Synthesis of aromatic polynitroso compounds: Towards functional azodioxy-linked porous polymers

The polymerization property of aromatic polynitroso compounds could be used to create azodioxy porous networks with possible application for the adsorption of CO2, the main greenhouse gas. Herein, we report the synthesis and characterization of new aromatic polynitroso compounds, with para-nitroso groups attached to the triphenylbenzene, triphenylpyridine, triphenyltriazine and triphenylamine moiety. The synthesis of the pyridine-based trinitroso compound was performed by reduction of the corresponding trinitro derivative to N-arylhydroxylamine followed by oxidation to the trinitroso product. For the synthesis of the benzene- and triazine-based trinitroso compounds, a novel synthetic strategy was implemented, which included cyclotrimerization of the 4-nitrosoacetophenone and 4-nitrosobenzonitrile, respectively. Reduction of the trinitro compound with triphenylamine unit produced the dinitroso product. In a solid state, all synthesized compounds form E-azodioxy oligomers or polymers. While azodioxy polymer with triphenylbenzene moiety is an amorphous solid, other azodioxy oligomers and polymers displayed sharp diffraction peaks pointing to their crystalline nature. A computational study indicated that eclipsed AA configurations are preferred over staggered AB and inclined AA' configurations. The serrated layers may be the most likely outcome when/if 2D layers form an organized polymer network of azodioxy linked triphenyltriazine-based building blocks.

An overview of the synthetic strategies of C3-symmetric polymeric materials containing benzene and triazine cores and their biomedical applications

C3-symmetric star-shaped materials are an emerging category of porous organic polymers with distinctive properties such as permanent porosity, good thermal and chemical stability, high surface area, and appropriate functionalization that promote outstanding potential in various applications. This review is mostly about constructing benzene or s-triazine rings as the center of C3-symmetric molecules and using side-arm reactions to add functions to these molecules. Over and above this, the performance of various polymerization processes has been additionally investigated in detail, including the trimerization of alkynes or aromatic nitriles, polycondensation of monomers with specific functional groups, and cross-coupling building blocks with benzene or triazine cores. Finally, the most recent progress in biomedical applications for C3-symmetric materials based on benzene or s-triazine have been summarized.

Synthesis and Characterization of Benzene- and Triazine-Based Azo-Bridged Porous Organic Polymers

Porous organic polymers incorporating nitrogen-rich functionalities have recently emerged as promising materials for efficient and highly selective CO₂ capture and separation. Herein, we report synthesis and characterization of new two-dimensional (2D) benzene- and triazine-based azo-bridged porous organic polymers. Different synthetic approaches towards the porous azo-bridged polymers were tested, including reductive homocoupling of aromatic nitro monomers, oxidative homocoupling of aromatic amino monomers and heterocoupling of aromatic nitro monomers and a series of aromatic diamines of different lengths and rigidity. IR spectroscopy, ¹³C CP/MAS NMR spectroscopy, powder X-ray diffraction, elemental analysis, thermogravimetric analysis, nitrogen adsorption-desorption experiments and computational study were used to characterize structures and properties of the resulting polymers. The synthesized azo-bridged polymers are all amorphous solids of good thermal stability, exhibiting various surface areas (up to 351 m² g^-1). The obtained results indicated that the synthetic methods and building units have a pronounced effect on the porosity of the final materials. Reductive and oxidative homocoupling of aromatic nitro and amino building units, respectively, lead to 2D azo-bridged polymers of substantially higher porosity when compared to those produced by heterocoupling reactions. Periodic DFT calculations and Grand-canonical Monte Carlo (GCMC) simulations suggested that, within the used approximations, linear linkers of different lengths do not significantly affect CO₂ adsorption properties of model azo-bridged polymers.

