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1.
J Am Chem Soc ; 2024 Jun 10.
Article in English | MEDLINE | ID: mdl-38859682

ABSTRACT

The selective splitting of hexane isomers without the use of energy-intensive phase-change processes is essential for the low-carbon production of clean fuels and also very challenging. Here, we demonstrate a strategy to achieve a complete splitting of the high-RON dibranched isomer from the monobranched and linear isomers, by using a nonlinear 3D ligand to form pillar-layered MOFs with delicate pore architecture and chemistry. Compared with its isoreticular MOFs with the same ted pillar but different linear 3D or linear 2D in-layer ligands, the new MOF constructed in this work, Cu(bhdc)(ted)0.5 (ZUL-C5), exhibited an interesting "channel switch" effect which creates pore space with reduced window size and channel dimensionality together with unevenly distributed alkyl-rich adsorption sites, contributing to a greatly enhanced ability to discriminate between mono- and dibranched isomers. Evidenced by a series of studies including adsorption equilibrium/kinetics/breakthrough tests, guest-loaded single-crystal/powder XRD measurement, and DFT-D modeling, a thermodynamic-kinetic synergistic mechanism in the separation was proposed, resulting in a record production time for high-purity 2,2-dimethylbutane along with a high yield.

2.
ACS Appl Mater Interfaces ; 16(17): 22455-22464, 2024 May 01.
Article in English | MEDLINE | ID: mdl-38642370

ABSTRACT

Improving the gas separation performance of metal-organic frameworks (MOFs) by crystal downsizing is an important but often overlooked issue. Here, we report three different-sized flexible ZUL-520 MOFs (according to the crystal size from large to small, the three samples are, respectively, named ZUL-520-0, ZUL-520-1, and ZUL-520-2) with the same chemical structure for optimizing trace acetylene (C2H2) removal from acetylene/ethylene (C2H2/C2H4) mixture. The three differently sized activated ZUL-520 (denoted as ZUL-520a) exhibited almost identical C2H2 uptake of 4.8 mmol/g at 100 kPa, while the C2H2 uptake at 1 kPa increased with a downsizing crystal. The C2H2 uptake of activated ZUL-520-2 (denoted as ZUL-520-2a) at 1 kPa was ∼55% higher than that of activated ZUL-520-0 (denoted as ZUL-520-0a). The adsorption isotherms and adsorption kinetics validated that gas adsorptive separation is governed not only by adsorption thermodynamics but also by adsorption kinetics. In addition, all three different-sized ZUL-520a MOFs showed high C2H2/C2H4 selectivity. Grand canonical Monte Carlo (GCMC) simulations and dispersion-corrected density functional theory (DFT-D) computations illustrated a plausible mechanism of C2H2 adsorption in MOFs. Importantly, breakthrough experiments demonstrated that ZUL-520a can effectively separate the C2H2/C2H4 (1/99, v/v) mixture and the C2H4 productivity obtained by ZUL-520-2a was much higher than that by ZUL-520-0a. Our work may provide an easy but powerful strategy for upgrading the performance of gas adsorptive separation in MOFs.

