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Here, we present a new diacetoxy-functionalized UiO-66 metal-organic framework (MOF) for the trace level detection of hydrazine in water. The MOF material (1) was solvothermally prepared by the reaction between ZrOCl2·8H2O and 2,5-diacetoxy-1,4-benzenedicarboxylic acid (H2BDC-(OCOCH3)2). The desolvated material (1') showed a highly selective fluorescent turn-on signal towards hydrazine in water, which can be visualized by the naked eye under a UV lamp. Within 1 min of hydrazine addition, there was 14-fold fluorescence enhancement. The probe can detect hydrazine up to the nanomolar level (detection limit = 78.8 nM) in water. This detection limit is the lowest among MOF-based fluorescent probes for hydrazine. The material was also utilized for the sensing of hydrazine in paper strips and environmental water samples. Hydrazine-selective deprotection of ester groups anchored with the ligand is the principal reason behind the switch-on nature of sensing.

A new CdII-based luminescent metal–organic framework (LMOF) with the formula {[Cd(BIBT)(NDC)]·solvents}n (JXUST-32, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2NDC = 2,6-naphthalenedicarboxylic acid) was successfully synthesized by a solvothermal method. JXUST-32 shows a two-dimensional (4,4)-connected network and exhibits significant fluorescence red shift and slight enhancement for H2PO4− and CO32− sensing with detection limits of 0.11 and 0.12 μM, respectively. In addition, JXUST-32 has good thermal stability, chemical stability and recyclability. Significantly, JXUST-32 represents a fluorescence red-shift dual response MOF sensor for H2PO4− and CO32− detection and the analytes can be identified by the naked eye, aerosol jet printing filter paper, light-emitting diode beads and luminescent films. [ABSTRACT FROM AUTHOR]

In this work, we present a Ag@Au nanoprism-metal-organic framework-paper based glucose sensor for rapid, sensitive, single-use and quantitative glucose determination in human serum. To achieve painless measurement of glucose with a non-invasive detection methodology, this biosensor was further tested in human urine. In this approach, a new hybrid-Ag@Au nanoprism loaded in close proximity to micrometer sized coordination polymers as phosphorescent luminophores significantly enhanced the emission intensity due to metal-enhanced phosphorescence and worked as reaction sites to support more dissolved oxygen. Reports of enhanced phosphorescence intensity are relatively rare, especially at room temperature. The true enhancement factor of Ag@Au-phosphorescent metal-organic frameworks on paper was deduced to be 110-fold, making it a better optical type glucose meter. The results demonstrate the validity of the intensity enhancement effect of the excitation of the overlap of the emission band of a luminophore with the surface plasmon resonance band of Ag@Au nanoprisms. Ag@Au nanoprisms were used not only to improve the detection limit of glucose sensing but also to extend the glucose sensing range by enhancing the oxygen oxidation efficiency. The oxidation of glucose as glucose oxidase is accompanied by oxygen consumption, which increases the intensity of the phosphorescence emission. The turn-on type paper-based biosensor exhibits a rapid response (0.5 s), a low detection limit (0.038 mM), and a wide linear range (30 mM to 0.05 mM), as well as good anti-interference, long-term longevity and reproducibility. Finally, the biosensor was successfully applied to the determination of glucose in human serum and urine.

Herein, we report the fast and selective detection of bilirubin by a recyclable Al(iii) based post-synthetically modified MIL-53 metal-organic framework (MOF) (1-NH2@THB). Post-synthetic modification was achieved by the aldimine condensation reaction between MIL-53-NH2 and 2,3,4-trihydroxy benzaldehyde. The post-synthetically modified compound was successfully characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis and X-ray powder diffraction (XRPD) experiments. The material has huge potential to detect bilirubin in HEPES buffer medium (pH = 7.4) by a fluorescence "turn-off" mechanism. The drastic quenching in the fluorescence emission intensity of the MOF material in the presence of bilirubin is due to the inner filter effect as well as molecular interactions between the MOF material and bilirubin. The probe displayed ultra-fast response (30 s), low detection limit (1.26 pM) and high selectivity towards bilirubin with the co-existence of several metal ions and biomolecules. Moreover, the real field application of the probe was thoroughly investigated in human bio-fluids (blood serum and urine samples) by the standard addition method. Furthermore, the quenching ability of the MOF material by bilirubin was also explored on a portable paper strip device. All the above discussions indicate that the probe is a potential candidate for the clinical detection of jaundice.

The effective integration of nanomaterials with underlying current collectors is a key factor affecting the performance of nonenzymatic glucose sensors, where an inappropriate integration structure often leads to poor electron transport and instability. In this work, a seamless integrated electrode was constructed by the in situ immobilizing of a nickel-based metal-organic framework (Ni-MOF) on a three-dimensional (3D) conductive nickel foam (NF) for highly sensitive and durable glucose sensing. Facilitated by a rapid microwave-assisted reaction, a robust interfacial interaction between the Ni-MOF and the substrate was established through in situ conversion from nickel oxide (NiO). The fabricated Ni-MOF/NF electrode exhibits an excellent limit of detection (LOD) of 2.65 μM and an impressive sensitivity (14.31 mA cm-2 mM-1) within the linear range (4-576 μM), which is significantly boosted compared with that of an electrode prepared by a typical drop-casting method (3.56 mA cm-2 mM-1 in 4-1836 μM). Characterization and electrochemical tests reveal that this integrated structure on the one hand contributes to fast electron transport and thus has enhanced sensitivity and on the other hand leads to exceptional durability with its structural integrity maintained under bending, shaking, and ultrasonication. Moreover, this seamless integration method was also employed to immobilize the Ni-MOF converted from the pre-chemically deposited NiO layer on another type of substrate, 3D carbon paper (CP), demonstrating the versatility of this facile strategy in creating diverse electrochemical electrodes for applications beyond glucose sensing. [ABSTRACT FROM AUTHOR]

