Stability In Organic Solvents Research Articles

Corrosion resistant solid-state carbon dots@silicalite-1 composite for latent fingerprints detection

The aggregation-induced quenching (AIQ) properties of the solid-state carbon dots (CDs) limit their wide-scale actual applications. Herein, a novel corrosion resistant solid-state CDs@Silicalite-1 (CDs@S-1) composite was synthesized via in situ embedding CDs into the S-1 matrix. Owing to the confinement effect, CDs are immobilized into the interrupted defects of the three-dimensional S-1 matrix. The as-prepared composite possesses high photoluminescence quantum yield (63%) and extra-high stability in common organic solvents and various pH solutions (pH=2–14). Moreover, the feasibility of the CDs@S-1 composite as a fluorescent label on various substrates was investigated. The results demonstrate the images with well-defined papillary ridges under ultraviolet (UV) light and show great potential for latent fingerprints detection in forensic science.

TWO NOVEL CLUSTERS OF NOCARDIOPSIS RECOVERED FROM HALOALKALINE ENVIRONMENT: POTENTIAL RESOURCE OF MULTI-ADVANTAGEOUS LIPASES

Wadi El Natrun district in the northwest of Cairo, Egypt, represents a highly stable unique ecology containing dual stress of salinity and alkalinity. Bioprospecting lipase producers in such an environment helps in finding enzymes of novel properties. Seven Nocardiopsis strains were recovered from Wadi El Natrun region, and their distribution within the phylogeny of the genus showed a particular pattern of two clusters descending from two evolutionary lineages. All strains produced highly alkaline lipase (optimum pH: 9- 11) in different amounts. The principal features of lipases from all strains, not only from the most potent one, were realized in a comparative profile to prospect more of their possible advantages in industrial biocatalysis. Most of the lipases were thermophilic; the optimum temperature was 50-55°C in lipases from five isolates. Activation energy of all lipases varied considerably between 5.52 and 13.58 Kcal/mole. WN4L lipase exhibited the highest thermal stability (half-life time=99 min at 70°C). Interestingly, different lipases exhibited good stabilities in water-immiscible organic solvents which highlighted their suitability in the two-partitioning system applications. A general prospect about characteristic features of Wadi El Natrun lipases was realized; they share the multi-advantages of high alkalophilicity, tendency to be thermophilic, and readiness to work in acetone and water-immiscible solvents. Considering the extensive variation, each lipase appeared of a unique profile that enables to choose the most compatible one according to the specific circumstances of the interested industrial process. Moreover, a cocktail enzyme preparation of such lipases could be used as a multi-task lipase formula.

Chiral core-shell microspheres β-CD-COF@SiO2 used for HPLC enantioseparation

Chiral covalent organic frameworks (CCOFs) have potential application in enantioseparation due to their advantages, such as large surface area, abundant chiral recognition sites and good chemical stability in organic solvents. However, the application of CCOFs in high performance liquid chromatography (HPLC) for enantioseparation has been rarely reported because of the shortcomings of CCOFs, such as light weight, irregular shape, and wide particle size distribution. In order to overcome the above shortcomings, a one-pot synthetic method was adopted to prepare a core-shell composite (β-CD-COF@SiO2) via the growth of chiral β-CD COF on the surface of amino-functionalized SiO2 microspheres. The as-prepared β-CD-COF@SiO2 microspheres were used as a stationary phase for HPLC enantioseparation. The resolution ability of the β-CD-COF@SiO2-packed column toward various chiral compounds was investigated using n-hexane/isopropanol as the mobile phase. The results show that the chiral β-CD-COF@SiO2-packed column exhibited excellent chiral recognition ability for 24 pairs of chiral compounds with good reproducibility. These successful applications indicate that the preparation of the chiral COFs@SiO2 core-shell microspheres as a novel stationary phase for enantioseparation has good application prospects in HPLC.

