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The presence of borate ions was confirmed experimentally and computationally, and B3O3(OH)52− existing in aqueous solutions was clearly solidified and its Raman vibrational band at 612 cm−1 was identified and reported for the first time.

Glutarimidedioxime favors 1 : 2 neutral uranyl complex species, whereas succinimidedioxime tends to form a cross-linked 2 : 2 binuclear complex with uranyl ions.

Discovery of remarkable porous materials for CO2 capture from wet flue gas is of great significance to reduce the CO2 emissions, but elucidating the most critical structure features for boosting CO2 capture capabilities remains a great challenge. Here, machine learning assisted computational screening on 516 experimental covalent organic frameworks (COFs) identify the superior secondary building units (SBUs) for wet flue gas separation, which are tetraphenylporphyrin unit in sql-type COFs and functional groups. Accordingly, 1233 COFs are assembled using the superior SBUs. Combined with DFT calculations, the “electron-donating induced vdW interaction” effect is discovered to design better-performing COFs with superior CO2 uptake, which can achieve 4.4 mmol·g-1 with CO2/N2 selectivity of 104.8; while the “electron-withdrawing induced vdW+electrostatic coupling interaction” effect is proposed to design better-performing COFs with superior CO2/N2 selectivity, which can arrive 277.6 with CO2 uptake of 2.2 mmol·g-1, in this case, H2O contributes to improving the CO2/N2 selectivity.

The complexation of solid uranyl nitrate with tri-n-butyl phosphate (TBP) in supercritical CO2 is quite different from that of a liquid–liquid extraction system because fewer water molecules are involved. Here, the complexation mechanism was investigated by molecular dynamics simulation, emphasising on speciation distribution analysis. In the anhydrous uranyl nitrate system, poly-core uranyl-TBP species [UO2(NO3)2]2·3TBP and [UO2(NO3)2]3·3TBP were formed in addition to the predominant [UO2(NO3)2]·1TBP and [UO2(NO3)2]·2TBP species. The poly-core species was mainly constructed via the linkage of UO⋯U contributed by pre-developed [UO2(NO3)2]·1TBP species. However, in the hydrated uranyl nitrate system, TBP·[UO2(NO3)2]·H2O species form, preventing the formation of the poly-core species. The complexation developed differently depending on the TBP to the uranyl nitrate ratio, the solute densities and the participation of water. It suggested that the kinetically favoring species would gradually convert into the thermodynamically stable species [UO2(NO3)2]·2TBP by ligand exchange.

CH4 /N2 separation is one of the great challenges in gas separation, which is of scientific and practical importance, such as in the upgrading of unconventional natural gas. Unfortunately, the separation performance is still quite low so far mainly due to their very close physical properties. In this work, a high-throughput computational screening method was performed to develop metal-organic frameworks (MOFs) for efficient CH4 /N2 separation. General designing rules as well as the correlation between selectivity and our proposed adsorbility (AD) parameter were obtained by carrying out systematic GCMC simulations of the existing 5109 CoRE MOFs. With the aid of this information, five virtual MOFs were screened out from the large database with 303 991 generated MOFs constructed in our previous work, exhibiting much higher selectivities than all the reported values. Among them, the selectivity of Zn-PYZ-BPY-1 can reach over 29.0, about 2.4 times of the highest value reported in the literature. These results may not only suggest promising candidates for CH4 /N2 separation but also provide useful information for large screening of MOFs for other specific separation mixtures.

The complexation of solid uranyl nitrate with tri

The complexity of secondary building units (SBUs), an indicator that can not only be calculated but also visually estimated, is proposed as a highly indicative predictor of hydrogen storage performance. With optimal pore sizes and void fractions, selecting COFs consisting of simple SBUs greatly improves the probability of top-performing COFs towards the ultimate DOE hydrogen storage target, as an easy principle for experimentalists to select hydrogen adsorbents.

