(Hmtbd)(H2mtbd)(H2O)3]·2H2O}n (1) and [Yb(Hmtbd)(H2mtbd)(H2O)3]n (2) carrying an N-heterocyclic carboxylate ligand 5-(3-methylformate-1H-1,2,4-triazole-1-methyl)benzen-1,3-dicarboxylate (H3mtbd) were prepared under solvothermal conditions. The single-crystal X-ray diffraction data demonstrate that 1 and 2 are isostructural and display 1D chain structure. Alternating current (AC) impedance measurements illustrate that the highest proton conductivities of 1 and 2 can attain 5.09 × 10-3 and 3.09 × 10-3 S·cm-1 at 100 °C and 98% relative humidity (RH), respectively. The value of 1 exceeds those of most reported lanthanide-based crystalline materials and ranks second among the described Er-CPs under similar conditions, whereas the value for 2 is the highest proton conductivity among the previous Yb-CPs. Coupled with the structural analyses of the two CPs and H2O vapor adsorption, the calculated Ea values help to deduce their proton conductive mechanisms. Notably, the N-heterocyclic units (triazole), carboxyl, and hydrogen-bonding network all play key roles in the proton-transfer process. The prominent proton conductive abilities of both CPs show great promise as efficient proton conductors.

One-dimensional Europium-coordination polymer as luminescent sensor for highly selective and sensitive detection of 2,4,6-trinitrophenol

Three isostructural lanthanide coordination polymers (LnCPs), [Ln(L)6(DMF)]n {HL = 2-(2-formylphenoxy) acetic acid, Ln = Sm (1); Eu (2); Tb (3)} have been synthesized by solvothermal reaction and characterized. Single crystal analyses revealed that the architectures of these LnCPs own one dimensional chain which can be further packed into two-dimensional architectures by hydrogen bonds. Moreover, these LnCPs can offer strategically placed uncoordinated formyl groups, which may act as hydrogen-bond acceptor in the sensing of nitro explosives. Luminescence measurements reveal that LnCPs 2 and 3 exhibit strong luminescence in solid states. LnCP 2 shows quick, highly selective and sensitive detection of 2,4,6-trinitrophenol (TNP) with the high quenching constant (2.6 × 104 M−1) and low detection limit (3.39 μM), which indicates that LnCP 2 is more efficient than most of Eu-based coordination polymers for the sensing of TNP. Furthermore, LnCP 2 represents the first example of one-dimensional Eu-based sensors with formyl group as hydrogen-bonding site in the detection of TNP.

Self-Assembly of 1D Double-Chain and 3D Diamondoid Networks of Lanthanide Coordination Polymers through In Situ-Generated Ligands: High-Pressure CO2 Adsorption and Photoluminescence Properties.

Two new lanthanide-based coordination polymers, [Sm2(bzz)(ben)6(H2O)3]·0.5H2O (1) and [Eu(bbz)(ben)3] (2), were synthesized and characterized. The described products were formed from in situ-generated benzoate (ben) and N’-benzoylbenzohydrazide (bbz) ligands, which were the products of transformation of originally added benzhydrazide (bzz) under hydrothermal conditions. Compound 1 exhibits a one-dimensional (1D) double-chain structure built up from the connection of the central Sm3+ ions with a mixture of bzz and ben ligands. On the other hand, 2 features a 3D network with a 4-connected (66) dia topology constructed from dinuclear [Eu2(ben)6] secondary building units and bbz linkers. High-pressure CO2 sorption studies of activated 1 show that maximum uptake increases to exceptionally high values of 376.7 cm3 g−1 (42.5 wt%) under a pressure of 50 bar at 298 K with good recyclability. Meanwhile, 2 shows a typical red emission in the solid state at room temperature with the decay lifetime of 1.2 ms.

Quantitative principal component analysis of multiple metal ions with lanthanide coordination polymer networks