3.
Endocr Connect ; 13(5)2024 May 01.
Article in English | MEDLINE | ID: mdl-38552311

ABSTRACT

Objective: Hashimoto's thyroiditis is an inflammatory disease, and research suggests that a low-carbohydrate diet may have potential anti-inflammatory effects. This study aims to utilize Dixon-T2-weighted imaging (WI) sequence for a semi-quantitative assessment of the impact of a low-carbohydrate diet on the degree of thyroid inflammation in patients with Hashimoto's thyroiditis. Methods: Forty patients with Hashimoto's thyroiditis were recruited for this study and randomly divided into two groups: one with a normal diet and the other with a low-carbohydrate diet. Antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) were measured for all participants. Additionally, thyroid water content was semi-quantitatively measured using Dixon-T2WI. The same tests and measurements were repeated for all participants after 6 months. Results: After 6 months of a low-carbohydrate diet, patients with Hashimoto's thyroiditis showed a significant reduction in thyroid water content (94.84 ± 1.57% vs 93.07 ± 2.05%, P < 0.05). Concurrently, a decrease was observed in levels of TPOAb and TgAb (TPOAb: 211.30 (92.63-614.62) vs 89.45 (15.9-215.67); TgAb: 17.05 (1.47-81.64) vs 4.1 (0.51-19.42), P < 0.05). In contrast, there were no significant differences in thyroid water content or TPOAb and TgAb levels for patients with Hashimoto's thyroiditis following a normal diet after 6 months (P < 0.05). Conclusion: Dixon-T2WI can quantitatively assess the degree of thyroid inflammation in patients with Hashimoto's thyroiditis. Following a low-carbohydrate diet intervention, there is a significant reduction in thyroid water content and a decrease in levels of TPOAb and TgAb. These results suggest that a low-carbohydrate diet may help alleviate inflammation in patients with Hashimoto's thyroiditis.

4.
Nat Commun ; 15(1): 2620, 2024 Mar 23.
Article in English | MEDLINE | ID: mdl-38521770

ABSTRACT

Extensive efforts have been made to improve the separation selectivity of hydrocarbon isomers with nearly distinguishable boiling points; however, how to balance the high regeneration energy consumption remains a daunting challenge. Here we describe the efficient separation of hexane isomers by constructing and exploiting the rotational freedom of organic linkers and inorganic SnF62- anions within adaptive frameworks, and reveal the nature of flexible host-guest interactions to maximize the gas-framework interactions while achieving potential energy storage. This approach enables the discrimination of hexane isomers according to the degree of branching along with high capacity and record mono-/di-branched selectivity (6.97), di-branched isomers selectivity (22.16), and upgrades the gasoline to a maximum RON (Research Octane Number) of 105. Benefitting from the energy regulation of the flexible pore space, the material can be easily regenerated only through a simple vacuum treatment for 15 minutes at 25 °C with no temperature fluctuation, saving almost 45% energy compared to the commercialized zeolite 5 A. This approach could potentially revolutionize the whole scenario of alkane isomer separation processes.

5.
Huan Jing Ke Xue ; 44(8): 4519-4529, 2023 Aug 08.
Article in Chinese | MEDLINE | ID: mdl-37694646

ABSTRACT

Trichloroethylene is a typical organic contaminant that has widely existed in industry sites and groundwater. Biochar-supported zero-valent iron material has been used to remove trichloroethylene in groundwater; however, it could affect the microbial communities in aquifer soil, leading to changes in the environmental behavior of trichloroethylene. In this study, biochar was prepared under oxygen-limited conditions and modified by NaOH and HNO3 agents. Then, a modified biochar-supported zero-valent iron composite (BC composites) was synthesized using ball milling technology. The effects of BC composites on the removal of trichloroethylene and the responses of the microbial community were investigated under the condition of simulated aquifer soil. The results showed that the specific surface areas of BC composites were increased after the modification with NaOH. The highest removal rate of trichloroethylene was observed in the BC_2 treatment, up to 90.01%. Except in the BC_1 treatment, the diversity and abundance of soil microorganisms were increased, and the microbial community structure was changed after the addition of different BC composites, in which Bacillus, Thiobacillus, and Pseudomonas might have been the potential degrading bacteria of trichloroethylene. The abundance of Thiobacillus and Pseudomonas increased under the BC_2 treatment, which was favorable to the removal of trichloroethylene. The stabilization of the microbial community structure was probably maintained by Nocardioideas, Thermincola, Lysobacter, Gemmatimonas, Microvirga, and Pseudomonas. According to the predictive analysis of microbial metabolic pathways, the abundance of xenobiotics biodegradation and metabolism genes and the folding, sorting, and degradation of genes were the highest under the BC_2 treatment. Thus, the NaOH-modified BC composite could prompt the removal of trichloroethylene in simulated aquifer soil, probably due to the increase in the abundance of soil-degrading bacteria and the expression of degradation genes, demonstrating that the NaOH-modified BC composite could be used for the remediation of the organic-contaminated industry sites as a new composite material.