A Rapid Analytical Approach for Monitoring Pharmaceuticals in Hospital Wastewater—A DPX-Based Procedure with Environmentally-Friendly Extraction Phase Coupled to High Performance Liquid Chromatography–Diode Array/Fluorescence Detectors

In this study, a novel analytical methodology based on disposable pipette extraction (DPX) was developed using an alternative extraction phase for the extraction/determination of six pharmaceutical compounds, including carbamazepine, diclofenac, naproxen, fluoxetine, losartan and 17α-ethinylestradiol, in samples of hospital wastewater by high-performance liquid chromatography coupled to diode array and fluorescence detectors. The performance of three extraction phases was examined, including 3-n-propyl (3-methylpyridinium) silsesquioxane chloride (Si3Py+Cl−), the conductive polymer polypyrrole (PPy), and polypyrrole modified with cetyltrimethylammonium bromide (PPy.CTAB). The optimization of the experimental parameters was performed through univariate and multivariate approaches. The optimized condition was obtained with the use of 20 mg of Si3Py+Cl− as extraction phase; six extraction cycles with 700 μL of sample in each cycle and 15 s of extraction time; three desorption cycles with 100 μL of ACN (same aliquot) and 15 s of desorption time; and sample pH adjusted at 3.5 and addition of 15% (w/v) of NaCl in the sample. The methodology proposed exhibited environmentally-friendly aspects with a significantly reduced volume of organic solvent (only 100 µL) and a small amount of extraction phase (20 mg). In addition, the extraction phase employed exhibits a simple synthetic procedure, low cost, and high stability in organic solvent. Moreover, the method developed exhibits high throughput (extraction time of 6.5 min per sample), and robustness. The analytical figures of merit were obtained using hospital wastewater, and the values were very satisfactory. The correlation coefficients were higher than 0.9710. LODs and LOQs ranged from 0.030 µg L−1 to 1.510 µg L−1 and 0.10 µg L−1 to 5.00 µg L−1, respectively. Relative recoveries varied from 80 to 127%, and intra-day (n = 3) and inter-day (n = 9) precision was lower than 19%.

Thermally-induced pore size tuning of multilayer nanoporous graphene for organic solvent nanofiltration

Graphene-based materials have been used for fabricating organic solvent nanofiltration membranes due to their excellent mechanical properties and chemical stability in organic solvents. However, graphene membranes exhibit low organic solvent permeation properties due to the large molecular size of the organic solvent molecules and their strong interactions with the graphene surface. Herein, a nanoporous graphene membrane was fabricated to enhance organic solvent permeation. Nanopores were generated on the basal plane of graphene by rapid thermal annealing of graphene oxide. The size of the nanopores was also tuned from micropores to nanopores by adjusting the activation temperatures. The optimized nanoporous graphene membrane showed ultrafast isopropyl alcohol permeance up to 295 Lm−2h−1bar−1 and a sharp molecular weight cut-off of 616 Da. The membrane showed excellent stability and diafiltration performance under cross-flow filtration with a separation factor of around 1000 for dye molecules mixed in isopropyl alcohol.

Oxalamide-Functionalized Metal Organic Frameworks for CO2 Adsorption.