Approaches oriented toward multi-target analysis are of practical value in obtaining comprehensive information. Herein, discrimination and quantification of multiple metal ions are achieved with fluorescent lanthanide coordination polymer networks (Ln-CPNs) and principal component analysis (PCA). By self-assembly of poly-phosphates (pyrophosphate, PPi or tripolyphosphate, STPP) and cerium ion (Ce3+), two Ln-CPNs are synthesized and emit intense fluorescence due to the ligand field effects of PPi and STPP on Ce3+. Relying on the coordination between poly-phosphates and various metal ions, additional metal ions may compete with Ce3+ for PPi or STPP, forming metal ion-doped Ln-CPNs and adjusting ligand field effect, which subsequently results in the variation of fluorescence intensity. The changes in fluorescence are further processed with PCA and presented with two principal component factors (PC1 and PC2). Accordingly, 14 lanthanide and 12 transition/post-transition metal ions can be evidently identified. Meanwhile, Cu2+ and Ag+ can be accurately quantified depending on relations between dominant PC1 and concentrations of metal ions. Moreover, the fluorescence-PCA sensor is employed to evaluate the composition of Eu3+/Tb3+ and Fe3+/Fe2+ pairs in their mixtures, manifesting its superiority over inductively coupled plasma-atomic emission spectroscopy. Therefore, this work provides an alternative perspective of developing nanomaterials-based fluorescence sensor for multi-target analysis.

RETRACTED ARTICLE: Lanthanide coordination polymer: crystal structure and application values on hypotension after anesthesia

In the present research, a new coordination polymer with the chemical formula of [PrCl(HL)] n (1) was synthesized by utilizing the pure chiral tricarboxyl ligand (S)-5-(((1-carboxy-2-phenylethyl)amino)methyl)isophthalic acid (H3L). The important role of the new compound on prevention of hypotension after anesthesia and the bio-toxicity was evaluated, and at the same time, the relevant mechanism was also be investigated. The conclusive outcome of the present work from the molecular docking simulation identification is that the carboxyl and imino groups are interacting with the active sites on the alpha-2A-adrenergic receptor, which reveals the underlaying reason of the biological activity of the complex.

RETRACTED ARTICLE: Two lanthanide coordination polymers: treatment activity on the endometrial carcinoma by inhibiting the VEGF signaling pathway

We, the Editors and Publisher of the journal Inorganic and Nano-Metal Chemistry, have retracted the following article: Xiao-Mei Yang, Yan Zhang, Hui Xue & Cui-Lan Gong (2021): Two lanthanide coordination polymers: treatment activity on the endometrial carcinoma by inhibiting the VEGF signaling pathway, Inorganic and Nano-Metal Chemistry, DOI: 10.1080/24701556.2021.1952245 Since publication, concerns have been raised about the integrity of the data in the article. When approached for an explanation, the authors have been unable to address the concerns raised and have not been able to provide sufficient supporting information. As verifying the validity of published work is core to the integrity of the scholarly record, we are therefore retracting the article. The corresponding author listed in this publication has been informed. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions. The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as ‘Retracted’.

RETRACTED: Two Dy(III) complexes: Crystal structures and treatment activity on cardiovascular disease

Two new lanthanide coordination polymers (CPs) of {[Dy(L) (H 2 O)]·3CH 3 CN} n ( 1 ) and {(Me 2 NH 2 ) 0.5 [Dy(L) (HCOO − ) 0.5 H 2 O]·DMF·4EtOH·H 2 O} n ( 2 ) have been prepared via utilizing the tris(4-carboxyphenyl)phosphane oxide (H 3 L) as the organic linker under solvothermal conditions. The treatment activity of the compounds on cardiovascular disease in children was evaluated. Several experiments were performed to develop new candidates for the cardiovascular disease treatment. For biological activity evaluation, the release of Creatine kinase isoenzyme (CK) and serum cardiac troponin (CT) was evaluated with enzyme linked immunosorbent assay (ELISA) detection kit. The cardiomyocytes apoptosis was determined by the apoptosis detection kit and Western blot. The accumulation of the ROS in the cardiomyocytes was also detected by flow cytometry. • Two lanthanide coordination polymers have been prepared. • The treatment activity of the compounds on cardiovascular disease in children was evaluated. • The treatment activity of the compounds on cardiovascular disease in children was evaluated.

Collaborative compounding of metal-organic frameworks and lanthanide coordination polymers for ratiometric visual detection of tetracycline

In current study, a ratiometric fluorescence sensor (FSS@MOF-5/GMP-Eu) based on self-assembly of Eu3+ and guanosine monophosphate (GMP) on the surface of fluorescein loaded MOF-5 (FSS@MOF-5) is designed and fabricated for visual detection of tetracycline (TC). As the TC recognizer, Eu3+ specifically reacts with TC to form EuTC complex and results in fluorescence enhancement due to the antenna effect. With the TC addition, visible fluorescence changes from yellowish-green to orange and finally to red can be easily observed by naked eyes. The proposed FSS@MOF-5/GMP-Eu displays an excellent linear relationship with TC (0–20 μM), providing a low detection limit of 18.5 nM. The ratiometric sensor exhibits excellent selectivity to TC against other interferents owing to the formation of EuTC complex. The prepared FSS@MOF-5/GMP-Eu can be employed for TC detection in milk and pork and will also be valuable for use in fluorescence sensor applications.

