Mixed-lanthanide Metal-organic Frameworks Research Articles

A NbO-type mixed lanthanide metal-organic framework for cryogenic temperature sensing.

A novel NbO-type Eu/Tb-mixed lanthanide metal-organic framework has been developed for the highly sensitive, self-calibrating detection of cryogenic temperature.

Use of Luminescence Modulation in a New Series of Mixed Lanthanide Metal-Organic Frameworks for Selective Firearm Ammunition Marking.

Metal-organic frameworks (MOFs) are coordination polymers that can generally be described by secondary building units (SBUs). These include lanthanide MOFs, specifically mixed lanthanide MOFs (m-LnMOFs), encompassing coordination polymers formed by two or more different Ln3+ ions. These compounds have been the subject of study by inorganic chemists worldwide, mainly due to the possibility of obtaining long-awaited tunable luminescence, i.e., compounds that emit luminescence in various visible spectrum regions. A wide range of emission color scan be obtained by inserting different Eu3+, Tb3+, and Gd3+ ion molar fractions in m-LnMOFs, which can also be adjusted by choosing the Ln3+ ion or its amount in each network. This study presents a new series of m-LnMOFs supported by 1,2,4,5-benzenetetracarboxylic acid (H4btec). These compounds were completely characterized in their solid state through different analytical and spectroscopic techniques, and an in-depth photophysical study was conducted. Due to their high thermal stability and multicolored emissions, these complexes were applied, for the first time, as selective ammunition markers, allowing for the unequivocal identification of the type of weapon used in forensic scenarios and the promotion of stricter ammunition trade control.

Orthogonal Postsynthetic Copolymerization of Hydrogen‐Bonded Organic Frameworks into a PolyHOF Membrane

AbstractHydrogen‐bonded organic frameworks (HOFs) have shown promise in various fields; however, the construction of HOF/polymer hybrid membranes that can maintain both structural and functional integrity remains challenging. In this study, we here fabricated a new HOF (HOF‐50) with reserved polymerizable allyl group via charge‐assisted H‐bonds between the carboxylate anion and amidinium, and subsequently copolymerized the HOF with monomers to construct a covalently bonded HOF/polymer hybrid (polyHOF) membrane. The resulting polyHOF membrane not only exhibits customizable mechanical properties and extreme stability, but also shows an exceptional ratiometric luminescent temperature‐sensing function with very high sensitivity and visibility even when the lanthanide content is two orders of magnitude lower than that of the reported mixed‐lanthanide metal–organic frameworks (MOFs) and lanthanide‐doped covalent organic frameworks (COFs). This orthogonal postsynthesis copolymerization strategy may provide a general approach for preparing covalently connected HOF/polymer hybrid membranes for diverse applications.

Orthogonal Postsynthetic Copolymerization of Hydrogen-Bonded Organic Frameworks into a PolyHOF Membrane.

Hydrogen-bonded organic frameworks (HOFs) have shown promise in various fields; however, the construction of HOF/polymer hybrid membranes that can maintain both structural and functional integrity remains challenging. In this study, we here fabricated a new HOF (HOF-50) with reserved polymerizable allyl group via charge-assisted H-bonds between the carboxylate anion and amidinium, and subsequently copolymerized the HOF with monomers to construct a covalently bonded HOF/polymer hybrid (polyHOF) membrane. The resulting polyHOF membrane not only exhibits customizable mechanical properties and extreme stability, but also shows an exceptional ratiometric luminescent temperature-sensing function with very high sensitivity and visibility even when the lanthanide content is two orders of magnitude lower than that of the reported mixed-lanthanide metal-organic frameworks (MOFs) and lanthanide-doped covalent organic frameworks (COFs). This orthogonal postsynthesis copolymerization strategy may provide a general approach for preparing covalently connected HOF/polymer hybrid membranes for diverse applications.