Metal-organic frameworks (MOFs) have received great attention in recent years as potential adsorbents for CO2 capture due to their unique properties. However, the high cost and their tedious synthesis procedures impede their industrial application. A series of new CO2-philic oxalamide-functionalized MOFs have been solvothermally synthesized: {[Zn3(μ8-OATA)1.5(H2O)2(DMF)]·5/2H2O·5DMF}n (Zn-OATA), {[NH2(CH3)2][Cd(μ4-HOATA)]·H2O·DMF}n (Cd-OATA), and {[Co2(μ7-OATA)(H2O)(DMF)2]·2H2O·3DMF}n (Co-OATA) (H4OATA = N,N'-bis(3,5-dicarboxyphenyl)oxalamide). In Zn-OATA, the [Zn2(CO2)4] SBUs are connected by OATA4- ligands into a 3D framework with 4-connected NbO topology. In Cd-OATA, two anionic frameworks with a dia topology interpenetrated each other to form a porous structure. In Co-OATA, [Co2(CO2)4] units are linked by four OATA4- to form a 3D framework with binodal 4,4-connected 42·84 PtS-type topology. Very interestingly, Cu-OATA can be prepared from Zn-OATA by a facile metal ions exchange procedure without damaging the structure while the CO2 adsorption ability can be largely enhanced when Zn(II) metal ions are exchanged to Cu(II). These new MOFs possess channels decorated by the CO2-philic oxalamide groups and accessible open metal sites, suitable for highly selective CO2 adsorption. Cu-OATA exhibits a significant CO2 adsorption capacity of 25.35 wt % (138.85 cm3/g) at 273 K and 9.84 wt % (50.08 cm3/g) at 298 K under 1 bar with isosteric heat of adsorption (Qst) of about 25 kJ/mol. Cu-OATA presents a very high selectivity of 5.5 for CO2/CH4 and 43.8 for CO2/N2 separation at 0.1 bar, 298 K. Cd-OATA exhibits a CO2 sorption isotherm with hysteresis that can be originated from structural rearrangements. Cd-OATA adsorbs CO2 up to 11.90 wt % (60.58 cm3/g) at 273 K and 2.26 wt % (11.40 cm3/g) at 298 K under 1 bar. Moreover, these new MOFs exhibit high stability in various organic solvents, water, and acidic or basic media. The present work opens a new opportunity in the development of improved and cost-effective MOF adsorbents for highly efficient CO2 capture.

Reinforcing the polybenzimidazole membrane surface by an ultrathin co-crosslinked polydopamine layer for organic solvent nanofiltration applications

Here, highly robust and tight PBI-based OSN membranes were developed by reinforcing the active layer with an ultrathin polydopamine (pDA) coating followed by the simultaneous co-crosslinking of the pDA-coated PBI membrane. Although the pDA layer thickness was just under 5 nm, the pDA layer can effectively improve the rejection properties of the pristine PBI membrane by reducing the overall pore size and filling the defects at the membrane surface. The chemical and physical changes clearly showed the effect of the ultrathin pDA layer and co-crosslinking on the membrane properties and separation performance. The modified PBI membranes showed the improved rejection property and excellent stability in various organic solvents, even in polar aprotic solvents. The co-crosslinked pDA-coated PBI membranes showed a very high rejection properties to low molecular weight solutes (97.6% for 236 Da styrene dimer and 99.9% for 308 Da PPG) with stable solvent permeance. Moreover, significantly improved solvent permeances were observed without a notable decrease in the rejection performance after the prefiltration of polar aprotic solvents. The results showed the effective separation performance enhancement of OSN membranes by ultrathin pDA coating and the potential applications of solvent purification, reuse and valuable chemical recovery in various fine chemical industries.

Conjugation with inulin improves the environmental stability of haloalkane dehalogenase DhaA

Haloalkane dehalogenase DhaA catalyzes the hydrolytic cleavage of carbon-halogen bonds and produces alcohol, a proton and a halide. However, DhaA suffers from the poor environmental stability, such as sensitivity to high temperature, low pH, hypersaline and organic solvent. In order to improve the environmental stability of DhaA, DhaA was covalently conjugated with inulin, a hydrophilic polysaccharide in the present study. Each DhaA was averagely conjugated with 7∼8 inulin molecules. The conjugated inulin could form a hydration layer around DhaA, which increased the conformational rigidity and decreased the entropy of the enzyme. Conjugation of inulin maintained 75.5 % of the enzymatic activity of DhaA and slightly altered the structure of DhaA. As compared with DhaA, the conjugate (inu-DhaA) showed slightly different kinetic parameters (Km of 2.9 μmol/L and Kcat of 1.0 s−1). Inulin conjugation could delay the structural unfolding and/or slow the protonation process of DhaA under undesirable environment, including the long-term storage, low pH, hypersaline and organic solvent stability. As a result, the environmental stability of DhaA was markedly increased upon conjugation with inulin. Thus, inulin conjugation was an effective approach to enhance the environmental stability of DhaA.

