The low structural stability of hydrogen‐bonded organic frameworks (HOFs) is a thorny issue retarding the development of HOFs. A rational design approach is now proposed for construction of a stable ...HOF. The resultant HOF (PFC‐1) exhibits high surface area of 2122 m2 g−1 and excellent chemical stability (intact in concentrated HCl for at least 117 days). A new method of acid‐assisted crystalline redemption is used to readily cure the thermal damage to PFC‐1. With periodic integration of photoactive pyrene in the robust framework, PFC‐1 can efficiently encapsulate Doxorubicin (Doxo) for synergistic chemo‐photodynamic therapy, showing comparable therapeutic efficacy with the commercial Doxo yet considerably lower cytotoxicity. This work demonstrates the notorious stability issue of HOFs can be properly addressed through rational design, paving a way to develop robust HOFs and offering promising application perspectives.
An ultra‐robust hydrogen‐bonded organic framework with high BET surface area and acid‐assisted crystalline recovery was developed through several rational design strategies. With periodic integration of photoactive pyrene in the framework, this material can efficiently encapsulate the drug doxorubicin for synergistic chemo‐photodynamic therapy, showing low cytotoxicity and prominent therapeutic efficacy.
Motivated by the LHCb's new observation of structures in the J/ψ-pair invariant mass spectrum, which could be classified as possible cccc tetraquark candidates, we systematically study 0+ ...fully-charmed tetraquark states through QCD sum rules. Developing the calculation techniques to fourfold heavy hadronic systems, four different configuration currents with 0+ are considered, and vacuum condensates up to dimension six are included in the operator product expansion. Finally, the mass values acquired for 0+ cccc tetraquark states agree well with the experimental data of the broad structure, which support that it could be a 0+ fully-charmed tetraquark state.
Motivated by the LHCb's very recent observation of exotic X0(2900) in the B+ → D+D−K+ process, for which could be a good open-charm ud¯c¯s tetraquark candidate, we endeavor to investigate its ...possibility by means of QCD sum rules. In technique, four configurations of interpolating currents with JP = 0+ are studied for the ud¯c¯s tetraquark state. In the end, mass values are calculated to be ... GeV for the axial vector diquark-axial vector antidiquark configuration and ... GeV for the scalar diquark-scalar antidiquark configuration, both of which are consistent with the experimental data 2.866 ± 0.007 ± 0.002 GeV of X0(2900) in view of the uncertainty. These results support that X0(2900) could be a 0+ tetraquark state with open-charm flavor.
The ever‐increasing demand for clean and renewable power sources has sparked intensive research on water splitting to produce hydrogen, in which the exploration of electrocatalysts is the central ...issue. Herein, a new strategy, metal–organic framework template‐directed fabrication of hierarchically structured Co3O4@X (X = Co3O4, CoS, C, and CoP) electrocatalysts for efficient oxygen evolution reaction (OER) is developed, where Co3O4@X are derived from cobalt carbonatehydroxide@zeolitic‐imidazolate‐framework‐67 (CCH@ZIF‐67). Unique hierarchical structure and synergistic effect of resulting catalysts endow abundant exposed active sites, facile ion diffusion path, and improved conductivity, being favorable for improving catalytic activity of them. Consequently, these derivatives Co3O4@X reveal highly efficient electrocatalytic performance with long‐term durability for the OER, much superior to previously reported cobalt‐based catalysts as well as the Ir/C catalyst. Particularly, Co3O4@CoP exhibits the highest electrocatalytic capability with the lower overpotential of 238 mV at the current density of 10 mA cm−2. Furthermore, Co3O4@X can also efficiently catalyze other small molecules through electro‐oxidation reaction (e.g., glycerol, methanol, or ethanol). It is expected that the strategy presented here can be extended to the fabrication of other composite electrode materials with hierarchical structures for more efficient water splitting.
A new strategy for the fabrication of hierarchically structured composites as highly effective and stable electrocatalysts is proposed. The oxidation, sulfurization, carbonization, and phosphorization of premade cobalt carbonate hydroxide@zeolitic‐imidazolate‐framework‐67 (CCH@ZIF‐67) produced Co3O4@X (X = Co3O4, CoS, C, and CoP) derivatives, respectively, which as electrocatalysts exhibit excellent performance in the oxygen evolution reaction with low overpotential and high stability.
