Isostructural Lanthanide Metal-organic Frameworks Research Articles

Two new isostructural lanthanide metal-organic frameworks based on 2,5-furandicarboxylic acid for highly efficient sensing of lysophosphatidic acid

Ovarian cancer (OC) is a serious health concern that is highly prevailing in women. In this regard, lysophosphatidic acid (LPA) is used as a biomarker for OC, and hence its early detection can help in a better treatment plan and cure of the disease. Thus, two new lanthanide metal-organic frameworks [Eu2(FDA)3(DMF)2(MeOH)2]n(Eu-MOF) and [Tb2(FDA)3(DMF)2(MeOH)2]n(Tb-MOF) were synthesized by using 2,5-furandicarboxylic acid as ligand under solvothermal method, which were in turn applied for the detection of LPA. Single-crystal X-ray diffraction indicated that both the Eu-MOF and Tb-MOF were isomorphic with tfz-d topology of {43}2{46.618.84} based on binuclear second building units to form 3D framework. Meanwhile, Eu-MOF realized highly selective detection for LPA through a strong fluorescence quenching with KSV = 1.17 × 104 M−1, effectively identified LPA compared to other major components of plasma. These findings conclude that Eu-MOF can be counted as a potential contender as a fluorescent sensor for the detection of LPA which can in turn help the early diagnosis of OC.

Stable Lanthanide–Organic Frameworks: Crystal Structure, Photoluminescence, and Chemical Sensing of Vanillylmandelic Acid as a Biomarker of Pheochromocytoma

Several isostructural lanthanide metal-organic frameworks, viz. [Ln(DCHB)1.5phen]n (Ln-MOFs, where Ln = Eu for 1, Tb for 2, Sm for 3 and Dy for 4), are successfully synthesized through the hydrothermal reactions of 4'-di(4-carboxylphenoxy)hydroxyl-2, 2'-bipyridyl (H2DCHB) and lanthanide nitrates as well as chelator 1,10-phenantroline (phen). These structures are characterized by single-crystal X-ray diffraction, and the representative Ln-MOF 1 is a fivefold interpenetrated framework with the uncoordinated Lewis base N sites form DCHB2- ligands. The photoluminescence research studies reveal that Ln-MOFs 1-4 exhibit characteristic fluorescent emissions from ligand-induced lanthanide Ln(III) ions, while the single-component emission spectra of Ln-MOF 4 are all located in a white region under different excitations. The absence of coordinated water and the interpenetration property of the structures are conducive to the structure rigidity, and the results display that Ln-MOF 1 has high thermal/chemical stabilities in common solvents and a wide pH range as well as the boiling water. Notably, luminescent sensing studies reveal that Ln-MOF 1 with prominent fluorescence properties can perform in highly sensitive and selective sensing of vanillylmandelic acid (VMA) in aqueous systems (KSV = 562.8 L·mol-1; LOD = 4.6 × 10-4 M), which can potentially establish a detection platform for the diagnosis of pheochromocytoma via multiquenching mechanisms. Moreover, the 1@MMMs sensing membranes comprised of Ln-MOF 1 and a poly(vinylidene fluoride) (PVDF) polymer can also be facilely developed for VMA detection in aqueous media, suggesting the enhanced convenience and efficiency of practical sensing applications.

Energy transfer, anticounterfeiting, white light emission and sensing in fine-regulating series of lanthanide metal-organic frameworks