Increased CO2 Affinity and Adsorption Selectivity in MOF-801 Fluorinated Analogues

The novel Zr^IV-based perfluorinated metal-organic framework (PF-MOF) [Zr₆O₄(OH)₄(TFS)₆] (ZrTFS) was prepared under solvent-free conditions using the commercially available tetrafluorosuccinic acid (H₂TFS) as a bridging ditopic linker. Since H₂TFS can be seen as the fully aliphatic and perfluorinated C₄ analogue of fumaric acid, ZrTFS was found to be isoreticular to zirconium fumarate (MOF-801). The structure of ZrTFS was solved and refined from X-ray powder diffraction data. Despite this analogy, the gas adsorption capacity of ZrTFS is much lower than that of MOF-801; in the former, the presence of bulky fluorine atoms causes a considerable window size reduction. To have PF-MOFs with more accessible porosity, postsynthetic exchange (PSE) reactions on (defective) MOF-801 suspended in H₂TFS aqueous solutions were carried out. Despite the different H₂TFS concentrations used in the PSE process, the exchanges yielded two mixed-linker materials of similar minimal formulae [Zr₆O₄(μ₃-OH)₄(μ₁-OH)_2.08(H₂O)_2.08(FUM)_4.04(HTFS)_1.84] (PF-MOF1) and [Zr₆O₄(μ₃-OH)₄(μ₁-OH)_1.83(H₂O)_1.83(FUM)_4.04(HTFS)_2.09] (PF-MOF2) (FUM^2- = fumarate), where the perfluorinated linker was found to fully replace the capping acetate in the defective sites of pristine MOF-801. CO₂ and N₂ adsorption isotherms collected on all samples reveal that both CO₂ thermodynamic affinity (isosteric heat of adsorption at zero coverage, Q_st) and CO₂/N₂ adsorption selectivity increase with the amount of incorporated TFS^2-, reaching the maximum values of 30 kJ mol^-1 and 41 (IAST), respectively, in PF-MOF2. This confirms the beneficial effect coming from the introduction of fluorinated linkers in MOFs on their CO₂ adsorption ability. Finally, solid-state density functional theory calculations were carried out to cast light on the structural features and on the thermodynamics of CO₂ adsorption in MOF-801 and ZrTFS. Due to the difficulties in modeling a defective MOF, an intermediate structure containing both linkers in the framework was also designed. In this structure, the preferential CO₂ adsorption site is the tetrahedral pore in the "UiO-66-like" structure. The extra energy stabilization stems from a hydrogen bond interaction between CO₂ and a hydroxyl group on the inorganic cluster.

Temperature-Dependent Nitrous Oxide/Carbon Dioxide Preferential Adsorption in a Thiazolium-Functionalized NU-1000 Metal-Organic Framework

Solvent-assisted ligand incorporation (SALI) of the ditopic linker 5-carboxy-3-(4-carboxybenzyl)thiazolium bromide [(H₂PhTz)Br] into the zirconium metal-organic framework NU-1000 [Zr₆O₄(OH)₈(H₂O)₄(TBAPy)₂, where NU = Northwestern University and H₄TBAPy = 1,3,6,8-tetrakis(p-benzoic-acid)pyrene], led to the SALIed NU-1000-PhTz material of minimal formula [Zr₆O₄(OH)₆(H₂O)₂(TBAPy)₂(PhTz)]Br. NU-1000-PhTz has been thoroughly characterized in the solid state. As confirmed by powder X-ray diffraction, this material keeps the same three-dimensional architecture of NU-1000 and the dicarboxylic extra linker bridges adjacent [Zr₆] nodes ca. 8 Å far apart along the crystallographic c-axis. The functionalized MOF has a BET specific surface area of 1560 m²/g, and it is featured by a slightly higher thermal stability than its parent material (T_dec = 820 vs. 800 K, respectively). NU-1000-PhTz has been exploited for the capture and separation of two pollutant gases: carbon dioxide (CO₂) and nitrous oxide (N₂O). The high thermodynamic affinity for both gases [isosteric heat of adsorption (Q_st) = 25 and 27 kJ mol^-1 for CO₂ and N₂O, respectively] reasonably stems from the strong interactions between these (polar) "stick-like" molecules and the ionic framework. Intriguingly, NU-1000-PhTz shows an unprecedented temperature-dependent adsorption capacity, loading more N₂O in the 298 K ≤ T ≤ 313 K range but more CO₂ at temperatures falling out of this range. Grand canonical Monte Carlo simulations of the adsorption isotherms confirmed that the preferential adsorption sites of both gases are the triangular channels (micropores) in close proximity to the polar pillar. While CO₂ interacts with the thiazolium ring in an "end-on" fashion through its O atoms, N₂O adopts a "side-on" configuration through its three atoms simultaneously. These findings open new horizons in the discovery of functional materials that may discriminate between polluting gases through selective adsorption at different temperatures.

