Cd-Based Metal-Organic Framework for Selective Turn-On Fluorescent DMSO Residual Sensing.

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a CdII metal-organic framework (MOF) SXU-4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn-on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@SXU-4), in combination with computational results uncover that the enhanced DMSO-MOF conjugation through multiple DMSO-MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.

Functionalized Metal-Organic Frameworks for Hg(II) and Cd(II) Capture: Progresses and Challenges.

Mercury and cadmium are deemed to be the most harmful heavy metal ions for elimination due to their persistent bio-accumulative and bio-expanding toxic effects. Although many technologies have been developed for capturing Hg(II) and Cd(II) ions from aqueous solution, developing efficient and practical capature technology remains a big challenge. Metal-organic frameworks (MOFs) have been considered as the most promising adsorbents for Hg(II) and Cd(II) removal due to their high porosity and easy functionalization, and various of MOF-based adsorbents based on different synthetic strategies have been prepared and studied. In this article, the progresses of MOF-based absorbents for Hg(II) and Cd(II) capture are described according to the synthetic strategies and the types of functional groups, and the comparison and practical analysis of various adsorbents are also presented.

Induction of Chirality in a Metal-Organic Framework Built from Achiral Precursors.

Induction of chirality from an achiral assembly system remains a huge challenge related to the origin of life. Here, induction of chirality in a metal-organic framework (MOF) built from achiral precursors has been realized. Assembling achiral H3 BTB ligands and ZnII /CdII clusters leads to a 2D coordination polymer (FJI-H16), while introduction of achiral pyridine into such assembly system leads to a 3D chiral MOF (FJI-H27 (M) or (P)). The driven force for chiral generation has been proved to be a pyridine participated kinetic-control assembly process, which can be controlled by changing the amount of pyridine and temperature, from no induction to partial induction to complete induction. The chiral generation process has been identified in detail through a pyridine-involved key intermediate (FJI-H28). The targeted modification of pyridine can selectively lead to FJI-H27 (M) or FJI-H27 (P), making the chiral orientation and distribution of bulk FJI-H27 samples can be controlled. Our work not only represents a new chiral induction process that may relate to the chiral origin in nature, but also firstly reveals how achiral external stimuli generate chirality from achiral precursors, and offers a guide for rational preparation of chiral MOFs.

Introduction of Flexibility into a Metal-Organic Framework to Promote Hg(II) Capture through Adaptive Deformation.

The development of a practical Hg(II) adsorbent is highly important for both environmental protection and public health. Herein, an adaptive metal-organic framework (MOF; FJI-H30) has been prepared from a highly flexible ligand [tris(pyridin-4-ylmethyl)amine] and Co(SCN)2 with cheap Hg(II) adsorption sites (SCN- groups) that not only has excellent chemical stability but also can capture Hg(II) from aqueous solution with high adsorption capacity (705 mg g-1). Moreover, it also has good anti-interference ability and can be used repeatedly and large-scale prepared. Further researches demonstrate that the relatively high Hg(II) adsorption capacity originates from the adsorbed Hg(II)-induced deformation of FJI-H30, and such an adaptive deformation will reduce the potential repulsive forces between the adsorbed Hg(II) ions, enabling almost all Hg(II) absorption sites to adsorb Hg(II) ions. Finally, how to induce the deformation of FJI-H30 by adsorbed Hg(II) also has been studied in detail. Our work not only provides a practical Hg(II) adsorbent for wastewater treatment but also offers a novel strategy for the design of novel MOFs for efficient heavy-metal-ion removal.

Acid-Base-Resistant Metal-Organic Framework for Size-Selective Carbon Dioxide Capture.

The development of practical porous materials for the selective capture of CO2 from flue gas and crude biogas is highly critical for both environment protection and energy safety. Here, a novel metal-organic framework (FJI-H29) has been prepared, which not only has excellent acid-base resistance but also possesses polar micropores (3.4-4.3 Å) that can match CO2 molecules well. FJI-H29 can selectively capture CO2 from N2 and CH4 with excellent separation efficiency and suitable adsorption enthalpy under ambient conditions. Breakthrough experiments further confirm its practicability for both CO2/N2 and CO2/CH4 separation. All of these confirm FJI-H29 is a practical CO2 adsorbent. Modeling calculations reveal that the confinement effect of micropores and the polar environment synergistically promotes the selective adsorption of CO2, which will provide a potential strategy for the synthesis of a practical metal-organic framework for CO2 capture.