2D Metal-Organic Framework-Based Thin-Film Nanocomposite Membranes for Reverse Osmosis and Organic Solvent Nanofiltration.

Metal-organic frameworks (MOFs) are promising candidates for membrane-based liquid separations due to their intrinsic microporosity, but many are limited by their insufficient stability. In this work, a copper-benzoquinoid (Cu-THQ) MOF was synthesized and demonstrated structural stability in water and organic solvents. After incorporation into the polyamide layer, the hydrophilicity of the membranes was enhanced. The resultant thin-film nanocomposite (TFN) membranes broke the permeability-selectivity tradeoff by showing 242 % increase in water permeance and slightly enhanced salt rejection at MOF loading of 0.0192 mg cm-2 . The underlying mechanism was probed by different chemical and morphological characterizations. The membranes also showed improved tolerance to chlorine oxidation. With their excellent stability, the Cu-THQ MOF-based membranes further demonstrated impressive performance in organic solvent nanofiltration involving dimethylformamide.

Au-Au/IrO2@Cu(PABA) Reactor with Tandem Enzyme-Mimicking Catalytic Activity for Organic Dye Degradation and Antibacterial Application.

Herein, a Au-Au/IrO2 nanocomposite with tandem enzyme-mimicking activity was innovatively synthesized, which can show outstanding glucose oxidase (GOx)-like activity and peroxidase-like activity simultaneously under neutral conditions. Moreover, a Au-Au/IrO2@Cu(PABA) reactor was prepared via encapsulation of the Au-Au/IrO2 nanocomposite in a Cu(PABA) metal organic framework. The reactor not only exhibits excellent organic solvent stability, acid resistance, and reusability but also displays better cascade reaction catalytic efficiency (kcat/Km = 148.86 min-1 mM-1) than the natural free enzyme system (GOx/HRP) (kcat/Km = 98.20 min-1 mM-1) and Au-Au/IrO2 nanocomposite (kcat/Km = 135.24 min-1 mM-1). In addition, it is found that the reactor can catalyze glucose or dissolved oxygen to produce active oxygen species (ROS) including HO, 1O2, and O2-· through its enzyme-mimicking activity. Finally, the novel reactor was successfully used in organic dye degradation and antibacterial application. The results show that it can effectively degrade methyl orange, methylene blue, and rhodamine B, which all can reach a degradation rate of nearly 100% after interacting with Au-Au/IrO2@Cu (PABA) for 3.5 h. Furthermore, the reactor also exhibits excellent antibacterial activity, so as to achieve a complete bactericidal effect to Staphylococcus aureus and Escherichia coli at a concentration of 12.5 μg mL-1.

Whole cell biosynthesis of luteolin glycosides by engineered Corynebacterium glutamicum harboring the amylosucrase gene

The transglycosylation activity of Deinococcus geothermalis amylosucrase (DgAS) expressed in Corynebacterium glutamicum (cDgAS) was optimized for luteolin glycoside synthesis using purified enzymes (PEs), whole cells (WCs) suspended in buffer (WCB) and WCs in ethanol (WCE). Unlike PE, both WCB and WCE had high transglycosylation yields exceeding 95% over a wide temperature range, with cells in ethanol exhibiting the greatest enzymatic activity for up to 48 h due to membrane degradation and the slow release of cDgAS, which led to lysis and death. Meanwhile, in buffer, protection of the cytoplasmic membrane and ideal pH conditions maintained activity for over 200 h. To improve their performance, WCs were immobilized on agarose and the resulting immobilized cells (ICs) had high stability in organic solvents, although WCB possessed greater thermal stability at 50 °C. The reaction parameters for PE, WCE, WCB, and IC transglycosylation were optimized using response surface methodology, and ICs required lower concentrations of substrates while synthesizing higher concentrations of reaction products in addition to producing the novel compound luteolin maltotrioside after several cycles of reuse. This study expanded on the range of possibilities for the industrial application of C. glutamicum in increasing the production and bioavailability of novel and improved products.