A Solvent-Polarity-Induced Interface Self-Assembly Strategy towards Mesoporous Triazine-Based Carbon Materials

Triazine-based materials with porous structure have recently received numerous attentions as a fascinating new class because of their superior potential for various applications. However, it is still a formidable challenge to obtain triazine-based materials with precise adjustable meso-scaled pore sizes and controllable pore structures by reported synthesis approaches. Herein, we develop a solvent polarity induced interface self-assembly strategy to construct mesoporous triazine-based carbon materials. In this method, we employ a mixed solvent system within a suitable range of polarity (0.223≤Lippert-Mataga parameter (Δf) ≤0.295) to induce valid self-assembly of skeleton precursor and surfactant. The as-prepared mesoporous triazine-based carbon materials possess uniform tunable pore sizes (8.2-14.0 nm), high surface areas and ultrahigh nitrogen content (up to 18 %). Owing to these intriguing advantages, the fabricated mesoporous triazine-based carbon materials as functionalized porous solid absorbents exhibit predominant CO₂ adsorption performance and exceptional selectivity for the capture of CO₂ over N₂ .

Multi-functional porous organic polymers for highly-efficient solid-phase extraction of β-agonists and β-blockers in milk

A simple, accurate, and highly sensitive analytical method was developed in this study for the determination of ten β-agonists and five β-blockers in milk. In this method, new adsorbent phosphonic acid-functionalized porous organic polymers were synthesized through a direct knitting method. The synthesis procedure of the materials and the extraction conditions (such as the composition of loading buffer and eluent) were optimized. Benefitting from the high surface area (545–804 m² g⁻¹), multiple functional framework and good porosity, the phosphonic acid-functionalized porous organic polymers showed a high adsorption rate and high adsorption capacity for β-agonists (224 mg g⁻¹ and 171 mg g⁻¹ for clenbuterol and ractopamine, respectively). The analytes were quantified by ultra-high-performance liquid chromatography coupled to high-resolution tandem mass spectrometry. It showed a good linearity (with R² ranging from 0.9950 to 0.9991 in the linear range of 3–5 orders of magnitude), with low limits of quantification ranging from 0.05 to 0.25 ng g⁻¹. The limits of detection of the method for the analytes were measured to be in the range of 0.02 to 0.1 ng g⁻¹. The recoveries of target analytes from real samples on the material were in the range of 62.4–119.4% with relative standard deviations of 0.6–12.1% (n = 4). Moreover, good reproducibility of the method was obtained with the interday RSD being lower than 11.7% (n = 5) and intraday RSD lower than 12.2% (n = 4). The proposed method was accurate, reliable and convenient for the simultaneous analysis of multiple β-agonists and β-blockers. Finally, the method was successfully applied for the analysis of such compounds in milk samples.

Novel phosphonic acid-functionalized porous organic polymers were synthesized through direct knitting method. It shows high adsorption efficiency and high adsorption capacity for multiple β-agonists and β-blockers analysis.

