3D Lanthanide Metal-organic Frameworks Research Articles

Reaction Time Induced a Two-Step Dissolution and Recrystallization Structural Transformation with Three Eu Metal-Organic Frameworks: Crystal Structures and Multiresponsive Fluorescence Detection.

Under solvothermal conditions, three 3D lanthanide metal-organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3 (3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1-3 underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2 demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV-visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Dual-functional fluorescence sensors based on 3D lanthanide metal–organic framework and its mixed matrix membrane

A new lanthanide metal–organic framework (Ln-MOF) {[Eu(DPB)(H2O)](Me2NH2+)}n (1) (H4DPB = (1,1′:3′,1′’-terphenyl)-3,3′’,5,5′’-tetracarboxylic acid）was synthesized under solvothermal conditions and presented a fascinating three-dimensional (3D) framework with 4,8-connected diamond topology, which were built from Eu3+ ions and tetra carboxylate groups. 1 showed strong red luminescence emission in the solid state at room temperature and exhibited good stability in different solvents. 1 could be used as a multi-responsive luminescent sensor for hemin and p-Nitrophenol (4-NP) with detection limits of 3.91 × 10−6 M and 1.98 × 10−4 mM, respectively. Moreover, using 1 as a filler and poly (vinylidene difluoride) (PVDF) as matrix, a mixed matrix membrane 1@PVDF was successfully prepared. 1@PVDF also exhibited fluorescence emission comparable to that of 1 and could be used for hemin and 4-NP sensing with good selectivity and remarkable recyclability.

Three-Dimensional Neodymium Metal–Organic Framework for Catalyzing the Cyanosilylation of Aldehyde and the Synthesis of 2,3-Dihydroquinazolin-4(1H)-one Derivatives

In this work, a novel 3D lanthanide metal–organic framework (Ln-MOF) Nd-cdip (H4cdip = 5,5′-carbonyldiisophthalic acid) was successfully synthesized, which could be used as an efficient heterogeneous catalyst for cyanosilylation and the synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives at room temperature based on the Lewis acid sites in the channels of the MOF. Moreover, Nd-cdip had an excellent turnover number (500) for catalyzing cyanosilylation in no solvent condition. Nd-cdip could be reused in both of the above-mentioned reactions at least five times without a significant decrease in yield. The possible mechanism of cyanosilylation catalyzed by Nd-cdip was studied by using the luminescence properties of Tb-cdip, which has the same structure and functions as Nd-cdip. Furthermore, both reactions catalyzed by Nd-cdip were fitted to zero-order dynamics.

Two isostructural Ln-MOFs containing triazole groups as luminescent probes for efficient sensing of NACs and Fe3+

Two new isostructural 3D lanthanide metal–organic frameworks (Ln-MOFs), [Ln2(L)3(H2O)2]·2H2O·2DMF (1-Ln, Ln = Eu3+ and Tb3+, H2L = 5-triazole isophthalic acid) with uncoordinated triazole groups decorating the channels were successfully synthesized via solvothermal reaction. The uncoordinated triazole groups act as reserved host–guest binding sites to adjust the luminescence intensity of the Ln3+ ion. Luminescence studies reveal that 1-Eu and 1-Tb as fluorescent probes both exhibit high sensitivities and excellent selectivities towards nitroaromatics (NACs) and Fe3+ in DMF system by luminescence quenching process. The quenching mechanisms were investigated through PXRD, DFT theory calculation, XPS, UV–vis and discussed in details.

Synthesis, structure and luminescence of 3D lanthanide metal–organic frameworks based on 1,3-bis(3,5-dicarboxyphenyl) imidazolium chloride

A series of novel three-dimensional lanthanide metal–organic frameworks (Ln-MOFs) were prepared under solvothermal conditions. These Ln-MOFs are formulated as [Ln4(L)3(H2O)8]n·3nNO3, [Ln = Sm (1), Eu (2), Gd (3), Tb (4), H4L+Cl- = 1,3-bis(3,5-dicarboxyphenyl) imidazolium chloride]. Complexes 1–4 were characterized by X-ray single-crystal diffraction, infrared spectroscopy, powder X-ray diffraction and thermogravimetric analysis. Compounds 1, 2 and 4 display the luminescence of the trivalent lanthanide ions, due to the 4fn-4fn transitions. In addition, the luminescence lifetime of 2 has been thoroughly investigated.

