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•Comperhensive review which covers the application and synthesis of MOF composites as green and sustanable catalyst.•The highlight of the synergistic effects between additive ...components and MOFs.•Presentation of two comprehensive tables about the types of used green MOF composites in organic reactions.•The explanation of the modification progress towards sustainable strategy.
Porous metal–organic frameworks (MOFs) have always been of interest to scientists in all fields of chemistry since their introduction. Due to their brilliant characteristic features, MOFs have been employed in various applications, especially as heterogeneous catalysts. The composite method is among the most important and practical approaches to optimize the performance of MOFs as a catalyst. Combination of MOFs with selected materials provides many benefits for the newly formed compounds (MOF composites) including the synergistic effect that has a vital role in catalysis applications, and elimination of the obstacles associated with the use of bare MOFs. However, environmental hazards should be considered during the synthesis and processing of MOF composites. This study reviews the recent developments in various classes of green MOF composites, their preparations, and use of MOF composites as a green and sustainable catalyst. The use of MOF composites as catalysts in several typical reactions including cycloadditions, CO2 insertions, cyanosilylations, and condensations are also investigated. Indeed, we try to illustrate that not only green reactants, including metal nodes, linkers, solvents, and guests, can impact reducing chemical pollution, but also catalysis reactions in mild or solvent-free conditions can promote their widely safe applicability at both scientific and industrial levels.
Ferrocene and its derivatives, especially ferrocene‐based coordination polymers (Fc‐CPs), offer the benefits of high thermal stability, two stable redox states, fast electron transfer, and excellent ...charge/discharge efficiency, thus holding great promise for electrochemical applications. Herein, we describe the synthesis and electrochemical applications of Fc‐CPs and reveal how the incorporation of ferrocene units into coordination polymers containing other metals results in unprecedented properties. Moreover, we discuss the usage of Fc‐CPs in supercapacitors, batteries, and sensors as well as further applications of these polymers, for example in electrocatalysts, water purification systems, adsorption/storage systems.
Iron strength: The incorporation of ferrocene as an organometallic building block into coordination polymers containing other metals to impart certain properties can afford attractive structures denoted as ferrocene‐based coordination polymers. This Review focuses on the synthesis and electrochemical applications (e. g., supercapacitors, batteries, electrosensors, and electrocatalysts) of these coordination polymers.
A no-reference (NR) learning-based approach to assess image quality is presented in this paper. The devised features are extracted from wide perceptual domains, including brightness, contrast, color, ...distortion, and texture. These features are used to train a model (scorer) which can predict scores. The scorer selection algorithms are utilized to help simplify the proposed system. In the final stage, the ensemble method is used to combine the prediction results from selected scorers. Two multiple-scale versions of the proposed approach are also presented along with the single-scale one. They turn out to have better performances than the original single-scale method. Because of having features from five different domains at multiple image scales and using the outputs (scores) from selected score prediction models as features for multi-scale or cross-scale fusion (i.e., ensemble), the proposed NR image quality assessment models are robust with respect to more than 24 image distortion types. They also can be used on the evaluation of images with authentic distortions. The extensive experiments on three well-known and representative databases confirm the performance robustness of our proposed model.
We introduce an implementation of the truncated many-body expansion, MBE(n), in which the n-body corrections are screened using the effective fragment potential force field, and only those that ...exceed a specified energy threshold are computed at a quantum-mechanical level of theory. This energy-screened MBE(n) approach is tested at the n = 3 level for a sequence of water clusters, (H2O) N=6–34. A threshold of 0.25 kJ/mol eliminates more than 80% of the subsystem electronic structure calculations and is even more efficacious in that respect than is distance-based screening. Even so, the energy-screened MBE(3) method is faithful to a full-system quantum chemistry calculation to within 1–2 kJ/mol/monomer, even in good quality basis sets such as aug-cc-pVTZ. These errors can be reduced by means of a two-layer approach that involves a Hartree–Fock calculation for the entire cluster. Such a correction proves to be necessary in order to obtain accurate relative energies for conformational isomers of (H2O)20, but the cost of a full-system Hartree–Fock calculation remains smaller than the cost of three-body subsystem calculations at correlated levels of theory. At the level of second-order Møller–Plesset perturbation theory (MP2), a screened MBE(3) calculation plus a full-system Hartree–Fock calculation is less expensive than a full-system MP2 calculation starting at N = 12 water molecules. This is true even if all MBE(3) subsystem calculations are performed on a single 40-core compute node, i.e., without significant parallelization. Energy-screened MBE(n) thus provides a fragment-based method that is accurate, stable in large basis sets, and low in cost, even when the latter is measured in aggregate computer time.
Scheme 1. Novozym 435 catalyzed transesterification of arbutin with palmitic acid ethyl ester in SC−CO2.
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•This is the first report of enzymatic synthesis of arbutin palmitate in ...SC−CO2.•Enzymatic transesterification is less energy-intensive and more robust.•Various reaction parameters were studied and optimised to get maximum yield.•The strategy overcomes difficult transesterification of polar arbutin in SC−CO2.•Stability and activity of enzymes depend on the SC−CO2 operational conditions.
In this study, a novel one-step enzymatic acylation was developed for the synthesis of hydrophobic arbutin ester, by using supercritical carbon dioxide (SC−CO2) as the reaction solvent. Immobilized Novozym 435 from Candida antarctica was identified as the best biocatalyst for producing arbutin palmitate through transesterification between arbutin and palmitic acid ethyl ester in SC−CO2. A transesterification yield of 85.21 % was obtained in batch operation using palmitic acid ethyl ester as the acyl donor, hexane/propylene glycol as the co-solvent and Novozym 435 as the enzyme at 10 MPa and 60 °C for 20 h in SC−CO2. The yield of arbutin palmitate increased with increasing temperature over the range of 40–60 °C in the current study. Operating at an arbutin/palmitic acid ethyl ester molar ratio of 5.0, the conversion of arbutin decreased, probably due to an inhibitory effect of the high concentration of palmitic acid ethyl ester on the enzyme. The 38 % original enzyme activity of Novozym 435 was maintained after being used for 3 cycles (60 h) under optimized conditions.