Covalent Triazine Frameworks Based on the First Pseudo-Octahedral Hexanitrile Monomer via Nitrile Trimerization: Synthesis, Porosity, and CO2 Gas Sorption Properties

Herein, we report the first synthesis of covalent triazine-based frameworks (CTFs) based on a hexanitrile monomer, namely the novel pseudo-octahedral hexanitrile 1,4-bis(tris(4'-cyano-phenyl)methyl)benzene 1 using both ionothermal reaction conditions with ZnCl2 at 400 °C and the milder reaction conditions with the strong Brønsted acid trifluoromethanesulfonic acid (TFMS) at room temperature. Additionally, the hexanitrile was combined with different di-, tri-, and tetranitriles as a second linker based on recent work of mixed-linker CTFs, which showed enhanced carbon dioxide captures. The obtained framework structures were characterized via infrared (IR) spectroscopy, elemental analysis, scanning electron microscopy (SEM), and gas sorption measurements. Nitrogen adsorption measurements were performed at 77 K to determine the Brunauer-Emmett-Teller (BET) surface areas range from 493 m2/g to 1728 m2/g (p/p0 = 0.01-0.05). As expected, the framework CTF-hex6 synthesized from 1 with ZnCl2 possesses the highest surface area for nitrogen adsorption. On the other hand, the mixed framework structure CTF-hex4 formed from the hexanitrile 1 and 1,3,5 tricyanobenzene (4) shows the highest uptake of carbon dioxide and methane of 76.4 cm3/g and 26.6 cm3/g, respectively, at 273 K.

Nitrogen-rich covalent triazine frameworks for high-efficient removal of anion dyes and the synergistic adsorption of cationic dyes

Efficient adsorption of organic dyes from effluent has great importance for ecological and environmental protection. Herein, covalent triazine frameworks (CTFs) were constructed via the polycondensation of melamine and cyanuric chloride directly. Due to the numerous basic nitrogen atoms as high as 58.98 wt%, high BET surface area (670.2 m g^-1), and hierarchical pore structure, CTFs demonstrated selective adsorption of anionic dyes in high capacity (e.g., a maximum adsorption capacity of 1581 mg g^-1 for Congo red at 30 °C). The mechanism of the outstanding adsorption performance was carefully verified and ascribed to the electrostatic attraction and hydrogen bonding between CTFs and anionic dyes. The amine groups linking two adjacent triazine rings have primary responsibility for the superior performance. Unexpectedly, CTFs expressed a tuning synergetic effect for removing cationic dyes in aqueous solution coexisting with anionic dyes, exhibiting a great superiority in the specific and comprehensive treatment of organic dyes contaminated water. Furthermore, CTFs were stable and had long-periodic availability for more than 6 times, ensuring the adsorption rate higher than 90%. For better operation, hybrid monolithic aerogels were constructed by incorporating CTFs into polyvinylidene fluoride then casting in melamine resin foams. The obtained aerogels expressed high-efficient removal of anionic dyes coupled with convenient operation. This well-established metal-free porous material is a promising adsorbent candidate for anionic dyes selectively and even synergetic adsorption of cationic dyes in water remediation.

A Pressure Swing Approach to Selective CO2 Sequestration Using Functionalized Hypercrosslinked Polymers

Functionalized hypercrosslinked polymers (HCPs) with surface areas between 213 and 1124 m²/g based on a range of monomers containing different chemical moieties were evaluated for CO₂ capture using a pressure swing adsorption (PSA) methodology under humid conditions and elevated temperatures. The networks demonstrated rapid CO₂ uptake reaching maximum uptakes in under 60 s. The most promising networks demonstrating the best selectivity and highest uptakes were applied to a pressure swing setup using simulated flue gas streams. The carbazole, triphenylmethanol and triphenylamine networks were found to be capable of converting a dilute CO₂ stream (>20%) into a concentrated stream (>85%) after only two pressure swing cycles from 20 bar (adsorption) to 1 bar (desorption). This work demonstrates the ease with which readily synthesized functional porous materials can be successfully applied to a pressure swing methodology and used to separate CO₂ from N₂ from industrially applicable simulated gas streams under more realistic conditions.