The combination of electron-deficient viologen ligands with electron-rich POMs is a typical acceptor–donor system that has recently received much attention. Under solvothermal and hydrothermal conditions, by introducing three symmetric viologen ligands into POM-based hybrid materials, we successfully constructed four POMs–viologen inorganic–organic hybrid compounds, namely (1,3-bcbpy)2·(δ-Mo8O26) (1) (1,3-bcbpy·2Cl = 1,1′-bis(3-carboxybenzyl)-4,4′-bipyridine dichloride), {CoII(1,4-bcbpy)2(H2O)2[H2(β-Mo8O26)]}·2H2O·2CH2O (2), (1,4-bcbpy)2·(δ-Mo8O26)·2H2O (3) (1,4-bcbpy·2Cl = 1,1′-bis(4-carboxybenzyl)-4,4′-bipyridine dichloride, CH2O = formaldehyde), and {CuII(1,1-pmbby)2(H2O)[H2(β-Mo8O26)2]}·5H2O·C2H7N (4) (1,1-pmbby·2Cl = 1,1′-[1,4-phenylbis(methylene)]bis-(4,4′-bipyridine)dichloride, C2H7N = dimethylamine). These four compounds exhibit different fascinating structures, especially compound 4 is a typical metal–organic framework. Compounds 1–4 exhibit good discoloration behaviors under various external stimuli. For example, compounds 1–4 showed a positive response to the irradiation from a 300 W Xe lamp. When a positive voltage was applied to the ECD based on compounds 1–4, 1/2/3/4-ECD underwent a significant color conversion. What's more, compound 4 also showed obvious discoloration results after heating. In a word, 1–4 are multifunctional discoloration materials under different external stimuli. In addition, the coated filter paper prepared based on compound 3 can be used as a new printing material medium and can be successfully applied in erasable inkless printing and dual anti-counterfeiting. [ABSTRACT FROM AUTHOR]

The integration of smartphones with visual-based paper strips has gained great attention because of the rapid, low-cost, and relible analysis. Herein, we report on the synthesis of a red luminescent europiumbased metal organic framework (Eu-MOF) for the detection of folic acid in pharmaceutical formulations. The Eu-MOF showed strong and stable red emission fluorescence (excited at 270 nm), and the emission was significantly quenched upon exposure to folic acid due to the inner filter effect. A fluorometric assay in solution and visual detection based on fluorescence on a paper strip were used independently to quantify folic acid. The paper strips were prepared using chromatography paper and with the aid of a smartphone, folic acid was visually detected. In solution, the calculated LOD was 0.3 mM with a dynamic linearity range from 1.0 to 12.50 mM. Meanwhile, in the visual detection based on a smartphone integrated with a paper test strip, the linearity was from 1.0 to 9.0 mM with 0.12 mM as the LOD. Color analysis, from the photographs taken with a smartphone, was performed via analyzing the RGB coordinates using the Image-J program. The luminescent probe was applicable to detect folic acid in various drug tablets with recovery data ranging from 95 to 103%. The application of smartphones and fluorescent paper strips provides reliable detection of folic acid for on-site analysis, particularly in remote rural areas. [ABSTRACT FROM AUTHOR]

The New Journal of Chemistry is a publication that focuses on the chemical sciences and aims to connect researchers worldwide. The document provided is a contents list for the journal's 2024 edition. It includes papers on various topics such as membrane modification, nanoparticle synthesis, targeted therapy, catalysis, and material properties. Two specific papers are highlighted: one discusses the use of cationic lipids in non-viral gene delivery, while the other explores the confinement of metal-organic framework (MOF) etching-induced hollow structures for enhanced activation of peroxymonosulfate. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. [Extracted from the article]

Bimetallic two-dimensional (2D) metal–organic framework (MOF) materials display excellent electrocatalytic performance due to the synergistic effect between metals and the advantage of the 2D structure. In this work, Cu was introduced into the 2D Co-MOF structure, and a 2D book-like CuCo-MOF structure was fixed on carbon fiber paper (CFP) for direct electrochemical glucose detection and oxygen evolution reaction (OER). The materials showed good electrocatalytic glucose detection performance with a sensitivity as high as 6.861 mA mM−1 cm−2 and a detection limit as low as 0.12 μM. For the OER, when the current density is 10 mA cm−2, the overpotential (η) is 340 mV, and good stability is maintained for about 10 h without current attenuation. This work not only exploits a new 2D MOF structure containing Cu, but also expands the potential of Cu-containing MOF materials in the electrocatalytic OER, making a contribution to the field of energy conversion and biomolecular sensing. [ABSTRACT FROM AUTHOR]

The fabrication of noble metal free catalysts with excellent performance and high stability by a simple, efficient, general and low-cost approach remains an urgent task for solving the problem of resource shortage. Herein, Cu-based metal organic frameworks (MOFs) immobilized on commercial filter papers were used as pyrolysis precursors to synthesize CuxO@C at various calcination temperatures. Notably, the resultant CuxO@C-400 exhibits an excellent catalytic performance toward the reaction of reducing 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). By virtue of the large specific surface area, well-developed porosity, good stability and high dispersity of CuxO nanoparticles, the obtained CuxO@C-400 could complete the reduction reaction within 11 min with a large apparent rate constant κapp value (4.8 × 10−3 s−1). Our strategy therefore opens a new avenue for the preparation of low-cost and high-performance noble metal free catalysts. [ABSTRACT FROM AUTHOR]

A europium-functionalized, dual-emissive, metal–organic framework-based fluorescence sensor (EuUCNDA) was constructed via post-synthetic modification of an UiO-66-type precursor through coordination interactions. EuUCNDA exhibited extremely high selectivity and sensitivity for malachite green (MG) with a low detection limit of 13.01 nM, a wide linear concentration range (0.05–50 μM), excellent anti-interference properties, a rapid response (<1 min), and the possibility of recycling. The good sensing performance of EuUCNDA enables the practical detection of MG in fish pond water and grass carp with good recoveries. Moreover, EuUCNDA can be reused for sensing MG and over 90% of fluorescence intensity can be restored after 7 cycles. Furthermore, EuUCNDA-embedded paper-based sensors combined with smartphone imaging afford portable and visual monitoring of MG in real samples. Notably, besides good sensing performance, EuUCNDA could efficiently remove MG from water. Hence, this work provides a recyclable and sensitive fluorescence sensor for portable, visual, rapid detection and efficient removal of MG. [ABSTRACT FROM AUTHOR]

The lanthanide metal organic framework compounds [Ln(BPTA)1.5(Bpy)]·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1a–5a) and [Ln(BPTA)1.5(Phen)]·0.5DMF (Ln = Y, Eu, Gd, Tb, Dy; 1b–5b) were prepared by employing 2,5-bis(prop-2-yn-1-yloxy)terephthalic acid (2,5-BPTA) as the primary ligand and 2,2′-bipyridine (1a–5a) and 1,10-phenanthroline (1b–5b) as the secondary ligands. Single-crystal structural studies on [Gd(BPTA)1.5(Bpy)]·0.5DMF (3a) and [Dy(BPTA)1.5(Phen)]·0.5DMF (5b) indicated that the compounds have a two-dimensional structure. The Y compound exhibits blue emission, and the other compounds exhibit emission in the expected regions (λex = 350 nm). White light emission was achieved by careful mixing of the red (Eu3+) and green (Tb3+) components in the blue emitting Y compound. Thus, Y0.96Tb0.02Eu0.02 (bpy) and Y0.939Tb0.06Eu0.001 (phen) were found to show white emission when excited using a wavelength of 350 nm. The introduction of N–N-containing ancillary ligands (i.e., bpy and phen) increased the overall quantum yield (QY) of white light emission to 31% and 43%, respectively. The high QY observed for the Tb and Eu compounds was found to be sensitive and selective for the fluorometric detection of azinphos-methyl pesticide and trinitrophenol (TNP) in an aqueous medium at the ppb level. The same behaviour was observed when utilising the compounds as onsite paper strip sensors. Their magnetic properties were also studied, revealing for the Tb and Dy derivatives slow relaxation of the magnetisation at low temperature. The present study highlights the usefulness of rigid π-conjugated molecules such as 2,2′-bipyridine and 1,10-phenanthroline in enhancing the many utilities of rare-earth-containing MOFs towards white light emission, the sensing of harmful and dangerous substances and magnetic properties. [ABSTRACT FROM AUTHOR]