Metal clusters have been very attractive due to their aesthetic structures and fascinating properties. Different from nanoparticles, each cluster of a macroscopic sample has a well-defined structure ...with identical composition, size, and shape. As the disadvantages of polydispersity are ruled out, informative structure–property relationships of metal clusters can be established. The formation of a high-nuclearity metal cluster involves the organization of metal ions into a complex entity in an ordered way. To achieve controllable preparation of metal clusters, it is helpful to introduce a directing agent in the formation process of a cluster. To this end, anion templates have been used to direct the formation of high nuclearity clusters. In this Account, the role of anions played in the formation of a variety of silver clusters has been reviewed. Silver ions are positively charged, so anionic species could be utilized to control the formation of silver clusters on the basis of electrostatic interactions, and the size and shape of the resulted clusters can be dictated by the templating anions. In addition, since the anion is an integral component in the silver clusters described, the physical properties of the clusters can be modulated by functional anions. The templating effects of simple inorganic anions and polyoxometales are shown in silver alkynyl clusters and silver thiolate clusters. Intercluster compounds are also described regarding the importance of anions in determining the packing of the ion pairs and making contribution to electron communications between the positive and negative counterparts. The role of the anions is threefold: (a) an anion is advantageous in stabilizing a cluster via balancing local positive charges of the metal cations; (b) an anion template could help control the size and shape of a cluster product; (c) an anion can be a key factor in influencing the function of a cluster through bringing in its intrinsic properties. Properties including electron communication, luminescent thermochromism, single-molecule magnet, and intercluster charge transfer associated with anion-directed silver clusters have been discussed. We intend to attract chemists’ attention to the role that anions could play in determining the structures and properties of metal complexes, especially clusters. We hope that this Account will stimulate more efforts in exploiting new role of anions in various metal cluster systems. Anions can do much more than counterions for charge balance, and they should be considered in the design and synthesis of cluster-based functional materials.
Optically active spirocyclic compounds play an important role in drug discovery, and new synthetic strategies for the efficient generation of spiro stereocenters are in much demand. Here we report a ...catalytic enantioselective cycloaddition using spirocyclic donor-acceptor cyclopropanes as a promising approach for the generation of spiro stereocenters. A diastereo- and enantioselective 3 + 3 cycloaddition of spirocyclopropyl oxindoles with both aldonitrones and ketonitrones is developed. The key to reaction development is the activation of spirocyclopropyl oxindoles by a suitable electron-withdrawing N-protecting group. This activation approach offers the promise of a general solution to enable spirocyclopropyl oxindoles as synthons for catalytic enantioselective synthesis of spirocyclic oxindoles featuring a C3 spiro stereocenter, a prominent structural motif in drugs and pharmaceutically active compounds. This protocol also constitutes the catalytic enantioselective reaction using unactivated achiral ketonitrones to construct tetrasubstituted carbon stereocenters.
•The catalytic activity of metal-organic frameworks (MOFs) can be boosted by other components.•MOF composites are among the most efficient catalysts to promote CO2 reduction.•The review covers MOF ...composites with conductive, semiconducting or porous materials and encapsulated guests.•The review covers electro-, photo-, photoelectron- and thermal catalysis for CO2 reduction.•Bottlenecks to further boost the activity of MOF composites are commented.
Global warming due to greenhouse gases is a major current environmental threat. In today’s world those applicable technologies which convert CO2 into valuable and environmentally friendly fuels and chemicals are of great importance. Thanks to functional sites or guests embedded in the structure, metal organic frameworks (MOFs) show a superb potential for such a conversion that is even further enhanced in MOF composites. The present review discusses the use of MOF composites, with an emphasis on their constituent components, as catalysts for CO2 reduction, converting it into various value-added and environmentally friendly chemicals such as saturated and unsaturated hydrocarbons, carboxylic acids and carboxylates, and carbon monoxide. The present review covers four major approaches for CO2 reduction, including electroreduction, photoreduction, photoelectroreduction, and hydrogenation. All reports on the design and development of appropriate MOF composites to be used in the above-mentioned CO2 reductions have been considered. Finally, the future outlook on the use of MOF composites in CO2 reduction is provided, giving some ideas for further design highly efficient MOF composites capable of converting CO2 to value-added products.
Remote sensing (RS) techniques are essential for studying hazardous landslide events because they capture information and monitor sites at scale. They enable analyzing causes and impacts of ongoing ...events for disaster management. There has been a plethora of work in the literature mostly discussing (1) applications to detect, monitor, and predict landslides using various instruments and image analysis techniques, (2) methodological mechanics in using optical and microwave sensing, and (3) quantification of surface geological and geotechnical changes using 2D images. Recently, studies have shown that the degree of hazard is mostly influenced by speed, type, and volume of surface deformation. Despite available techniques to process lidar and image/radar-derived 3D geometry, prior works mostly focus on using 2D images, which generally lack details on the 3D aspects of assessment. Thus, assessing the 3D geometry of terrain using elevation/depth information is crucial to determine its cover, geometry, and 3D displacements. In this review, we focus on 3D landslide analysis using RS data. We include (1) a discussion on sources, types, benefits, and limitations of 3D data, (2) the recent processing methods, including conventional, fusion-based, and artificial intelligence (AI)-based methods, and (3) the latest applications.
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