Ionic liquid/metal–organic framework (IL/MOF) composites show great potential in CO2 capture. Here, we report a large-scale computational assembly of 550 357 IL/MOF composites for CO2/CH4 separation by developing a configurational-bias Monte Carlo (CBMC)-based incorporation method rather than applying the long-time Molecular Dynamics (MD) method. The introduction of ILs into MOFs shows both improvement and good balance of selectivity and working capacity. The results show that the high performing IL/MOF composites are mainly the wire-tube type structures originating from 1,3-dimethyl-imidazolium tetrafluoroborate [MMIM][BF4] and MOFs in sql topology with a pore size of ∼9 A, in which ILs are well confined in the MOFs to form the continuous, cation–anion alternately connected electronic nanowires. This work finds that synergistic adsorption sites can be formed in this wire-tube structure with a suitable size, providing useful information that can guide the future design of IL/MOF composites with improved CO2 capture performance.

Membrane based CO2/CH4 separation is an effective and energy saving way for highly demanded natural gas upgrading. Herein, high-throughput computational screening of covalent organic frameworks (CO...

CH4 storage associated with adsorbed natural gas technology attracts considerable researches on finding porous materials with remarkable CH4 delivery performance. In this work, we update the online accessible computation-ready, experimental (CoRE) covalent organic frameworks (COFs) database with 280 COFs in 12 topologies. All framework structures are constructed and compiled from the respective experimental studies and are further evaluated for CH4 delivery. The highest deliverable capacity (DC) between 65 and 5.8 bar among the CoRE COFs is 190 v(STP)/v at 298 K achieved by 3D PI-COF-4. Structure–property relationships show that large volumetric surface area generally benefits CH4 delivery. 2D-COFs can also be top performing materials if constructing their pore channels is passable in three dimensions, as the volumetric surface area will be increased accordingly. This idea can be realized by enlarging the interlayer spacings of 2D-COFs. We also evaluate the DC of CoRE COFs under conditions of 233 K, 65 ba...

The globally increasing concentrations of greenhouse gases in atmosphere after combustion of coal- or petroleum-based fuels give rise to tremendous interest in searching for porous materials to efficiently capture carbon dioxide (CO2) and store methane (CH4), where the latter is a kind of clean energy source with abundant reserves and lower CO2 emission. Hundreds of thousands of porous materials can be enrolled on the candidate list, but how to quickly identify the really promising ones, or even evolve materials (namely, rational design high-performing candidates) based on the large database of present porous materials? In this context, high-throughput computational techniques, which have emerged in the past few years as powerful tools, make the targets of fast evaluation of adsorbents and evolving materials for CO2 capture and CH4 storage feasible. This review provides an overview of the recent computational efforts on such related topics and discusses the further development in this field. Keywords: High-throughput computation, Screening and design, Nanoporous materials, CO2 capture, CH4 storage.

Two novel molecules (AnRhB-1 and AnRhB-2) were synthesized using Rhodamine B and anthracene as building units via Schiff base chemistry with different spacers. This small structural variation led to a dramatic difference in mechanochromic and photochromic properties in the solid state. They both showed a force-induced color change. However, AnRhB-1 not only displayed two color changes due to the ring-opening isomerization of the rhodamine derivatives, but also exhibited rarely reported photochromic properties. The photochromic behaviour of AnRhB-1 resulted from its large free volume in the amorphous solid state and the relatively high stability of its zwitterionic species in its ring-open form. In contrast, AnRhB-2 gave a tricolored switch upon force action but no photochromic behavior is observed. The three-color variations in this molecule originated from the transformation of the different physical packing modes of anthracene and force-triggered chemical reaction of Rhodamine B lactam. The Schiff base group for the molecular design of mechanochromic and photochromic materials can be extended to other systems, which may open a new strategy to provide a broad perspective for the development of multi-stimuli responsive materials.

An ultramicroporous MOF material, {[Fe(OH)(H2bta)](H2O)}n, was diligently selected for the experimental investigations of ultralow-temperature separation of H2/D2 through quantum sieving. With an extreme two-dimensional confinement experienced by hydrogen molecules, an extraordinary separation factor as high as 41.4 ± 0.4 at 20 K was for the first time obtained from experiment.