Electric-Field Assisted In†Situ Hydrolysis of Bulk Metal-Organic Frameworks (MOFs) into Ultrathin Metal Oxyhydroxide Nanosheets for Efficient Oxygen Evolution.

Facile preparation of low-cost electrocatalysts for efficient oxygen evolution reaction (OER) remains a big challenge. Herein, a novel strategy for ultrafast (20 s) transformation of bulk metal-organic frameworks (MOFs) into ultrathin metal oxyhydroxide nanosheets for efficient OER has been developed. For two isomeric MOFs (FJI-H25Fe and FJI-H25FeCo), only the metastable FJI-H25FeCo bulk can immediately transform into FeCo-oxyhydroxides nanosheets through electric-field assisted hydrolysis. The potential evolution process from MOF bulk to FeCo-oxyhydroxides nanosheets has been investigated in detail. The as-made nanosheets exhibit excellent OER performances, showing an extremely low overpotential of 231 mV at the current density of 10 mA cm-2 , a relatively small Tafel slope of 42 mV dec-1 , and long-term durability of at least 30 h. This work not only provides a novel strategy for facile preparation of low-cost and efficient OER electrocatalysts, but also represents a new way for preparation of metal oxyhydroxides nanosheets with good crystallinity and morphology, and a fresh method for mild synthesis of nanosized derivatives from MOF materials.

Metal-Organic Framework Supported on Processable Polymer Matrix by In Situ Copolymerization for Enhanced Iron(III) Detection.

Metal-organic frameworks (MOFs) represent a promising class of porous materials. However, MOFs show poor processability that impedes their full potential in applications. This work develops a composite strategy to skillfully load MOFs on a polymer plate to afford processability for these powder materials. A predesigned mesoporous MOF with active -NH2 groups around the pore walls was prepared and its copolymerization with the -NCO groups of macromonomers (polyurethane acrylate) could be facilely induced by an initiator under mild conditions. Notably, the target MOF-polymer composite is transparent, elastic, and shows enhanced Fe3+ detection compared with that of the individual MOF functional component. This result can be ascribed to the synergistic effect of the composite with newly formed chemical bonds between the MOF particle and polymer matrix.

Quest for the Ncb-type Metal-Organic Framework Platform: A Bifunctional Ligand Approach Meets Net Topology Needs.

A custom-designed bifunctional ligand was used to connect an in situ formed Co3(OH) cluster affording a porous metal-organic framework, which represents the first case of ncb-type networks constructed from a single kind of ditopic ligand. Noticeably, the activated MOF shows high volumetric C2H2 uptake and excellent adsorption selectivity for C2H2/CO2 separation at room temperature with a low sorption heat.

Microporous Cobalt(II)-Organic Framework with Open O-Donor Sites for Effective C2H2 Storage and C2H2/CO2 Separation at Room Temperature.

The self-assembly of a bifunctional organic ligand with a formate-bridged rod-shaped secondary building unit leads to a new microporous metal-organic framework (MOF). This MOF shows a moderately high C2H2 storage capacity (145 cm3/g) and an excellent adsorption selectivity for C2H2/CO2 (11) at room temperature. Furthermore, its discriminatory sorption behavior toward C2H2 and CO2 was probed by computational analysis in detail.

Charge Control in Two Isostructural Anionic/Cationic CoII Coordination Frameworks for Enhanced Acetylene Capture.

Two isostructural CoII -based metal-organic frameworks (MOFs) with the opposite framework charges have been constructed, which can be simply controlled by changing the tetrazolyl or triazolyl terminal in two bifunctional ligands. Notably, the cationic MOF 2 can adsorb much more C2 H2 than the anionic MOF 1 with an increase of 88 % for C2 H2 uptake at 298 K in spite of more active nitrogen sites in 1. Theoretical calculations indicate that both nitrate and triazolyl play vital roles in C2 H2 binding and the C2 H2 adsorption isotherm confirms that the enhanced C2 H2 uptake for 2 (225 and 163 cm3 g-1 at 273 and 298 K) is exceptionally high for MOF materials without open metal sites or uncoordinated polar atom groups on the frameworks.

