- Record-Setting Sorbents for Reversible Water Uptake by Systematic Anion Exchanges in Metal-Organic Frameworks
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The reversible capture of water vapor at low humidity can enable transformative applications such as atmospheric water harvesting and heat transfer that uses water as a refrigerant, replacing environmentally detrimental hydro- and chloro-fluorocarbons. The driving force for these applications is governed by the relative humidity at which the pores of a porous material fill with water. Here, we demonstrate modulation of the onset of pore-filling in a family of metal-organic frameworks with record water sorption capacities by employing anion exchange. Unexpectedly, the replacement of the structural bridging Cl- with the more hydrophilic anions F- and OH- does not induce pore-filling at lower relative humidity, whereas the introduction of the larger Br- results in a substantial shift toward lower relative humidity. We rationalize these results in terms of pore size modifications as well as the water hydrogen bonding structure based on detailed infrared spectroscopic measurements. Fundamentally, our data suggest that, in the presence of strong nucleation sites, the thermodynamic favorability of water pore-filling depends more strongly on the pore diameter and the interface between water in the center of the pore and water bound to the pore walls than the hydrophilicity of the pore wall itself. On the basis of these results, we report two materials that exhibit record water uptake capacities in their respective humidity regions and extended stability over 400 water adsorption-desorption cycles.
- Rieth, Adam J.,Wright, Ashley M.,Skorupskii, Grigorii,Mancuso, Jenna L.,Hendon, Christopher H.,Dincǎ, Mircea
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- Kinetics and mechanisms of the gas-phase reactions of the NO3 radical with aromatic compounds
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The kinetics and nitrated products of the gas-phase reactions of the NO3 radical with methoxybenzene, 1,2-, 1,3-, and 1,4-dimethoxybenzene, dibenzofuran and dibenzo-p-dioxin have been investigated at 297 ± 2 K and in the presence of one atmosphere of air. A relative rate method was used for the kinetic measurements. No reactions of methoxybenzene or dibenzofuran with the NO3 radical were observed. The dimethoxybenzenes were observed to react by H-atom abstraction and NO3 radical addition to the aromatic ring, while dibenzo-p-dioxin reacted by NO3 radical addition to the aromatic rings. For these compounds, the NO3 radical addition pathways were observed to be reversible. At the NO2 concentrations employed, the NO3-aromatic adducts reacted with NO2 and the observed rate constants increased with increasing NO2 concentration. However, for dibenzo-p-dioxin the observed rate constant became independent of the NO2 concentration for concentrations ≥ 4.8 × 1013 molecule cm-3, and under these conditions the rate constant of 6.8 × 10-14 cm3 molecule-1 s-1 was taken to be that for addition of the NO3 radical to the aromatic rings. The proposed NO3 radical reaction mechanisms are discussed.
- Kwok,Atkinson,Arey
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- Intrinsic self-trapped broadband emission from zinc halide-based metal-organic frameworks
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Organolead halide perovskites are an emerging class of intrinsic self-trapped broadband emitters, but suffer from lead toxicity and stability problems. Herein, we report a series of metal-organic frameworks (MOFs) based on 0-D zinc halide secondary building units (SBUs), which emit large Stokes shifted broadband bluish-white light. A variety of photophysics studies demonstrate that the broadband emission probably originates from self-trapped excitons, owing to the structurally deformable SBUs. Among the intrinsic self-trapped emitters, these MOFs are very rare examples that exhibit both long-term environmental stability and contain non-toxic elements. Moreover, the open porosity enables the MOF to serve as a host matrix for encapsulating green-emitting Alq3 molecules, exhibiting cold white-light chromatic coordinates of (0.27,0.36) and a correlated color temperature of 8321 K.
- Ma, Wen,Song, Xueling,Yin, Jinlin,Fei, Honghan
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- Insights into Catalytic Hydrolysis of Organophosphonates at M-OH Sites of Azolate-Based Metal Organic Frameworks
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Organophosphorus nerve agents, a class of extremely toxic chemical warfare agents (CWAs), have remained a threat to humanity because of their continued use against civilian populations. To date, Zr(IV)-based metal organic framework (MOFs) are the most pre
- Cao, Ran,Chen, Haoyuan,Farha, Omar K.,Islamoglu, Timur,Kirlikovali, Kent O.,Mian, Mohammad Rasel,Snurr, Randall Q.
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supporting information
p. 9893 - 9900
(2021/07/19)
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- Guanidine compound for preventing and treating chronic pain medication (by machine translation)
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The invention relates to a guanidine compound as shown in general formula (I) as a guanidine compound for preventing and treating chronic pain disease. A pharmaceutically acceptable salt thereof, a prodrug thereof, a solvate thereof, a deuterated substanc
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Paragraph 0333-0337
(2020/08/27)
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- The organic electroluminescent element using the compound and an organic electroluminescent element
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PROBLEM TO BE SOLVED: To provide a compound for an organic electroluminescent element capable of sufficiently reducing drive voltage and suppressing electrical power consumption when used as a constituent material of an organic electroluminescent element, and an organic electroluminescent element using this compound.SOLUTION: A compound for an organic electroluminescent element is represented by the general formula (1). [In the formula, Rrepresents a hydrogen atom, an alkyl group which may have a substituent, an aryl group which may have a substituent, an aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an aromatic heterocyclic group which may have a substituent, or a divalent group generated in that plurally existing Rare bonded to each other. a is an integer of 0 to 4 and b is an integer of 1 to 3. At least one of Arto Aris represented by the general formula (2) or (3).]
