Functionalized linkers can greatly increase the activity of metal–organic framework (MOF) catalysts with coordinatively unsaturated sites. A clear linear free‐energy relationship (LFER) was found ...between Hammett σm values of the linker substituents X and the rate kX of a carbonyl‐ene reaction. This is the first LFER ever observed for MOF catalysts. A 56‐fold increase in rate was found when the substituent is a nitro group (see picture).
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•Recent progress on MOF sensors for NACs detection was reviewed.•MOF-based sensor was developed to high-valance MOFs or composites mixed with polymers for the detection.•Porous ...organic based-sensors for NACs detection was reviewed for the first time.•Perspectives on porous material-based sensors were presented for further progress.
The detection of explosives, especially nitroaromatic compounds (NACs), is a crucial issue in anti-terrorism and homeland security due to their frequent use in acts of terrorism and their negative impact on the environment. Metal-organic frameworks (MOFs) have been viewed as a promising material for detecting NACs due to their large surface area, structural diversity, and various functionalities. Many review have focused on NACs sensing using MOFs with sensing mechanisms, but there has been no systematic review of new emerging porous solids such as porous organic materials amorphous porous organic polymers (POPs), crystalline covalent organic frameworks (COFs), and hydrogen-bonded organic frameworks (HOFs), and porous composite materials. This work reviews porous materials that have been developed recently into practical materials for detecting explosive NACs.
A Mobile Ad-hoc Network (MANET) is an accumulation of portable hubs which impart over proportion. These systems have an essential preferred standpoint; they don't require any current foundation or ...focal organization. Portable specially appointed systems are appropriate for transitory correspondence joins. One of the significant issues in MANET is steering because of the versatility of the hubs. Directing means the demonstration of moving data over a web work from a source to a goal. The Enhanced Ant Routing Algorithm (EARA) depends on subterranean insect calculations. This calculation is enlivened from the insect states life. Forward bundles are utilized to gather data about the system and in reverse parcels are utilized to refresh the directing data in the hubs. EARA has two stages course disclosure and course support and furthermore utilities the idea of backtracking when the parcels are achieves goal hub. Re-enactment comes about accomplish better parcel conveyance proportion and lessen the normal end-to-end defer as contrast with its partner
This paper explores the 20-year evolution of the social-ecological systems framework (SESs). Although a first definition of SES dates back to 1988, Berkes and Folke more thoroughly used the concept ...in 1998 to analyze resilience in local resource management systems. Since then studies of interlinked human and natural systems have emerged as a field on its own right, promoting interdisciplinary dialogue and collaboration in a wide set of fields and practices. As the SES concept celebrates its 20-year existence we decided to make an overview of how authors use the concept in relation to research that deals with social and ecological linkages. Hence, we conducted a review of the SES concept using the Scopus database, analyzing a random set of journal articles on social-ecological systems (n = 50) regarding definitions of SES, authors’ main sources of inspiration in using the concept, as well as document type, subject area, and other relevant information. Although there is a steady increase of SES publications, we found that 61% of the papers analyzed did not even provide a definition of the term social-ecological system(s), a shortcoming that makes case comparisons difficult and reduces the usefulness of the concept. We also found three common SES frameworks that authors seem to be most commonly inspired by, referred to here as the original, the robustness, and multitier frameworks, respectively. The first can be characterized as a descriptive framework, the latter two more as diagnostic frameworks, useful for modeling. Although it would be a bit presumptuous of us to come up with a more thorough definition of the SES concept in this paper, we urge SES scholars to be more meticulous in making explicit what they mean by a social-ecological system when conducting SES research.