Lanthanide Coordination Polymers through Design for Exceptional Catalytic Performances in CO2 Cycloaddition Reactions

Lanthanide Coordination Polymers through Design for Exceptional Catalytic Performances in CO₂ Cycloaddition Reactions

Luminescence-Color-Changing Sensing toward Melamine Based on a White-Light-Emitting Film

Isostructural lanthanide coordination polymers, [Ln(d-DBTA)(d-HDBTA)(H2O)5]n (Ln-d-DBTA; d-H2DBTA = d-O,O′-dibenzoyl tartaric acid; Ln = La, Ce, Nd, Eu, Gd, and Tb), are synthesized and characterized. By uniformly doping this amphophilic Ln-d-DBTA into a poly(methyl methacrylate) (PMMA) matrix, we prepare stable films with tunable luminescence color, even white-light emission. Except for providing the blue-light component, the PMMA matrix plays indispensable roles in dispersing the 1D LnCPs via hydrogen bonds, transferring electrons to organic ligands by means of photoinduced electron transfer, and further sensitizing the luminescence of lanthanide ions. Then, a bifunctional sensing process toward melamine in various dairy products is conducted in terms of luminescent intensity and color. Consequently, the as-prepared white-light-emitting film exhibits 0.012 mg/kg limit of detection and obvious luminescence-color changes from white to blue. The excellent sensitivity, reliability, selectivity, stability, competitiveness, and recyclability state the promising practicality in monitoring quality of dairy products. In this work, using a battery of experimental techniques and theoretical calculation, we show how the PMMA matrix connects the LnCPs and promotes their photophysical properties, what changes have taken place for the energy- and electron-transfer pathways of the as-prepared chemosensor after adsorbing melamine, and why this convenient testing material is applicable.

Simple fluorescence optosensing probe for spermine based on ciprofloxacin-Tb3+ complexation.

We developed a facile detection method of spermine based on the fluorescence (FL) quenching of the ciprofloxacin-Tb3+ complex, which shows astrong green emission. Ciprofloxacin (CP) makes efficient bondings to Tb3+ ion as a linker molecule through carboxylic and ketone groups to form a kind of lanthanide coordination polymer. The addition of spermine that competes with Tb3+ ions for the interaction with CP due to its positive charge brings about weakened coordination linkage of CP and Tb3+. The probe exhibited high sensitivity, selectivity, and good linearity in the range of 2–180 μM with a low limit of detection of 0.17 μM. Moreover, we applied this method on the paper strip test (PST), along with the integration of a smartphone and Arduino-based device. The practical reliability of the developed probe was evaluated on human serum samples with acceptable analytical results.

Structural insights into new luminescent 2D lanthanide coordination polymers using an N, N′-disubstituted benzimidazole zwitterion. Influence of the ligand

A series of novel lanthanide coordination polymers (Ln-CPs) were herein prepared from lanthanide salts and a zwitterionic common ligand, under hydrothermal conditions. These cationic Ln homometallic frameworks with two-dimensional architectures, designated as [Ln(BCBI)(NO3)2(H2O)]n, where Ln = Sm (1), Eu (2), Gd (3), Tb (4), Dy (5), and HBCBI = 1,3-bis(carboxymethyl)benzimidazole zwitterion, have been characterized by X-ray single-crystal diffraction, infrared spectroscopy, elemental and thermogravimetric analyses. Due to the 4fn-4fn transition, complexes 1, 2, 4 and 5 show the luminescence characteristic for trivalent lanthanides. Moreover, the fluorescence lifetime of 2 and the phosphorescence spectrum of 5 at 77 K have been investigated. The relationships between the lowest triplet state energy level of the HBCBI ligand and the lowest resonance energy levels of the Sm3+, Eu3+, Tb3+ and Dy3+ ions were examined. The results showed that the energy transfer from the HBCBI ligand is effective. The structural impact of the ligand is also highlighted.