Subject(s)
Microbiota , Trichloroethylene , Soil , Sodium Hydroxide , Iron
6.
J Am Chem Soc ; 145(16): 9254-9263, 2023 Apr 26.
Article in English | MEDLINE | ID: mdl-37053465

ABSTRACT

Developing adsorbents with multiple merits in capacity, selectivity, mass transfer, and stability toward C2H2/CO2 separation is crucial and challenging for producing high-purity C2H2 for advanced polymers and the electronic industry. Here, we demonstrate a vertex strategy to create adsorbents combining these merits through rationally designing the vertex groups of a wavy-shaped framework in layered 2D metal-organic frameworks (MOFs) to finely regulate the local conformation and stacking interactions, which creates the optimal inter- and intralayer space to realize simultaneous improvement of adsorption thermodynamics and kinetics. Two new hydrolytically stable MOFs, ZUL-330 and ZUL-430, were prepared, and diverse experiments and modeling on both adsorption equilibrium and diffusion were performed. Record separation selectivities coupled with extraordinary dynamic C2H2 capacities were achieved for C2H2/CO2 mixtures with different proportions (50/50 or 10/5, v/v), along with a small diffusion barrier and fast mass transfer. Consequently, polymer-grade (99.9%) and electronic-grade (99.99%) C2H2 were obtained with excellent productivities of up to ∼6 mmol cm-3.

7.
J Autoimmun ; 141: 103050, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37120327

ABSTRACT

OBJECTIVES: To investigate the compositional and functional characteristics of the gut microbiota in primary Sjögren's syndrome (pSS) and compare them with those in systemic lupus erythematosus (SLE). METHODS: Stool samples from 78 treatment-naïve pSS patients and 78 matched healthy controls were detected by shotgun metagenomic sequencing and compared with those from 49 treatment-naïve SLE patients. The virulence loads and mimotopes of the gut microbiota were also assessed by sequence alignment. RESULTS: The gut microbiota of treatment-naïve pSS patients had lower richness and evenness and showed a different community distribution than that of healthy controls. The microbial species enriched in the pSS-associated gut microbiota included Lactobacillus salivarius, Bacteroides fragilis, Ruminococcus gnavus, Clostridium bartlettii, Clostridium bolteae, Veillonella parvula, and Streptococcus parasanguinis. Lactobacillus salivarius was the most discriminating species in the pSS patients, especially in those with interstitial lung disease (ILD). Among the differentiating microbial pathways, the superpathway of l-phenylalanine biosynthesis was also further enriched in pSS complicated with ILD. There were more virulence genes carried by the gut microbiota in pSS patients, most of which encoded peritrichous flagella, fimbriae, or curli fimbriae, three types of bacterial surface organelles involved in bacterial colonization and invasion. Five microbial peptides with the potential to mimic pSS-related autoepitopes were also enriched in the pSS gut. SLE and pSS shared significant gut microbial traits, including community distribution, altered microbial taxonomy and pathways, and enriched virulence genes. However, Ruminococcus torques was depleted in pSS patients but enriched in SLE patients compared to healthy controls. CONCLUSIONS: The gut microbiota in treatment-naïve pSS patients was disturbed and shared significant similarity with that in SLE patients.