A robust cluster-based Eu-MOF as multi-functional fluorescence sensor for detection of antibiotics and pesticides in water

Abstract As a hot issue of global concern, the abuse of organic pollutants, including pesticides and antibiotics poses a great threat to the human health and ecological environment. Effective and accurate detection of these species is of profound significance in many fields. In this work, a novel 3D metal-organic framework (MOF) [Eu2(dtztp)(OH)2(DMF)(H2O)2.5]·2H2O (1) was solvothermally synthesized. 1 is a three-dimensional framework based on tetranuclear [Eu4(μ3-OH)4(μ2-OH2)]8+ clusters, and reveals the great chemical stability and excellent tolerance in water and organic solvents. The MOF also shows strong fluorescence that was undisturbed by the pH in aqueous water (pH = 3–12). Importantly, 1 can quickly detect metronidazole (MDZ) and dimetridazole (DMZ) antibiotics as well as 2,6-dichloro-4-nitroaniline (DCN) pesticide in water with good recyclability and low detection limit. MDZ, DMZ and DCN were also successfully detected in calf serum and lake water, respectively. The mechanism of fluorescence quenching was disclosed through the combination of experiments and density functional theory calculations.

Covalent organic framework membranes with limited channels filling through in-situ grown polyaniline for efficient dye nanofiltration

Due to the high porosity and ordered channels, covalent organic framework (COF) membranes with ultrathin selective layer and high permeance have gained increasing attention in the field of nanofiltration (NF). However, it remains a challenge to fabricate ultrathin and dense COF NF membranes with both high permeance and high rejection. This work presents a facile and efficient method to fabricate COF membrane with limited channel filling through in-situ growth of polyaniline (PANI) layer. Specifically, interfacial polymerized COF-TpPa membrane was fabricated with ~ 1.8 nm pore channel, and then the in-situ grown PANI layer could fill the partial of channels and reduce the effective pore size of COF-TpPa. The obtained PANI-TpPa composite membrane exhibited excellent performance with pure water permeance up to 85.2 L·m−2·h−1·bar−1, congo red rejection above 99.4%, and acid fuchsin rejection above 81.0%. The whole membrane fabrication just cost 3 h and took place at room temperature, which was much more efficient than other membranes with similar performance. Besides, the PANI-TpPa composite membrane showed excellent stability in acidic environment and organic solvent, and maintained great performance in long-term test.

Utilization of polyvinyl butyral-zirconium alkoxide hybrid hollow tube as an enzyme immobilization carrier

We developed a Polyvinyl butyral (PVB)-zirconium alkoxide hybrid hollow tube by air-gap spinning. Enzyme (β-galactosidase and lipase) was physically entrap-immobilized and disseminated throughout the hollow tube architecture. The enzyme immobilized PVB-Zr hybrid tube shown its stability in phosphate buffer solution, electrolyte solution, and other organic solvents. The apparent Michaelis constant Km for immobilized β-galactosidase (IβG) was 0.079 mol/l compared to 0.067 mol/l for free enzyme. The maximum velocity Vmax was 4.9 μmol.min−1, whereas it was 11.5 μmol.min−1 for free enzyme. The preserved activity of IβG was found to be 90%, after ten reaction cycles. Moreover, up to 70% conversion for citronellyl acetate after 50 h. was achieved by immobilized lipase (IL) in hexane solution. The activity of IL was found to be 62% after 8 repeated uses where free enzyme retained 15% activity. Overall, it was considered that the enzyme activity employed both in the interior and the vicinity of the hollow tube surface.

Isolation, characterization and genomic analysis of vB-AhyM-AP1, a lytic bacteriophage infecting Aeromonas hydrophila.