Abstract
We report the synthesis, structural characterization, and porous properties of two isomeric supramolecular complexes of (Cd(NH
2
bdc)(bphz)
0.5
⋅DMF⋅H
2
O}
n
(NH
2
...bdc=2‐aminobenzenedicarboxylic acid, bphz=1,2‐bis(4‐pyridylmethylene)hydrazine) composed of a mixed‐ligand system. The first isomer, with a paddle‐wheel‐type Cd
2
(COO)
4
secondary building unit (SBU), is flexible in nature, whereas the other isomer has a rigid framework based on a μ‐oxo‐bridged Cd
2
(μ‐OCO)
2
SBU. Both frameworks are two‐fold interpenetrated and the pore surface is decorated with pendant −NH
2
and NN functional groups. Both the frameworks are nonporous to N
2
, revealed by the type II adsorption profiles. However, at 195 K, the first isomer shows an unusual double‐step hysteretic CO
2
adsorption profile, whereas the second isomer shows a typical type I CO
2
profile. Moreover, at 195 K, both frameworks show excellent selectivity for CO
2
among other gases (N
2
, O
2
, H
2
, and Ar), which has been correlated to the specific interaction of CO
2
with the −NH
2
and NN functionalized pore surface. DFT calculations for the oxo‐bridged isomer unveiled that the −NH
2
group is the primary binding site for CO
2
. The high heat of CO
2
adsorption (Δ
H
ads
=37.7 kJ mol
−1
) in the oxo‐bridged isomer is realized by NH
2
⋅⋅⋅CO
2
/aromatic π⋅⋅⋅CO
2
and cooperative CO
2
⋅⋅⋅CO
2
interactions. Further, postsynthetic modification of the −NH
2
group into −NHCOCH
3
in the second isomer leads to a reduced CO
2
uptake with lower binding energy, which establishes the critical role of the −NH
2
group for CO
2
capture. The presence of basic −NH
2
sites in the oxo‐bridged isomer was further exploited for efficient catalytic activity in a Knoevenagel condensation reaction.
Dopamine: Just the Right Medicine for Membranes Yang, Hao‐Cheng; Waldman, Ruben Z.; Wu, Ming‐Bang ...
Advanced functional materials,
February 21, 2018, Letnik:
28, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Mussel‐inspired chemistry has attracted widespread interest in membrane science and technology. Demonstrating the rapid growth of this field over the past several years, substantial progress has been ...achieved in both mussel‐inspired chemistry and membrane surface engineering based on mussel‐inspired coatings. At this stage, it is valuable to summarize the most recent and distinctive developments, as well as to frame the challenges and opportunities remaining in this field. In this review, recent advances in rapid and controllable deposition of mussel‐inspired coatings, dopamine‐assisted codeposition technology, and photoinitiated grafting directly on mussel‐inspired coatings are presented. Some of these technologies have not yet been employed directly in membrane science. Beyond discussing advances in conventional membrane processes, emerging applications of mussel‐inspired coatings in membranes are discussed, including as a skin layer in nanofiltration, interlayer in metal‐organic framework based membranes, hydrophilic layer in Janus membranes, and protective layer in catalytic membranes. Finally, some critical unsolved challenges are raised in this field and some potential pathways are proposed to address them.
Mussel‐inspired polydopamine is a rising star in membrane science and technology. The most recent advances in polydopamine deposition are highlighted and summarized, as well as its emerging applications in nanofiltration, metal‐organic framework composite membranes, Janus membranes, and photocatalytic membranes.
Guest and anion dependent: Structural dynamism and luminescence of a cationic porous framework (see picture) are investigated by different analytical techniques, such as ...single‐crystal‐to‐single‐crystal structural transformation. The compound shows size‐selective sorption of hydrophobic guest molecules, easy exchange of anions of the framework, and interesting anion‐responsive luminescence.
In the presence of Cu2+, the yellow fluorescence of dual-emissive BYCDs@ZIF-8 nanocomposite is enhanced, while its blue fluorescence is quenched. Upon addition of glutathione on Cu2+- BYCDs@ ZIF-8 ...system, the fluorescence of both peaks restored to their original states gradually.
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•Yellow and blue emitting carbon dots were synthesized by totally green way.•Synthesized composite exhibited the characteristic emissions of yellow emitting and blue emitting carbon dots.•The ratiometric fluorescent sensor can detect glutathione in subnanomolar levels.•The sensor detects glutathione discriminatively in the presence of other biothiols.