The exploitation of photo-responsive metal–organic frameworks (MOFs) is important in the field of optical switching, advanced detection, and molecular machines. However, it remains challenging due to the heavy dependence on conventional organic photochromic molecules. Herein, a novel photochromic MOF based on benzophenone units, [Zn4(μ2-O)(μ3-O)(cdip)2(DMF)]n (H4cdip = 5,5′-carbonyldiisophthalic acid) (1), has been successfully synthesized. Compound 1 exhibits instant and reversible photochromic behavior under 365 nm UV and X-ray irradiation through the radical formation of benzophenone units. Furthermore, the fluorescence of 1 can be reversibly modulated during the photochromic process. The excellent stability and reproducibility make it suitable for inkless erasable printing paper. [ABSTRACT FROM AUTHOR]

The pyrolysis of metal–organic frameworks (MOFs) has emerged as a promising route to synthesize carbon/metal oxide-based materials with diverse phase compositions, morphologies, sizes and surface areas. In this paper, 1,3,5-benzoic acid (BTC) and 2,4,6-tri(4-pyridinyl)-1-pyridine (TPP) were used as ligands to prepare a novel cobalt-based MOF (Co-MOF) which was used as a precursor to obtain five carbon-based materials at different temperatures (Co-C200/400/600/800/1000). Furthermore, five dyes were used as degradation targets to investigate the photocatalytic degradation performance of the title materials under UV light irradiation. Co-C1000 exhibited the best photocatalytic degradation performance for methyl orange (MO), and the degradation rate could reach 99.21%. The enhanced photocatalytic activity was attributed to narrower band-gaps and a synergistic effect originating from the well-aligned straddling band structures between Co/CoO/Co3O4 and C, also resulting in a faster interfacial charge transfer during the photocatalytic reaction. This study will aid in the development of photocatalysts generated from carbon-based materials via the pyrolysis transformation of MOFs, therefore greatly enhancing the photocatalytic performance. [ABSTRACT FROM AUTHOR]

The development of a rapid and selective method for the identification of dipicolinic acid (DPA), a specific biomarker in Bacillus anthracis spores, is of great importance for the avoidance of anthrax infection. Herein, a chain-based EuIII metal–organic framework with the formula {[Eu3(BTDB)3(μ3-OH)3(H2O)]·solvents}n (JXUST-38, H2BTDB = (benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid) was obtained using 2-fluorobenzoic acid as the pH regulator. JXUST-38 exhibits good chemical and thermal stability and can specifically recognize DPA in N,N-dimethylformamide solution through luminescence enhancement and blue-shift effects with a detection limit of 0.05 μM. Furthermore, the significant luminescence enhancement and blue shift under UV lamps are obviously observable by the naked eye. The luminescence sensing mechanism is attributed to absorbance-induced enhancement between JXUST-38 and DPA. Test paper and mixed-matrix membrane based on JXUST-38 are designed for DPA detection. In addition, the feasibility of using JXUST-38 in biosensing is discussed in detail. [ABSTRACT FROM AUTHOR]

We present the synthesis, through a simple, microwave-assisted method, of lanthanoid-based 2D metal–organic frameworks (MOFs) of general formula [LnxLn′1−x(MeCOO)(PhCOO)2], including homonuclear compounds (x = 1), Ln＝Eu, Tb, and heterometallic compounds, [TbEu]. The crystalline material is formed by neutral nanosheets held together by van der Waals interactions, which can be easily exfoliated by sonication. Photoluminescent emission in the visible range was observed for all of the synthesized 2D MOF compounds via excitation of the ligand, showing benzoates are efficient antenna ligands. Efficient energy transfer from Tb → Eu was observed in the heterometallic [TbEu] compounds, which could potentially perform as luminescent thermometers. Inks containing nanosheets of 2D MOFs exfoliated in solution were prepared, and luminescent prints of Tb and Eu 2D MOFs on paper were made to show the possible application for anticounterfeiting. Frequency-dependent ac susceptibility results show the occurrence of slow magnetic relaxation in [TbEu] compounds through direct relaxation mechanisms, affected by bottleneck effect. A slowing down of the relaxation time is observed as the Eu/Tb ratio increases. [ABSTRACT FROM AUTHOR]

Numerous attempts have been made to replace commercial bulky gas chromatography (GC) systems with compact GC systems for monitoring volatile organic compounds in indoor air. However, recently developed compact GC systems are still too bulky in terms of user convenience, portability, and on-site analysis. Hence, an advanced miniaturization of compact GC systems is needed. Importantly, the small and high-performance gas pretreatment chip devices should be developed for compact GC systems. This paper reports the development of a metal–organic framework (MOF)-coated hybrid micro gas chromatography column chip (hybrid GC chip) capable of preconcentration and separation on harmful volatile organic compounds at low-concentration in one single chip device. The hybrid GC chip, 2 cm × 2 cm in size, was fabricated using a microelectromechanical systems process. The synthesized MOF-5 particles were coated on the inner wall of the fabricated hybrid GC chip and acted as an adsorbent and a stationary phase. The developed hybrid GC chip afforded high preconcentration factors with 1033–1237 and high separation resolutions with 3.8–13.3. The developed column showed good performance as a gas preconcentrator and separation column, and is the first device to perform both roles in one single chip device. [ABSTRACT FROM AUTHOR]