Subject(s)
Gastrointestinal Microbiome , Lung Diseases, Interstitial , Lupus Erythematosus, Systemic , Sjogren's Syndrome , Humans , Sjogren's Syndrome/genetics , Lupus Erythematosus, Systemic/complications , Metagenome
8.
ACS Appl Mater Interfaces ; 15(2): 3387-3394, 2023 Jan 18.
Article in English | MEDLINE | ID: mdl-36608268

ABSTRACT

The selective capture of C2H6 from C2H6/C2H4 mixtures is of critical importance to realize the efficient one-step purification of C2H4 but remains challenging due to their similar properties and smaller quadrupole moment of C2H6 that usually result in C2H4-preferring adsorption. Herein, we reported two isostructural pillared-layer metal-organic frameworks, ZUL-C3 and ZUL-C4, which were constructed by mixed polycycloalkane-type ligands. Their low-polar pore environment along with more accessible low-polar C-H binding sites on the pore surface are conducive to generate more van der Waals interactions with C2H6 while the carboxylic groups distributed at four corners of pores form stronger and more dipolar interactions with C2H6, cooperatively resulting in a good C2H6/C2H4 uptake ratio of 1.50 for ZUL-C3 and 1.72 for ZUL-C4 in static adsorption experiments and a high C2H4 (>99.99% purity) productivity of 10.1 L/kg for ZUL-C3 and 14.6 L/kg for ZUL-C4 from an equimolar C2H6/C2H4 mixture in breakthrough experiments.

9.
J Autoimmun ; 134: 102958, 2022 Nov 28.
Article in English | MEDLINE | ID: mdl-36455385

ABSTRACT

OBJECTIVES: To investigate the compositional and functional characteristics of the gut microbiota in primary Sjögren's syndrome (pSS) and compare them with those in systemic lupus erythematosus (SLE). METHODS: Stool samples from 78 treatment naïve pSS patients and 78 matched healthy controls were detected by shotgun metagenomic sequencing and compared with those from 49 treatment naïve SLE patients. The virulence loads and mimotopes of the gut microbiota were also assessed by sequence alignment. RESULTS: The gut microbiota of treatment naïve pSS patients had lower richness and evenness and showed a different community distribution than that of healthy controls. The microbial species enriched in the pSS-associated gut microbiota included Lactobacillus salivarius, Bacteroides fragilis, Ruminococcus gnavus, Clostridium bartlettii, Clostridium bolteae, Veillonella parvula, and Streptococcus parasanguinis. Lactobacillus salivarius was the most discriminating species in the pSS patients, especially in those with interstitial lung disease (ILD). Among the differentiating microbial pathways, the superpathway of l-phenylalanine biosynthesis was also further enriched in pSS complicated with ILD. There were more virulence genes carried by the gut microbiota in pSS patients, most of which encoded peritrichous flagella, fimbriae, or curli fimbriae, three types of bacterial surface organelles involved in bacterial colonization and invasion. Five microbial peptides with the potential to mimic pSS-related autoepitopes were also enriched in the pSS gut. SLE and pSS shared significant gut microbial traits, including the community distribution, altered microbial taxonomy and pathways, and enriched virulence genes. However, Ruminococcus torques was depleted in pSS patients but enriched in SLE patients compared to that in healthy controls. CONCLUSIONS: The gut microbiota in treatment naïve pSS patients was disturbed and shared significant similarity with that in SLE patients.

10.
J Am Chem Soc ; 144(46): 21417-21424, 2022 11 23.
Article in English | MEDLINE | ID: mdl-36356164

ABSTRACT

The separation of C8 aromatics (xylenes and ethylbenzene) remains one of the most challenging industrial separations due to their similar structures and properties. Suitable adsorbents that can distinguish the small differences among isomers are urgently demanded. Herein, we demonstrate a strategy to realize the precise discrimination of C8 aromatics by constructing a nonaromatic confined pore environment with mixed polycycloalkane-type ligands. The nonaromatic low-polar pore environment avoids strong convergent interactions between the framework and the common phenyl rings while creating possibilities to amplify the difference between host-guest/guest-guest interactions regarding the different methyl (ethyl) group positions of isomers. The resultant metal-organic framework, ZUL-C3, with either tetragonal or monoclinic lattice, exhibits outstanding separation performance for C8 aromatics, not only realizing the simultaneous separation of four isomers from each other but also setting a benchmark for the dynamic separation performance of OX/PX and OX/MX.


