Portably and Visually Sensing Cytisine through Smartphone Scanning Based on a Post-Modified Luminescence Center Strategy in Zinc-Organic Frameworks.

Cytisine (CTS) is a useful medicine for treating nervous disorders and smoking addiction, and exploring a convenient method to detect CTS is of great significance for long-term/home medication to avoid the risk of poisoning, but it is full of challenges. Here, a modified metal-organic framework sensor Tb@Zn-TDA-80 with dual emission centers was prepared using a post-modified luminescence center strategy. The obtained Tb@Zn-TDA-80 can serve as a CTS sensor with high sensitivity and selectivity. To achieve portable detection, Tb@Zn-TDA-80 was further fabricated as a membrane sensor, M-Tb@Zn-TDA-80, which displayed an obvious CTS-responsive color change by simply dropping a CTS solution onto its surface. Benefiting from this unique functionality, M-Tb@Zn-TDA-80 successfully realized the visual detection and quantitative monitoring of CTS in the range of 5.26-52.6 mM by simply scanning the color with a smartphone. The results of nuclear magnetic resonance spectroscopy and theoretical computation illustrated that the high sensing efficiency of Tb@Zn-TDA-80 for CTS was attributed to the N-H⋅⋅⋅π and π⋅⋅⋅π interactions between the ligand and CTS. And luminescence quenching may result from the intramolecular charge transfer. This study provides a convenient method for ensuring long-term medication safety at home.

Luminescent Sensor with High Sensitivity and Selectivity for Amikacin Detection in a Serum using a Unique Gallium-Organic Framework.

Amikacin is a widely used antibiotic in the treatment of Gram-negative bacteria, but high concentrations of amikacin can cause cochlear nerve damage. Therefore, accurate and quick detection of the concentration of amikacin is desired and important. In this work, we have synthesized a new gallium-organic framework {[(CH3)2(NH2)Ga(PPTA)]·0.5DMF}n (1) (H4PPTA = 4,4',4″,4″'-(1-4-phenlene-bis(pyridine-4,2,6-triyl)) with good solvent and pH stabilities. A structure analysis reveals that 1 is a twofold interpenetrated framework exhibiting a large 1D square aperture with a size of 10.8 Å × 14 Å. The experimental results show that 1 can be used as a stable, fast, and recyclable luminescent probe for the detection of amikacin in aqueous solution and serum. The limit of detection is 2.9 × 10-7 mol/L, which is lower than the harmful concentration of amikacin in human serum. This is the first example of a metal-organic framework used for luminescence sensing of amikacin.

A Facile Strategy to Obtain Low-Cost and High-Performance Gold-Based Catalysts from Artificial Electronic Waste by [Zr48 Ni6 ] Nano-Cages in MOFs for CO2 Electroreduction to CO.

Expensive gold-based catalysts are frequently used for electrochemical CO2 reduction into CO. A feasible approach to obtain low-cost Au-based catalysts is needed. Herein, a novel framework 1 assembled from [Zr48 Ni6 ] nano-cages is prepared. It exhibits a high BET surface area of 1569 m2 g-1 and high solvents/pH stability. 1 can not only selectively extract AuCl4 - from artificial electronic waste, but can then be transformed into low-cost catalyst Au nanoparticle@1-x (Au NPs@1-x, x=1, 2, 3, 4) with tuneable Au NPs sizes. The CO2 RR investigations revealed that the Au NPs@1-3 displayed an excellent FECO of 95.2 % with a current density of 102.9 mA cm-2 at -1.1 V, and such high catalytic activity can be maintained for at least 15 h without obvious decrease because the confinement effect of [Zr48 Ni6 ] nano-cages prevents Au NPs agglomeration. This work offers a facile strategy to obtain low-cost and high-performance Au-based catalysts for various reactions activated by Au.

Selectively Regulating Lewis Acid-Base Sites in Metal-Organic Frameworks for Achieving Turn-On/Off of the Catalytic Activity in Different CO2 Reactions.

Regulating Lewis acid-base sites in catalysts to investigate their influence in the chemical fixation of CO2 is significant but challenging. A metal-organic framework (MOF) with open metal Co sites, {(NH2 Me2 )[Co3 (µ3 -OH)(BTB)2 (H2 O)]⋅9 H2 O⋅5 DMF}n (1), was obtained and the results of the catalytic investigation show that 1 can catalyze cycloaddition of CO2 and aziridines to give 99 % yield. The efficiency of the cyclization of CO2 with propargyl amines is only 32 %. To improve the catalytic ability of 1, ligand XN with Lewis base sites was introduced into 1 and coordinated with the open Co sites, resulting in a decrease of the Lewis acid sites and an increase in the Lewis base sites in a related MOF 2 ({(NH2 Me2 )[Co3 (µ3 -OH)(NHMe2 )(BTB)2 (XN)]⋅8 H2 O⋅4 DMF}n ). Selective regulation of the type of active centers causes the yield of oxazolidinones to be enhanced by about 2.4 times, suggesting that this strategy can turn on/off the catalytic activity for different reactions. The catalytic results from 2 treated with acid solution support this conclusion. This work illuminates a MOF-construction strategy that produces efficient catalysts for CO2 conversion.

