Construction of Hydrocarbon Nanobelts Shi, Tan‐Hao; Tong, Shuo; Wang, Mei‐Xiang
Angewandte Chemie International Edition,
May 11, 2020, Volume:
59, Issue:
20
Journal Article
Peer reviewed
Linearly fused hydrocarbon nanobelts are a unique type of double‐stranded macrocycles that would serve as not only the powerful hosts in supramolecular science but also the templates to grow zig‐zag ...carbon nanotubes with defined diameters. Fully conjugated hydrocarbon nanobelts such as beltnarenes would also possess unique physical and chemical properties. Despite the importance, both fully conjugated and (partially) saturated hydrocarbon nanobelts remain largely unexplored because of the lack of cyclization methods. Reported here is the construction of nanometer sized H12‐belt12arenes based on the strategy to close up all fjords of resorcin6arene by means of six‐fold intramolecular alkylation reactions of resorcin6arene derivatives. All resulting H12‐belt12arenes produce a very similar nanobelt core structure with six benzene rings and six boat 1,4‐cyclohexadiene rings being alternately linear‐fused to give a nearly equilateral hexagonal cylinder. The average long diagonal is around 1 nm and the height of the cylinder is about 0.3 nm. The acquired H12‐belt12arenes would be the potential precursors to various hydrocarbon nanobelts including fully conjugated belt12arenes.
Stitching all fjords! H12‐Belt12arenes as a novel type of hydrocarbon nanobelts were constructed effectively from one‐pot six‐fold intramolecular alkylation reactions of both hexa(isopropenyl)‐substituted and hexa(hydroxyl(aryl)methyl)‐substituted resorcin6arene derivatives.
Pillar
n
arenes are pillar-shaped macrocyclic compounds owing to the methylene bridges linking the para-positions of the units. Owing to their unique pillar-shaped structures, these compounds exhibit ...various excellent properties compared with other cyclic host molecules, such as versatile functionality using various organic synthesis techniques, substituent-dependent solubility, cavity-size-dependent host-guest properties in organic media, and unit rotation along with planar chiral inversion. These advantages have enabled the high-yield synthesis and rational design of pillar
n
arene-based mechanically interlocked molecules (MIMs). In particular, new types of pillar
n
arene-based MIMs that can dynamically convert between interlocked and unlocked states through unit rotation have been produced. The highly symmetrical pillar-shaped structures of pillar
n
arenes result in simple NMR spectra, which are useful for studying the motion of pillar
n
arene wheels in MIMs and creating sophisticated MIMs with higher-order structures. The creation and application of polymeric MIMs based on pillar
n
arenes is also discussed.
This review discusses pillar
n
arene-based MIMs such as rotaxanes, catenanes, polyrotaxanes, single-component mechanically self-locked molecules, and supramolecular polymers.
Whether nonalcoholic fatty liver disease (NAFLD) is associated with an increased risk of mortality remains controversial. The present study aimed to clarify this issue. A systematic search of PubMed ...and Embase was conducted through October 2018. Studies providing risk estimates of NAFLD and mortality were included. A random-effects model was employed to calculate summary risk estimates. Subgroup analyses were performed to identify potential effect modifiers. Fourteen studies, involving 498501 subjects and 24234 deaths, were included. Patients with NAFLD were found to be at an elevated risk of all-cause mortality compared with those without hazard ratio (HR) = 1.34; 95% confidence interval (CI) 1.17-1.54). The significantly positive association between NAFLD and all-cause mortality could not be modified by age, sex, follow-up duration, and adjustment for body mass index, diabetes, smoking or hypertension (all P
> 0.05), and remained in sensitivity analyses. No significant associations of NAFLD with CVD (HR = 1.13; 95% CI 0.92-1.38) and cancer (HR = 1.05; 95% CI 0.89-1.25) mortality were found. In conclusion, NAFLD is a predictor of increased all-cause mortality but not CVD and cancer mortality. These findings have important implications for decision making in public health and clinical practice, and highlight the urgency of developing effective treatments for NAFLD.
The practical implementation of electrolytic water splitting systems (especially those powered by renewable energy resources, such as solar and wind) requires active and stable catalysts for the ...hydrogen evolution reaction (HER). The development of catalysts that can compete with, or exceed, the performance of the exorbitant platinum (Pt)-based benchmark is highly desirable. Here, we demonstrate the development of a highly active HER catalyst electrode, exhibiting Pt-like performances in both neutral electrolytes and natural seawater. The catalyst was obtained by pyrolysing a manganese-based metal organic framework (Mn-MOF) on nickel foam (Ni-F). We discovered for the first time that nickel foam not only acts as the substrate for catalyst growth but also provides nickel species that interact with the Mn-MOF, resulting in the formation of Mn doped nickel oxide/nickel hetero-structures on Ni-F (Mn–NiO–Ni/Ni-F). The potential utilization of this catalyst electrode for commercial applications was demonstrated in a self-customized water electrolyzer pack powered by photovoltaic cells.