A 2D mixed-lanthanide metal‒organic framework as dual-emitting luminescent sensor for ratiometric detection of tetracycline and nitrophenols

A 2D mixed-lanthanide metal‒organic framework as dual-emitting luminescent sensor for ratiometric detection of tetracycline and nitrophenols

Dual-Emitting Mixed-Lanthanide Metal-Organic Framework for Ratiometric and Quantitative Visual Detection of 2,6-Pyridine Dicarboxylic Acid.

The detection of the major biomarker of Bacillus anthracis, 2,6-dipicolinic acid (DPA), has attracted great interest in recent years. In this work, mixed-lanthanide metal-organic frameworks (M'LnMOFs), TbxEu1-x-cppa (cppa = 5-(5-carboxypyridin-3-yl)isophthalic acid), with different Tb/Eu ratios, were solvothermally synthesized. The results reveal that ratiometric fluorescent probe [Tb0.533Eu0.467-(Hcppa)1.5(H2O)(DMF)]·3H2O is water and acid-base stable and exhibits excellent sensitivity (LOD = 2.286 μM), high selectivity, and fast response (<2 min) for the detection of DPA. Due to the blocked energy transfer from Tb3+ to Eu3+ and the inner filter effect upon the addition of DPA, the fluorescent probe shows a distinct color change from orange-red to green. Furthermore, the visual detection of DPA was realized by identifying the RGB values of MOF-based agarose hydrogel films via a smartphone, highlighting the practical application of the fluorescent probe for DPA detection under aqueous solution conditions.

Ratiometric luminescent thermometer based on a mixed Ce/Tb metal-organic framework

Ratiometric luminescent thermometer based on a mixed Ce/Tb metal-organic framework

Terbium-based metal-organic frameworks through energy transfer modulation for visual logical sensing zinc and fluorine ions

Zinc is the second most abundant trace element in the human central nervous system, which is closely related to various physiological activities in the human body. Fluoride ion is one of the most harmful elements in drinking water. Excessive intake of F- may cause dental fluorosis, renal failure, or DNA damage. Therefore, it is urgent to develop sensors with high sensitivity and selectivity for the detection of Zn2+ and F- ions at the same time. In this work, a series of mixed lanthanide metal-organic frameworks (Ln-MOFs) probes are synthesized using a simple method of in situ doping. The luminous color can be finely modulated by changing the molar ratio of Tb3+ and Eu3+ during synthesis. Benefiting from the unique energy transfer modulation mechanism, the probe has the continuous detection capability of zinc ions and fluoride ions. The detection of Zn2+ and F- in a real environment shows that the probe has a good practical application prospect. The as-designed sensor at 262nm excitation can sequentially detect Zn2+ concentrations ranging from 10-8 to 10-3M (LOD=4.2nM) and F- levels ranging from 10-5 to 10-3M (LOD=3.6μM) with high selectivity. Based on different output signals, a simple Boolean logic gate device is constructed to realize intelligent visualization of Zn2+ and F- monitoring.

Dual-functional ratiometric fluorescent sensor based on mixed-lanthanide metal–organic frameworks for the detection of trace water and temperature

A mixed-lanthanide MOF with multiple readouts has been developed, which presents a promising paradigm for real-time and in situ determination of trace water and temperature.

Ratiometric fluorescence for sensitive detection of phosphate species based on mixed lanthanide metal organic framework.

