Lanthanide Coordination Research Articles

Constructing coordination-connected flexible-rigid structures for the interfacial enhancement of CF/polyetheretherketone composites

Carbon fiber (CF) reinforced polymer composites have found widespread application due to their exceptional properties, including high specific strength and modulus, thermal stability, and chemical durability. However, since the interface serves as the bridge for load transfer between fiber and resin, the interfacial property directly affects the holistic performance of the composites. Considering the inertness of CF and polyetheretherketone (PEEK), as well as the modulus gap between them, we propose a flexible-rigid sizing agent to enhance the interfacial interaction. The sizing layers are constructed by the transition layer of polyetherimide (PEI) and the hybrid nanoparticles consisting of rare-earth coordination bonded flexible aramid nanofiber and rigid nano-TiO2. Calculated by density functional theory (DFT), the electron density difference (EDD) result displays the transfer of electrons between aramid nanofiber and nano-TiO2 acted by rare-earth element. This treatment with flexible-rigid sizing agent significantly improves the surface activity, roughness, and wettability of CF. Meanwhile, the flexural strength and interlaminate shear strength (ILSS) of as-prepared CF/PEEK composites are 91.4% (810.2 MPa) and 58.2% (82.6 MPa) higher than those of unmodified CF/PEEK composites. This work presents a robust and promising approach for fabricating high-performance CF/PEEK composites.

Lanthanoid Semiquinonate/Tropolonate Complexes: Redox Chemistry and Luminescence

AbstractHeteroleptic lanthanoid (Ln = Eu, Gd, Tb, Dy, Ho and Yb) complexes featuring hydro‐tris(1‐pyrazolyl)borate (Tp−) ligands combined with the bidentate O‐donor ligands tropolonate (trop−) or 3,5‐di‐tertbutylseminquinonate (dbsq⋅−) have been synthesized and investigated. Despite the similarity of the bidentate O‐donor trop− and dbsq⋅− ligands, and the lanthanoid coordination geometries, the complexes [LnTp2dbsq] (Ln‐dbsq) and [LnTp2trop] (Ln‐trop) exhibit markedly different redox and photophysical properties. The electrochemistry of Ln‐dbsq is dominated by processes associated with the readily redox‐active dbsq⋅− moiety. In contrast, the relative redox inactivity of Ln‐trop allows for the observation of the Eu(III) to Eu(II) reduction process. Photophysical measurements reveal no sensitized emission for the Ln‐dbsq family, while the trop− antenna ligand is able to sensitize emission in the visible range for Eu(III) and Ho(III), and in the near‐infrared for Ho(III) and Yb(III).

Pre-Service Chemistry Teachers’ Preconceptions about Rare Earth Coordination Chemistry: Results from an Explorative Interview Study

This research aims to identify students' preconceptions about rare earth coordination chemistry. The method used in this research is exploratory interviews. This research involved 25 pre-service chemistry teacher at a university in West Java Province, Indonesia. The collected data was analyzed using qualitative content analysis. The research results showed that 60% of students were able to identify electronic waste as a source of valuable metals, but others did not know that there were rare earth metals contained in it. As many as 32% know ionic liquids as environmentally friendly solvents, but the majority of students do not understand the physicochemical properties of ionic liquids and the interactions between ionic liquids and rare earth metals. As many as 8% of students were able to explain the reaction to form rare earth metal coordination compounds correctly, while only 4% were able to explain the concept of luminescence in these compounds. These findings indicate the need for coordination chemistry course design that accommodates students' learning needs and links them to relevant environmental contexts to improve students' understanding and systems thinking skills.