Ligand Symmetry Modulation for Designing Mixed-Ligand Metal-Organic Frameworks: Gas Sorption and Luminescence Sensing Properties.

Herein, we report the synthesis of a new mixed-linker Zn(II)-based metal-organic framework (MOF), {[Zn2(atz)2(bpydb)](DMA)8}n (1) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4'-(4,4'-bipyridine-2,6-diyl) dibenzoic acid, DMA = N,N-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N2 uptake: 617 cm(3)/g; BET surface area: 2393 m(2)/g) with 1D helical channels. The adsorption properties of desolved 1 were investigated by H2, C2H2, CO2, and CH4 sorption experiments, which showed that 1 exhibited high uptake capacity for H2 at 77 K and C2H2 around room temperature. More importantly, the high C2H2 uptake capacity but low binding energy makes this MOF a promising candidate for effective C2H2 capture from C2H2/CO2 and C2H2/CH4 mixed gases with low regenerative energy cost. In addition, 1 shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and p-xylene (PX).

Ligand Symmetry Modulation for Designing a Mesoporous Metal-Organic Framework: Dual Reactivity to Transition and Lanthanide Metals for Enhanced Functionalization.

A promising alternative strategy for designing mesoporous metal-organic frameworks (MOFs) has been proposed, by modifying the symmetry rather than expanding the length of organic linkers. By means of this approach, a unique MOF material based on the target [Zn8(ad)4] (ad = adeninate) clusters and C3-symmetric organic linkers can be obtained, with trigonal microporous (ca., 0.8 nm) and hexagonal mesoporous (ca., 3.0 nm) 1D channels. Moreover, the resulting 446-MOF shows distinct reactivity to transition and lanthanide metal ions. Significantly, the transmetalation of Co(II) or Ni(II) on the Zn(II) centers in 446-MOF can enhance the sorption capacities of CO2 and CH4 (16-21%), whereas the impregnation of Eu(III) and Tb(III) in the channels of 446-MOF will result in adjustable light-emitting behaviors.

Vitrification-enabled enhancement of proton conductivity in hydrogen-bonded organic frameworks.

Hydrogen-bonded organic frameworks (HOFs) are versatile materials with potential applications in proton conduction. Traditional approaches involve incorporating humidity control to address grain boundary challenges for proton conduction. This study finds vitrification as an alternative strategy to eliminate grain boundary effect in HOFs by rapidly melt quenching the kinetically stable HOF-SXU-8 to glassy state HOF-g. Notably, a remarkable enhancement in proton conductivity without humidity was achieved after vitrification, from 1.31 × 10-7 S cm-1 to 5.62× 10-2 S cm-1 at 100 °C. Long term stability test showed negligible performance degradation, and even at 30 °C, the proton conductivity remained at high level of 1.2 × 10-2 S cm-1. Molecule dynamics (MD) simulations and X-ray total scattering experiments reveal the HOF-g system is consisted of three kinds of clusters, i.e., 1,5-Naphthalenedisulfonic acid (1,5-NSA) anion clusters, N,N-dimethylformamide (DMF) molecule clusters, and H+-H2O clusters. In which, the H+ plays an important role to bridge these clusters and the high conductivity is mainly related to the H+ on H3O+. These findings provide valuable insights for optimizing HOFs, enabling efficient proton conduction, and advancing energy conversion and storage devices.

Plasma-Assisted Defect Engineering on p-n Heterojunction for High-Efficiency Electrochemical Ammonia Synthesis.

A defect-rich 2D p-n heterojunction, Cox Ni3- x (HITP)2 /BNSs-P (HITP: 2,3,6,7,10,11-hexaiminotriphenylene), is constructed using a semiconductive metal-organic framework (MOF) and boron nanosheets (BNSs) by in situ solution plasma modification. The heterojunction is an effective catalyst for the electrocatalytic nitrogen reduction reaction (eNRR) under ambient conditions. Interface engineering and plasma-assisted defects on the p-n Cox Ni3-x (HITP)2 /BNSs-P heterojunction led to the formation of both Co-N3 and B…O dual-active sites. As a result, Cox Ni3-x (HITP)2 /BNSs-P has a high NH3 yield of 128.26 ± 2.27 µg h-1 mgcat. -1 and a Faradaic efficiency of 52.92 ± 1.83% in 0.1 m HCl solution. The catalytic mechanism for the eNRR is also studied by in situ FTIR spectra and DFT calculations. A Cox Ni3- x (HITP)2 /BNSs-P-based Zn-N2 battery achieved an unprecedented power output with a peak power density of 5.40 mW cm-2 and an energy density of 240 mA h gzn -1 in 0.1 m HCl. This study establishes an efficient strategy for the rational design, using defect and interfacial engineering, of advanced eNRR catalysts for ammonia synthesis under ambient conditions.