Temporary (P[double bond, length as m-dash]O) directing group enabled carbazole ortho arylation via palladium catalysis

A palladium-catalyzed, temporary P(O) directing group assisted C-H bond arylation of carbazoles was achieved. The release of the directing group occurs spontaneously in the reaction and the mechanistic studies indicate that acid is essential for N-P bond cleavage.

Creation of Carbazole-Based Fluorescent Porous Polymers for Recognition and Detection of Various Pesticides in Water

The development of sensitive, fast, and portable methods for detecting the residual toxic pesticides is essentially important because of the increasing concerns for public health and safety. For this purpose, three fluorescent porous organic polymers containing pendant N-benzyl carbazole, N-benzyl dibromo-carbazole, and N-benzyl dimethoxy-carbazole groups were synthesized via a one-step polymerization reaction. The resultant polymers emit bright cyan, blue, and green light under the ultraviolet lamp, respectively, with the Brunauer-Emmett-Teller area up to 858 m² g^-1 and tunable pore sizes in the range of 0.5-36 nm. Six pesticides including trifluralin, isopropalin, glyphosate, fenitrothion, imidacloprid, and cyfluothrin are selected as the analytes to investigate the recognition and detection ability of polymers in terms of the different photo-physical properties of polymers, chemical structure of organic pesticides as well as the pore sizes of polymers, and molecular sizes of pesticides. It is interesting to find that, even though in water medium, the measured fluorescent quenching Stern-Volmer coefficient for trifluralin still reaches 26,040 L mol^-1 and is nearly unchanged under both acidic or basic service conditions. Moreover, the test paper prepared from the polymer exhibits a rapid fluorescent response when contacting the aqueous trifluralin dispersion liquid, and the sensitivity remains stable after recycling use for twelve times.

An unsymmetrical covalent organic polymer for catalytic amide synthesis

Herein, we present the first report on the Covalent Organic Polymer (COP) directed non-classical synthesis of an amide bond. An economical route has been chosen for the synthesis of APC-COP using p-aminophenol and cyanuric chloride. APC-COP acts as a smart, valuable and sustainable catalyst for efficient access to the amide bond under mild conditions at room temperature in 30 min. APC-COP exhibits selectivity towards carboxylic acids over esters. The key features of this protocol involve the variety of parameters, viz. wider substrate scope, no use of additive and recyclability, which makes this approach highly desirable in gramscale synthesis. Moreover, we have shown the practical utility of the present method in the catalytic synthesis of paracetamol.

A novel indole-based conjugated microporous polymer for highly effective removal of heavy metals from aqueous solution via double cation-π interactions

A novel indole-based conjugated microporous polymer (PTIA) with three coplanar indole units, designed and synthesized by an oxidative coupling reaction, was utilized as a platform for removing heavy metals. Owing to the conjugation of the three coplanar indoles, the highly electron-rich large π planes can simultaneously attract six heavy metal atoms via double cation-π interactions, endowing this microporous material with remarkable heavy metal adsorption capacity and efficiency.

A novel carboxylic-functional indole-based aerogel for highly effective removal of heavy metals from aqueous solution via synergistic effects of face-point and point-point interactions

A new type of carboxylic-functional indole-based aerogel (CHIFA) has been successfully prepared via a facile sol–gel technology, which possessed a highly effective removal of heavy metals from aqueous solution through the synergistic effects of face–point and point–point interactions.

A new type of carboxylic-functional indole-based aerogel (CHIFA) has been successfully prepared, which possessed highly effective removal of heavy metals from aqueous solution through the synergistic effects of face–point and point–point interactions.