Preparation of the high value-added chemical 2,5-dimethylfuran (2,5-DMF) from the biomass-derived platform molecule 5-hydroxymethylfurfural (HMF) is of great significance in the preparation of biofuels. Here, a bottom-up strategy was used to prepare a metal–organic framework (MOF) material with a two-dimensional nanosheet morphology, named CPM, in which an additive 2-methylimidazole was introduced into the hydrothermal process of Cu2+ ions and terephthalic acid. Subsequently, CPM-700 prepared by heat treatment under an inert atmosphere showed excellent catalytic performance in the reaction of HMF hydrodeoxygenation to 2,5-DMF. The materials before and after pyrogenation were characterized by PXRD, XPS, TEM, N2 adsorption and desorption and so on. It was confirmed that compared with the catalyst derived from the cubic MOF material self-assembled by Cu2+ and terephthalic acid, the morphology of 2D nanosheets was beneficial for the reaction of HMF to 2,5-DMF. Combined with the experimental data, the possible reaction path of 2,5-DMF preparation from HMF is that 2,5-dihydroxymethylfuran was formed by hydrogenation of the aldehyde group on the furan ring, and then 2,5-DMF was obtained by hydrogenolysis. This paper provides an effective route for 2D MOF-derived catalytic materials in the selective hydrogenation of HMF. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have been broadly applied in biomedical and other fields. MOFs have high porosity, a large comparative area, and good biostability and have attracted significant attention, especially in cancer therapies. This paper presents the latest applications of MOFs in chemodynamic therapy (CDT), sonodynamic therapy (SDT), photodynamic therapy (PDT), photothermal therapy (PTT), immunotherapy (IT), and combination therapy for breast cancer. A combination therapy is the combination of two different treatment modalities, such as CDT and PDT combination therapy, and is considered more effective than separate therapies. Herein, we have also discussed the advantages and disadvantages of combination therapy in the treatment of breast cancer. This paper aims to illustrate the potential of MOFs in new cancer therapeutic approaches, discuss their potential advantages, and provide some reflections on the latest research results. [ABSTRACT FROM AUTHOR]

2,6-Pyridine dicarboxylic acid (DPA) is considered one of the main anthrax biomarkers, and the detection of DPA is of great significance. This work presents a Zn(II)-based metal–organic framework (MOF) with the formula {[Zn2(2,6-NBC)2(vlpy)Zn(2,6-NBC)(vlpy)0.5]·0.8(2,6-H2NBC)·H2O}n (1) assembled from 2,6-naphthalenedicarboxylic acid (2,6-H2NBC) and 4,4′-vinylenedipyridine (vlpy) for a photoluminescence sensor matrix for DPA detection. 1 features a 3D pillar–layer framework with nanopore sizes of ca.13.165 Å × 12.731 Å, 12.725 Å × 11.018 Å and 13.114 Å × 13.165 Å along the three directions, occupied by lattice water and disordered 2,6-H2NBC molecules. The obtained 1 can be used as a turn-on fluorescence sensor for the detection of DPA with high selectivity, excellent sensitivity and recyclability. The luminescence of 1 demonstrates an obvious color change from blue to purplish blue as the DPA concentration rises. Furthermore, a linear correlation is presented between the fluorescence and a low DPA concentration of 0–0.3 mM, and the detection limit can reach as low as 128 nM, much lower than that of an infectious dose to a human of anthrax spores (60 μM). A fluorescence test paper is fabricated to detect DPA rapidly through color change. DFT calculations indicate the intermolecular photoinduced electron-transfer transition and hydrogen-bonding interaction between DPA molecules and the skeleton of 1 induces the "turn-on" fluorescence sensing of DPA behavior. [ABSTRACT FROM AUTHOR]

We report the solvothermal synthesis of a dansyl anchored hafnium based fluorescent metal–organic framework (MOF) having the formula [Hf6O4(OH)4(L)6]·H2O·6DMF (H2L = 2-((5-(dimethylamino)naphthalene)-1-sulfonamido)terephthalic acid). The synthesized material showed high fluorescence emission properties as well as high thermal (stable up to 330 °C) and chemical stability. It also exhibited a wide range of pH tolerance as well as a high BET surface area of 703 m2 g−1. The activated MOF showed ultra-fast (detection time < 10 s) and ultra-sensitive sensing properties towards Cu(II) and the biologically important biomarker 3-nitrotyrosine (3-NTyr) in a HEPES medium at a physiological pH of 7.4. Along with high selectivity, very low detection limits of 229 nM and 539 nM were obtained for Cu(II) and 3-NTyr respectively. Furthermore, this probe was utilised for the detection and quantification of Cu(II) and 3-NTyr in biosamples (urine and serum) with very low RSD values (2.3–4.8%). Additionally, this probe was employed to detect the presence of Cu(II) as a pollutant in various environmental water samples. Furthermore, for rapid economic detection of Cu(II), a MOF coated fluorescent paper strip was demonstrated. Thorough mechanistic investigations displayed that a complexometric interaction between Cu(II) and the probe is the main reason for the quenching of fluorescence intensity. This proposed mechanism was well supported by experimental evidence. On the other hand, the FRET mechanism is proposed based on the experimental observations for dynamic quenching of the fluorescence intensity of the probe in the presence of 3-NTyr. [ABSTRACT FROM AUTHOR]

A novel three-dimensional Eu3+-based metal–organic framework with the formula {[(CH3)2NH2][Eu(BTDI)]·H2O·DMF}n (JXUST-25) was prepared by solvothermal method based on Eu3+ and 5,5′-(benzothiadiazole-4,7-diyl)diisophthalic acid (H4BTDI) with benzothiadiazole (BTD) luminescent groups. Due to the presence of Eu3+ and organic fluorescence ligand, JXUST-25 displays turn-on and blue-shift fluorescence toward Cr3+, Al3+ and Ga3+ with limits of detection (LOD) of 0.073, 0.006 and 0.030 ppm, respectively. Interestingly, the alkaline environment can change the fluorescence of JXUST-25 toward Cr3+/Al3+/Ga3+ and the addition of HCl solution realizes the reversible change of the fluorescence of JXUST-25 toward Cr3+/Al3+/Ga3+. It is noteworthy that the fluorescent test paper and light-emitting diode lamp based on JXUST-25 can effectively detect Cr3+, Al3+ and Ga3+ by the visual changes. In addition, the turn-on and blue-shift fluorescence between JXUST-25 and M3+ ions may be caused by the host–guest interaction and the absorbance caused enhancement mechanism. [ABSTRACT FROM AUTHOR]

The development of sensors with high sensitivity, selectivity, long-term stability and other excellent performances is still the focus of current research on gas sensors. In this paper, biomorphic zinc oxide composite reduced graphene oxide nanomaterials (C–Z–ZnO–rGO) based on a metal–organic framework are synthesized by an impregnation calcination method using cotton as a biological template. The microscopic morphologies and structural composition of the composites are characterized. The response value of C–Z–ZnO–rGO to acetic acid gas is much higher than that of other gas sensors. At an operating temperature of 350 °C, the C–Z–ZnO–rGO gas-sensitive sensors have a response value of 410 for 100 ppm acetic acid, a response time of 43 s, and a recovery time of 18 s, and have good repeatability and long-term stability. The response value of 2.614 for 1 ppm of acetic acid gas further indicates that the C–Z–ZnO–rGO sensor has a low detection limit. The hollow structure of the C–Z–ZnO–rGO composites has the advantages of high specific surface area, multiple pores, diverse structures and abundant active sites, which improves the adsorption performance on acetic acid gas. [ABSTRACT FROM AUTHOR]