Subject(s)
Metal-Organic Frameworks , Isomerism , Xylenes
11.
Front Pharmacol ; 13: 944735, 2022.
Article in English | MEDLINE | ID: mdl-36105211

ABSTRACT

Purpose: We aimed to establish the transcriptome diagnostic signature of postmenopausal osteoporosis (PMOP) to identify diagnostic biomarkers and score patient risk to prevent and treat PMOP. Methods: Peripheral blood mononuclear cell (PBMC) expression data from PMOP patients were retrieved from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were screened using the "limma" package. The "WGCNA" package was used for a weighted gene co-expression network analysis to identify the gene modules associated with bone mineral density (BMD). Least absolute shrinkage and selection operator (LASSO) regression was used to construct a diagnostic signature, and its predictive ability was verified in the discovery cohort. The diagnostic values of potential biomarkers were evaluated by receiver operating characteristic curve (ROC) and coefficient analysis. Network pharmacology was used to predict the candidate therapeutic molecules. PBMCs from 14 postmenopausal women with normal BMD and 14 with low BMD were collected, and RNA was extracted for RT-qPCR validation. Results: We screened 2420 differentially expressed genes (DEGs) from the pilot cohort, and WGCNA showed that the blue module was most closely related to BMD. Based on the genes in the blue module, we constructed a diagnostic signature with 15 genes, and its ability to predict the risk of osteoporosis was verified in the discovery cohort. RT-qPCR verified the expression of potential biomarkers and showed a strong correlation with BMD. The functional annotation results of the DEGs showed that the diagnostic signature might affect the occurrence and development of PMOP through multiple biological pathways. In addition, 5 candidate molecules related to diagnostic signatures were screened out. Conclusion: Our diagnostic signature can effectively predict the risk of PMOP, with potential application for clinical decisions and drug candidate selection.

12.
J Am Chem Soc ; 144(31): 14322-14329, 2022 Aug 10.
Article in English | MEDLINE | ID: mdl-35849509

ABSTRACT

The fine-tuning of the pore structure of metal-organic frameworks (MOFs) is of critical importance to developing energy-efficient processes for the challenging separation of structurally similar molecules. Herein, we demonstrate a strategy to realize a quasi-three-dimensional refinement of the pore structure that utilizes the tunability of ring size and number in polycycloalkane-dicarboxylate ligands. Two hydrolytically stable MOFs with a confined aliphatic pore environment, ZUL-C1 and ZUL-C2, were, for the first time, synthesized and applied in separating low-concentration C2-C3 hydrocarbons from natural gas and ultralow-concentration Xe from used nuclear fuel (UNF) off-gas. Validated by X-ray diffraction and modeling, an expansion of the polycycloalkane moiety enables sub-angstrom contraction in specific directions and forms a pore surface with more alkyl sites, which affords stronger trapping of guest molecules with relatively higher polarizability. The resultant material exhibits record C2H6/CH4 and C3H8/CH4 selectivities coupled with a benchmark low-pressure C2H6 capacity in alkane mixture separation and also a benchmark Xe capacity at extremely diluted feed concentration and record Kr productivity for the Xe/Kr (20:80, v/v) mixture in Xe/Kr separation.

13.
Nat Commun ; 13(1): 2955, 2022 May 26.
Article in English | MEDLINE | ID: mdl-35618705

ABSTRACT

Refineries generally employ multiple energy-intensive distillation/adsorption columns to separate and purify complicated chemical mixtures. Materials such as multi-functional molecular separators integrating various modules capable of separating molecules according to their shape and chemical properties simultaneously may represent an alternative. Herein, we address this challenge in the context of one-step removal of alkynes and propadiene from cracking gases (up to 10 components) using a multi-functional and responsive material ZU-33 through a guest/temperature dual-response regulation strategy. The responsive and guest-adaptive properties of ZU-33 provide the optimized binding energy for alkynes and propadiene, and avoid the competitive adsorption of olefins and paraffins, which is verified by breakthrough tests, single-crystal X-ray diffraction experiments, and simulation studies. The responsive properties to different stimuli endow materials with multiple regulation methods and broaden the boundaries of the applicability of porous materials to challenging separations.