The effect of the outer-sphere cations on the photophysical and magnetic properties of rare earth complexes with 2,2,2-trichloro-N-(diphenylphosphoryl)acetamide

Two series of rare earth coordination compounds have been synthesized (Na[RE(L4)] (labeled as 1RE) and PPh4[RE(L4)] (labeled as 2RE), where RE = Y3+, Eu3+, Tb3+, L = 2,2,2-trichloro-N-(diphenylphosphoryl)acetamide) to determine the possibility of modifying their photophysical and magnetical properties by changing the counterion. The crystal structure of 1RE was determined based on the single-crystal X-ray diffraction and the crystal structure of 2RE was determined based on quantum chemistry computational procedures. Characterization of the physicochemical properties of the compounds was carried out using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), 1H and 31P NMR spectroscopy as well as FT-IR, absorption and luminescence spectroscopy in the temperature range of 300 - 77 K. The rate constants of radiative (Arad) and non-radiative (Anrad) transitions, intrinsic (QLnLn) and overall (QLnL) emission quantum yields, sensitization efficiency (ηsens), the experimental and theoretical intensity parameters (Ωλ), the forward (WS, WT) and backward (WbS, WbT) intramolecular energy transfer (IET) rates were determined. Magnetic properties of Tb3+ compounds were studied in a constant field of 0.5 T in the temperature range of 1.8–300 K. Dynamic AC magnetic susceptibility measurements were carried out as a function of temperature and frequency for 1Tb and 2Tb. Only in the case of 2Tb, in the presence of an external DC field, a slight temperature dependence of in-phase χ′ and out-of-phase χ'' susceptibility was recorded. Based on experimental and theoretical results, the significant effect of counterion on the photophysical and magnetic properties of RE chelates has been demonstrated and clarified, providing valuable guidance for the design of bifunctional electromagnetic radiation converters.

Eu‐based coordination polymer with fluorescence enhancement for Cu2+/prochloraz and quenching for nitrobenzene/pyrimethanil

The detection of pollutants is an important part of environmental protection. A one‐dimensional Eu(III) coordination polymer (CP1), [Eu2(3‐pyia)2(Ac)2 (H2O)4]·(2,2′‐bipy)0.5·4.25H2O, based on 5‐(pyridin‐3‐ylmethoxy) isophthalic acid (3‐H2pyia) and 2,2′‐bipyridine (2,2′‐bipy) was designed and prepared under hydrothermal condition. The structure was characterized as one‐dimensional ladder‐like structure with water and 2,2′‐bipy guest molecules. The excellent luminescence properties of CP1 prompted us to investigate its fluorescence sensing performance for pollutants. It exhibited fluorescence enhancement for Cu2+ and prochloraz, but quenching for nitrobenzene and pyrimethanil, and the fluorescence sensing mechanism has been further investigated by experimental and density functional theory (DFT) calculations. This work expands the exploitation of rare earth coordination polymers for fluorescence sensing and contributes to pollutant detection.

Correlation of rare earth coordination and spectral properties in Er3+ doped Na2O–Al2O3–SiO2 glasses with different Al2O3 concentrations by molecular dynamics simulations

The molecular structure of Er2O3 doped Na2O–Al2O3–SiO2 glasses with varying Na2O/Al2O3 ratios is explored via molecular dynamics (MD) simulations using the so-called inherent structure sampling method, which allows the calculation of a large number of local structures of low concentration, as needed to determine the surrounding of low concentration dopants. General structural parameters, including radial distribution functions, coordination numbers and interatomic distances of all network forming and network modifying ions are reported. However, in this work, special attention is devoted to the effect of Al2O3 concentration on the local surrounding of the doped Er3+ ions. It is shown that the Er atoms coordinate 5–6 oxygen ions in their first coordination sphere in the investigated glasses. The Er–O coordination number increases monotonically with increasing Al2O3 concentration and decreasing Na2O/Al2O3 ratio. It is found that the Er atoms are preferably connected to non-bridging oxygen atoms (NBO) in all glasses, even in the peraluminous composition. Additionally, the MD simulation results are compared to the glasses spectral properties that were already investigated in detail by Tanabe and Hanada. The increasing Er-NBO coordination number derived by MD simulations could be correlated with the increased peak splitting of the Er3+ absorption peaks reported by Tanabe and Hanada. Furthermore, a correlation between the Judd-Ofelt parameters published by Tanabe and Hanada and the Er3+ coordination in the glass structure is discussed. It is shown that the Er–O coordination increases with increasing Ω2 parameter as the Al2O3 concentration increases in the glass composition. A correlation of the average overall Er–O coordination number with the symmetry of the local Er site is proposed.