CeO2, an n-type semiconductor material, has been widely used in microwave absorption (MA) due to its unique structural features such as oxygen vacancies and interstitial atoms. In this paper, Co/CeO2/C composites were prepared by a hydrothermal method followed by a pyrolysis process. The effect of different pyrolysis temperatures (650–950 °C) on the MA property of the composites was investigated. When the pyrolysis temperature was 850 °C, the Co/CeO2/C-850 composite exhibited outstanding MA behavior in the frequency range of 2–18 GHz, displaying a minimum reflection loss (RLmin) of −45.22 dB and an effective absorption bandwidth (EAB) of 4.61 GHz at a thin thickness of 1.75 mm. The MA performance of the Co/CeO2/C composites is mainly attributed to the dielectric loss due to interfacial polarization originating from different interfaces and dipole polarization caused by the oxygen vacancies in CeO2. In addition, the introduction of Co nanoparticles not only provides the magnetic loss but also modulates impendence matching for the current magnetoelectric coupling system. [ABSTRACT FROM AUTHOR]

The construction of a new electrochemical sensing platform based on a copper metal-organic framework (Cu-MOF) heterostructure is described in this paper. Drop-casting Cu-MOF suspension onto the electrode surface primed the sensor for glutathione detection. The composition and morphology of the Cu-MOF heterostructure were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FT-IR), and UV-visible spectroscopy. The Cu-MOF heterostructure can identify glutathione (GSH) with an enhanced sensitivity of 0.0437 μA μM -1 at the detection limit (LOD; 0.1 ± 0.005 μM) and a large dynamic range of 0.1-20 μM. Boosting the conductivity and surface area enhances electron transport and promotes redox processes. The constructed sensors were also adequately selective against interference from other contaminants in a similar potential window. Furthermore, the Cu-MOF heterostructure has outstanding selectivity, long-term stability, and repeatability, and the given sensors have demonstrated their capacity to detect GSH with high accuracy (recovery range = 98.2-100.8%) in pharmaceutical samples.

Biological metal-organic frameworks (bio-MOFs) constitute a growing subclass of MOFs composed of metals and bio-ligands derived from biology, such as nucleobases, peptides, saccharides, and amino acids. Bio-ligands are more abundant than other traditional organic ligands, providing multiple coordination sites for MOFs. However, bio-MOFs are typically prepared using hazardous or harmful solvents or reagents, as well as laborious processes that do not conform to environmentally friendly standards. To improve biocompatibility and biosafety, eco-friendly synthesis and functionalization techniques should be employed with mild conditions and safer materials, aiming to reduce or avoid the use of toxic and hazardous chemical agents. Recently, bio-MOF applications have gained importance in some research areas, including imaging, tumor therapy, and targeted drug delivery, owing to their flexibility, low steric hindrances, low toxicity, remarkable biocompatibility, surface property refining, and degradability. This has led to an exponential increase in research on these materials. This paper provides a comprehensive review of updated strategies for the synthesis of environmentally friendly bio-MOFs, as well as an examination of the current progress and accomplishments in green-synthesized bio-MOFs for drug delivery aims and tumor treatments. In conclusion, we consider the challenges of applying bio-MOFs for biomedical applications and clarify the possible research orientation that can lead to highly efficient therapeutic outcomes.

Metal-organic frameworks (MOFs) have been broadly applied in biomedical and other fields. MOFs have high porosity, a large comparative area, and good biostability and have attracted significant attention, especially in cancer therapies. This paper presents the latest applications of MOFs in chemodynamic therapy (CDT), sonodynamic therapy (SDT), photodynamic therapy (PDT), photothermal therapy (PTT), immunotherapy (IT), and combination therapy for breast cancer. A combination therapy is the combination of two different treatment modalities, such as CDT and PDT combination therapy, and is considered more effective than separate therapies. Herein, we have also discussed the advantages and disadvantages of combination therapy in the treatment of breast cancer. This paper aims to illustrate the potential of MOFs in new cancer therapeutic approaches, discuss their potential advantages, and provide some reflections on the latest research results.

The electrochemical reduction of CO2 to CO is a powerful approach to achieving carbon neutrality. Herein, we report a five-nuclear copper cluster-based metal–azolate framework CuTz-1 as an electrocatalyst for the electrochemical CO2 reduction reaction. It achieved a faradaic efficiency (FE) of 62.7% for yielding CO with a partial current density of −35.1 mA cm−2 in flow cell device, which can be preserved for more than ten hours with negligible changes of the current density and FE(CO). Studies of electrocatalytic mechanism studies revealed that the distance of Cu–N was increased, and the coordination number of the Cu ion was reduced, while the oxidation state of Cu was decreased after the electrocatalysis. These findings offer valuable insights into structural changes that influence the performance of the catalyst during the process of the electrochemical reduction of CO2 process. [ABSTRACT FROM AUTHOR]

A novel water-stable CdII-based metal–organic framework, namely {[Cd(BIBT)(TDC)]·2H2O}n (JXUST-28, BIBT = 4,7-bi(1H-imidazol-1-yl)benzo-[2,1,3]thiadiazole and H2TDC = 2,5-thiophenedicarboxylic acid), was synthesized using a mixed-ligand strategy. Structural analysis demonstrates that JXUST-28 exhibits a two-dimensional layer structure with 4-connected sql topology. Intriguingly, JXUST-28 presents good stability in boiling water (at least 5 days), common organic solvents and aqueous solutions with different pH values of 2–12 (more than 24 hours). Furthermore, fluorescence experiments revealed that JXUST-28 could sense Hg2+ ions in aqueous solution via a quenching effect with a detection limit of 0.097 μM. Meanwhile, JXUST-28 can also be regenerated at least 5 times to detect Hg2+ ions. In addition, light-emitting diode lamps, luminescent films, and test papers of JXUST-28 have been successfully developed for practical applications. [ABSTRACT FROM AUTHOR]

The development of high-performance and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is critical to renewable energy conversion and storage technologies. Among of them, metal organic frameworks (MOFs) have been proved to be effective substitutes for precious metals. In this paper, a series of mixed NiCoFe-MOFs with low crystallinity were synthesized by a simple one-step solvothermal method, which can be used as a direct electrocatalyst for the OER. Notably, the flower-like nanocatalyst NiCoFe-MOF-2 exhibits a hierarchical pore network and a large specific surface area (149.6 m2 g−1), which results in an adjustable electronic structure, effective mass transfer, and abundant exposed active sites. In addition, due to the synergy between the three metals Fe, Co and Ni, NiCoFe-MOF-2 can exhibit excellent electrocatalytic OER performance, with a low overpotential of 321 mV at 10 mA cm−2, superior to commercial RuO2 (379 mV), a Tafel slope of 48 mV dec−1 and long-term stability. The result may stimulate more designs of MOF-derived catalysts with multi-scale structures and multi-components designed for various electrochemical energy conversion devices. [ABSTRACT FROM AUTHOR]