14.
Nat Commun ; 13(1): 2335, 2022 Apr 28.
Article in English | MEDLINE | ID: mdl-35484150

ABSTRACT

A modular and efficient method for constructing angular tri-carbocyclic architectures containing quaternary carbon center(s) from 1,3-dicycloalkylidenyl ketones is established, which involves an unconventional synergistic cascade of a Nazarov cyclization and two ring expansions. It features high selectivity, mild conditions and convenient operation, wide scope and easy availability of substrate. Substitution with R1 and R2 at the 4πe-system with electron-donating group favors this reaction, while that with electron-withdrawing group or proton disfavors. The electron-donating group as R1 directs the initial ring expansion at its own site, while the p-π- or n-π- associated substituent as R2 favors selectively the later ring expansion near its location because of the beneficial maintenance of an original conjugated system. The stereoselectivity has proved to be governed by either the steric effect of R3 and R4 at the expanded rings, or the migration ability of the migrating atom. Density Functional Theory calculation suggests the initial Nazarov cyclization would be the rate-determining step. A racemic total synthesis of the natural (±)-waihoensene is realized in 18 steps by use of this methodology.

15.
Nat Commun ; 12(1): 6747, 2021 Nov 19.
Article in English | MEDLINE | ID: mdl-34799574

ABSTRACT

Progress over the past decades in water confinement has generated a variety of polymers and porous materials. However, most studies are based on a preconception that small hydrophobic pores eventually repulse water molecules, which precludes the exploration of hydrophobic microporous materials for water confinement. Here, we demonstrate water confinement across hydrophobic microporous channels in crystalline covalent organic frameworks. The frameworks are designed to constitute dense, aligned and one-dimensional polygonal channels that are open and accessible to water molecules. The hydrophobic microporous frameworks achieve full occupation of pores by water via synergistic nucleation and capillary condensation and deliver quick water exchange at low pressures. Water confinement experiments with large-pore frameworks pinpoint thresholds of pore size where confinement becomes dominated by high uptake pressure and large exchange hysteresis. Our results reveal a platform based on microporous hydrophobic covalent organic frameworks for water confinement.

16.
Angew Chem Int Ed Engl ; 60(35): 19419-19427, 2021 Aug 23.
Article in English | MEDLINE | ID: mdl-34143926

ABSTRACT

The ordered π skeletons of covalent organic frameworks make them viable light-emitting materials but their limited tunability has precluded further implementation. Here we report the synthesis of hydrazone-linked frameworks which are stable in water, acid, and base, and demonstrate their utility as a platform for light emission. The polygonal backbone is designed to be luminescent and partially π conjugated while the pore wall is docked with single atom or unit to induce resonance, hyperconjugation, and tautomerization effects. These effects can be transmitted to the backbone, so that the framework can emit three primary colors of light. The wall can be perturbated with multiple surface sites, rendering the material able to edit diverse emission colors in a predesignable and digital way. The systems show high activity, stability, tunability, and sensibility: a set of features attractive for light-emitting and sensing applications.