Lanthanide coordination polymers@CuO nanoparticles: Enhanced self-cascade nanoenzyme activity and ratiometric fluorescence assay of glutathione

Tandem enzyme can catalyze some cascade reactions with high efficiency, and some few tandem enzyme-like mimics have been discovered recently. Further improving the catalytic efficiency of tandem nanoenzymes with facile method may undoubtedly promote and broaden their applications in various fields. In this work, cupric oxide nanoparticles (CuO NPs) with dual-functional enzyme mimics were synthesized using the rapid deposition method in advance, which simultaneously combined with lanthanide infinite coordination polymers (Ln ICPs) during the self-assemble of Tb3+, guanine-5′-triphosphate (GTP) and auxiliary ligand terephthalic acid (TA). Excitingly, the obtained Tb-GTP/TA@CuO ICPs, not only displayed obviously enhanced tandem catalytic activity compared with pure CuO NPs, but also provided a versatile ratiometric platform for ultrahigh selective and sensitive detection of glutathione (GSH) under single-wavelength excitation. A good linear relationship between the ratio signal and the GSH concentration was spanning from 0.001 to 20 μM with an impressive detection limit of 0.50 nM. This study opens a new and universal avenue for preparing integrated multifunctional probes by coupling of nanoenzyme catalytic activity with superior luminescent Ln ICPs through facile method.

Spectral Tuning and Emission Enhancement through Lanthanide Coordination in a Dual Visible–Near-Infrared Emissive Cyanide-Bridged Heterometallic Ru(II)–Er(III) Complex

Spectral Tuning and Emission Enhancement through Lanthanide Coordination in a Dual Visible–Near-Infrared Emissive Cyanide-Bridged Heterometallic Ru(II)–Er(III) Complex

A multi-color fluorescent sensing system integrated with color recognition, liquid crystal display, and voice output module for intelligent detection of two targets

Both tetracycline antibiotics (TC) and Bacillus anthracis are highly resistant to extreme environments. However, there are few studies on the intelligence detection of these two substances by establishing different detection channels. In this research, dual rare-earth coordination polymers were prepared for the detection of Bacillus anthracis and tetracycline. As a unique biomarker of B. anthracis, 2,6-pyridine dicarboxylic acid (DPA) can enhance the green fluorescence emission of Tb3+, achieving a fluorescence change from red to yellowish-green under 282 nm excitation light. Under the excitation light of 395 nm, the TC can coordinate to Eu3+ and sensitize Eu3+ to emit light through the “antenna effect,” thus achieving the fluorescence change from colorless to red. To validate the protocol's applicability in environmental samples, we detected tetracycline and Bacillus anthracis in milk, honey, and tap water. In addition, quick sensing of Bacillus anthracis in soil and tetracycline on the surface of fruits was also achieved by glove-based portable sensors. Furthermore, combined with the color recognition, liquid crystal display, and intelligent voice output system in 51 microcontrollers, it can realize the intelligent and instantaneous detection of various target molecules in real life, which had a wide range of application value and prospects.

Two isomorphic rare earth coordination polymer based on 1-imidazol-1-yl-2,4,6-phenyltricarboxylic acid ligand: Synthesis, structure, fluorescence sensing and practical applications

Two three-dimensional metal organic framework {[Ln2 (ttc)3]∙1.5 DMF}n{Ln3+=Tb3+(1), Sm3+(2)} was synthesized by solvothermal reaction of rare earth metal Ln3+ ions and 1-imidazol-1-yl-2,4,6-benzene-tricarboxylic acid (H3ttc). The crystal characteristics and composition of the two compounds were confirmed by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG), and the single crystal X-ray diffraction confirmed that they are isomorphic. The luminescence and sensing properties of the two compounds were investigated in detail, the Tb-MOF exhibits characteristic emission of Tb3+ through effective sensitization by antenna effect and emits bright green fluorescence under excitation light of 254 nm. Fluorescence experiments show that Tb-MOF has high selectivity and sensitivity for the detection of TNP, Cr2O72−, and Al3+ with the limit of detection of 2.89×10−8 mol·L−1, 2.35×10−8 mol·L−1 and 2.69×10−8 mol·L−1, respectively. In addition, possible luminescence quenching mechanisms are discussed. As a result, such a Tb-MOF will be a promising candidate and applies to the field of fluorescent ink and fingerprint retrieval.