The design of an efficient OER catalyst is significant for water splitting. Metal–organic frameworks (MOFs) are emerging as promising electrocatalysts due to their diversity of structure and tunability of function. In this paper, 2D FexCo1−x-MOF1/NF with an extended ligand (biphenyl-4,4′-dicarboxylic acid, BPDC) is constructed on nickel foam by a solvothermal method. Compared with the MOF2 synthesized by using BDC (1,4-bezenedicarboxylate), MOF1 shows excellent performance. Among MOF1, Fe0.5Co0.5-MOF1/NF exhibits outstanding performance with a low overpotential (217 mV) and a small Tafel slope (31.16 mV Dec−1) at 10 mA cm−2 and performs well at a high current density. In addition, the catalyst is remarkable in terms of durability both in alkaline solution and simulated seawater. The synergetic effect between Fe and Co and more active sites exposed play an important role in improving the OER activity. This work provides an effective strategy for the rational design of MOFs as inexpensive electrocatalysts. [ABSTRACT FROM AUTHOR]

A zirconium-MOF with a sulphonic acid functionalized biphenyldicarboxylic acid linker was synthesized by a solvothermal process. The material was characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, infrared (IR) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), and FESEM analysis. The fluorescence sensing experiment towards the detection of Cu2+ was carried out. The detection time for Cu2+ was only 15 s with a very low limit of detection, which is 0.22 μM. The Stern–Volmer constant was found to be 5.5 × 105 M−1. For easy handling and real field application purposes, we developed a paper-strip based sensing device. The systematic study of the mechanism by EDX, PXRD, TRPL, and UV-Vis spectroscopy revealed that the quenching of fluorescence intensity by copper(II) was due to the fluorescence resonance energy transfer. [ABSTRACT FROM AUTHOR]

Optically-active luminescent materials based on lanthanoid ions attract significant attention due to their unique spectroscopic properties and the possibility of application as chemical sensors. Five isostructural lanthanoid metal organic frameworks, namely {[Pr(3,4-PDA)(Glu)0.5(H2O)2]CH3CN}(1) and [Ln(3,4-PDA)(Glu)0.5(H2O)2]: Ln = Nd (2), Sm (3), Eu (4), and Tb (5) (where 3,4-PDA = pyridine-3,4-dicarboxylic acid, Glu = glutaric acid), synthesized via the solvothermal method are reported. These lanthanoid metal–organic frameworks were characterized by FTIR, single-crystal X-ray diffraction, powder X-ray diffraction, BET, Hirshfeld surface analysis, DFT calculations, electronic spectroscopy, and photoluminescence techniques. MOFs 1–5 show porous two-dimensional (2D) structures. The luminescence properties of MOFs 4 and 5 demonstrated the range of sensing capabilities for some toxic heavy metals. However, MOFs 4 and 5 are highly sensitive for the detection of Pb2+, exhibiting the most effective luminescence quenching with the lowest detectable change in the signal occurring at ∼0.014 and ∼0.013 ppm of Pb2+ with MOFs 4 and 5, respectively, at room temperature in minutes. The MOF-based luminescence sensors designed in this paper demonstrate a successful and feasible strategy to use pyridine-3,4-dicarboxylic acid-based ligand as an antenna, which can efficiently sensitize Eu3+ and Tb3+ emission. MOFs 4 and 5 show great potential in the application of environmental detection of Pb2+ in water. [ABSTRACT FROM AUTHOR]

A nanozyme-like colorimetric sensing strategy based on persulfate activation on Co-based metal – organic frameworks is developed for biomolecule detection in solution and on paper strips. By switching from H2O2 activation on nanozymes to catalytic persulfate activation, this general strategy provides higher sensitivity, faster speed, and wider application ranges for detection. [ABSTRACT FROM AUTHOR]

We developed a porous diamino group-functionalized Zr(IV) metal–organic framework (MOF). The synthesized MOF has a similar structure to DUT-52 (DUT = Dresden University of Technology), which has a face-centered cubic structure with an Fm3¯m space group. The synthesized material (DUT-52-(NH2)2-1) was solvent exchanged with methanol (MeOH) and activated at 100 °C overnight. Both the as-synthesized and activated materials (DUT-52-(NH2)2-1′) are thermally stable until 300 °C. The Brunauer–Emmett–Teller (BET) surface area of DUT-52-(NH2)2-1′ was found to be 413 m2 g−1. DUT-52-(NH2)2-1′ showed a significant quenching of fluorescence response after coming in contact with free chlorine (ClO−) in an aqueous medium. The selectivity of DUT-52-(NH2)2-1′ towards ClO− was not significantly hampered in the presence of any competitive ion. The limit of detection (LOD) value was found to be 0.08 μM in phosphate-buffered saline (PBS, pH = 7.4). DUT-52-(NH2)2-1′ is recyclable and very sensitive towards ClO−. Moreover, the paper strip method was developed for onsite identification of ClO−. Furthermore, the catalytic activity of DUT-52-(NH2)2-1′ was tested in the Knoevenagel condensation between benzaldehyde and cyanoacetamide. The experimental results clearly indicate that DUT-52-(NH2)2-1′ exhibits high activity with very high selectivity towards condensation products. The solid was reusable three times with no decay in its activity, as evidenced by powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM) and fourier transform infrared (FT-IR). [ABSTRACT FROM AUTHOR]

Porphyrins are naturally occurring organic molecules that have attracted widespread attention for their potential in the field of biomedical research. Porphyrin-based metal-organic frameworks (MOFs) that utilize porphyrin molecules as organic ligands have gained attention from researchers due to their excellent results as photosensitizers in tumor photodynamic therapy (PDT). Additionally, MOFs hold significant promise and potential for other tumor therapeutic approaches due to their tunable size and pore size, excellent porosity, and ultra-high specific surface area. Active delivery of nanomaterials via targeted molecules for tumor therapy has demonstrated greater accumulation, lower drug doses, higher therapeutic efficacy, and reduced side effects relative to passive targeting through the enhanced permeation and retention effect (EPR). This paper presents a comprehensive review of the targeting methods employed by porphyrin-based MOFs in tumor targeting therapy over the past few years. It further discusses the applications of porphyrin-based MOFs for targeted cancer therapy through various therapeutic methods. The objective of this paper is to provide a valuable reference and source of ideas for targeted therapy using porphyrin-based MOF materials and to inspire further exploration of their potential in the field of cancer therapy.