Amide-bridged Eu(III) coordination polymer for stable luminescent glass material

A novel lanthanide coordination polymer composed of Eu(III) ion, low-vibrational frequency hfa (hfa: hexafluoroacetylacetonato), and phosphine oxide ligand with amide groups (dpba: N,N'-(ethane-1,2-diyl)bis(4-(diphenylphosphoryl)benzamide)), Eu-dpba is reported. A lanthanide coordination polymer with alkyl groups (dph: 1,6-bis(diphenylphosphoryl)hexane), Eu-dph is also prepared, as a reference sample. Eu-dpba showed phase transition behavior at 128 °C, although alkyl-bridged Eu-dph showed no phase transition behavior by differential scanning calorimeter measurements. The smooth surface on the Eu-dpba after heat treatment was observed using scanning electron microscope. The photophysical properties were estimated using the emission spectra and the emission lifetimes. We found that the emission quantum yield of Eu-dpba with heat treatment is the same as that of Eu-dpba without heat treatment.

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.

Ratiometric fluorescence detection of sulfide ions based on lanthanide coordination polymer using guanosine diphosphate as ligand

The efficiency of energy transfer from guanine nucleotide to terbium ion (Tb3+) is affected by the phosphate group significantly. Compared with the biomolecules 5′-GMP (guanosine monophosphate), guanosine diphosphate (GDP) exhibits better sensitize ability to Tb3+ ions luminescence. Assisted with the carboxycoumarin ligand, we synthesized a more stable optical Coumarin@GDP-Tb polymer with the characteristic emission peaks located on 440 nm and 545 nm in this work. The Coumarin@GDP-Tb polymer is not only rich in metal binding sites, but also maintains a moderate ionic binding force, which helps metal ions to bind or leave it easily. Experiment result shows that Coumarin@GDP-Tb polymer has the appropriate binding force for Fe2+ ions, which can be destroyed by sulfur ions (S2−) as the formation of FeS precipitation. Based on this, Coumarin@GDP-Tb was designed as the ratio fluorescence probe for sulfur ions detection, where the fluorescence at 545 nm can be selectively quenched by Fe2+ ions, while that at 440 nm was unaffected, in the presence of S2− ions, the quenched fluorescence can be recovered remarkably. With the increasing S2− ions from 0.1–45 μM, the ratio of fluorescence intensity at 545 nm to 440 nm (F545/F440) is linear to S2− concentration, and the detection limit of S2− was calculated to be 0.073 μM. Contrast to those fluorescence probes with single wavelength emission, Coumarin@GDP-Tb displays a comparable sensitivity, the introduced self-adjust wavelength improved the detection accuracy efficiently. The above 98.1 % recovery rates of S2− ions in the actual water sample demonstrated the practicability of Coumarin@GDP-Tb fluorescence probe.

Europium(III), Terbium(III), and Gadolinium(III) Oxamato-Based Coordination Polymers: Visible Luminescence and Slow Magnetic Relaxation.

The reaction of aqueous solutions of EuIII, TbIII, and GdIII ions with Na2Hpcpa [H3pcpa = N-(4-carboxyphenyl)oxamic acid] afforded three new isostructural oxamate-containing lanthanide(III) coordination polymers of general formula {LnIII2(Hpcpa)3(H2O)5·H2O}n [Ln = Eu (1),Tb (2), and Gd(3)]. Their structure is made up of neutral zigzag chains running parallel to the [101] direction where double syn-syn carboxylate(oxamate)-bridged dilanthanide(III) pairs (Ln1 and Ln2) are linked by three Hpcpa2- ligands, one of them with the μ-κ2O,O':κO″ coordination mode and the other two with the μ3-κ2O,O':κO″:κO'''. Additionally, two of those chains are interlinked through hydrogen bonding and π-π type interactions, resulting in a porous structure with channels where water molecules are hosted. The emission properties of 1 and 2 are evaluated as a function of the temperature, exhibiting an emission in red and green, respectively. The external quantum yield for 2 is approximately 7 times that obtained for 1, indicating that the oxamate ligand is a better sensitizer for TbIII ions. The temperature dependence of the dc magnetic properties of 1-3 reveals a different magnetic behavior depending on the nature of the LnIII ion. A continuous decrease of χMT occurs for 1 upon cooling, and finally χMT tends to vanish, as expected for the thermal depopulation of the six magnetic 7FJ excited states (J = 1-6) of the EuIII ion with a nonmagnetic 7F0 ground state. χMT for 2 decreases sharply with decreasing the temperature due to the depopulation of the splitted mJ levels of the 7F7 ground state of the magnetically anisotropic TbIII ion. A very weak antiferromagnetic interaction between the magnetically isotropic GdIII ions across the double carboxylate(oxamate) bridge is responsible for the small decrease of χMT at low temperatures for 3. The dynamic (ac) magnetic properties of 2 and 3 reveal a slow magnetic relaxation with very incipient frequency-dependent χM″ signals below 6.0 K (2) and frequency-dependent χM″ peaks below 10.0 K (3) under nonzero applied dc magnetic fields, being thus new examples of field-induced single molecule magnets (SMMs).