Water-stable europium(III) and terbium(III)-metal organic frameworks as fluorescent sensors to detect ions, antibiotics and pesticides in aqueous solutions

The reliable, convenient and rapid detection methods for various environmental pollutants using fluorescent sensors had attracted great attention. Herein, we reported the assembly and characterizations of two new fluorescent 3D lanthanide metal-organic frameworks (Ln-MOFs), namely [Eu(PMBB)1.5(H2O)2] (Eu-MOF) and [Tb(PMBB)1.5(H2O)2] (Tb-MOF) (H2PMBB = 4,4′-((1,4-phenylenebis(methylene))bis(oxy))dibenzoic acid). The fluorescent sensing results reveal that the two MOFs exhibit effective sensitivity toward Fe3+, Cr2O72−, cefixime (CFX), nitrofurazone (NFZ), imidacloprid (IMI) and nitenpyram (NTP) in aqueous medium. Notably, the Tb-MOF is more sensitive toward MnO4− than Eu-MOF due to the enhanced fluorescence resonance energy transfer (FRET) effect. This work provides the example for more effective designs to employ Ln-MOFs as fluorescent sensors for detection of environmental pollutants in aqueous solution.

A novel 3D terbium metal-organic framework as a heterogeneous Lewis acid catalyst for the cyanosilylation of aldehyde.

A novel 3D lanthanide(iii) metal–organic framework (MOF) (namely Tb-MOF), was synthesized by self-assembly from Tb(iii) ion nitrate and the rigid organic ligand H2sbdc (H2sbdc = 5,5-dioxo-5H-dibenzo[b,d]thiophene-3,7-dicarboxylic acid), and could work as an efficient heterogeneous catalyst for the cyanosilylation of aromatic aldehydes at room temperature. The obtained Tb-MOF has been characterized and analysed in detail by single crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and so on. The pores of Tb-MOF provided a microenvironment that was beneficial for the substrates to be close to the Lewis acid catalytic sites. The IR spectrogram and the fluorescence titration proved that the substrates could be activated inside the channel of Tb-MOF. The heterogeneous Tb-MOF catalyst with fine catalytic efficiency exhibited a high TON (TON = 460), and could be recycled at least three times without significantly reducing its activity.

Water-Stable Europium(III) and Terbium(III)–Metal Organic Frameworks as Fluorescent Sensors to Detect Inorganic Ions, Antibiotics and Pesticides in Aqueous Solutions

Development of reliable, convenient and rapid detection methods for environmental pollutants using fluorescent sensors has attracted great attention. Herein, we reported the assembly and characterizations of two new fluorescent 3D lanthanide metal-organic frameworks (Ln-MOFs), namely [Eu(PMBB)1.5(H2O)2] (Eu-MOF) and [Tb(PMBB)1.5(H2O)2] (Tb-MOF) (H2PMBB = 4,4'-((1,4-phenylenebis(methylene))bis(oxy))dibenzoic acid). The structural data veal that both of the structures constructed in 3D network, in view of topology, Eu-MOF is in a bnn net and Tb-MOF is in an mab net. The fluorescent sensing results revealed that the two MOFs exhibit effective sensitivity toward Fe3+, Cr2O72-, cefixime (CFX), nitrofurazone (NFZ), imidacloprid (IMI) and nitenpyram (NTP) in aqueous medium. Notably, the Tb-MOF is more sensitive toward MnO4- in fluorescent quenching tests than Eu-MOF due to the Forstert resonance energy transfer (FRET) effect. This work provides the first example to employ MOFs as fluorescent sensors for detection of IMI in aqueous solution.