Three lanthanide ions and a rigid (1,1'-biphenyl)-2,4,6-tricarboxylic acid (H3bptc) ligand led to the isostructural lanthanide metal-organic frameworks (Ln-MOFs) {[Ln(bptc) (H2O)3]·3H2O}n (Lnbptc, Ln = Eu, Tb, Gd, EuxTb1–x, EuxGd1–x, TbxGd1–x, and Eu0.12Tb0.52Gd0.36). The density functional theory (DFT) and time-dependent DFT calculation were expanded on H3bptc, which point to the occurrence of “antenna effect”. The minor diameter samples of Eubptc, Tbbptc, and Gdbptc can also be attained via the microwave synthesis and employed for handwriting anticounterfeiting. Interestingly, the typical red emission of Eu3+ and green emission of Tb3+ could be fine-tuned by Gd3+ via chemical mixing to be full-color emissions bimetallic doped EuxTb1–xbptc, EuxGd1–xbptc, and TbxGd1–xbptc. The above synthetic bimetallic MOFs can be fixed in positioning boxes of quick response (QR) codes with diverse emission for anticounterfeiting. The message can be decoded under the irradiation of 365 nm ultraviolet lamp while invisible in the daylight. Notably, the trimetallic doped Eu0.12Tb0.52Gd0.36bptc emits white light with the CIE color coordinate (0.34, 0.34). Furthermore, Tbbptc is demonstrated to be a sensitive probe toward nitrobenzene and acetone with multiple mechanisms.

Four isostructural lanthanide metal–organic frameworks: luminescence properties and fluorescence sensing for Fe3+and Cr2O72−ions

The isostructural 3D lanthanide metal–organic frameworks reveal better luminescence sensing properties for the detection of Fe3+ions and Cr2O72−anions.

Highly pH-stable lanthanide MOFs: a tunable luminescence and ratiometric luminescent probe for sulfamethazine.

By selecting a bisphosphonic ligand H4L (H4L = 4-F-C6H4CH2N(CH2PO3H2)2) and a coligand oxalate (H2C2O4), three isostructural lanthanide metal-organic frameworks (Ln-MOFs) with a 2D layer structure, [Ln(H3L)(C2O4)]·2H2O (Ln = Eu (1), Gd (2), or Tb (3)), were hydrothermally prepared. By tuning the molar ratio of Eu3+, Gd3+, and Tb3+ in the above reactions, six bimetallic or trimetallic doped Ln-MOFs (EuxTb1-x (x = 0.02 (4), 0.04 (5), and 0.06 (6)), Gd0.94Eu0.06 (7), Gd0.96Tb0.04 (8) and Gd0.95Tb0.03Eu0.02 (9)) were obtained. The powder X-ray diffraction (PXRD) patterns of doped Ln-MOFs 4-9 show that they are isomorphous with 1-3. The bimetallic doped Ln-MOFs show a gradual variation of luminous colors between yellow-green, yellow, orange, pink, and light blue. Meanwhile, the trimetallic doped Gd0.95Tb0.03Eu0.02 Ln-MOF (9) displays near white-light emission with a quantum yield of 11.39%. Interestingly, the luminous inks of 1-9 are invisible and color tunable, which makes it possible to promote their anti-counterfeiting applications. Additionally, 3 displays good thermal, water, and pH stabilities, which provides the feasibility for its sensing application. The luminescence sensing experiments show that 3 can serve as a highly selective, reusable, and ratiometric luminescent sensor of sulfamethazine (SMZ). Moreover, 3 shows an excellent SMZ detection performance in real samples, such as mariculture water and real urine. Owing to the visible variation of the response signal under a UV lamp, portable SMZ test paper was prepared.

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.

Stable Lanthanide Metal-Organic Frameworks with Ratiometric Fluorescence Sensing for Amino Acids and Tunable Proton Conduction and Magnetic Properties.