A new water-stable three-dimensional (3D) Eu(III) metal–organic framework with the formula of {[Eu3(BTDC)4(HCOO)(H2O)2]·solvents}n (JXUST-9) was successfully obtained by the solvothermal reaction of 2,1,3-benzothiadiazole-4,7-dicarboxylic acid (H2BTDC) and Eu(NO3)3·6H2O. The PXRD patterns indicate that JXUST-9 exhibits good stability when soaked in boiling water for at least 24 h. The fluorescence experiments indicate that JXUST-9 could be considered as a good multi-responsive sensing material for detecting Fe3+, MnO4− and Cr2O72− in aqueous solutions via the turn-off effect, and the detection limits are 0.94 μM, 1.23 μM and 1.23 μM, respectively. JXUST-9 can also be regenerated at least five times for sensing Fe3+, MnO4− and Cr2O72−. Moreover, a rapid detection test paper incorporated with JXUST-9 has been produced, which is helpful for carrying out visual detection of Fe3+, MnO4− and Cr2O72− in daily applications. [ABSTRACT FROM AUTHOR]

In this paper, we showed an example of acid-directed hydrothermal synthesis of three Cd-based metal–organic frameworks (MOFs) under similar conditions, namely, [Cd(TIDB)(AA)0.5(NO3)]n (1), [Cd3(TIDB)2(AA)2(H2O)2(HCOO)2]n (2), and {[Cd4(TIDB)(AA)4(H2O)5](C2H5OH)2(H2O)2}n (3) (TIDB = 1,3,5-tri(1H-imidazol-1-yl)benzene, H2AA = anthracene-9,10-dicarboxylic acid). Compound 1 was synthesized by the introduction of HNO3 as a structure-directing agent. It has 2D coordination networks with the 3,4-c bey topology. The porous 3D supramolecular framework in compound 1 is stabilized by H-bonds. Compound 2 was formed with the use of a HCOOH agent. It has a 3D coordination network with a new 3,4,5-c underlying net topology, and it is also porous. Compound 3 was obtained using a CH3COOH agent. It has a disordered non-porous 3D coordination network. Because 3 was hard to purify, 1 and 2 were chosen for further property investigation. On the one hand, fluorescence studies showed that 1 and 2 are both blue-emitting MOFs with quantum yields of 2.3% and 0.8%, respectively. On the other hand, CO2 cycloaddition performance was also tested, which revealed that 2 has a superior catalytic conversion of epoxybutane at 60 °C and 1 atm with a high yield of up to 95.6%. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF) derived porous carbon materials have been widely applied as active materials for supercapacitors due to their large specific surface area and ordered pore structure. This paper presents a facile and effective strategy to regulate the morphology of a zinc-based metal–organic framework (Zn-trimesic acid, Zn-BTC) by adjusting the ethanol content in a solvent, which can effectively change the pore structure of Zn-BTC derived porous carbon (PC). The optimal PC prepared in 50% ethanol displays a rodlike structure with a large specific surface area (SSA) of 1930 m2 g−1 and an average pore size of 2.9 nm. This material shows an excellent rate performance with 78.8% capacitance retention when the current density increases from 1 A g−1 to 100 A g−1 and outstanding electrochemical stability with only 2.2% decline of capacitance after 200 000 cycles at 50 A g−1. Moreover, the assembled symmetrical capacitor shows a high energy density of 16.09 W h kg−1 at 698 W kg−1 and 11.89 W h kg−1 at a high power density of 41.56 kW kg−1. This method would provide a new pathway for the preparation of carbon materials with an adjustable pore size for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Excessive Fe3+ and Bi3+ can cause serious hazards to human-beings and microorganisms. However, it remains a great challenge to exploit more efficient methods to detect them. In this work, a two-dimensional (2-D) metal–organic framework (MOF) [Cd(3-L)(NDA)(H2O)]n (1) (3-L = 3,3′-((9H-fluoren-9-ylidene)-methylene)dipyridine; H2NDA = 1,4-naphthalenedicarboxylic acid) was successfully fabricated by a new fluorenyl-containing aggregation-induced emission (AIE) functional ligand. 1 features a 2-D (4,4) network, and good water and thermal stabilities. In its stacking structure, the fluorene rings from neighboring layers overlap with each other in the opposite direction, and show very weak π–π interactions. Accordingly, 1 exhibits superior luminescence enhancement ("turn-on") sensing of Fe3+ and Bi3+ with extremely high sensitivity in aqueous media. The detection limits of 1 for Fe3+ and Bi3+ are 4.86 × 10−4 and 1.87 × 10−5 mM, respectively, which are significantly lower than the corresponding reported works (only 23.6% and 0.8%). Interestingly, it has obviously enhanced Bi3+ detecting ability because of the larger ionic radius of Bi3+. More importantly, this is the first MOF-based "turn-on" sensor for Bi3+ reported to date. [ABSTRACT FROM AUTHOR]

A new metal–organic-framework (MOF) called UiO-66-NH-COCF3 was prepared using a trifluoroacetamido-functionalized terephthalic acid ligand. Powder X-ray diffraction (PXRD), infrared (IR) spectroscopy, thermogravimetric analysis (TGA) and a Brunauer Emmett–Teller (BET) experiment were carried out to investigate the phase purity, functionality, thermal stability and surface area, respectively, of the newly synthesized MOF material. The solvent-free MOF material (1′) was obtained by stirring the as-synthesized material in methanol for 24 h and then heated at 100 °C in vacuum. A systematic fluorescence study of 1′ showed an ultrafast, highly selective turn-on response towards the lethal cyanide (CN−) ion. A 300-fold increment in fluorescence intensity was observed, which has not previously been reported for any probe for cyanide sensing. To check the selectivity of 1′ towards CN− over other interfering anions, fluorescence sensing experiments were performed with 1′ in the presence of a wide range of anions, none of which caused significant interference. The detection time for the probe 1′ towards CN− was only 1 min, with a very low limit of detection (LOD) (0.28 μM). A fluorescence study was carried out in different pH media to check its usefulness towards the sensing of CN− in a wide pH range. Naked-eye detection of CN− was achieved by a paper strip coated with MOF material, which showed promise for more realistic applications. The reversibility of the CN− sensor was demonstrated using trifluoroacetic acid as the proton source. Furthermore, we could utilize the probe to detect CN− in food and real water samples. [ABSTRACT FROM AUTHOR]