Phosphate (PO43-) plays a major role in aquatic ecosystems and biosystems. Developing a highly sensitive and selective ratiometric fluorescence probe for detection of PO43- is of great significance to the ecological environment and human health. In this work, a novel dual lanthanide metal organic framework was synthesized via hydrothermal reaction based on Tb3+ and Ce3+ as the center metal ions and terephthalic acid as the organic ligand (designated as Tb-Ce-MOFs). The fluorescence of Tb-Ce-MOFs shows emission at 375nm. In the presence of PO43-, with increased concentration of PO43-, the fluorescence intensity of Tb-Ce-MOFs at 500nm and 550nm increased, while the intensity at 375nm was reduced. Hence, ratiometric fluorescence detecting of PO43- can be achieved by measuring the ratio of fluorescence at 550nm (FL550) to 375nm (FL375) in the fluorescent spectra of the Tb-Ce-MOFs. In this sensing approach, the Tb-Ce-MOFs probe exhibits highly sensitive and selective for detection of PO43-. The limit of detection is calculated to be 28nM and the detection range is 0.1 to 10μM. In addition, the Tb-Ce-MOFs were used in the detection of PO43- in real samples. We design and synthesize a mixed lanthanide metal organic framework fluorescence probe (Tb-Ce-MOFs) for ratiometric fluorescence for the detection of PO43- based on Tb3+ and Ce3+ as the center metal ions and terephthalic acid as the organic ligand.

Simple reductive synthesis of a novel mixed-lanthanide metal–organic framework with excellent cycling ability as a binder-free supercapacitor electrode

Abstract In this work, a novel mixed-lanthanide metal–organic framework (ML-MOF, ML = La3+, Gd3+ and Tm3+) is synthesized for the first time through a simple reductive electrodeposition procedure onto nickel foam and its charge storage ability is investigated. The as-prepared ML-MOF is characterized through FE-SEM, EDS, XRD, FT-IR and TGA analyses. The results of these analyses confirmed deposition of the crystalline well-defined rod-like ML-MOF with composition of {La2Gd0.5Tm0.5 BTC]. xH2O}n onto Ni foam. The fabricated ML-MOF/NF electrode delivered specific capacity values of 965F g−1 and 594 F g−1 at 5 and 50 A g−1, and capacity retention of 94.5% after 6000 cycles at high current load of 5 A g−1, which confirmed its superior rate ability and excellent cycling performance. Based on the results, the applied electrochemical strategy is introduced as a simple facile way for synthesis of various ML-MOF materials for different electrochemical applications.

Visual Detection of Fluoride Anions Using Mixed Lanthanide Metal-Organic Frameworks with a Smartphone.

Fluoride ion (F-) is one of the most harmful elements in drinking water. Over-intake of F- can result in dental fluorosis, kidney failure, or DNA damage. Therefore, developing affordable, equipment-free, and reliable methods for F- detection is an important goal. In this work, a series of mixed lanthanide metal-organic frameworks were synthesized using a triazine-based planar ligand, 4,4',4″-s-triazine-2,4,6-triyltribenzoate (TATB) and mixed lanthanide ions (Tb3+ and Eu3+). The luminescent color of the Tb/Eu(TATB) can be finely modulated by changing the Tb3+/Eu3+ ratio in the synthesis procedure. Benefiting from the unique host-guest interaction (e.g., Lewis acid-base interaction), between F- and MOF host, a highly selective, sensitive, and reliable fluoride sensor was then developed. Moreover, visual detection of F- was achieved with a smartphone by identifying the RGB value. Drinking water samples were analyzed for F-, and the results obtained by our ratiometric luminescent method were consistent with those by ion chromatographic strategy. This easy-to-use sensor provides reliable detection of F- in everyday applications for nonexpert users, especially in remote rural areas.

Mixed-LnMOFs with tunable color and white light emission together with multi-functional fluorescence detection

Abstract A series of mixed lanthanide metal-organic frameworks: [(EuxTb1-x)2(TDC)3(CH3OH)2·(CH3OH)] ((abbreviated as EuxTb1-x-MOFs, x = 0.5, 0.067, 0.05, 0.01, 0.00833, 0.00667, 0.005, x represents the molar ratio of Eu in the total amounts), H2TDC = 2, 5-thiophenedicarboxylic acid) have been prepared under solvothermal condition by adjusting the molar ratio of Eu3+ to Tb3+ ions. The emission colors of EuxTb1-x-MOFs have been tuned by controlling the molar ratio of Eu3+/Tb3+ and changing the excitation wavelength. Fortunately, a white light-emitting material Eu0.00667Tb0.99333-MOF has been obtained at the excitation wavelength of 350 nm. The CIE coordinate of (0.3333, 0.3394) is very close to the standardized coordinate for pure white light (0.3333, 0.3333). Furthermore, the fluorescence sensing performance of Eu0.00667Tb0.99333-MOF for hazardous phenolic compounds and physiological temperature were tested upon excitation at 320 nm. The results reveal that Eu0.00667Tb0.99333-MOF can be used as a multi-target sensor for selective sensing β-naphthol and physiological temperature from 288 to 353 K with good sensing reproducibility.