The investigation of crystal structure, thermodynamic properties, and fluorescence properties of three new rare earth coordination compounds

Three new rare earth coordination compounds [REL3Ph]2(RE = Pr(1), Sm(2)); [ErL3Ph]2·4C2H5OH(3); (L = 2,6-dimethylbenzoate, Ph = o-phenanthroline) were synthesized. The crystal structures of the three compounds were measured by X-ray single-crystal diffraction. From the results, we made out that compounds 1–3 were binuclear structures, and 1D chain-like structures could be formed by hydrogen bonding. The thermal degradation data of the compounds and the three-dimentional infrared cumulative spectra of the gaseous decomposed products were obtained by TG/DSC-FTIR technique, and the thermal degradation patterns were explained. The isobaric molar heat capacity of compounds 1 and 2 in the low-temperature region was obtained by the DSC technique and the thermodynamic parameters were derived. The fluorescence spectrum of compound 2 was determined, showing that it had potential application value in the orange-red luminescence region.

An Ultra-stable Eu3+ Doped Yttrium Coordination Polymer with Dual-function Sensing for Cr(VI) and Fe(III) Ions in Aqueous Solution

The exploration of a dual-functional sensor is the key to effectively detect the Cr(VI) and Fe(III) cations in water, which is important to human health and environmental sustainability. Because of the phase stability and excellent luminescence, the rare-earth coordination polymers have great potential as dual-functional sensors. Here, we develop a Y0.91Eu0.09(H2O)2{C6H3(CO2)3}(MIL-92(Y):9%Eu3+)-based dual-function luminescent sensor on Cr(VI) and Fe(III), which exhibits excellent phase stability and dispersibility in water. The luminescence of MIL-92(Y):9%Eu3+ aqueous suspension quenches on Fe3+ with Stern-Volmer constant Ksv of 1.79 × 103 M-1 and limit of detection of 17 μM. The MIL-92(Y):9%Eu3+ aqueous suspension also has turn-off sensing ability towards Cr2O72- and CrO42- with Ksv values of 3.5 × 103 and 6.14 × 103 M-1, respectively. It has detection limitations of 10 and 5 μM on Cr2O72- and Cr2O72- ions, respectively.

Synthesis, Characterization, Antimicrobial and Antimalarial Activities of 5-((2- phenylacetoxy) carbonyl)-1H-pyrazole-3-carboxylic Acid and its Ce(III), Pr(III) and Nd(III) Complexes

In the past decade, the lanthanoid coordination chemistry was one of the most focused areas of research due to their wide applications as catalyst, magnetism, luminescence and diagnostic tools in biological studies. In this study, novel pyrazole; 5-((2-phenylacetoxy) carbonyl)-1Hpyrazole-3-carboxylic acid derivative and its lanthanoid complexes are designed and tested for potential antimicrobial and antimalarial activities. The binuclear ligand bridge complexes were obtained by the interaction of the ligand with the lanthanide salts. The compounds were characterized by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, UltravioletVisible spectroscopy, Fourier Transform infrared (FT-IR) spectroscopy, Mass spectrometry (MS), Elemental analysis and Magnetic susceptibility measurements. The in vitro antimicrobial assay was done by Agar well diffusion method and in vivo antimalarial studies were performed based on Peter’s method. The results were analysed using one way analysis of variance (ANOVA). The antimicrobial and antiparasitic effects of these compounds were found to be dose-dependent and they showed greater effects at higher doses.&nbsp

