Europium Metal-organic Framework Research Articles

A novel photo- and hydrochromic europium metal–organic framework with good anion sensing properties

A new multifunctional Eu-MOF based on a cationic viologen ligand has been synthesized. It exhibits interesting photochromism, hydrochromism and sensing ability for detection of toxic Cr2O72− and CrO42− anions.

Synthesis of europium metal–organic framework (Eu-MOF) and its performance in adsorptive desulfurization

Europium metal organic framework (Eu-MOF) was synthesized using Europium as metal ion center and 1,3,5-trimesic acid (H3BTC) as organic ligand under hydrosolvothermal conditions. The dynamic performance of the Eu-MOF material in adsorption desulfurization processes was investigated using a solution of thiophene/n-octane as sulfur containing quality model oil. The adsorption desulfurization kinetics equations and adsorption desulfurization isotherms of Eu-MOF were also studied. The results have shown that Eu-MOF catalyst has very good adsorption desulfurization abilities under optimum desulfurization conditions of madsorbent: mmodel oil ratio of 1:100 and reaction temperature of 303 K. After 4 h of desulfurization reaction, the adsorption rate and the adsorption desulfurization capacity has reached 64.70% and 24.59 mgS/gMOF respectively. The Eu-MOF adsorption desulfurization process of thiophene on Eu-MOF fits well the quasi two level dynamic model using Langmuir isotherm, Freundlich isotherm and Dubinin–Radushkevich isotherm equations. The Dubinin–Radushkevich isotherm can be a suitable description of adsorption process for Eu-MOF absorbent on thiophene/n-octane mode oil. However the Freundlich isotherm equation model with fitting R 2 value closer to 1, can be a better description for the adsorption of thiophene. The adsorption of thiophene over Eu-MOF absorbent has two types of adsorption that occur simultaneously. These are the monolayer physical adsorption and the multilayer chemical adsorption.

Highly selective luminescent sensing of picric acid based on a water-stable europium metal-organic framework

A water-stable metal-organic framework (MOF) EuNDC has been synthesized for selective detection of the well-known contaminant and toxicant picric acid (PA) in aqueous solution. Due to the photo-induced electron transfer and self-absorption mechanism, EuNDC displayed rapid, selective and sensitive detection of PA with a detection limit of 37.6 ppb. Recyclability experiments revealed that EuNDC retains its initial luminescent intensity and same quenching efficiency in each cycle, suggesting high photostability and reusability for long-term sensing applications. The excellent detection performance of EuNDC makes it a promising PA sensing material for practical applications.

Multifunctional Three-Dimensional Europium Metal-Organic Framework for Luminescence Sensing of Benzaldehyde and Cu(2+) and Selective Capture of Dye Molecules.

A multifunctional three-dimensional lanthanide metal-organic framework has been rationally constructed. Highly selective sensing of benzaldehyde and Cu(2+) ions makes it a potential bifunctional sensor. Also, it could serve as a good candidate material for the removal of dyes from effluents based on the size exclusion.

A novel europium metal-organic framework as luminescent probe for detecting Al3 +

A novel three-dimensional europium metal-organic framework (Eu-MOF), [Eu(L)(OAc)(DMA)]n (1), has been successfully obtained based on a newly designed ligand 4′-(3,5-dicarboxyphenyl)-4,2′:6′,4″-terpyridine (H2L). The structure of 1 was established by single crystal X-ray diffraction technique, and structure analysis shows that two Eu3+ in 1 are 4-fold bridged by two η1:η1:μ2 carboxylates from L2− and the other two η1:η2:μ2 carboxylates from acetic acid, respectively. The binuclear [Eu2] were further linked by L2− to form a 3D framework. The investigations on luminescent properties reveal that 1 can detect Al3+ quickly with relatively high sensitivity and selectivity. More importantly, it displays high thermal and solvent stability. Additionally, a self-made fluorescence test paper fabricated based on 1 was used to detect Al3+ in practice.

Dual-Emission of Lanthanide Metal–Organic Frameworks Encapsulating Carbon-Based Dots for Ratiometric Detection of Water in Organic Solvents

Nitrogen and sulfur codoped carbon-based dots (N,S-CDs) with strong blue light emission are encapsulated into red light-emitting europium metal-organic frameworks (Eu-MOFs) to form two color light-emitting nanohybrids (Eu-MOFs/N,S-CDs). In organic solvents, the encapsulated N,S-CDs are aggregated and confined in the cavities of the Eu-MOFs, exhibiting only a very weak photoluminescence (PL) signal. Therefore, the nanohybrids show red light emission of the Eu-MOFs. Contrarily, when the Eu-MOFs/N,S-CDs are dispersed in water, the encapsulated N,S-CDs are released into solution while the red light emission of the Eu-MOFs is quenched due to the effect of O-H oscillators. The nanohybrids are used as the probe for the water content in organic solvents. Take ethanol as an example; as the water content is increased from 0.2 to 30%, the nanoprobe provides distinguishable PL color change. The ratio of light intensity at 420 nm to that at 623 nm (I420/I623) increases linearly with increasing water content in the range from 0.05 to 4% with a low detection limit of 0.03%.