Design of a white-light emitting material based on a mixed-lanthanide metal organic framework

The design of white-light emitting materials for solid-state lighting technology is governed by the combination of independent red, green and blue emitting centers. Many mixed-lanthanide single phase white-light source materials have been produced so far by a careful trial and error combination of lanthanide ions during the synthetic procedure. In this work we propose a simple and efficient method for the direct preparation of the desired material with the optimal combination of metal ions, avoiding the trial and error multiple synthetic approach. In the proposed strategy, the emission profiles of the isostructural complexes of each lanthanide ion for a chosen excitation wavelength are compared relative to their ion density and the necessary final composition of the material is calculated in order to obtain the white-light CIE coordinates. Using this method, we prepared a white-light emitting material which is a metal-organic framework built from oxydiacetate ligand, lanthanide ions (Eu, Tb and Dy emitting red, green and blue respectively) and zinc (a closed shell metal ion that has proven to be ideal for optical applications). The compound [Dy 1.60 Eu 0.38 Tb 0.02 Zn 3 (oda) 6 (H 2 O) 6 ]·12H 2 O was prepared and fully characterized by single crystal x-ray diffraction, its optical properties were also measured. The proposed rational mixing of lanthanide ions could be useful for the preparation of white-light source materials in analogous systems, provided the single-lanthanide compounds are isostructural along the series and no optical interaction is operative among ions. White-light emitting materials design shortcut for solid-state lighting technology exemplified by the synthesis and full characterization of [Dy 1.60 Eu 0.38 Tb 0.02 Zn 3 (oda) 6 (H 2 O) 6 ]·12H 2 O. • Rational design of white-light emitting materials. • Mixed-lanthanide single phase compounds with tunable luminescence profile. • Each lanthanide optic contribution modeled using ion density. • Oxydiacetate metal organic framework crystal structure.

Biomimetic mineralization of nanoscale lanthanide metal-organic frameworks with thermo-sensitive polymer as organic ligands for solvent recognition and water detection

Novel nanoscale lanthanide and mixed lanthanide metal-organic frameworks with thermo-sensitive polymer as organic links were successfully prepared. They were obtained through biomimetic mineralization approach. This is the first report of fabrication of polymer-metal-organic frameworks via biomimetic mineralization. The particle size was in the range from 200 to 500 nm. The photoluminescent properties of the materials have also been studied. The fluorescence intensity changed in different solvent (N, N-dimethylformamide, tetrahydrofuran, ethanol, acetone, dichloromethane, water), so solvent recognition can be achieved by using the polymer-metal-organic frameworks. The materials are also very sensitive to water (even trace water) in the mixed solutions composed of water and organic solvents. Especially the mixed lanthanide polymer-metal-organic frameworks can be designed to a ratiometric fluorescent nanosensor. The novel fluorescence detection materials have very important potential applications in the field of chemical industry.

One‐Step Synthesis of Mixed Lanthanide Metal–Organic Framework Films for Sensitive Temperature Mapping

AbstractMixed lanthanide metal–organic framework (LnMOF) films are directly grown on a quartz substrate through a wet chemical synthesis. Thermometric properties of the LnMOF films originating from temperature dependent emission intensity ratio of Tb/Eu are systematically investigated in the 298–383 K range. At an optimized Tb/Eu concentration ratio of 98.0:2.0, the ratiometric thermometer registers a high relative sensitivity of 16.14% K−1 at 359 K. As the temperature increases from 298 to 383 K, the LnMOF film thermometer also displays a distinct change in emission color from green to red, corresponding to a shift in Commission International de l'Eclairage (CIE) chromaticity coordinates from (0.3882, 0.5271) to (0.5459, 0.4037). The colorimetric property of the LnMOF film thermometer is exploited for real‐time temperature mapping with a high sensitivity.