Enhanced interfacial adhesion of CF/PEEK-titanium hybrid laminates via rare-earth coordination interaction

Improving the adhesion between metal sheet and resin is an important issue for the development of high-performance fiber metal laminates (FMLs). In this study, a novel rare-earth surface modification is applied for the first time to enhance the interfacial bonding strength of titanium sheets and polyetheretherketone (PEEK). Density functional theory (DFT) calculations show that cerium element could form coordination bonds at the interfaces between metallic titanium and resin. The surface wettability of titanium sheet is boosted, which is beneficial to PEEK infiltration and physical adhesion improvement. Meanwhile, with the existence of coordination bonds at the interface, the interfacial shear strength between titanium and PEEK, and the flexural strength and interlaminar shear strength of CF/PEEK-Ti laminates are enhanced significantly. Therefore, the cerium surface modification method proposed in this study has great potentials for FMLs, which provides a new strategy for generating chemical bond at interfaces between metal and resin.

Anthracene-based lanthanide coordination polymer for the sensitive detection of 2-thiazolidinethione-4-carboxylic acid and temperature

An anthracene-based rare earth coordination polymer (CP) [Tb2Cl2(adip)(NMP)3(H2O)] (1) was prepared by solvothermal assembling of Tb3+ and 5,5′-(anthracene-9,10-diyl)diisophthalic acid (H4adip, NMP = N-methylpyrrolidone) and possesses a 3D framework and ligand-based blue emission. 1 could be used as a fluorescent probe to detect 2-thiazolidinethione-4-carboxylic acid (TTCA) and temperature with excellent selectivity, sensitivity and anti-interference ability. Between 0 and 10 μM concentration range of TTCA, the fluorescence quenching constant (Ksv) of 1 reaches 9.78 × 104 M−1 with the limit of detection of 92.6 nM. 1 could also be used as a temperature sensor within 0–60 °C. The maximum relative sensitivity (Sr) was calculated as 5.74% °C−1 at 60 °C and the temperature resolution (δT) is 0.013–0.003 °C corresponding to the above ambient temperature range. The sensitivities of 1 have reached the best level of reported chemical sensors so far. In addition, the mechanisms of fluorescence quenching were studied.

The Effect of Glass Structure on the Luminescence Spectra of Sm3+-Doped Aluminosilicate Glasses.

Peralkaline Sm3+-doped aluminosilicate glasses with different network modifier ions (Mg2+, Ca2+, Sr2+, Ba2+, Zn2+) were investigated to clarify the effect of glass composition and glass structure on the optical properties of the doped Sm3+ ions. For this purpose, the Sm3+ luminescence emission spectra were correlated with the molecular structure of the glasses derived by molecular dynamics (MD) simulations. The different network modifier ions have a clear and systematic effect on the peak area ratio of the Sm3+ emission peaks which correlates with the average rare earth site symmetry in the glasses. The highest site symmetry is found for the calcium aluminosilicate glass. Glasses with network modifier ions of lower and higher ionic radii show a notably lower average site symmetry. The symmetry could be correlated to the rare earth coordination number with oxygen atoms derived by MD simulations. A coordination number of 6 seems to offer the highest average site symmetry. Higher rare earth coordination probabilities with non-bridging oxygen result in an increased splitting of the emission peaks and a notable broadening of the peaks. The zinc containing glass seems to play a special role. The Zn2+ ions notably modify the glass structure and especially the rare earth coordination in comparison to the other network modifier ions in the other investigated glasses. The knowledge on how glass structure affects the optical properties of doped rare earth ions can be used to tailor the rare earth absorption and emission spectra for specific applications.

Lanthanoid coordination prompts unusually distorted pseudo-octahedral NiII coordination in heterodinuclear Ni-Ln complexes: synthesis, structure and understanding of magnetic behaviour through experiment and computation.