Construction of a highly stable lanthanide metal-organic framework for effective detection of aryl-organophosphorus flame retardants in simulated wastewater and fruit juices

Three isostructural 3D lanthanide metal-organic frameworks, [Ln2(L)2(μ3-OH)2]·2H2O (Ln = Gd (1), Eu (2). Tb (3); H2L = 2,4-pyridinedicarboxylic acid) were synthesized by solvothermal reactions. Compounds 1–3 are constituted by rod-shaped inorganic building units {Ln2(μ3-OH)2}n, which are assembled by the ligands to form 3D channel-type frameworks. Compound 3 exhibits high thermal stability and outstanding chemical resistance in various refluxing organic solvents and boiling aqueous solutions of pH = 2 and 12. Significantly, 3 can be utilized for the first time to detect CDP (cresyl diphenyl phosphate) and TPP (triphenyl phosphate) in wastewater with high sensitivities, low detection limits and good recyclability. This sensing system possesses excellent anti-interference ability toward pH and other retardants, allowing steady sensing of CDP and TPP in real samples such as fresh fruit juices over a broad pH range.

Three Lanthanide Metal-Organic Frameworks Based on an Ether-Decorated Polycarboxylic Acid Linker: Luminescence Modulation, CO2 Capture and Conversion Properties.

Three new isostructural 3D lanthanide metal-organic frameworks (Ln-MOFs), {H[LnL(H2 O)]⋅2 H2 O}n (1-Ln) (Ln=Eu3+ , Gd3+ and Tb3+ ), based on infinite lanthanide-carboxylate chains were constructed by employing an ether-separated 5,5'-oxydiisophthalic acid (H4 L) ligand under solvothermal reaction. 1-Eu and 1-Tb exhibit strong red and green emission, respectively, through the antenna effect, as demonstrated through a combination of calculation and experimental results. Moreover, a series of dichromatic doped 1-Eux Tby MOFs were fabricated by introducing different concentrations of Eu3+ and Tb3+ ions, and they display an unusual variation of luminescent colors from green, yellow, orange to red. 1-Eu with channels decorated by ether O atoms and the open metal sites displays good performance for CO2 capture and conversion between CO2 and epoxides into cyclic carbonates.

Isostructural lanthanide metal-organic frameworks comprised of left-handed helical chains: Synthesis, structure and luminescent properties

Six isostructural three-dimensional (3D) lanthanide metal-organic frameworks (Ln-MOFs), [Ln(μ2-OH)(PDC)(H2O)2]·DMF (Ln=Pr (1), Nd (2), Eu (3), Tb (4), Ho (5), and Yb (6), H2PDC=pyridine-3,5-dicarboxylic acid), have been successfully synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, IR spectroscopy, elemental analysis and thermal gravimetric analysis. The framework contains unusual Ln-carboxylate/μ2-OH left-handed helical chains, which are extended by PDC2− linkers to form 3D networks with 1D hexagonal channel. The lanthanide contraction effect induces the decreases of average Ln- distances from Pr to Yb. Due to the efficient sensitization of PDC2− ligand, complexes 2 and 6 display strong characteristic luminescence in the near-infrared (NIR) region, respectively. Moreover, the luminescent properties of complexes 3 and 4 are also studied in the solid state at room temperature.

2D and 3D lanthanide metal–organic frameworks constructed from three benzenedicarboxylate ligands: synthesis, structure and luminescent properties

Nineteen Ln-MOFs with four different crystal structures were prepared and the luminescence was studied.

Design and construction of lanthanide metal-organic frameworks through mixed-ligand strategy: Sensing property of acetone and Cu2+

Four isostructural 3D lanthanide metal-organic frameworks (Ln-MOFs) {[Ln(L)(ox)0.5(H2O)2]·H2O}n (Ln=Pr 1, Nd 2, Sm 3 and Eu 4) were constructed by 5-hydroxyisophthalic acid (H2L) and oxalate (ox) through solvothermal methods, which show a (4,5)-connected tcs net with the point symbol of (44·62)(44·66). Compound 4 exhibits an intense red fluorescence in solid state and is an excellent dual-functional recyclable luminescent sensor which can sense acetone and Cu2+ with high sensitivity and selectivity simultaneously.