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Paragraph 0126-0128
(2018/09/20)
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- Base-promoted nucleophilic fluoroarenes substitution of C–F bonds
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With the use of KOH/DMSO as the superbase medium, the nucleophilic fluoroarene substitution for C–F bonds is presented. The transformation proceeds smoothly with the use of fluoroarenes bearing not only electron-withdrawing group, but also electron-donating group and a variety of nucleophiles such as alcohols, phenols, amines, amides and nitrogen-heterocyclic compounds. The double nucleophilic substitution using ortho-difluoroarenes and nucleophiles bearing ortho-dinucleophilic groups results in the formation of 2,3-dihydro-1,4-benzodioxins, dibenzo[b,e][1,4]dioxins and 10H-phenoxazines in moderate to good yields.
- Su, Ji,Chen, Qian,Lu, Le,Ma, Yuan,Auyoung, George Hong Lok,Hua, Ruimao
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supporting information
p. 303 - 307
(2017/12/11)
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- Synthesis of novel oxazolidinone antimicrobial agents
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The oxazolidinone class of antimicrobials represents a promising advance in the fight against resistant Gram-positive bacterial infections. Four novel oxazolidinone antimicrobial compounds, each containing a benzodioxin ring system, have been prepared. The general synthesis of each compound begins with the construction of a benzodioxin ring system containing a nitro substituent that ultimately becomes the nitrogen of the oxazolidinone ring. Three of the compounds utilize high yielding 'click chemistry' in their final step. The antimicrobial activities of the new oxazolidinones have been measured and the MIC against Staphylococcus aureus for one of the antimicrobials was determined to be 2-3 μg/mL, which is comparable to the well-known oxazolidinone, linezolid.
- Ebner, David C.,Culhane, Jeffrey C.,Winkelman, Tyler N.,Haustein, Mitchell D.,Ditty, Jayna L.,Ippoliti, J. Thomas
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p. 2651 - 2656
(2008/09/21)
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- Synthesis of nitropolychlorinated dibenzo-p-dioxins (NPCDDs) and their photochemical reaction with nucleophiles
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A series nitropolychlorodibenzo-p-dioxins (NPCDDs) was synthesized by condensation between catechols and 2,6-dinitrochalobenzene derivatives.In the presence of sodium ethoxide in anhydrous ethanol, these underwent photochemical SN2Ar* substitutions meta to the nitro group in high chemical yield and moderate quantum yield.Both ring-opening and chloride replacement reactions were observed.The reactions involved the triplet excited state of the NPCDD, and showed a linear relationship between Φ-1 and -1.Analogous reactions with KCN in methanol showed similar behaviour, but the products could not be isolated.Key words: photosubstitution, SN2Ar*, dibenzo-p-dioxins.
- Merica, Simona G.,Bunce, Nigel J.
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p. 826 - 834
(2007/10/03)
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- An Improved Synthesis of Substituted Dibenzodioxines
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An improved general synthesis of substituted dibenzodioxines by reaction of catechol and substituted 1,2-dichloro- or 2-chloronitro-benzenes with metallic potassium in hexamethylphosphoramide is reported.The yields are generally superior to those in published methods, and in particular the reaction appears the one of choice for the synthesis of both the parent dibenzodioxine and the 1-carboxy derivative.
- Lee, Ho H.,Denny, William A.
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p. 1071 - 1074
(2007/10/02)
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- ELECTRON TRANSFER AS ELEMENTARY STAGE IN ELECTROPHILIC NITRATION OF DIBENZO-p-DIOXIN
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The formation of the radical-cation of dibenzo-p-dioxin in the reaction of dibenzo-p-dioxin with nitrating agents was recorded by the ESR method and electronic spectroscopy.Photometric investigation of the reaction of this compound with nitric acid in trifluoroacetic acid showed that the nature and composition of the products depend on the molar ratio of nitric acid and the substrate.With a deficiency of nitric acid the radical-cation or its mixture with the dinitro derivatives of dibenzo-p-dioxin are formed, whereas with an excess of nitric acid only a mixture of the dinitro compounds is formed.Analysis of these facts led to the conclusion that the nitration of dibenzo-p-dioxin with nitric acid in trifluoroacetic acid includes the stage of one-electron oxidation of the initial aromatic compound.
- Morkovnik, A. S.,Belinskii, E. Yu.,Dobaeva, N. M.,Okhlobystin, O. Ya.
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p. 328 - 335
(2007/10/02)
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