Tuning Carbon Dioxide Adsorption Affinity of Zinc(II) MOFs by Mixing Bis(pyrazolate) Ligands with N-Containing Tags

The four zinc(II) mixed-ligand metal-organic frameworks (MIXMOFs) Zn(BPZ)_x(BPZNO₂)_1-x, Zn(BPZ)_x(BPZNH₂)_1-x, Zn(BPZNO₂)_x(BPZNH₂)_1-x, and Zn(BPZ)_x(BPZNO₂)_y(BPZNH₂)_1-x-y (H₂BPZ = 4,4'-bipyrazole; H₂BPZNO₂ = 3-nitro-4,4'-bipyrazole; H₂BPZNH₂ = 3-amino-4,4'-bipyrazole) were prepared through solvothermal routes and fully investigated in the solid state. Isoreticular to the end members Zn(BPZ) and Zn(BPZX) (X = NO₂, NH₂), they are the first examples ever reported of (pyr)azolate MIXMOFs. Their crystal structure is characterized by a three-dimensional open framework with one-dimensional square or rhombic channels decorated by the functional groups. Accurate information about ligand stoichiometric ratio was determined (for the first time on MIXMOFs) through integration of selected ligands skeleton resonances from ¹³C cross polarized magic angle spinning solid-state NMR spectra collected on the as-synthesized materials. Like other poly(pyrazolate) MOFs, the four MIXMOFs are thermally stable, with decomposition temperatures between 708 and 726 K. As disclosed by N₂ adsorption at 77 K, they are micro-mesoporous materials with Brunauer-Emmett-Teller specific surface areas in the range 400-600 m²/g. A comparative study (involving also the single-ligand analogues) of CO₂ adsorption capacity, CO₂ isosteric heat of adsorption (Q_st), and CO₂/N₂ selectivity in equimolar mixtures at p = 1 bar and T = 298 K cast light on interesting trends, depending on ligand tag nature or ligand stoichiometric ratio. In particular, the amino-decorated compounds show higher Q_st values and CO₂/N₂ selectivity vs the nitro-functionalized analogues; in addition, tag "dilution" [upon passing from Zn(BPZX) to Zn(BPZ)_x(BPZX)_1-x] increases CO₂ adsorption selectivity over N₂. The simultaneous presence of amino and nitro groups is not beneficial for CO₂ uptake. Among the compounds studied, the best compromise among uptake capacity, Q_st, and CO₂/N₂ selectivity is represented by Zn(BPZ)_x(BPZNH₂)_1-x.

Rational design of functionalized covalent organic frameworks and their performance towards CO2 capture

We describe the design and synthesis of two new functionalized covalent organic frameworks, named Cz-COF and Tz-COF, by using monomers containing carbazole and benzobisthiazole as building blocks. The resultant materials possess high crystallinity, permanent porosities as well as abundant heteroatom activated sites in the framework. As solid adsorbents, both COFs exhibit excellent CO2 uptake (11.0 wt% for Cz-COF and 15.4 wt% for Tz-COF), high adsorption selectivity for CO2 over N2 and good recyclability.

Efficient and Selective Methane Borylation Through Pore Size Tuning of Hybrid Porous Organic-Polymer-Based Iridium Catalysts

As a new energy source that could replace petroleum, the global reserves of methane hydrate (combustible ice) are estimated to be approximately 20 000 trillion cubic meters. A large amount of methane hydrate has been found under the seabed, but the transportation and storage of methane gas far from coastlines are technically unfeasible and expensive. The direct conversion of methane into value-added chemicals and liquid fuels is highly desirable but remains challenging. Herein, we prepare a series of iridium complexes based on porous polycarbazoles with high specific areas and good thermochemical stabilities. Through structure tuning we optimized their catalytic activities for the selective monoborylation of methane. One of these catalysts (CAL-3-Ir) can produce methyl boronic acid pinacol ester (CH₃ Bpin) in 29 % yield in 9 h with a turnover frequency (TOF) of approximately 14 h^-1 . Because its pore sizes favor monoborylated products, it has a high chemoselectivity for monoborylation (CH₃ Bpin:CH₂ (Bpin)₂ =16:1).