Four new isostructural lanthanide metal-organic frameworks (MOFs), namely {[Ln(DMTP-DC)1.5(H2O)3]·DMF}n [H2DMTP-DC = 2',5'-dimethoxytriphenyl-4,4″-dicarboxylic acid; LnIII = EuIII (1), GdIII (2), TbIII (3), and DyIII (4)], have been synthesized and characterized. Single-crystal structure analysis reveals that 1-4 are three-dimensional Ln-MOFs with rich H-bonding of coordinated H2O molecules in the network channels. The X-ray diffraction patterns indicate that Ln-MOF 1 displays good stabilities in organic solvents and aqueous solutions with distinct pH values. Both 1 and 3 show characteristic emission of LnIII ions. Ln-MOF 1 can be used as a ratiometric fluorescence sensor for arginine and lysine in aqueous solution, and the detection limits are 24.38 μM for arginine and 9.31 μM for lysine. All 1-4 show proton conductivity related to relative humidity (RH) and temperature, and the maximum conductivity values of 1-4 at 55 °C and 100% RH are 9.94 × 10-5, 1.62 × 10-4, 1.71 × 10-4, and 2.67 × 10-4 S·cm-1, respectively. The value of σ increases with the decrease in ionic radius, indicating that the radius of the LnIII ions can regulate the proton conductivity of these MOFs. Additionally, 2 exhibits a significant magnetocaloric effect (MCE) with a magnetic entropy change (-ΔSm) of 18.86 J kg-1 K-1 for ΔH = 7 T at 2 K, and 4 shows weak field-induced slow relaxation of magnetization. The coexistence of good fluorescence sensing capability, attractive proton conductivity, and relatively large MCE in Ln-MOFs is rare, and thus, 1-4 are potentially multifunctional MOF materials.

Lanthanide-Organic Frameworks with Uncoordinated Lewis Base Sites: Tunable Luminescence, Antibiotic Detection, and Anticounterfeiting.

Several new isostructural lanthanide metal-organic frameworks (Ln-MOFs), {[Ln2(L)3DMA4]·2DMA}n (1-Ln, where Ln = Eu, Tb, or EuxTb1-x), were first constructed via the solvothermal reactions of 4,6-di(4-carboxyphenyl)pyrimidine and Ln3+ ions. 1-Ln exhibits a 4-connected two-dimensional framework endowed with uncoordinated Lewis base sites. An exploration of luminescence sensing demonstrated 1-Eu can be used for the selectivity detection of dimetridazole and metronidazole antibiotics in other antibiotics, blood plasma, and urine, acting as an exceptional recyclable luminescent probe. More importantly, the luminescent inks of 1-Ln are invisible, color adjustable, and stabilized, which may greatly improve their anticounterfeiting applications.

A series of isostructural lanthanide metal–organic frameworks: effective fluorescence sensing for Fe3+, 2,4-DNP and 4-NP

A series of isostructural lanthanide metal–organic frameworks were constructed under solvothermal conditions. Among them, JLU-MOF201-Y and JLU-MOF201-Tb display high sensitivity and selectivity for Fe3+, 2,4-dinitrophenol and 4-hydroxyderricin.

White light emission phosphor modulation, nitrobenzene sensing property and barcode anti-counterfeiting via lanthanides post-functionalized metal-organic frameworks

Three isostructural lanthanide metal-organic frameworks (Ln-MOFs) [Ln2(L)3(H2O)5]n (1-Ln, Ln ​= ​Eu, Tb, Dy and Eu/Tb), and a transition MOF {[Cd(L)(H2O)2]·H2O}n (1-Cd) based on 1-(4-carboxyphenyl)-1H-pyrazole-3-carboxylic acid (H2L) ligand were obtained by solvothermal method. The white-light-emitting (WLE) material Eu3+/Tb3+@1-Cd with the CIE coordinate (0.33, 0.34) was successfully modulated by introducing Eu3+ and Tb3+ into the blue-emitting 1-Cd. The post-synthetic doping provides a facile and practical strategy for the development of WLE materials. Besides, the luminescence sensing experiments showed that 1-Ln can be used as an excellent probe for nitrobenzene detecting. And the multi-color barcode of 1-Ln showed great potential in commodity anti-counterfeiting and information security.

Selective Photocatalytic Oxidation of Sulfides in Lanthanide Metal -Organic Frameworks Incorporating Ru(2,2'-bpy)3 photosensitizer.

Three isostructural lanthanide metal-organic frameworks (Ln-MOFs) were synthesized with uncoordinated N^N site, and the Ru(N^N)3 photosensitizer was introduced via coordination link. These functionalized frameworks showed excellent performance in the photocatalytic oxidation of sulfides with good conversion and high sulfoxide selectivity.