In this work, a new family of binuclear NiII-LnIII complexes with the formula [NiLn(L)2(NO3)3]·0.5H2O (Ln = Gd, 1; Tb, 2; Dy, 3; Ho, 4; Er, 5; Yb, 6; Y, 7) was synthesized using a thioether group-bearing Schiff base. Due to the strict hard/soft dichotomy between the 4f and 3d metal ions, selective coordination of NiII and 4f metal ions was achieved with the adjacent soft ONS and hard OO binding pockets of the ligand. All the complexes 1-7 exhibit a NiII centre in a distorted pseudo-octahedral geometry with the LnIII centres in distorted bicapped square-antiprism geometry. The huge distortion around the NiII centres is triggered for the accommodation of larger lanthanoids to the adjacent OO coordination site, and this forces the NiII centres to have a tridentate coordination from the ONS, as intermediate between meridional and facial binding. Field-induced single-molecule magnetic behaviour was observed for heterodinuclear complexes involving Kramers lanthanide ions (LnIII = Dy, Er and Yb), with magnetic relaxation occurring through an Orbach process only for 5. DFT calculations using various functionals (BP86, B3LYP, PBE0, TPSSh, PWPB95, R2SCAN) were applied to calculate the isotropic exchange, showing good agreement with the experiment (JGd-Ni = +1.78 cm-1). CASSCF calculations for NiII and LnIII ions were also performed to reveal detailed information about their electronic structure and magnetic anisotropy, supporting the experimental observations. This study accentuates the mutual distortion of coordination geometry induced by flexibility of the ligand backbone with the simultaneous binding of two different metal ions.

Perfectly Encoding π‐Conjugated Anions in the RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) Family with Strong Second Harmonic Generation Response and Balanced Birefringence

AbstractNonlinear optical (NLO) crystal, which simultaneously exhibits strong second‐harmonic‐generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE5(C3N3O3)(OH)12 (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a “three birds with one stone” strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5–4.2× KH2PO4), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π‐conjugated (C3N3O3)3− anions. These findings provide high‐performance short‐wavelength NLO materials and highlight the exploration of cyanurates as a new research area.

Perfectly Encoding π-Conjugated Anions in the RE5 (C3 N3 O3 )(OH)12 (RE=Y, Yb, Lu) Family with Strong Second Harmonic Generation Response and Balanced Birefringence.

Nonlinear optical (NLO) crystal, which simultaneously exhibits strong second-harmonic-generation (SHG) response and desired optical anisotropy, is a core optical material accessible to the modern optoelectronics. Accompanied by strong SHG effect in a NLO crystal, a contradictory problem of overlarge birefringence is ignored, leading to low frequency doubling efficiency and poor beam quality. Herein, a series of rare earth cyanurates RE5 (C3 N3 O3 )(OH)12 (RE=Y, Yb, Lu) were successfully characterized by 3D electron diffraction technique. Based on a "three birds with one stone" strategy, they enable the simultaneous fulfillment of strong SHG responses (2.5-4.2× KH2 PO4 ), short UV cutoff (ca. 220 nm) and applicable birefringence (ca. 0.15 at 800 nm) by the introduction of rare earth coordination control of π-conjugated (C3 N3 O3 )3- anions. These findings provide high-performance short-wavelength NLO materials and highlight the exploration of cyanurates as a new research area.

Atomically precise control of rotational dynamics in charged rare-earth complexes on a metal surface

Complexes containing rare-earth ions attract great attention for their technological applications ranging from spintronic devices to quantum information science. While charged rare-earth coordination complexes are ubiquitous in solution, they are challenging to form on materials surfaces that would allow investigations for potential solid-state applications. Here we report formation and atomically precise manipulation of rare-earth complexes on a gold surface. Although they are composed of multiple units held together by electrostatic interactions, the entire complex rotates as a single unit when electrical energy is supplied from a scanning tunneling microscope tip. Despite the hexagonal symmetry of the gold surface, a counterion at the side of the complex guides precise three-fold rotations and 100% control of their rotational directions is achieved using a negative electric field from the scanning probe tip. This work demonstrates that counterions can be used to control dynamics of rare-earth complexes on materials surfaces for quantum and nanomechanical applications.