Europium metal-organic frameworks as recyclable and selective turn-off fluorescent sensors for aniline detection.

Seven Eu-(H)BDC compounds, [RMI][Eu2(BDC)3Cl] (R = ethyl (1), propyl (2), butyl (3), H2BDC = 1,4-benzenedicarboxylic acid), [EMI]2[Eu2(BDC)3(H2BDC)Cl2] (4), [Eu(BDC)(HCOO)] (5), [Eu(BDC)Cl(H2O)] (6) and [Eu3(BDC)4Cl(H2O)6] (7), were synthesized under ionothermal conditions. Compounds 4 and 6 behave as potential highly selective turn-off fluorescent sensors for aniline, which can be detected in mixtures of aniline with contrast organic amides or alkylbenzenes. Fluorescence quenching can be observed when compounds 4 and 6 mix with the samples containing aniline. Compounds 4 and 6 show basically unchanged emission intensities and rapid response to aniline after ten recycling tests, suggesting that the compounds have high stable recycle repeatabilities.

A stable europium metal-organic framework as a dual-functional luminescent sensor for quantitatively detecting temperature and humidity.

We report a luminescent Eu metal-organic framework (MOF) with a one-dimensional, open channel filled with water molecule assemblies; this MOF can serve as a dual-functional luminescent sensor for detecting temperature and humidity. Using this MOF, we have developed a self-calibrating ratiometric thermometer that operates within the cryogenic temperature range and simultaneously functions as a luminescent humidity sensor within the relative humidity (RH) range from 33.0% to 85.1%.

A luminescent europium metal–organic framework with free phenanthroline sites for highly selective and sensitive sensing of Cu2 + in aqueous solution

A luminescent europium metal–organic framework [Eu(HL)(L)(H2O)2]·2H2O (1) (H2L=(2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid) with uncoordinated phenanthroline nitrogen sites was hydrothermally synthesized. It exhibits highly sensitive and selective sensing of Cu2+ in aqueous solution. To the best of our knowledge, complex 1 is the first luminescent Eu-MOF with uncoordinated phenanthroline nitrogen sites for selective sensing of Cu2+ in aqueous solution. The probable sensing mechanism was discussed in detail.

A Temperature-Responsive Smart Europium Metal-Organic Framework Switch for Reversible Capture and Release of Intrinsic Eu3+ Ions.

Stimuli‐responsive structural transformations are emerging as a scaffold to develop a charming class of smart materials. A EuL metal‐organic framework (MOF) undergoes a reversible temperature‐stimulated single‐crystal to single‐crystal transformation, showing a specific behavior of fast capture/release of free Eu3+ in the channels at low and room temperatures. At room temperature, compound 1a is obtained with one free carboxylate group severing as further hook, featuring one‐dimensional square channels filled with intrinsic free europium ions. Trigged by lowering the ambient temperature, 1b is gained. In 1b, the intrinsic free europium ions can be fast captured by the carboxylate‐hooks anchored in the framework, resulting in the structural change and its channel distortion. To the best of our knowledge, this is the first report of such a rapid and reversible switch stemming from dynamic control between noncovalent and covalent Eu–ligand interactions. Utilizing EuL MOF to detect highly explosive 2,4,6‐trinitrophenol at room temperature and low temperature provides a glimpse into the potential of this material in fluorescence sensors.

Microwave-assisted synthesis of nanoscale Eu(BTC)(H2O)·DMF with tunable luminescence

Nanoscale europium(III) metal-organic frameworks, Eu(BTC)(H2O)·DMF, were synthesized by rapid microwave-assisted method. The components of the as-prepared products were confirmed by the elemental analysis, X-ray powder diffraction (XRD), thermal gravimetric analysis (TGA) and Fourier-transform infrared spectra (FTIR) analyses. Eu(BTC)(H2O)·DMF with various morphologies, including particle-like, rod-like, straw-sheaf-like nanostructures, could be simply prepared by controlling the concentrations of the starting reactants. The optical measurements on the obtained Eu(BTC)(H2O)·DMF indicated that all the nanomaterials show the characteristic emissions of the Eu3+ ions at 578, 590, 612, 650, and 699 nm, which were attributed to 5D0→7F J (J=0–4) transitions of the Eu3+ ion, respectively. It was also noticed that the luminescent properties of the as-prepared products were heavily dependent on the morphologies and sizes of the nanomaterials. The assembled straw-sheaf-like architectures displayed the strongest emissions and the longest luminescence lifetime, which was mainly due to the fewest surface defects.

Dual-emitting MOF⊃dye composite for ratiometric temperature sensing.

A strategy to achieve a ratiometric thermometer by encapsulating luminescent perylene dye into the pores of a europium metal-organic framework (MOF) is developed. The resulting MOF⊃dye thermometer exhibits highly temperature-dependent luminescence intensity ratio over the physiological temperature range, with a maximum sensitivity of 1.28% °C(-1) at 20 °C.