17.
Chem Soc Rev ; 50(1): 120-242, 2021 Jan 07.
Article in English | MEDLINE | ID: mdl-33283811

ABSTRACT

Covalent organic frameworks offer a molecular platform for integrating organic units into periodically ordered yet extended two- and three-dimensional polymers to create topologically well-defined polygonal lattices and built-in discrete micropores and/or mesopores. This polymer architecture is unique as it enables predesigning both primary- and high-order structures, greatly enhancing our capabilities of designing organic materials to produce predictable structures and to achieve unique properties and functions. Progress over the past 15 years in the design, synthesis and functional exploration of COFs has successively established the basis of the COF field and COFs have shown the great potential of chemistry in developing a class of amazing organic materials. In this review, we focus on analysing the historic developments of COFs to uncover a full materials and application picture by providing comprehensive yet clear guidance for molecular design, synthetic control and functional exploration. We scrutinise the structural components of COFs including building blocks, reactive sites and functional groups with the aim of finding the origins of structural designability and diversity, as well as multiple functionalities. We disclose strategies for designing and synthesising frameworks to construct various tailor-made interfaces, and for exploring skeletons and pores to design properties and functions. With well-defined skeletons, pores and interfaces that offer a chemical basis to trigger and control interactions with photons, excitons, phonons, polarons, electrons, holes, spins, ions and molecules, we illustrate the current status of our understandings of structure-property correlations, and unveil the principles for establishing a regime to design unique functions that originate from and are inherent to structures. We predict the key central issues in design and synthesis, the challenges in functional design and the future directions from the perspectives of chemistry, physics and materials science.

18.
Nat Commun ; 11(1): 6259, 2020 Dec 07.
Article in English | MEDLINE | ID: mdl-33288766

ABSTRACT

Three-dimensional metal-organic frameworks (MOFs) are cutting-edge materials in the adsorptive removal of trace gases due to the availability of abundant pores with specific chemistry. However, the development of ideal adsorbents combining high adsorption capacity with high selectivity and stability remains challenging. Here we demonstrate a strategy to design adsorbents that utilizes the tunability of interlayer and intralayer space of two-dimensional fluorinated MOFs for capturing acetylene from ethylene. Validated by X-ray diffraction and modeling, a systematic variation of linker atom oxidation state enables fine regulation of layer stacking pattern and linker conformation, which affords a strong interlayer trapping of molecules along with cooperative intralayer binding. The resultant robust materials (ZUL-100 and ZUL-200) exhibit benchmark capacity in the pressure range of 0.001-0.05 bar with high selectivity. Their efficiency in acetylene/ethylene separation is confirmed by breakthrough experiments, giving excellent ethylene productivities (121 mmol/g from 1/99 mixture, 99.9999%), even when cycled under moist conditions.

19.
Angew Chem Int Ed Engl ; 59(49): 21954-21958, 2020 12 01.
Article in English | MEDLINE | ID: mdl-32851781

ABSTRACT

A tandem Bischler-Napieralski/semipinacol rearrangement reaction has been developed for the purpose of assembling a bis(spirocyclic) indole framework, a privileged structural unit of aspidofractinine-type monoterpenoid indole alkaloids, and was used in combination with a subsequent Mannich reaction to expeditiously construct the central bridged bicyclo[2.2.1]heptane ring system of these molecules with contiguous quaternary centers. The development of this novel strategy culminated in the collective total synthesis of four aspidofractinine alkaloids.

20.
Angew Chem Int Ed Engl ; 59(31): 12725-12730, 2020 Jul 27.
Article in English | MEDLINE | ID: mdl-32329164

ABSTRACT

C2 -C3 alkyne/alkene separation is of great importance; however, designing materials for an efficient molecular sieving of alkenes from alkynes remains challenging. Now, two hydrolytically stable layered MOFs, [Cu(dps)2 (GeF6 )] (GeFSIX-dps-Cu, dps=4,4'-dipyridylsulfide) and [Zn(dps)2 (GeF6 )] (GeFSIX-dps-Zn), can achieve almost complete exclusion of both C3 H6 and C2 H4 from their alkyne analogues. GeFSIX-dps-Cu displays a notable advanced threshold pressure for alkynes adsorption and thus substantial uptakes at lower pressures, providing record C3 H4 /C3 H6 uptake ratios and capacity-enhanced C2 H2 /C2 H4 sieving for a wide composition range. Metal substitution (Zn to Cu) affords fine tuning of linker rotation and layer stacking, creating slightly expanded pore aperture and interlayer space coupled with multiple hydrogen-bonding sites, allowing easier entrance of alkyne while excluding alkene. Breakthrough experiments confirmed tunable sieving by these MOFs for C3 H4 /C3 H6 and C2 H2 /C2 H4 mixtures.

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