Aeromonas hydrophila is a zoonotic pathogen displaying resistance to multiple antibiotics. Here, we aim to develop a candidate biocontrol agent against A. hydrophila. In this study, we isolated and characterized the phage vB-AhyM-AP1 from sewage. It showed lytic activity against A. hydrophila strains. One-step growth curve revealed that the latent period lasted for 40min. The burst size of one lytic cycle was 1413 PFU per infected cell. Temperature stability studies showed that the phage vB-AhyM-AP1 was active over temperatures ranging from 4 to 45°C for 1h. pH stability studies indicated that the phage remained active within a pH range of 5-10 after 24h of incubation. Stability tests in salt solutions showed that the phage was stable at salinities ranging from 0·1 to 2%. The phage also showed stabilities in organic solvents when incubated for 10min. The Illumina Hiseq sequencing of its genome indicated that the phage vB-AhyM-AP1was a jumbo phage with a genome size of 2, 54490bp and GC content of 40·3%. The phylogenetic analysis of the terminase large subunit and major capsid protein indicated that the phage closely clustered with other Tevenvirinae phages. The genome encoded 455 ORFs and 22 tRNAs. The phage resulted in a reduction of 0·8 log units of viable A. hydrophila cells in biofilms grown on PVC coupons maintained in a low nutrient medium for 10days. The phage showed lytic activity against planktonic and biofilm cells of A. hydrophila. Genome-based prediction showed it to be a strictly lytic phage without any virulence or antibiotic resistance genes indicating safety for environmental and clinical applications. The multidrug-resistant strains of A. hydrophila pose a significant health risk to both cultured fishes and consumers leaving few options for treatment. Phage vB-AhyM-AP1 may be used as a candidate biocontrol agent against A. hydrophila strains.

Trends in lipase engineering for enhanced biocatalysis.

Lipases, also known as triacylglycerol hydrolases (E.C.No. 3.1.1.3), are considered as leading biocatalysts in the lipid modification business. With properties like ease of availability, capability to work in heterogeneous media, stability in organic solvents, property of catalyzing at the lipid-water interface and even in nonaqueous conditions, have made them a versatile choice for applications in the food, flavor, detergent, pharmaceutical, leather, textile, cosmetic, and paper industries [1]. The increasing alertness toward sustainable technologies, lesser waste generation and solvent usage and minimization of energy input has brought light toward the production and usage of recombinant/improved lipases. For example, Novozym 435, a broadly used recombinant lipase isolated from Candida antarctica, dominates the lipase industry and has even created a supplier bias in the market. This shows that there is a desperate need for novel, low-cost lipases with better properties. For this, mining of existing extremophilic genomes seems more rewarding. But considering the diversity of industrial requirements such as types of solvents used or carrier systems employed for enzyme immobilization, tailor-designed enzymes are an unrealized pressing priority. Therefore, protein engineering strategies in collaboration with the discovery of new lipases can serve as a vital tool to obtain tailor-made enzymes with specific characteristics.

Water-Stable Cobalt-Based MOF for Water Oxidation in Neutral Aqueous Solution: A Case of Mimicking the Photosystem II.

Inspired by the highly efficient water oxidation of Mn4CaO5 in natural photosynthesis, development of novel artificial water oxidation catalysts (WOCs) with structure and function mimicked has inspired extensive interests. A novel 3D cobalt-based MOF (GXY-L8-Co) was synthesized for promising artificial water oxidation by employing the Co4O4 quasi-cubane motifs with a similar structure as the Mn4CaO5 as the core. The GXY-L8-Co not only shows good chemical stability in common organic solvents or water for up to 10 days but also exhibits oxygen evolution performance. It has been demonstrated that the uniform distribution of Co4O4 catalytic active sites confined in the MOF framework should be responsible for the good robustness and catalytic performance.

