"All in One" Strategy for Achieving Superprotonic Conductivity by Incorporating Strong Acids into a Robust Imidazole-Linked Covalent Organic Framework.

The fabrication of solid-state proton-conducting electrolytes possessing both high performance and long-life reusability is significant but challenging. An "all-in-one" composite, H3PO4@PyTFB-1-SO3H, including imidazole, sulfonic acid, and phosphoric acid, which are essential for proton conduction, was successfully prepared by chemical post-modification and physical loading in the rationally pre-synthesized imidazole-based nanoporous covalent organic framework (COF), PyTFB-1. The resultant H3PO4@PyTFB-1-SO3H exhibits superhigh proton conductivity with its value even highly up to 1.15 × 10-1 S cm-1 at 353 K and 98% relative humidity (RH), making it one of the highest COF-based composites reported so far under the same conditions. Experimental studies and theoretical calculations further confirmed that the imidazole and sulfonic acid groups have strong interactions with the H3PO4 molecules and the synergistic effect of these three groups dramatically improves the proton conductivity properties of H3PO4@PyTFB-1-SO3H. This work demonstrated that by aggregating multiple proton carriers into one composite, effective proton-conducting electrolyte can be feasibly achieved.

N2H4 Derived Sulfonic Acids: Hydrazine Disulfonate, [(SO3)HNNH(SO3)]2-, and Hydrazine Iso-disulfonate, [H2NN(SO3)2]2.

The reaction of hydrazinium sulfate and chlorosulfonic acid in pyridine leads to the pyridinium salt of the hydrazine disulfonate anion, [(SO3)HNNH(SO3)]2-. The salt is the starting material for the preparation of further hydrazine disulfonates, for example of alkaline metals and barium. In all compounds, the [(SO3)HNNH(SO3)]2- anion adopts the gauche conformation. The conformer is chiral but all of the investigated compounds crystallize as racemates. The disulfonate anion can occur in another constitution with the two sulfonate groups attached to only one nitrogen atom. This so-called hydrazine iso-disulfonate, [H2NN(SO3)2]2-, has been prepared through a substitution reaction between potassium imidodisulfonate, K2[HN(SO3)2], and hydroxylamine-O-sulfonic acid, H2NOSO3H. The hydrazine iso-disulfonate anion has been crystallized as potassium and barium compound, respectively. The compounds were characterized by XRD, vibrational spectroscopy, DFT calculations and thermal analyses.

Functionalization of High-Density Polyethylene Capillaries for Open Tubular Ion Chromatography.

Ion chromatography is the anion analysis benchmark. A miniature form, Open Tubular Ion Chromatography (OTIC), has attractive attributes for efficient ion separations. Here, we fabricate and characterize high-density polyethylene (HDPE) open tubular anion exchange columns (OTCs). We attach positively charged latex particles onto negatively charged capillary surfaces. For efficient OTIC, column diameters need to be < ∼20 µm; functionalizing the bore is challenging. Methods to introduce acid groups to an HDPE capillary bore, e.g., sulfonation using chlorosulfonic or sulfuric acid solutions, with or without grafting of an aromatic ring through photo- or chemical grafting first, are explored. Following quaternary ammonium latex attachment, the ion exchange capacity and separating abilities of each OTC were measured as an index of OTC performance. Gradual loss of capacity was observed for many of these; high-resolution mass spectrometry confirmed the leaching of detached oxidized/sulfonated oligomeric fragments and consequent poisoning of the latex sites. Ways to ameliorate this and/or to rejuvenate the columns are also described.

Rearrangement of Arylsulfamates and Sulfates to Para-Sulfonyl Anilines and Phenols.