Playing with covalent triazine framework tiles for improved CO2 adsorption properties and catalytic performance

The rational design and synthesis of covalent triazine frameworks (CTFs) from defined dicyano-aryl building blocks or their binary mixtures is of fundamental importance for a judicious tuning of the chemico-physical and morphological properties of this class of porous organic polymers. In fact, their gas adsorption capacity and their performance in a variety of catalytic transformations can be modulated through an appropriate selection of the building blocks. In this contribution, a set of five CTFs (CTF1-5) have been prepared under classical ionothermal conditions from single dicyano-aryl or heteroaryl systems. The as-prepared samples are highly micro-mesoporous and thermally stable materials featuring high specific surface area (up to 1860 m2·g-1) and N content (up to 29.1 wt %). All these features make them highly attractive samples for carbon capture and sequestration (CCS) applications. Indeed, selected polymers from this series rank among the CTFs with the highest CO2 uptake at ambient pressure reported so far in the literature (up to 5.23 and 3.83 mmol·g-1 at 273 and 298 K, respectively). Moreover, following our recent achievements in the field of steam- and oxygen-free dehydrogenation catalysis using CTFs as metal-free catalysts, the new samples with highest N contents have been scrutinized in the process to provide additional insights to their complex structure-activity relationship.

Highly Porous Hypercrosslinked Polymers Derived from Biobased Molecules

Highly porous and hyper-cross-linked polymers (HCPs) have a range of applications and are typically synthesized in an unsustainable manner. Herein, HCPs were synthesized from abundant biobased or biorelated compounds in sulfolane with iron(III) chloride as Lewis acid catalyst. As reactants, quercetin, tannic acid, phenol, 1,4-dimethoxybenzene, glucose, and a commercial bark extract were used. The HCPs had high CO₂ uptake (up to 3.94 mmol g^-1 at 0 °C and 1 bar), total pore volumes (up to 1.86 cm³  g^-1 ), and specific surface areas (up to 1440 m²  g^-1 ). ¹ H NMR, ¹³ C NMR, and IR spectroscopy, wide-angle X-ray scattering, elemental analysis, and SEM revealed, for example, that the HCPs consisted of amorphous and cross-linked aromatic and phenolic structures with significant contents of aliphatics, oxygen, and sulfur.

Amino-functionalized hypercrosslinked polymers for highly selective anionic dye removal and CO2/N2 separation

Recently, great improvements have been achieved in the fabrication of adsorbents.

Amino-decorated bis(pyrazolate) metal–organic frameworks for carbon dioxide capture and green conversion into cyclic carbonates

The amino-tagged bis(pyrazolate) MOF Zn(BPZNH2) is an excellent CO₂ adsorbent and CO₂ epoxidation catalyst under green conditions.

Fabrication and adsorption performance for CO2 capture of advanced nanoporous microspheres enriched with amino acids

Advanced porous organic materials with high gas storage capacity and high selectivity have been rapidly developed for CO₂ adsorbents in the recent decade, due to extremely high surface area and nanoscale pore size. Here, novel amino acids-incorporated solid adsorbents based on porous hypercrosslinked polymers were fabricated by a dispersion polymerization of an aromatic monomer and quaternary ammonium salt comonomer, subsequently a hypercrosslinked reaction and an ion-exchange step. The developed adsorbents presented mesopores structure with BET surface area up to 864 m²/g and an extremely high CO₂ capturing capacity up to 60.7 wt% (13.8 mmol/g) at 273 K/1 bar. The results also showed the adsorbent had an excellent recycling ability over repetitive adsorption-desorption cycles. All the results suggest that the amino acids-modified porous sorbents are promising CO₂ sorbents that can meet the challenges of the current CO₂ capture and storage technology.

Engineering nanoporous organic frameworks to stabilize naked Au clusters: a charge modulation approach

A simple charge modulation approach has been developed to stabilize naked Au clusters on a nanoporous conjugated organic network. Through engineering pore walls with regulated charges, the controllable growth of Au nanoclusters has been realized. The resulting supported catalyst exhibits excellent performance in the aerobic oxidation of alcohols.