Preparation of MIL-101-NH2 MOF/triazine based covalent organic framework hybrid and its application in acid blue 9 removals

Due to the increasing environmental pollution from the textile industry, synthesizing efficient adsorbents to remove coloring agents from waste streams is of practical interest and importance to chemists and material scientists. Metal-organic framework (MOF) and covalent organic framework (COF) are multidimensional, porous, and crystalline. Owing to their high BET surface area, they are both right choices for dye adsorption. A superior feature of COF materials compared to MOFs is their stability in organic solvents and acidic environments. Herein, considering the importance of the complete removal of acid blue 9 and economic aspects, a new hybrid of aminated chromium-based MOF and triazine-based COF (MIL-101-NH2@COF) was synthesized and used for the removal of the dye from textile wastewater. These materials were characterized by FT-IR spectra, PXRD, elemental analysis, and BET. Since the hybrid adsorbent had a mesoporous structure of a large surface area for nitrogen adsorption, it would be the right candidate for solving the coloring agent pollution problem. Some essential parameters, such as pH, contact time, temperature, and adsorbent dosage, were optimized. The optimum condition was pH = 2, absorbent dosage 0.01 g, contact time 90 min, and temperature 35 °C. The obtained maximum adsorption capacity was 256 mg g−1. The experimental results, in general, agree with those of the Langmuir model and the pseudo-second-order kinetics, suggesting that acid blue 9 was adsorbed to the hybrid adsorbent in monolayers due to its chemical affinity.

A stable terbium(III) metal-organic framework as a dual luminescent sensor for MnO4− ions and nitroaromatic explosives

A new terbium(III) metal-organic framework [Tb2(BTZ)(μ2-H2O)(μ3-OH)2] (ZH-101, H2BTZ ​= ​3.5-bis(4’-carboxy-phenyl)-1,2,4-triazole) was synthesized with BTZ ligands under solvothermal conditions for the luminescent study. It is constructed of [Tb2(μ2-O)(μ3-O)2]n 2D layered structure and is further connected by BTZ ligands with rich triazole-N sites to form a water-stable 3D net framework. ZH-101 displays excellent chemical stability in common organic solvents and water in the wide pH range of 0–11. The luminescence test experiment of ZH-101 in water containing different anions shows selective fluorescence quenching for MnO4− with low detection limit (0.16 ​mM). In addition, ZH-101 also displays excellent luminescence stability in different solvents and can selectively detect nitroaromatic explosives in DMF solutions, especially for 4-nitrophenol with Ksv ​= ​3.38 ​× ​104 ​M-1, and low detection limit of 0.20 ​mM. It still retains original fluorescence intensity and chemical stability after five cycles experiments, exhibiting remarkable long-term cycle and reversibility. Therefore, ZH-101 is a competitive and promising candidate for sensing MnO4− ions and nitroaromatic explosives.

An anionic potassium-organic framework for selective removal of uranyl ions.

Effective and selective removal of radioactive metal ions from aqueous solutions is of great importance due to their harmful effects on humans and other living species. However, it is a big challenge for researchers to develop effective adsorbents with high selectivity and a wide pH application range even if some progress has been achieved. Herein, we report an anionic potassium organic framework (UPC-K1) with protonated dimethylamine (Me2NH2+) residing inside the rhomboid channels. The unique 3D firm structure of UPC-K1 is constructed by the cross-linking of the 2D arrangement using weak K-O bonds (2.9270 Å) and strong hydrogen bonds (1.6498 Å), which endows it with excellent chemical stability in organic solvents, boiling water, and aqueous solution in the pH range 3-10. Based on the cation exchange, depending on pore size selectivity, UPC-K1 shows excellent adsorption performance towards UO22+ in aqueous solutions at 298 K with the following characteristics: (1) effective removal in the pH range 3-10; (2) high selectivity over other metal cations; (3) a high adsorption capacity of 551.4 mg g-1; (4) a rapid adsorption equilibrium within 3 hours under stirring; and (5) effective adsorption at low concentrations, with a residual concentration of 0.69 ppm even at an initial concentration of 10.3 ppm after stirring for 24 hours. These results indicate the great potential of UPC-K1 in the treatment of uranium-containing nuclear wastewater.