Search

Considering that cyclotriphosphazene polycarboxylic acid is a kind of organic ligand with fantastic structures and performances and the unique luminescence characteristics of rare earth ions, a series of porous lanthanide metal–organic frameworks (Ln-MOFs) (CH3)2NH2[Ln3(HCPCP)1.5(CH3COO)]·6DMA (Ln = Ce (1), Sm (2), Eu (3), Tb (4), HCPCP = hexa(4-carboxyphenoxy)cyclotriphosphazene, and DMA = N,N-dimethylacetamide) were synthesized with novel topological network structures. Compound 4 exhibited a sensitive recognition of –NO2, and had a fluorescence quenching phenomenon for seven kinds of nitro aromatic compounds (NACs). In particular, it showed the best fluorescence response to 2,4,6-trinitrophenol (TNP) and 2,4-dinitrophenol (DNP), and the KSV values were 2.86 × 105 M−1 and 8.21 × 104 M−1, and the limit of detection (LOD) values were 0.20 μM and 0.71 μM, respectively. At the same time, we successfully doped different concentrations of Eu3+ into compound 4 to obtain a series of doped Ln-MOF materials x%Eu3+@4 (x = 0.5, 2.5, 5, 7.5, 10, 15 and 20). With the increase of Eu3+ doping ratios, the characteristic peaks of Tb3+ and Eu3+ changed regularly, and the energy transfer from Tb3+ to Eu3+ ions occurred. By changing the excitation wavelength of the samples with different Eu3+ doping concentrations, a higher quality white light emitting material 7.5%Eu3+@4 (λex = 340 nm) was finally obtained, with a CIE coordinate of (0.3268, 0.3212). [ABSTRACT FROM AUTHOR]

Herein we report two new TPE‐based 3D MOFs, that is, Sr‐ETTB and Co‐ETTB (TPE=Tetraphenylethylene, H8ETTB=4′,4′′′,4′′′′′,4′′′′′′′‐(ethene‐1,1,2,2‐tetrayl)tetrakis(([1,1′‐biphenyl]‐3,5‐dicarboxylic acid))). Through tailoring outer shell electron configurations of SrII and CoII cations, the fluorescence intensity of the MOFs is tuned from high emission to complete non‐emission. Sr‐ETTB with strong blue fluorescence shows reversible fluorescence variations in response to pressure and temperature, which is directly related to the reversible deformation of the crystal structure. In addition, non‐emissive Co‐ETTB counterpart exhibits a turn‐on fluorescent enhancement under the stimulation of analyte histidine. In the process, TPE‐cored linkers in the MOFs are released through competitive coordination substitution and subsequently reassembled to perform aggregation‐induced luminescence behavior originated from the organic linkers. [ABSTRACT FROM AUTHOR]

Two new isostructural 3D lanthanide-organic frameworks [H2N(Me)2] [Ln3(OH)(bpt)3(H2O)3] (DMF)2⋅(H2O)4 ( 1-Ln; Ln=Sm and Eu) with a 1D channel (25 Å) have been successfully assembled from the rare trinuclear [Ln3(OH)(COO)9] clusters and biphenyl-3,4′,5-tricarboxylic acid (H3bpt) and exhibit high stability towards water in the pH range 3-10. MOF 1-Eu is a promising luminescent probe for sensing Fe3+ in aqueous solution and is also selective towards rhodamine B (RhB) with a superior adsorption capacity of 735 mg g−1, which is the highest among the reported Ln-MOFs for RhB removal so far. Periodic DFT calculations further confirmed the selective adsorption of rhodamine B over other dyes. [ABSTRACT FROM AUTHOR]

Two microporous complexes, [Zn(TATAB)(OCH3)] ⋅2 H3O+ ( 1; TATAB=4,4′,4′′-[(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)]tribenzoic acid), [Cu1.5(μ2-O)TATAB*] ( 2; TATAB*=4,4′-{[6-(dimethylamino)-1,3,5-triazine-2,4-diyl]bis(azanediyl)}dibenzoic acid) have been synthesized and characterized by elemental analysis, IR spectroscopy, UV absorption spectroscopy, and thermogravimetric analysis, and by powder XRD and single-crystal XRD analysis. Structural analyses revealed that complex 1 possesses a 3D porous framework with uncoordinated water molecules trapped in the pores; the dimensions of the channels are approximately 29.2×12.3 Å2. Complex 2 has a 3D microporous network structure. In addition, the surface photovoltage and photocatalytic activities were also studied. The photocatalytic properties of the two complexes were investigated by the decomposition of methylene blue under UV and visible-light irradiation. The results revealed that 2 possessea a higher photocatalytic activity than 1 under UV or visible-light irradiation. The potential semiconductor and dye degradation properties of complexes 1 and 2 may be widely applied in the fields of chemical semiconductors and environmental protection in the future. [ABSTRACT FROM AUTHOR]

Two novel lanthanide metal organic frameworks [Eu4(bpt)4(DMF)2(H2O)6]·(DMF)5·(H2O)4 (1) and [Tb4(bpt)4(DMF)2(H2O)8]·(DMF)5·(H2O)3 (2) were synthesized under hydrothermal conditions, forming a three-dimensional structure (H3bpt = biphenyl-3,4′,5-tricarboxylate). Single crystal X-ray diffraction reveals that compounds 1 and 2 are heteromorphic and have different topologies due to the change of metal ions with different radii and coordination steric hindrance. The unique luminescence properties of Eu3+ and Tb3+ ions motivated us to dope different amounts of Tb3+ into a single host to obtain light tunable materials. The tunable multicolor emissions, including red, red-orange, orange, yellow and green, can be readily achieved from the doped Ln-MOFs 3–6 by increasing the concentration of Tb3+. In addition, compounds 5 and 6 also exhibit different temperature-dependent luminescence behaviors when the concentration of Eu3+ is low, generating new Ln-MOF thermometers. [ABSTRACT FROM AUTHOR]

Inorganic pyrophosphate (P 2 O 7 4−, PPi) plays a vital role in a variety of metabolic processes, therefore, the development of a highly sensitive and selective detection method for PPi is of great significance. In this work, a fluorescence sensor based on luminescence metal-organic frameworks (LMOFs) via covalent post-synthetic modification (PSM) was prepared and applied to the fluorescence detection of PPi. The sensor with high fluorescence quantum yield was synthesized based on Schiff base reaction between 2-pyridinecarboxaldehyde (2-PC) and TMU-17-NH 2. It was designed according to the strong binding affinity between metal ion and PPi, and Cu2+ was selected as the mediating ion in this experiment. The fluorescence of TMU-PC is quenched by Cu2+ through photoelectron transfer (PET) mechanism, and the quenched fluorescence can be restored after adding PPi, forming an "on-off-on" fluorescence sensor, which can realize the sequential detection of Cu2+ and PPi. TMU-PC sensor has the advantages of fast response time, wide linear range, high sensitivity, and high specificity for PPi detection, and can be constructed as a fluorescence IMPLICATION logic gate. This work is the first attempt to prepare LMOFs via PSM for fluorescence detection of PPi, which has excellent application prospects for the clinical detection of related diseases. [Display omitted] • It is the first attempt to prepare LMOFs via PSM for PPi fluorescence detection. • An "on-off-on" fluorescence platform was designed based on the mediating ion Cu2+. • The detection was completed within 30 s with high specificity for PPi. • The sensor was used to detect PPi in human urine and synovial fluid samples. [ABSTRACT FROM AUTHOR]