Metal–organic frameworks (MOFs) have emerged as porous solids of a superior type for the fabrication of membranes. However, it is still challenging to prepare a uniformly dispersed robust MOF hybrid ...membrane. Herein, we propose a simple and powerful strategy, namely, coordination‐driven in situ self‐assembly, for the fabrication of MOF hybrid membranes. On the basis of the coordination interactions between metal ions and ligands and/or the functional groups of the organic polymer, this method was confirmed to be feasible for the production of a stable membrane with greatly improved MOF‐particle dispersion in and compatibility with the polymer, thus providing outstanding separation ability. As an experimental proof of concept, a high‐quality ZIF‐8/PSS membrane was fabricated that showed excellent performance in the nanofiltration and separation of dyes from water.
Mopping up the mess: A hybrid membrane composed of the metal–organic framework (MOF) ZIF‐8 and poly(sodium 4‐styrenesulfonate) was prepared by a coordination‐driven in situ self‐assembly method. The MOF particles were well‐dispersed in the polymer in the resulting stable membrane (see picture), which showed excellent performance in the nanofiltration and separation of dyes from water.
Electrocatalytic CO2 reduction (ECR) is a promising technology to simultaneously alleviate CO2‐caused climate hazards and ever‐increasing energy demands, as it can utilize CO2 in the atmosphere to ...provide the required feedstocks for industrial production and daily life. In recent years, substantial progress in ECR systems has been achieved by the exploitation of various novel electrode materials. The anodic materials and cathodic catalysts that have, respectively, led to high‐efficiency energy input and effective heterogenous catalytic conversion in ECR systems are comprehensively reviewed. Based on the differences in the nature of energy sources and the role of materials used at the anode, the fundamentals of ECR systems, including photo‐anode‐assisted ECR systems and bio‐anode‐assisted ECR systems, are explained in detail. Additionally, the cathodic reaction mechanisms and pathways of ECR are described along with a discussion of different design strategies for cathode catalysts to enhance conversion efficiency and selectivity. The emerging challenges and some perspective on both anode materials and cathodic catalysts are also outlined for better development of ECR systems.
Electrode materials are considered to be important components for electrocatalytic CO2 reduction systems, as they affect the energy input method and CO2 conversion efficiencies. Various photo‐anode and bio‐anode materials for lowering external bias and progress on cathode catalysts for improving CO2 conversion efficiencies are comprehensively reviewed. Moreover, enhancement strategies in the design of these electrode materials are highlighted.
Computational methodologies for metal--organic frameworks and their application in gas separations were investigated. Topics related to molecular modeling are also addressed.
The rate and mechanism of protein sequence evolution have been central questions in evolutionary biology since the 1960s. Although the rate of protein sequence evolution depends primarily on the ...level of functional constraint, exactly what determines functional constraint has remained unclear. The increasing availability of genomic data has enabled much needed empirical examinations on the nature of functional constraint. These studies found that the evolutionary rate of a protein is predominantly influenced by its expression level rather than functional importance. A combination of theoretical and empirical analyses has identified multiple mechanisms behind these observations and demonstrated a prominent role in protein evolution of selection against errors in molecular and cellular processes.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SBMB, UILJ, UKNU, UL, UM, UPUK
Metal-organic frameworks (MOFs) are a new class of porous crystalline materials constructed from organic ligands and metal ions/clusters. Owing to their unique advantages, they have attracted more ...and more attention in recent years and numerous studies have revealed their great potential in various applications. Many important applications of MOFs inevitably involve harsh alkaline operational environments. To achieve high performance and long cycling life in these applications, high stability of MOFs against bases is necessary. Therefore, the construction of base-stable MOFs has become a critical research direction in the MOF field. This review gives a historic summary of the development of base-stable MOFs in the last few years. The key factors that can determine the robustness of MOFs under basic conditions are analyzed. We also demonstrate the exciting achievements that have been made by utilizing base-stable MOFs in different applications. In the end, we discuss major challenges for the further development of base-stable MOFs. Some possible methods to address these problems are presented.
This review focuses on the construction and the application of base-stable MOFs.
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