Construction of a Stable Lanthanide Metal-Organic Framework as a Luminescent Probe for Rapid Naked-Eye Recognition of Fe3+ and Acetone.

Four lanthanide metal-organic frameworks (Ln-MOFs), namely {[Me2NH2][LnL]·2H2O}n (Ln = Eu 1, Tb 2, Dy 3, Gd 4), have been constructed from a new tetradentate ligand 1-(3,5-dicarboxylatobenzyl)-3,5-pyrazole dicarboxylic acid (H4L). These isostructural Ln-MOFs, crystallizing in the monoclinic P21/c space group, feature a 3D structure with 7.5 Å × 9.8 Å channels along the b axis and the point symbol of {410.614.84} {45.6}2. The framework shows high air and hydrolytic stability, which can keep stable after exposed to humid air for 30 days or immersed in water for seven days. Four MOFs with different lanthanide ions (Eu3+, Tb3+, Dy3+, and Gd3+) ions exhibit red, green, yellow, and blue emissions, respectively. The Tb-MOF emitting bright green luminescence can selectively and rapidly (<40 s) detect Fe3+ in aqueous media via a fluorescence quenching effect. The detection shows excellent anti-inference ability toward many other cations and can be easily recognized by naked eyes. In addition, it can also be utilized as a rapid fluorescent sensor to detect acetone solvent as well as acetone vapor. Similar results of sensing experiments were observed from Eu-MOF. The sensing mechanism are further discussed.

Isostructural Single- And Dual-Lanthanide Metal-Organic Frameworks Based On Substituent-Group-Modifying Tetracarboxylate Ligands for Ratiometric Temperature Sensing.

In this study, two substituent-group-modifying tetracarboxylate ligands, 2',5'-dimethoxy-[1,1':4',1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid (H4TPTC-2OMe) and 2',5'-dimethyl-[1,1':4',1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid (H4TPTC-2Me), with similar geometries were used as the organic linkers to construct isostructural lanthanide metal-organic frameworks (LnMOFs). The as-prepared LnTPTC-2OMe and LnTPTC-2Me were structurally elucidated by means of single-crystal and powder X-ray diffraction in addition to thermogravimetric analysis and were assessed as luminescence ratiometric thermometers by obtaining the temperature dependence of the luminescence behaviors. We found that both the single lanthanide EuTPTC-2OMe and the dual lanthanide Eu0.05Tb0.95TPTC-2Me exhibited a distinct S-type luminescence response to temperatures in the range from 313 to 473 K, and their ratiometric parameters can be understood on the basis of the classic Mott-Seitz model. Energy transfers from the ligand to Tb3+ (or Eu3+) and from Tb3+ to Eu3+ in these two systems were investigated theoretically as well as with low-temperature (77 K) time-resolved photoluminescence spectroscopy, quantum yield, and lifetime analysis. Therefore, these two materials possess a good relative sensitivity, a small temperature uncertainty, and a favorable spectral repeatability in addition to a remarkable emission color change, enhancing their potential use for temperature measurement and in situ monitoring in microelectronics.

Two multifunctional LnMOFs as recyclable luminescent sensors for sensitive detection of nitro-aromatic compounds

Two isostructural lanthanide metal-organic frameworks (LnMOFs), MOF1 and MOF2, were synthesized by solvothermal reaction. The composition and morphology of MOF1 and MOF2 were characterized by FT-IR, EDX, TG, PXRD, et al. The fluorescence spectra show that MOF1 and MOF2 have the significant characteristic emission bands of Eu3+ and Tb3+ ions, respectively. Based on the characteristic emissions of Eu3+ and Tb3+ in MOF1 and MOF2, we studied the fluorescence sensing experiments of them to aromatic compounds. The results show that MOF1 and MOF2 both exhibit significant fluorescence quenching effect toward p-nitroaniline, o-nitrophenol and p-nitrophenol with good selectivity and sensitivity. Furthermore, the anti-interference and recyclability were carried out. All the results confirm MOF1 and MOF2 can be used as potential sensing materials for the selective detection of environment pollutants.