Anchoring Ag(I) into Nitro-Functionalized Metal-Organic Frameworks: Effectively Catalyzing Cycloaddition of CO2 with Propargylic Alcohols under Mild Conditions.

Carboxylative cyclization of propargylic alcohols with CO2 is significant in synthetic chemistry, but harsh conditions are often needed according to reported results. Herein, a new stable nitro-functionalized metal-organic framework (MOF) of {[Co3(L)2(bpy)4(H2O)2]·DMF·H2O·bpy}n (1) was fabricated through the solvothermal reaction, which exhibited excellent stability in acid and basic solutions. Owing to the porous structure, unsaturated metal sites, and uncoordinated 4,4'-bpy ligands, 1 can serve as an excellent platform for catalytic applications. Hence, Ag(I) ions were incorporated in 1 through a postsynthetic method, and the as-synthesized Ag-1 catalyst with low metal loading (0.64 mol %) displayed excellent catalytic performance in the chemical fixation of CO2 with alkynols under room temperature and atmospheric pressure. The results of 1H NMR analyses further confirmed that Ag-1 can efficiently activate hydroxyl groups and promote the reaction. Moreover, the turnover frequency (TOF) of the Ag-1 catalyst can reach 262 h-1 in a short period of time, which is a high TOF value among the state-of-the-art MOF-based catalysts for catalyzing cycloaddition of CO2 with propargylic alcohols.

Recyclable Luminescence Sensor for Dinotefuran in Water by Stable Cadmium-Organic Framework.

Due to the widespread use of dinotefuran around the world, its impact on food and environmental safety has aroused great concern, and the establishment of a rapid and convenient approach for dinotefuran detection is necessary but challenging. Herein, we synthesized a unique three-dimensional framework {[(CH3)2NH2]2[Cd3(BCP)2]·10H2O·3.5DMF}n (1). Single-crystal X-ray analysis indicates that 1 possesses a 4,8-connected anion framework that corresponds to alb topology, with a one-dimensional rectangular channel along the c-axis with the size of 4 Å × 10 Å. Compound 1 displays satisfactory solvent and thermal stability. Luminescent investigations reveal that 1 can selectively detect dinotefuran by fluorescence quenching among other pesticides, displaying excellent anti-interference performance with common ions in water. Importantly, the limit of detection is as low as 2.09 ppm, which is far below the residual concentration of the U.S. food standard. A fluorescence quenching mechanism study shows that there exists competitive energy absorption and static quenching processes. To our knowledge, 1 is the first MOF-based fluorescence probe for dinotefuran detection.

Highly Sensitive and Selective Luminescence Sensor Based on Two-Fold Interpenetrated MOFs for Detecting Glutamate in Serum.

Glutamate is a biomarker for many nervous system diseases, and sensitively detecting glutamate is meaningful in the clinic. Therefore, a unique 3D framework of Cd-MOF (1) is synthesized and characterized. A single-crystal X-ray study reveals that it is a two-fold interpenetration (4,4)-connected framework with a PtS topology, where a large 1D rhombic channel with a size of 8 × 14 Å exists and the total potential void volume can reach 62%. Luminescence results demonstrate that 1 has good luminescence stability and can sensitively detect glutamate in water with a detection limit of 1.15 × 10-7 mol/L, which makes it the most sensitive MOF-based luminescence sensor of glutamate to date. More importantly, it also can serve as a luminescence sensor to detect glutamate in serum, and the quenching concentration needs to be only 43.1 µmol/L, which is much lower than the harmful level of glutamate (400 µmol/L) in glioma patients' blood. Compound 1 can be used at least five cycles. These results show that 1 has a potential application in monitoring glutamate in clinical scenarios.

Two Stable Heterometal-MOFs as Highly Efficient and Recyclable Catalysts in the CO2 Coupling Reaction with Aziridines.