3D lanthanide metal-organic frameworks constructed from 2,6-naphthalenedicarboxylate ligand: synthesis, structure, luminescence and dye adsorption

A series of novel isostructural 3D lanthanide metal-organic frameworks {[Ln2(NDC)3(H2O)4]·(DMF)4}n (Ln=Eu(1), Gd(2), Tb(3), Er(4), Yb(5), Dy(6), Y(7), Lu(8), H2NDC =2,6-Naphthalenedicarboxylic acid, DMF=N,N-dimethylformamide) with a rhombic channel along the b axis and high thermal stabilities, have been successfully synthesized under solvothermal conditions. The network can be described as 2, 4, 5-connected net with Schäfli symbol of (42.62.82)2(42.63.85)2(6). Luminescent studies illustrate that 1, 2, 7 and 8 exhibit strong luminescent emitting of the corresponding Ln(III) centers in the visible range, while 5 shows near-infrared range (NIR) luminescence. Further studies of 1 and 2A (activated product of 2) show that 1 displays good stability in different solvents and excellent fluorescence sensing for organic solvent small molecules and 2A ([Gd2(NDC)3(H2O)4]n) exhibits good adsorption capacity for organic dyes in water, especially for crystal violet.

Construction of a series of lanthanide metal–organic frameworks (Ln-MOFs) based on a new symmetrical penta-aromatic carboxylate strut: Structure, luminescent and magnetic properties

Solvothermal reactions of Ln(NO3)3·6H2O (Ln=Nd, Pr, Sm and Eu) with a new penta-carboxylate strut obtain a series of 3D lanthanide metal–organic frameworks (Ln-MOFs), namely, {[Ln3(bpbc)(Hbpbc)(H2O)8]·3H2O} (1) 1-Ln (Ln=Nd, Pr, Sm and Eu). The four compounds are all isostructural as confirmed by the analysis of single crystal and powder X-ray diffractions. The compounds exhibit the 3D networks with a 3-nodal (4,5,7)-connected (413·68)2(44·62)(48·62)2 topology. 1-Nd and 1-Pr exhibit characteristic luminescence in the near-infrared (NIR) region, resulting from the vary degree sensitization of bpbc5− with different Ln3+ ions. Moreover, the other solid properties such as the luminescence of 1-Sm and 1-Eu and the magnetic properties of 1-Nd, 1-Pr and 1-Eu have also been investigated.

3D Lanthanide Metal–Organic Frameworks Based on Mono-, Tri-, and Heterometallic Tetranuclear Clusters as Highly Selective and Sensitive Luminescent Sensor for Fe3+ and Cu2+ Ions

Five novel three-dimensional lanthanide metal–organic frameworks (Ln–MOFs) constructed by 4-(3′,5′-dicarboxylphenoxy) phthalic acid (H4dcppa), namely, {[Eu(Hdcppa)(H2O)2]·H2O}n (Eu-1), [Eu1.5(dcppa) (HCOO)0.5(H2O)2]n (Eu-2), {[Ln2K2(dcppa)2(H2O)6]·mH2O}n (Ln = Eu-3, Tb-4, Gd-5, m = 5 for Eu-3 and Tb-4; m = 4 for Gd-5) (HCOOH = formic acid) have been prepared by hydro(solvo)thermal method and fully characterized. Structural analyses indicated that H4dcppa ligand took four different coordination fashions in 1–5 and, thus, resulted in diversity of the targeted Ln–MOFs: Eu-1 displays the rare 3D (5,5)-connected vbk net, containing one-dimensional left- and right-handed helical chains; Eu-2 possesses a 3D (3,8)-connected tfz-d topology constructed by trinuclear paddlewheel [Eu3(CO2)6] SBUs; 3–5 are isostructural and show 3D (Ln-dcppa4–) + 2D (K-dcppa4–) → 3D (LnK-dcppa4–) structure. Eu-3, with regular 1D channels and open Lewis basic oxygen atoms on the pore surface was utilized for specific sensing and bindin...