Discovering high-performance metal-organic frameworks (MOFs) with open metal sites has become an increasingly hot research topic in the field of safe storage and transportation of acetylene. Following the concept of Materials Genomics proposed recently, a database of 502 experimental MOFs was built by searching the structures deposited in the CSD with the dicopper paddle-wheel node Cu2(COO)4 as the characteristic materials gene. On the basis of the developed ab initio force field, a high-throughput computational screening was conducted to examine the property-performance relationships of MOFs containing Cu-OMS for C2H2 storage at ambient conditions. The optimal ranges of the structural and energetic features for the design of such MOFs were suggested. From our computational screening, three potentially promising MOFs were identified which exhibit a performance outperforming those MOFs reported experimentally so far with record high gravimetric C2H2 uptakes, both in the total and deliverable adsorption capacities. This article is protected by copyright. All rights reserved.

In this work, a 2D covalent triazine-based framework was prepared by using 1,3-dicyanobenzo[c]thiophene (DCBT) as monomer to effectively capture CO2. The resulting CTF-DCBT was characterized by FT-IR, XPS, PXRD, elemental analysis, SEM, TEM, and N2 adsorption-desorption. The results indicate that CTF-DCBT is partially crystalline and has ultramicropore (6.5 A) as well as high heteroatom contents (11.24 wt% and 12.61 wt% for N and S, respectively). In addition, the BET surface area and total pore volume of CTF-DCBT are 500 m2/g and 0.26 cm3/g, respectively. CTF-DCBT possesses excellent thermal stability (450 °C) and chemical stability towards boiling water, 4 M HCl, and 1 M NaOH. The CO2 adsorption capacity of CTF-DCBT is 37.8 cm3/g at 1 bar and 25 °C. After six adsorption–desorption cycles, there is no obvious loss of CO2 uptake observed. Due to the ultramicropore and high heteroatom contents, CTF-DCBT has high isosteric heats of adsorption for CO2 and high selectivities of CO2 over N2 and CH4. At 25 °C, the CO2/N2 and CO2/CH4 selectivities are 112.5 and 10.3, respectively, which are higher than those of most POFs. Breakthrough curves indicate that CTF-DCBT could effectively separate CO2/N2 and CO2/CH4 mixtures.

In this work, a computation-ready, experimental covalent organic framework (CoRE COF) database that nearly covers all the existing COFs was constructed and provided, which contains 187 COFs with disorder-free and solvent-free structures. Using the CoRE COF database established, structure-property relationships of COFs for Kr/Ar, Xe/Kr and Rn/Xe separations were studied. The conditions of industrial vacuum (VSA) and pressure swing adsorption (PSA) processes were considered in the computation. Qualitative rules of COFs for noble gas separations were clarified, and structural features of COFs with excellent separation performance were summarized and suggested. In addition, COFs with good separation performance were identified from our database for industrial cyclic process. The knowledge obtained in this work may give guidance for experimental efforts in seeking advanced materials for noble gas separation, and the CoRE COF database will facilitate the fundamental research of COFs as well as the development of novel functional materials toward practical applications.

CH

Effective capture of radioactive iodic contaminants from nuclear wastes is of great importance for public safety as well as the secure utility of nuclear energy. In this work, a computational study was performed to systematically evaluate the performance of 187 experimentally reported covalent organic frameworks (COFs) for gaseous I2 and CH3I adsorption under real industrial conditions. The results show that 3D-COFs present better performance than 2D-COFs for both I2 and CH3I adsorption. 3D-Py-COF was identified with the highest I2 uptake of 16.7 g g−1, outperforming the adsorbents reported to date. In addition, based on the obtained structure–property relationships, a new 3D-COF with an even higher I2 uptake of 19.9 g g−1 was designed. For CH3I adsorption, the pore morphology plays an important role, and 3D-COFs with ctn topology having a pore size of around 9 A show superiority compared with other COFs. COF-103 was identified as the best material with a CH3I uptake of 2.8 g g−1, which is much higher than those of traditional adsorbents like activated carbons, alumina and zeolites.