A dual-emissive metal−organic frameworks was prepared by encapsulating yellow emitting and blue emitting carbon dots into the zeolitic imidazolate framework (BYCDs@ZIF-8) which acted as a ratiometric probe for Glutathione. The composite shows dual-emissions which are centered at 565 and 440 nm under a single excitation wavelength of 365 nm. In the presence of Cu2+, the fluorescence of yellow emitting carbon dots in the nanocomposite was selectively enhanced, while the fluorescence of the blue emitting carbon dots was quenched. Upon addition of glutathione on Cu2+- BYCDs@ZIF-8 system, the fluorescence of both carbon dots gradually restored to their original amounts due to the strong interaction between glutathione and Cu2+. Detection progress can be observed by unaided eyes with a visual color change from yellow to blue under ultraviolet irradiation. Under the optimal conditions, glutathione determined in the range of 3–25 nM with a limit of detection of 0.90 nM (Signal/Noise = 3). The employed composite with distinct size-selectivity not only decreases the background interference from large molecule but it is also able to strongly accumulate the target analytes and thus greatly amplifies the sensing signal and specificity. Also, the ratiometric strategy provided built-in self-calibration for signal correction and improved precision and accuracy. This method was applied for the detection of glutathione in fruit samples and showed satisfactory results.
The electrochemical nitrogen reduction reaction (NRR), a contributor for producing ammonia under mild conditions sustainably, has recently attracted global research attention. Thus far, the design of ...highly efficient electrocatalysts to enhance NRR efficiency is a specific focus of the research. Among them, defect engineering of electrocatalysts is considered a significant way to improve electrocatalytic efficiency by regulating the electronic state and providing more active sites that can give electrocatalysts better physicochemical properties. Recently, metal–organic frameworks (MOFs), along with their derivatives, have captured immense interest in electrocatalytic reactions owing to not only their large surface area and high porosity but also the ability to create rich defects in their structures. Hence, they can provide plenty of exposed active sites for electron transfer, NN cleavage, and N2 adsorption to enhance NRR performance. Herein, the concept, the in situ characterizations techniques for defects, and the most common ways to create defects into MOFs have been summarized. Furthermore, the recent advances of MOF‐based electrocatalysts towards NRR have been recapitulated. Ultimately, the major challenges and outlook of defects in MOFs for NRR are proposed. This paper is anticipated to provide critical guidelines for optimizing NRR electrocatalysts.
Nitrogen reduction reaction (NRR) is one of the most attractive topics for achieving clean and sustainable ammonia. This review discusses the recent progress of defect engineering of metal–organic frameworks (MOFs) for NRR. There are different types of MOF‐derived materials that enhance NRR performance. These outputs render MOFs to be the centerpiece for various applications especially energy conversion applications.
In this review, we gather a great deal of information about magnetic nanocomposites, which are made from the combination of Fe3O4 magnetic nanoparticles (MNPs) and metal‐organic frameworks (MOFs). ...Due to the high saturation magnetization, biocompatibility, low toxicity, stability, and cost‐effectiveness, MNPs have attracted a lot of interest in recent years. Furthermore, MOFs, which are porous materials, formed by the connection between organic linkers and metal ions. The combination of MNPs and MOFs results in the formation of magnetic framework composites (MFCs). The information about the MFCs is classified according to their applications and we provide brief information about the synthesizing of these materials. MFCs have a wide array of uses in various fields such as catalysis, biomedical, extraction, etc. We discussed these applications in detail. This information has been amassed to provide researchers with a proper chance to obtain enough information about these materials. Researchers are also able to become aware of some drawbacks in each field, and they can propose some solutions to overcome those drawbacks. We aimed to prepare a well‐organized review to respond to the desire of using MFCs in different fields.
A combination of Fe3O4 magnetic nanoparticles and metal‐organic frameworks leads to the formation of magnetic framework composites with unique design principles by various synthesis methods. Promising applications in different areas such as catalysis, biomedical, extraction, are discussed. The recent advances are summarized, and evaluations are given in this review.
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