A series of multifunctional lanthanide metal-organic frameworks for luminescent sensing and photocatalytic applications

A series of isostructural lanthanide metal-organic frameworks (LnMOFs), [EuxTb1-xL(DMF)2(NO3)] (Tb-MOF for x = 0; Eu-MOF for x = 1; EuxTb1-x-MOF for x = 0.001, 0.005, 0.01, 0.05, 0.07 and 0.09, H2L =2, 2′- bipyridine-4, 4′-dicarboxylic acid) have been obtained under solvothermal conditions by adjusting the ratio of Eu3+ to Tb3+. The emission colors of the series of LnMOFs have been tuned from green to red due to the energy transfer from Tb3+ to Eu3+ ions. Furthermore, the luminescent sensing performances of the LnMOFs for hazardous phenolic compounds and pH values were studied. The results revealed that the LnMOFs can be used as luminescent sensors for selective detection β-naphthol and pH in the range of 6–1. The sensing mechanism for β-naphthol may be due to the absorption competition of the energy between the LnMOFs and β-naphthol. The different protonation levels of the uncoordinated pyridine nitrogen atom with varying pH may be the reason for the pH dependent effect. In addition, the photocatalytic activities of the LnMOFs for degradation of Rhodamine (RhB) were also studied. The results demonstrate that the LnMOFs have the efficient photocatalytic performances under UV light irradiation and show good stabilities.

Hypersensitive Self‐Referencing Detection Traces of Water in Ethyl Alcohol by Dual‐Emission Lanthanide Metal–Organic Frameworks

A sequence of isostructural lanthanide metal–organic frameworks (MOFs) [TbxEu1–xNa(HL2)2(H3L2)0.5]·EtOH [H3L2 = 5‐hydroxy‐isophthalic acid] (x = 0.1–0.9) are successfully obtained by doping TbIII and EuIII into the same framework. A fluent change in their photoluminescence is achieved by varying the ratio of TbIII/EuIII from 1:9 to 9:1. Among the obtained lanthanide MOFs, [Tb0.5Eu0.5Na(HL2)2(H3L2)0.5]·EtOH displays remarkable dual emission, with macroscopic bright red–orange luminescence in ethyl alcohol that is easily quenched, even with a low water content, thus presenting an innovative approach for an ideal chemical sensor for the detection of trace amounts of water in ethyl alcohol. As the water content increases, the probe exhibits a distinguishable change in its luminescence. To the best of our knowledge, it is quite rare for a self‐referencing luminescent sensor to be able to quantify the amount of water in ethyl alcohol over a wide range (0.01–3.2 %). The detection limit of the codoped Ln MOFs is 0.01 %, which is ahead of other reported MOF‐based sensors.

Color tunable and white light emitting lanthanide metal-organic framework materials

Abstract In our previous work, a family of isostructural lanthanide metal-organic frameworks, [Ln3(L)3(H2O)2]·(H3O)3·(H2O)4·(DMF)3 (abbreviated as Ln3(L)3(H2O)2, Ln = Eu, Tb, Sm, Dy and Gd) were synthesized under solvothermal conditions based on a semi-rigid tetravalent carboxylic tetracarboxylic acid (3,3′,5,5′-biphenyltetracarboxylic acid, H4L). Due to the good sensitization of the H4L ligand, Ln3(L)3(H2O)2 all show the intense characteristic emission bands of the corresponding lanthanide ions. The optical properties of Ln3(L)3(H2O)2 can be easily tuned by doping different lanthanide ions into the same host frameworks. Moreover, white-light emission can be successfully realized for four kinds of codoped compounds Tb0.005Eu0.005Gd0.990L, Dy0.006Eu0.006Gd0.988L, Dy0.0002Sm0.001Gd0.9988L and Tb0.002Sm0.006Gd0.992L (the value refer to the starting molar ratios of Ln3+ ions).