Hydrocarbon belts including fully conjugated beltarenes and their (partially) saturated analogs have fascinated chemists for decades due to their aesthetic structures, tantalizing properties, and ...potential applications in supramolecular chemistry and carbon nanoscience and nanotechnology. However, synthesis of hydrocarbon belts still remains a formidable challenge. We report in this communication a general approach to hydrocarbon belts and their derivatives. Closing up all four fjords of resorcin4arene derivatives through multiple intramolecular Friedel–Crafts alkylation reactions in an operationally simple one-pot reaction manner enabled efficient construction of octohydrobelt8arenes. Synthesis of belt8arene from DDQ-oxidized aromatization of octohydrobelt8arene under different conditions resulted in aromatization and simultaneous 4 + 2 cycloaddition reactions with DDQ or TCNE to produce selectively tetrahydrobelt8arene-DDQ2, tetrahydrobelt8arene-TCNE2, and belt8arene-DDQ4 adducts. Formation of belt8arene, a fully conjugated hydrocarbon belt, was observed from retro-Diels–Alder reaction of a belt8arene-DDQ4 adduct with laser irradiation under MALDI conditions. The new and practical synthetic method established would open an avenue to create belt-shaped molecules from easily available starting materials.
In this work, we demonstrate cerium (Ce) based metal–organic frameworks (MOFs) combined with carbon nanotubes (CNTs) to form Ce-MOF/CNT composites as separator coating material in the Li–S battery ...system, which showed excellent electrochemical performance even under high sulfur loading and much better capacity retention. At the sulfur loading of 2.5 mg/cm2, initial specific capacity of 1021.8 mAh/g at 1C was achieved in the Li–S cell with the Ce-MOF-2/CNT coated separator, which was slowly reduced to 838.8 mAh/g after 800 cycles with a decay rate of only 0.022% and the Coulombic efficiency of nearly 100%. Even at a higher sulfur loading of 6 mg/cm2, the cell based on Ce-MOF-2/CNT separator coating still exhibited excellent performance with initial specific capacity of 993.5 mAh/g at 0.1 C. After 200 cycles, the specific capacity of 886.4 mAh/g was still retained. The excellent performance is ascribed to the efficient adsorption of the Ce-MOF-2 to Li2S6 species and its catalytic effect toward conversion of polysulfides, resulting in suppressed shuttle effect of polysulfides in the Li–S batteries.
Pillarnarenes can be constructed using a Friedel–Crafts alkylation process. However, due to the reversible nature of the alkylation, mixture of large pillarnarenes (n≥7) are obtained as minor ...products, and thus laborious purification are necessary to isolate the larger pillarnarenes. Moreover, inert methylene bridges are introduced during the alkylation process, and the multi‐functionalization of the bridges has never been investigated. Herein, an irreversible Friedel–Crafts acylation is used to prepare pillarnarenes. Due to the irreversible nature of the acylation, the reaction of precursors bearing carboxylic acids and electron‐rich arene rings results in a size‐exclusive formation of pillarnarenes, in which the ring‐size is determined by the precursor length. Because of this size‐selective formation, laborious separation of undesired macrocycles is not necessary. Moreover, the bridges of pillarnarenes are selectively installed with reactive carbonyl groups using the acylation method, whose positions are determined by the precursor used. The carbonyl bridges can be easily converted into versatile functional groups, leading to various laterally modified pillarnarenes, which cannot be accessed by the alkylation strategy.
Different lateral functionalized pillarnarenes can be obtained using Friedel–Crafts acylation. The irreversible nature of acylation results in the macrocycles being obtained selectively in terms of ring sizes and functional positions. Further derivatization of the ketones is also possible to afford various laterally modified pillarnarenes that cannot be accessed by general Friedel–Crafts alkylation reactions.
This Perspectives paper draws attention to what I would call “industry-focused research” as an approach in management research that I believe can potentially contribute to the improvement of ...non-academic impact of the research. Industry-focused research refers to a type of studies in management that are based on an in-depth understanding of particular industry environments and that take account of the contextual details of the industries under investigation. Given that the industrial context in different locations tends to vary, industry-focused research can also contribute to the contextualization of management research in the Asia Pacific region.
Referring expressions are natural language constructions used to identify particular objects within a scene. In this paper, we propose a unified framework for the tasks of referring expression ...comprehension and generation. Our model is composed of three modules: speaker, listener, and reinforcer. The speaker generates referring expressions, the listener comprehends referring expressions, and the reinforcer introduces a reward function to guide sampling of more discriminative expressions. The listener-speaker modules are trained jointly in an end-to-end learning framework, allowing the modules to be aware of one another during learning while also benefiting from the discriminative reinforcer's feedback. We demonstrate that this unified framework and training achieves state-of-the-art results for both comprehension and generation on three referring expression datasets.
Lysosome is a key subceilular organelle in the execution of the autophagic process and at present little is known whether lysosomal function is controlled in the process of autophagy. In this study, ...we first found that suppression of mammalian target of rapamycin （mTOR） activity by starvation or two mTOR catalytic inhibitors （PP242 and To- rinl）, but not by an allosteric inhibitor （rapamycin）, leads to activation of lysosomal function. Second, we provided evidence that activation of lysosomal function is associated with the suppression of mTOR complex 1 （mTORC1）, but not mTORC2, and the mTORC1 localization to lysosomes is not directly correlated to its regulatory role in lysosomal function. Third, we examined the involvement of transcription factor EB （TFEB） and demonstrated that TFEB acti- vation following mTORC1 suppression is necessary but not sufficient for lysosomal activation. Finally, Atg5 or Atg7 deletion or blockage of the autophagosome-lysosome fusion process effectively diminished lysosomal activation, sug- gesting that lysosomal activation occurring in the course of autophagy is dependent on autophagosome-lysosome fu- sion. Taken together, this study demonstrates that in the course of autophagy, lysosomal function is upregulated via a dual mechanism involving mTORC1 suppression and autophagosome-lysosome fusion.
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