Multifunctional chemical sensors and luminescent thermometers based on lanthanide metal–organic framework materials

Six new highly symmetrical and isostructural 3D lanthanide metal–organic frameworks (Ln-MOFs) {[Ln2(Ccbp)3·6H2O]·3Cl−·4H2O} Ln = Tb (1), Eu (2), Gd (3), Sm (4), Er (5) and Yb (6), Ccbp− = 4-carboxy-1-(4-carboxybenzyl)pyridinium, and the mixed Ln-MOF {[Tb1.828Eu0.172(Ccbp)3·6H2O]·3Cl−·4H2O} (7) have been successfully synthesized and fully characterized. The complex 1 was utilized as a representative chemosensor to detect small molecules, cations and anions, respectively. Interestingly, 1 exhibited dual-functional detection of Pb2+ and Fe3+ ions in ethanol with excellent linear variation to quantify the corresponding concentration change. In addition, the temperature-dependent luminescence properties of 1, 2 and 7 have also been investigated systematically, which demonstrated that both 1 and 7 have potential to quantitatively detect temperature as a luminescent thermometer over a wide range from 10–300 K for 1 and 10–170 K for 7. Thus, the as-obtained Ln-MOF materials have potential to serve as the first examples of a multifunctional luminescent sensor for quantitatively detecting the temperature (10–300 K) and the concentration of Pb2+ and Fe3+ ions in ethanol solution.

Novel heteroleptic lanthanide organic frameworks containing pyridine-2,5-dicarboxylic acid and in situ generated piperazine-2,5-dicarboxylic acid from piperazine: Hydrothermal synthesis and luminescent properties

Two novel 3D lanthanide metal-organic frameworks [Ln(pydc)(pip)1/2(H2O] (Ln=Ce (1) and Pr (2), H2pydc=2,5-pyridinedicarboxylic acid, H2pip=2,5-piperazinedicarboxylic acid have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), powder X-ray diffractions (PXRD), and single-crystal X-ray diffractions. Field emission scanning electron microscopy (FESEM) was used for morphological analysis. Complexes are isostructural and feature interesting 3D frameworks. Both compounds crystallize in the monoclinic system, space group P21/c. Structural analyses of 1 and 2 show that Ln3+ ions connect with each other through H2pydc and H2pip. To the best of our knowledge, they are the first heteroleptic lanthanide polymers obtained through in situ 2,5-piperazinedicarboxylic acid syntheses. Moreover, thermal and luminescent properties of the compounds have been investigated.

Real-Time Detection of Traces of Benzaldehyde in Benzyl Alcohol as a Solvent by a Flexible Lanthanide Microporous Metal-Organic Framework.

Luminescent 3D lanthanide metal-organic framework (Ln-MOF) {[Tb2 (TATAB)2 ]⋅4 H2 O⋅6 DMF}n (1) was synthesized under solvothermal conditions by using flexible ligand 4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoate (TATAB). A phase transition was observed between low temperature and room temperature. The luminescence of 1 could be enhanced by formaldehyde and quenched efficiently by trace amounts of benzaldehyde in solvents such as benzyl alcohol (0.01-2.0 vol %) and ethanol (0.01-2.5 vol %). This is the first use of a Ln-MOF as chemical sensor for both formaldehyde and benzaldehyde. The high sensitivity and selectivity of the luminescence response of 1 to benzaldehyde allows it to be used as an excellent sensor for identifying benzaldehyde and provides a simple and convenient method for detecting traces of benzaldehyde in benzyl alcohol based injections. This work establishes a new strategy for detection of benzaldehyde in benzyl alcohol by luminescent MOFs.

3D lanthanide metal–organic frameworks constructed from lanthanide formate skeletons and 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole connectors: synthesis, structure and luminescence

3D Ln-MOFs constructed from lanthanide formate skeletons and 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole connectors show tunable luminescence emission including white light emission.