Augmentation of Neodymium Ions Removal from Water Using Two Lanthanides-Based MOF: Ameliorated Efficiency by Synergistic Interaction of Two Lanthanides

To overcome the shortage of freshwater resources and provide clean water for worldwide population, along with the elimination or reduction of water contamination, we have synthesized the mixed-lanthanide metal–organic framework (MOF) with the formula m(x)M(1–x)BTC(DMF) {m = Ce(III), M = La(III), x = 0.8} via the solvothermal technique to separate Nd ions from water. The cooperative interaction between La(III) and Ce(III) has intensified the nonlinear properties of Ce0.8La0.2BTC(DMF) resulting in the high interaction between fabricated MOF and Nd ions. The as-prepared MOF was considered for various structural analyses and experimental conditions. Significantly, over 80% of Nd ions have been removed within 5 min and the maximum Nd uptake capacity (qmax) determined by the Langmuir isotherm was 142.8 mg/g.

Dual-Function Mixed-Lanthanide Metal-Organic Framework for Ratiometric Water Detection in Bioethanol and Temperature Sensing.

In order to accurately and conveniently measure temperature and water content in bioethanol, a dual-function ratiometric luminescence sensor has been fabricated successfully based on mixed lanthanide metal-organic frameworks (MOFs) Eu0.02Dy0.18-MOF. In this MOF, the two lanthanides and ligand (H4L) form three luminescence centers, and they have different sensitivity toward water and temperature. Using the ratio of luminescence intensity at 416 and 614 nm, the MOF could quantitatively determine the concentration of water in dry ethanol and in bioethanol with recoveries of 91% -107%, and a detection limit of 0.1%, which is much lower than that in hydrated ethyl alcohol fuel (AEHC), 0.8% in China, 1.0% in the United States, and 4.9% in Brazil. Using the luminescence intensity ratio of Eu3+5D0 → 7F2 (614 nm) transition to Dy3+4F9/2 → 6H13/2 (573 nm) transition, the MOF could also sense temperature in range of 293 to 373 K, and 150 to 290 K with high accuracy, excellent linear relationship, reversibility, and recyclability.

A stable mixed lanthanide metal-organic framework for highly sensitive thermometry.

A family of lanthanide-based MOFs (Ln-MOFs) with high thermal and chemical stability have been successfully synthesized by a solvothermal method. Owing to the intrinsic robustness of the framework and temperature-dependent luminescence behaviour of lanthanides, Eu3+/Tb3+-mixed MOFs ([(CH3)2NH2]Eu0.036Tb0.964BPTC) have also been successfully synthesized and targeted for developing excellent luminescent thermometers. The obtained mixed Ln-MOF exhibits ratiometric temperature sensing based on the distinguished characteristic emission of lanthanides with a wide temperature range from 77 K to 377 K. Particularly, the temperature sensor shows good linear responses from 220 K to 310 K with the maximum relative sensitivities (Sm) of 9.42% per K at 310 K. This value is comparable to those of the most excellent Ln-MOF thermometers reported. Besides, the temperature-dependent luminescent colours could also be systematically tuned from green, through yellow to red with increasing temperature, which can be clearly and directly observed even by the naked eye or a camera, thus also allowing colorimetric luminescence thermometry.

Synthesis, structure and temperature sensing of a lanthanide-organic framework constructed from a pyridine-containing tetracarboxylic acid ligand

A high sensitive, thermostable mixed lanthanide metal–organic framework, Eu0.19Tb0.81PDDI, was developed as a self-calibrated thermometer effective in the high temperature range of 313 to 473 K.