Automobile exhaust gases, plastic pollutants, smoking, and other harmful substances can cause serious harm to human beings and the environment. Styrene, as a common airborne toxin, enters the human body through breathing or the skin and is discharged in the form of phenylglyoxylic acid (PGA). Therefore, specific, sensitive and trace detection of PGA is particularly important. Here, two zinc-based metal–organic frameworks {[Zn2L1(DMF)2H2O](DMF)2H2O}n, {[Zn4(L2)2(DMF)2(H2O)3](DMF)8}n (L1 = 2,5-bis((3-carboxylphenyl)amino)terephthalic acid, L2 = 2,5-bis((4-carboxyphenyl)amino)terephthalic acid) have been reported as 1 and 2, respectively. Both 1 and 2 present 3D structures, which can both be simplified as 4,4,4-c net topology. It is worth mentioning that 2 has two different kinds of Zn SBUs as connecting nodes in the structure. Besides, compared with the other materials for the detection of PGA, 1 and 2 exhibit relatively low detection limits (LODs), both in water and in urine (where the LODs for 1 in water and urine were 0.33 μM and 0.43 μM in the range of 0–0.39 mM, and those for 2 were 0.28 μM and 0.49 μM in the range of 0–0.59 mM, respectively). In addition, the sensors have excellent anti-interference ability, high stability, rapid response, and can easily distinguish between different concentrations of PGA with the naked eye. The developed paper probes were suitable for practical sensing applications for portable detection of PGA in urine. [ABSTRACT FROM AUTHOR]

Three new three-dimensional metal–organic frameworks were synthesized based on a naphthalenediimide derivative ligand, all of which exhibit photochromic behaviour due to the presence of the naphthalenediimide core. Interestingly, two of them possess significant colour changes under light, excellent stability, and appropriate photochromic lifetimes, thus showing potential for application in inkless and erasable printing media. [ABSTRACT FROM AUTHOR]

In this paper, three new cobalt-based metal organic frameworks (MOFs) with different topologies, namely, {[Co(HL)(tib)(H2O)]·2H2O}n (1), [Co3(L)2(bibp)4(H2O)2]n (2) and [Co2(L)(bip)(μ3-OH)]n (3) (H3L = 3-(3,5-dicarboxylphenoxy)-6-carboxylpyridine, tib = 1,3,5-tirs(1-imidazolyl)benzene, bibp = 4,4′-bis(imidazolyl)biphenyl, bip = 3,5-bis(imidazoly-1-yl)toluene) synthesized by a hydrothermal method, were investigated. Different auxiliary ligands led to the diversity of the three MOFs in terms of structure and properties. Hereafter, the adsorption properties of the MOFs on different dyes were investigated; of interest is that the adsorption performance of MOF 3 on Congo red dye is particularly outstanding, including excellent performance in terms of removal rates, selectivity and recyclability. Its adsorption kinetics and adsorption isotherms were also investigated. Finally, its possible adsorption mechanism was analyzed by zeta potential measurements, infrared spectroscopy and N2 adsorption–desorption isotherms. It was hypothesized that the exquisite confined microenvironments consisting of electrostatic interactions, a suitable pore volume, and complicated van der Waals forces of hydrogen bonding and π–π stacking played a critical role during the adsorption process. It was shown that MOF 3 can be used as an effective adsorbent for the adsorption of Congo red dye in wastewater. [ABSTRACT FROM AUTHOR]

As a newly emerging class of molecular crystal materials, metal-organic frameworks (MOFs) are extensively used in a variety of fields including catalysis, separation, energy storage, and biosensors, by virtue of their large specific surface area, excellent chemical stability, and adjustable pore size. In particular, several functional materials have been integrated into the MOF structure, which greatly improves the conductivity of MOFs and facilitates the application of MOFs in the field of electrochemical biosensing. Herein, this review highlights the recent applications of MOF composites for photoelectrochemical (PEC) and electrochemiluminescence (ECL) biosensors. This paper first briefly describes the classification and various synthesis methods of MOFs. Then, it comprehensively summarizes different types of MOF-based biosensors in PEC and ECL and their applications. Finally, the challenges and outlook for future work in MOF-based PEC and ECL biosensors are tentatively proposed.

2,6-Pyridine dicarboxylic acid (DPA) is considered one of the main anthrax biomarkers, and the detection of DPA is of great significance. This work presents a Zn(II)-based metal-organic framework (MOF) with the formula {[Zn 2 (2,6-NBC) 2 (vlpy)Zn(2,6-NBC)(vlpy) 0.5 ]·0.8(2,6-H 2 NBC)·H 2 O} n (1) assembled from 2,6-naphthalenedicarboxylic acid (2,6-H 2 NBC) and 4,4'-vinylenedipyridine (vlpy) for a photoluminescence sensor matrix for DPA detection. 1 features a 3D pillar-layer framework with nanopore sizes of ca. 13.165 Å × 12.731 Å, 12.725 Å × 11.018 Å and 13.114 Å × 13.165 Å along the three directions, occupied by lattice water and disordered 2,6-H 2 NBC molecules. The obtained 1 can be used as a turn-on fluorescence sensor for the detection of DPA with high selectivity, excellent sensitivity and recyclability. The luminescence of 1 demonstrates an obvious color change from blue to purplish blue as the DPA concentration rises. Furthermore, a linear correlation is presented between the fluorescence and a low DPA concentration of 0-0.3 mM, and the detection limit can reach as low as 128 nM, much lower than that of an infectious dose to a human of anthrax spores (60 μM). A fluorescence test paper is fabricated to detect DPA rapidly through color change. DFT calculations indicate the intermolecular photoinduced electron-transfer transition and hydrogen-bonding interaction between DPA molecules and the skeleton of 1 induces the "turn-on" fluorescence sensing of DPA behavior.

We report the solvothermal synthesis of a dansyl anchored hafnium based fluorescent metal-organic framework (MOF) having the formula [Hf 6 O 4 (OH) 4 (L) 6 ]·H 2 O·6DMF (H 2 L = 2-((5-(dimethylamino)naphthalene)-1-sulfonamido)terephthalic acid). The synthesized material showed high fluorescence emission properties as well as high thermal (stable up to 330 °C) and chemical stability. It also exhibited a wide range of pH tolerance as well as a high BET surface area of 703 m 2 g -1 . The activated MOF showed ultra-fast (detection time < 10 s) and ultra-sensitive sensing properties towards Cu(II) and the biologically important biomarker 3-nitrotyrosine (3-NTyr) in a HEPES medium at a physiological pH of 7.4. Along with high selectivity, very low detection limits of 229 nM and 539 nM were obtained for Cu(II) and 3-NTyr respectively. Furthermore, this probe was utilised for the detection and quantification of Cu(II) and 3-NTyr in biosamples (urine and serum) with very low RSD values (2.3-4.8%). Additionally, this probe was employed to detect the presence of Cu(II) as a pollutant in various environmental water samples. Furthermore, for rapid economic detection of Cu(II), a MOF coated fluorescent paper strip was demonstrated. Thorough mechanistic investigations displayed that a complexometric interaction between Cu(II) and the probe is the main reason for the quenching of fluorescence intensity. This proposed mechanism was well supported by experimental evidence. On the other hand, the FRET mechanism is proposed based on the experimental observations for dynamic quenching of the fluorescence intensity of the probe in the presence of 3-NTyr.