Facile preparation of microporous organic polymers functionalized macroporous hydrophilic resin for selective enrichment of glycopeptides

A macroporous adsorption resin (MAR) with ∼10 μm diameter was synthesized by seed-swelling polymerization and further modified with a layer of microporous organic polymers (MOP) by "one-pot" solvothermal reaction. The resulting MAR@MOP exhibited high specific surface area of 131.3 m²/g, which was higher than that of pristine MAR (57.8 m²/g). The contact angle also decreased from 58.8° (MAR) to 24° (MAR@MOP), indicating that the MOP was successfully grafted onto the surface of MAR. The chemical composition of MAR@MOP was confirmed by Fourier-transform infrared spectroscopy, ¹³C NMR and element analysis. The enrichment efficiency of MAR@MOP to glycopeptides was demonstrated by trapping N-linked glycopeptides from tryptic digests of human immunoglobulin G (IgG), horseradish peroxidase (HRP) and bovine fetuin. Furthermore, 879 unique N-glycosylation sites in 811 unique glycopeptides sequence mapped to 516 N-glycosylated proteins were identified in three replicate analyses of proteins extracted from mouse liver. Therefore, this hydrophilic MOP-coated adsorbent would be applied in the enrichment and identification of low-abundance N-linked glycopeptides in complicated biological samples.

Nitrogen and sulfur Co-doped microporous activated carbon macro-spheres for CO2 capture

Millimeter-sized nitrogen and sulfur co-doped microporous activated carbon spheres (NSCSs) were first synthesized from poly(styrene-vinylimidazole-divinylbenzene) resin spheres through concentrated H₂SO₄ sulfonation, carbonization and KOH activation. Styrene (ST) and N-vinylimidazole (VIM) were carbon and nitrogen sources, while the sulfonic acid functional groups introduced by the simple concentrated sulfuric acid sulfonation worked simultaneously as cross-linking agent and sulfur source during the following thermal treatments. It was found that the surface chemistries, textural structures, and CO₂ adsorption performances of the NSCSs were significantly affected by the addition of VIM. The NSCS-4-700 sample with a molar ratio of ST: VIM = 1: 0.75 showed the best CO₂ uptake at different temperatures and pressures. An exhaustive adsorption evaluation indicated that CO₂ sorption at low pressures originated from the synergistic effect of surface chemistry and micropores below 8.04 Å, while at the moderate pressure of 8.0 bar, CO₂ uptake was dominated by the volume of micropores. The thermodynamics suggested the exothermic and orderly nature of the adsorption process, which was dominated by a physisorption mechanism. The high CO₂ adsorption capacity, fast kinetic adsorption rate, and great regeneration stability of the nitrogen and sulfur co-doped activated carbon spheres indicated that the as-prepared carbon adsorbents were good candidates for large-scale CO₂ capture.

Hypercrosslinked porous polymer materials: design, synthesis, and applications

Hypercrosslinked polymers (HCPs) are a series of permanent microporous polymer materials initially reported by Davankov, and have received an increasing level of research interest. In recent years, HCPs have experienced rapid growth due to their remarkable advantages such as diverse synthetic methods, easy functionalization, high surface area, low cost reagents and mild operating conditions. Judicious selection of monomers, appropriate length crosslinkers and optimized reaction conditions yielded a well-developed polymer framework with an adjusted porous topology. Post fabrication of the as developed network facilitates the incorporation of various chemical functionalities that may lead to interesting properties and enhance the selection toward a specific application. To date, numerous HCPs have been prepared by post-crosslinking polystyrene-based precursors, one-step self-polycondensation or external crosslinking strategies. The advent of these methodologies has prompted researchers to construct well-defined porous polymer networks with customized micromorphology and functionalities. In this review, we describe not only the basic synthetic principles and strategies of HCPs, but also the advancements in the structural and morphological study as well as the frontiers of potential applications in energy and environmental fields such as gas storage, carbon capture, removal of pollutants, molecular separation, catalysis, drug delivery, sensing etc.