Tunable Emission and Selective Luminescence Sensing in a Series of Lanthanide Metal–Organic Frameworks with Uncoordinated Lewis Basic Triazolyl Sites

Four isostructural lanthanide metal–organic frameworks (Ln-MOFs) {[Ln(L)1.5(H2O)]·4H2O}n (1-Ln) (Ln = Sm, Eu, Gd, and Tb) have been successfully synthesized under solvothermal conditions with 2-(1H-1,2,4-triazol-1-yl) terephthalic acid (H2L) and Ln(NO3)3·nH2O (n = 0, 6). 1-Ln shows a binodal (3,8)-connected three-dimensional framework that possesses a one-dimensional pore channel decorated with uncoordinated Lewis basic triazolyl sites. 1-Eu and 1-Tb exhibit bright red and green emissions with absolute quantum yields of 9.1% for 1-Eu and 53.3% for 1-Tb. The luminescence explorations demonstrated that 1-Tb exhibits high quenching efficiency and low detection limit for sensing Fe3+ and nitrobenzene. Meanwhile, the fluorescence intensity of the quenched 1-Tb samples was resumed after washing with ethanol, which shows highly selective and recyclable luminescence sensing for Fe3+ and nitrobenzene. Importantly, by doping different concentrations of Eu3+ and Tb3+ ions, a series of dichromatic doped 1-EuxTb1-x MOFs were fabricated, showing an unusual fluent change of the emissions color from green, yellow, orange, orange-red, and red.

Luminescence Modulation, White Light Emission, and Energy Transfer in a Family of Lanthanide Metal–Organic Frameworks Based on a Planar π-Conjugated Ligand

Three isostructural lanthanide metal–organic frameworks (Ln-MOFs), {[Ln2(BDPO)1.5(DMA)3(H2O)]·5H2O }n (1-Ln, Ln = Eu, Gd, and Tb) were constructed by a less-investigated large delocalized π-electron conjugated ligand N,N′-bis(3,5-dicarboxyphenyl)-oxalamide (H4BDPO). 1-Ln reveals unprecedented trinodal (4,4,6)-connected networks based on binuclear cluster units and planar BDPO linkers. Density functional theory (DFT) and time dependent-DFT calculations were performed on the ground and excited states to provide insight into geometries, the frontier molecular orbitals, and singlet and triplet state energies of H4BDPO ligand. 1-Eu and 1-Tb exhibit strong typical red and green emission of Eu3+ and Tb3+ ions, respectively, originating from the highly efficient energy transfer from BDPO to metal centers, as demonstrated by the comparison of triplet excited energies of ligands and metal ions. Importantly, by doping different concentrations of Eu3+ and Tb3+ ions, a series of dichromatic doped 1-EuxTb1-x MOFs were ...

Highly Efficient White-Light Emission and UV–Visible/NIR Luminescence Sensing of Lanthanide Metal–Organic Frameworks

A series of new isostructural lanthanide metal–organic frameworks (Ln-MOFs), [Ln2(L)2(DMAC)2]·nH2O [Ln = La (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Tb (7), and Tm (8); H4L = 5-(bis(4-carboxybenzyl)amino)-isophthalic acid, DMAC = N,N′-dimethylacetamide], have been isolated. Single-crystal X-ray diffraction analysis reveals that all complexes exhibit a rare (4,8)-connected alb-4,8-P topology with binuclear [Eu2(COO)8]n secondary building units as 8-connected nodes and H4L ligands as 4-connected nodes. Two mixed-lanthanide analogues of single-lanthanide MOFs were designed and prepared [Ln = La0.93Eu0.02Tb0.05 (9) and Tm0.47Eu0.18Tb0.35 (10)] by way of careful regulation of the relative concentration of lanthanide ions which are able to emit pure white light. Luminescent sensing of complexes 3 and 5 has been investigated. Strikingly, complex 5 exhibits an excellent luminescent sensing to TNP with a high Ksv value of 3.58 × 104 M–1 and a low detection limit of 4.66 × 10–4 mM. Complex 3 reveals high select...