Novel aptasensing strategy for efficiently quantitative analyzing Staphylococcus aureus based on defective copper-based metal-organic framework.

We have proposed a novel electrochemical aptasensing strategy for efficiently detecting staphylococcus aureus (S. aureus) based on copper-based metal-organic framework encapsulated with plenty of Cu2O nanocrystals (represented by ML-Cu2O@Cu-MOF) synthesized using the mixed ligands of diphenylethyne-3,3',5,5'-tetracarboxylic acid, 1,3,5-benzenetricarboxylic acid, and terephthalic acid. The ML-Cu2O@Cu-MOF nanospheres comprised multiple Cu valence states (Cu0/Cu+/Cu2+) and Cu2O nanocrystals, possessed defect-rich crystal structure, high anchoring ability toward aptamer and boosted electrical conductivity. The gained ML-Cu2O@Cu-MOF-based biosensor exhibited lower limit of detection toward S. aureus, as low as 2.0 and 1.6 CFU mL-1 within the S. aureus concentration from 10 to 1 × 108 CFU mL-1 obtained by electrochemical impedance spectroscopy and differential pulse voltammetry techniques, respectively. Additionally, the developed aptasensor also demonstrated high superior stability, excellent reproducibility, acceptable regeneration ability, and wide practicality. The present work can give rise to an alternative aptasensing strategy for analyzing foodborne bacteria or other food containments and ensuring food safety assessment.

Effects of Qigong, Tai Chi, acupuncture, and Tuina on cancer-related fatigue for breast cancer patients: A protocol of systematic review and meta-analysis.

BACKGROUNDS: Cancer-related fatigue (CRF) is one of the most common and disabling outcomes in patients with breast cancer (BC). Traditional Chinese medicine (TCM) nonpharmacological interventions are becoming increasingly popular for cancer treatment and rehabilitation interventions. However, their efficacy and safety remain unclear and there is no systematic review or meta-analysis focusing fully on this issue. We aim to evaluate the effects of representative TCM nonpharmacological interventions, including Qigong, Tai Chi, acupuncture, and Tuina, on CRF in BC patients. METHODS: Published randomized controlled trials (RCTs) that assessed the efficacy of these interventions on CRF for BC patients will be included. We will search from the following electronic databases: PubMed, Cochrane Library, EMBASE, MEDLINE, Web of Science, Scopus, PsycINFO, PSYINDEX, CINAHL, China National Knowledge Infrastructure (CNKI), WanFang Database, and Chinese Biomedical Literature Database (CBM). The primary outcomes are the improvement of CRF, which will be evaluated by the Piper Fatigue Scale (PFS), the Functional Assessment of Cancer Therapy (FACT)-Fatigue Scale, Schwartz Cancer Fatigue Scale (SCFS), the Multidimensional Fatigue Inventory (MFI). The secondary outcomes are quality of life and safety. The meta-analysis will be performed using RevMan ver 5.3(Cochrane) statistical software. RESULTS: We will provide more practical results investigating the efficacy of Qigong, Tai Chi, acupuncture, Tuina for BC patients with CRF from several respects including the improvement of fatigue, quality of life, and safety. CONCLUSIONS: This review will generate more stronger evidence in BC patients for TCM nonpharmacological interventions, including Qigong, Tai Chi, acupuncture, Tuina, in the treatment of CRF and help to inform clinicians and policymakers. ETHICS DISSEMINATION: Ethical approval is not necessary because all of the study base in our review will be based on published research. We will submit our results to a peer-reviewed journal. STUDY REGISTRATION NUMBER: The study is priorly registered through International Platform of Registered Systematic Review and Meta-analysis Protocol on October 2, 2020 (INPLASY 2020100003).

Metal-organic tube or layered assembly: reversible sheet-to-tube transformation and adaptive recognition.