Multi-functional lanthanide coordination polymers for multi-modal detection of nitroaromatics and trace water in organic solvents

Multifunctional materials used for multimodal sensors are of great significance both for enriching variety of materials and overcoming the shortcomings of traditional single signal sensors. This work reports the ultrafast preparation of multifunctional coordination polymer (CP) spheres with metalloligand Ru (II)[4,4′-(COOH)2-bpy]3▪Cl2 (L) and Gd3+ ions. Gd-L CPs were used for multi-modal detection of nitroaromatic explosives and trace water in organic solvents with their red fluorescence and magnetic resonance response. The red fluorescence was derived from the ligand, which is electron-rich because of the bipyridine rings. There were different emission behaviors when Gd-L CPs reacted with nitroaromatic explosives that have various electron-deficient properties through electron transfer donor–acceptor mechanism. The changes in the emission depended closely on the nitroaromatic explosives ability to withdraw electrons. Gd-L CPs also showed magnetic resonance response with r1 of 12.1 mM−1s−1 due to the integration of the paramagnetic property of Gd3+ ions. Smart sensing of trace water in organic solvents was achieved by magnetic signals. The fluorescence of Gd-L CPs was enhanced and there was a tiny blue-shift in protonic solvents with increased polarity. The fluorescence sensor used in detecting trace water had a consistent result like the MR response. Thus, Gd-L CPs enabled the use of fluorescence and magnetic resonance sensors simultaneously for the first time to overcome the shortcoming of single modal sensor and expand the application of magnetic resonance relaxation.

Facile solvothermal syntheses of isostructural lanthanide(III) formates: Photocatalytic, photoluminescent chemosensing properties, and proficient precursors for metal oxide nanoparticles

Three isostructural lanthanide coordination polymers (CPs) with the formula C3H3LnO6 [Ln = Pr (1), Ce (2), and Dy (3)] were solvothermally synthesized by self-assembly of lanthanide(III) and in-situ generated methanoic acid by the hydrolysis of N,N-dimethyl formamide. These CPs were characterized by FTIR, elemental analysis, PXRD, and single crystal analysis. The metal centered luminescence properties of these coordination polymers revealed that only the dysprosium based CP exhibited significant luminescence, and it was found to be selective for chemosensing of picric acid. 3 showed quenching efficiency of 89.7% with KSV value of 2.89 × 104 M−1. These coordination polymers were also exploited as photocatalysts for degradation of methylene blue, and the dysprosium based CP proved to be a fantastic photocatalyst with the degradation activity of 92% owing to its effective electronic transitions. The solvent-free thermolysis of these LnCPs fabricated CeO2 and Pr6O11 nanoparticles characterized by PXRD, FTIR, particle size analyzer, and elemental analysis.

Lanthanide-Aromatic Iminodiacetate Frameworks with Helical Tubes: Structure, Properties, and Low-Temperature Heat Capacity.

A series of lanthanide coordination polymers [LnL(H2O)2]n [Ln = Pr (1), Nd (2), Sm (3), Eu (4), and Gd (5), H3L = N-(4-carboxy-benzyl)iminodiacetic acid] was hydrothermally prepared and structurally characterized. All the five compounds have been confirmed as 3D Ln-CPs with one-dimensional helical tunnels composed of four helical chains, although there are different coordination geometries around Ln3+. Enantiomeric helixes in 1–3, and absolute left-handed and right-handed helical chains in 4 and 5, respectively, lead to different tunnel spaces. Their conformations can also be featured by different space groups and unit cell dimensions. Photoluminescence measurement on 3 and 4 show characteristic emission peaks of Sm3+ and Eu3+ ions, respectively. The low-temperature heat capacity of 1–4 has been investigated in the temperature range of 1.9–300 K. Their heat capacity values are nearly equal below 10 K and display a crossover with the value order Cp,m(2) > Cp,m(1) ≈ Cp,m(4) > Cp,m(3) above 10 K. The measured heat capacities have been fitted, and the corresponding thermodynamic functions were consequently calculated based on the fitting parameters. The standard molar entropies at 298.15 K have been determined to be (415.71 ± 4.16), (451.32 ± 4.51), (308.53 ± 3.09), and (407.62 ± 4.08) J·mol–1·K–1 for 1, 2, 3, and 4, respectively.