Two stable heterometal-organic frameworks, {Na[LnCo(DATP)2 (Ac)(H2 O)](NO3 )⋅DMA⋅11 H2 O}n (Ln=Er(1) and Yb(2)), have been prepared with H2 DATP (4'-(3,5-dicarboxyphenyl)-2,2':6',2'''-terpyridine) as organic building block. These two isostructural compounds featuring two-dimensional layer architectures possess outstanding thermal stabilities and excellent chemical stabilities in common organic solvents and different acid/base solutions with pH range changing from 1 to 13. Moreover, compounds 1 and 2 serving as heterogeneous catalysts can efficiently catalyse the CO2 fixation reaction with various aziridines to result in corresponding oxazolidinones at 70 °C. Importantly, a good recyclable performance of 1 for at least 10 cycles is observed based on the experimental results, which are further confirmed by PXRD, TGA and ICP analyses.

Luminescent Detection of Colchicine by a Unique Indium-Organic Framework in Water with High Sensitivity.

Colchicine is highly toxic to creatures, and sensitively detecting colchicines is of profound significance in the pharmaceutical, clinical, food, and breeding industries. We herein designed and constructed a unique luminescent indium-organic framework {[(CH3)2NH2][In(L)]·9DMF}n (V105) via an in situ ligand-mediated method, which possesses a 2-fold interpenetrated 3D anionic framework. Due to the large channels that exist in the framework with the size of 12 Å × 14 Å, V105 can rapidly remove harmful cationic dyes from water in a few minutes. Importantly, luminescent experiments demonstrate that V105 can selectively detect colchicine with high sensitivity in water, and the limit of detection can reach 1.0 × 10-7 M. To our knowledge, this is the first example of a metal-organic framework-based luminescent sensor for detecting colchicine.

Triple-Interpenetrated Lanthanide-Organic Framework as Dual Wave Bands Self-Calibrated pH Luminescent Probe.

pH value is a key parameter in reflecting the health status, reaction process, and water quality. The construction of highly sensitive pH luminescent ratiometric is important but challenging. Herein we designed and synthesized a unique triple-interpenetrated luminescent lanthanide-organic framework {[Eu(PPTA)0.5(NO3)(DMF)2]·H2O} n(V104) based on an amphoteric ligand 4,4',4'',4'''-(1,4-phenylenebis(pyridine-4,2,6-triyl))tetrabenzoic acid (H4PPTA). Compound V104 possesses high solvent and acid/alkaline stabilities. Luminescent investigations reveal that V104 exhibits dual emission peaks at 390 and 480 nm, and these two peaks can separately detect OH- and H+ among various anions and cations. Importantly, V104 can serve as a self-calibrated pH ratiometric to quantitatively detect pH value, and the sensitivity can reach 403.2% per pH for OH-, and 129.5% per pH for H+. Furthermore, by encapsulating magnetic γ-Fe2O3 nanoparticles in V104, the pH sensor can be readily separated from the analyte by external magnet and recycled at least four times, suggesting as-synthesized γ-Fe2O3@V104 has potential for monitoring pH fluctuations in water. To our knowledge, this is the first self-calibrated ratiometric pH-sensor based on two responsive wave bands which can separately detect OH- and H+.

A Noble-Metal-Free Metal-Organic Framework (MOF) Catalyst for the Highly Efficient Conversion of CO2 with Propargylic Alcohols.

Cyclization of propargylic alcohols with CO2 is an important reaction in industry, and noble-metal catalysts are often employed to ensure the high product yields under environmentally friendly conditions. Herein a porous noble-metal-free framework 1 with large 1D channels of 1.66 nm diameter was synthesized for this reaction. Compound 1 exhibits excellent acid/base stability, and is even stable in corrosive triethylamine for one month. Catalytic studies indicate that 1 is an effective catalyst for the cyclization of propargylic alcohols and CO2 without any solvents under mild conditions, and the turnover number (TON) can reach to a record value of 14 400. Furthermore, this MOF catalyst also has rarely seen catalytic activity when the biological macromolecule ethisterone was used as a substrate. Mechanistic studies reveal that the synergistic catalytic effect between CuI and InIII plays a key role in the conversion of CO2 .

Interpenetration-Dependent Luminescent Probe in Indium-Organic Frameworks for Selectively Detecting Nitrofurazone in Water.

Two novel anionic In-MOFs V101 and V102 were synthesized and structurally characterized. The structrual transformation from 2-fold interpenetration to noninterpenetration was completed by changing solvent from DMF to DEF. Luminescence investigations reveal that only V102 not V101 can sensitively and selectively detect traces of antibiotics nitrofurazone in water solution via an environmentally friendly manner, and the detection limit can reach to 0.2 ppm. The luminescent difference between V101 and V102 mainly originates from the divergence of interpenetration structures. Namely, through interpenetration-control, the luminescent probe can switch on or off to detect nitrofurazone. This is the first example of interpenetration-dependent MOFs-based luminescent probe.