Rational preparation of an adaptive cavity-like enzyme is a great challenge for chemists. Herein, a new self-assembly strategy for the rational preparation of metal-organic tubes with nano-channels has been developed; both 1D metal-organic tube and corresponding 2D layered assemblies can be selectively synthesized driven by different templates; reversible sheet-to-tube transformation can be realized and the key intermediate has been identified. Furthermore, the newly formed nano-channel displays excellent polarity-selectivity for encapsulation of guest molecules, and can be further expanded or contracted through guest-driven adaptive deformation; even induced by very similar guest molecules, the adaptive deformations can also be obviously distinguished. Finally, the key chemicals benzene/hexane with a similar size can also be effectively separated by such nano-channels in the liquid phase. Our work not only provides a new synthetic strategy for the rational synthesis of metal-organic tubes with a reversible sheet-to-tube transformation character, but also gives a potential method for the construction of adaptive host-like enzymes and an in-depth understanding of the nature of adaptive host and guest molecules.

Rhodium(III)-Catalyzed Cascade [5 + 1] Annulation/5-exo-Cyclization Initiated by C-H Activation: 1,6-Diynes as One-Carbon Reaction Partners.

The catalytic [5 + 1] annulation/5-exo-cyclization reaction of amidines with diynes is reported herein. This protocol provides highly atom-economical access to fabricate two nitrogen-containing heterocycles in one step with high efficiency and selectivity. Significantly, this reaction represents the first example of using diyne as a one-carbon reaction partner in C-H functionalization. Kinetic isotope effects suggested that the catalytic cycle of this reaction is initiated by the cleavage of the ortho C-H bond in the N-phenyl ring of amidines, which is likely involved in the rate-limiting step. Calculations based on density functional theory (DFT) indicated that C-H activation and the formation of Rh(V) species via 5-exo-cyclization could be vital processes for this cascade transformation.

Co/Fe-bimetallic organic framework-derived carbon-incorporated cobalt-ferric mixed metal phosphide as a highly efficient photocatalyst under visible light.

A new bimetallic Co/Fe-MOF was synthesized and phosphatized to produce a visible-light-active Co/Fe binary metal phosphide embedded in a mesoporous carbon matrix (denoted by CoP/Fe2P@mC). The results of X-ray diffraction and photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy reveal the formation of CoP and Fe2P nanoparticles together with the Co and Fe metallic state. Combining the high electron-hole separation rate of Fe2P@mC, fast electron transfer of CoP@mC, and the strong adsorption of mesoporous carbon, the as-prepared CoP/Fe2P@mC catalyst exhibits substantially enhanced photocatalytic activity toward rhodamine B (RhB) degradation under visible light irradiation. Visible light harvesting efficiency is enhanced by the suitable bandgap structure of the CoP/Fe2P@mC photocatalyst. Moreover, the possible photocatalytic mechanism of CoP/Fe2P@mC toward RhB degradation was proposed on the basis of radical trapping and electron spin resonance results. This finding illustrates a potential utilization of bimetallic MOF-derived metal phosphide as a photocatalyst to remove dye pollutants in the environment.

Tracking the Superefficient Anion Exchange of a Dynamic Porous Material Constructed by Ag(I) Nitrate and Tripyridyltriazole via Multistep Single-Crystal to Single-Crystal Transformations.

To avoid the instability and inefficiency for anion-exchange resins and layered double-hydroxides materials, we present herein a flexible coordination network [Ag(L243)](NO3)(H2O)(CH3CN) (L243 = 3-(2-pyridyl)-4-(4-pyridyl)-5-(3-pyridyl)-1,2,4-triazole) with superefficient trapping capacity for permanganate, as a group-7 oxoanion model for radiotoxic pertechnetate pollutant. Furthermore, a high-throughput screening strategy has been developed based on concentration-gradient design principle to ascertain the process and mechanism for anion exchange. Significantly, a series of intermediates can be successfully isolated as the qualified crystals for single-crystal X-ray diffraction. The result evidently indicates that such a dynamic material will show remarkable breathing effect of the three-dimensional host framework upon anion exchange, which mostly facilitates the anion trapping process. This established methodology will provide a general strategy to discover the internal secrets of complicated solid-state reactions in crystals at the molecular level.