The C(sp2)-aryl sulfonate functional group is found in bioactive molecules, but their synthesis can involve extreme temperatures (>190 °C or flash vacuum pyrolysis) and strongly acidic reaction conditions. Inspired by the 1917 Tyrer industrial process for a sulfa dye that involved an aniline N(sp2)-SO3 intermediate en route to a C(sp2)-SO3 rearranged product, we investigated tributylsulfoammonium betaine (TBSAB) as a milder N-sulfamation to C-sulfonate relay reagent. Initial investigations of a stepwise route involving TBSAB on selected anilines at room temperature enabled the isolation of N(sp2)-sulfamate. Subsequent thermal rearrangement demonstrated the intermediary of a sulfamate en route to the sulfonate; however, it was low-yielding. Investigation of the N-sulfamate to C--sulfonate mechanism through control experiments with variation at the heteroatom positions and kinetic isotope experiments (KIEH/D) confirmed the formation of a key N(sp2)-SO3 intermediate and further confirmed an intermolecular mechanism. Furthermore, compounds without an accessible nitrogen (or oxygen) lone pair did not undergo sulfamation- (or sulfation) -to-sulfonation under these conditions. A one-pot sulfamation and thermal sulfonation reaction was ultimately developed and explored on a range of aniline and heterocyclic scaffolds with high conversions, including N(sp2)-sulfamates (O(sp2)-sulfates) and C(sp2)-sulfonates, in up to 99 and 80% (and 88% for a phenolic example) isolated yield, respectively. Encouragingly, the ability to modulate the ortho-para selectivity of the products obtained was observed under thermal control. A sulfonated analog of the intravenous anesthetic propofol was isolated (88% yield), demonstrating a proof-of-concept modification of a licensed drug alongside a range of nitrogen- and sulfur-containing heterocyclic fragments used in drug discovery.

UiO-66 with Both Brønsted and Lewis Acid Sites for Catalytic Synthesis of Biodiesel.

In the present study, an acid catalyst (UiO-66-SO3H) with Brønsted and Lewis acid sites was synthesised for the preparation of highly efficient biodiesel from oleic acid and methanol using chlorosulphonic acid sulfonated metal-organic frameworks (UiO-66) prepared with acetic acid as a moderator. The prepared catalysts were characterised using XRD, SEM, FT-IR and BET. The catalytic efficiency of the sulfonated catalysts was significantly improved and successful sulfonation was demonstrated by characterisation techniques. Biodiesel was synthesised by the one-pot method and an 85.0% biodiesel yield was achieved under optimum conditions of the reaction. The esterification reaction was determined to be consistent with a proposed primary reaction and the kinetics of the reaction was investigated. A reusability study of the catalyst (UiO-66-SO3H) was also carried out with good reproducibility. In conclusion, the present study provides some ideas for the synthesis of catalysts with high catalytic activity for the application in the catalytic preparation of biodiesel.

Efficient Preparation of Biodiesel Using Sulfonated Camellia oleifera Shell Biochar as a Catalyst.

This study prepared sulfonated Camellia oleifera shell biochar using Camellia oleifera shell agricultural waste as a carbon source, and evaluated its performance as a catalyst for preparing biodiesel. The biochar obtained from carbonizing Camellia oleifera shells at 500 °C for 2 h serves as the carbon skeleton, and then the biochar is sulfonated with chlorosulfonic acid. The sulfonic acid groups are mainly grafted onto the surface of Camellia oleifera shell biochar through covalent bonding to obtain sulfonic acid type biochar catalysts. The catalysts were characterized by Scanning Electron Microscope (SEM), X-ray diffraction (XRD), Nitrogen adsorption-desorption Brunel-Emmett-Taylor Theory (BET), and Fourier-transform infrared spectroscopy (FT-IR). The acid density of the sulfonated Camellia oleifera fruit shell biochar catalyst is 2.86 mmol/g, and the specific surface area is 2.67 m2/g, indicating high catalytic activity. The optimal reaction conditions are 4 wt% catalyst with a 6:1 alcohol to oil ratio. After esterification at 70 °C for 2 h, the yield of biodiesel was 91.4%. Under the optimal reaction conditions, after four repeated uses of the catalyst, the yield of biodiesel still reached 90%. Therefore, sulfonated Camellia oleifera shell biochar is a low-cost, green, non-homogeneous catalyst with great potential for biodiesel production by esterification reaction in future development.

Speciation and molecular characterization of thiophenic and sulfide compounds in petroleum by sulfonation and methylation followed by electrospray mass spectrometry.

Thiophenes and sulfides are the dominant sulfur-containing compounds in petroleum and have been widely of concern in the fields of petroleum refining and geochemistry. In this study, a novel approach was developed for selective separation and characterization of petroleum-derived thiophenic and sulfide compounds. Thiophenic compounds were selectively converted to sulfonates in the presence of vitriolic acid and can be characterized by negative ion electrospray mass spectrometry. Thiophenic sulfonates were further separated from the oil by silica chromatography and enabled the molecular characterization of sulfides in the residual oil. Various model sulfur compounds and a vacuum gas oil were used to validate the method; thiophenic and sulfide biomarker compounds in a well-documented crude oil were selectively characterized. The results indicate that the approach is feasible for molecular characterization of thiophenic and sulfide compounds, which is complementary to recently developed methods for separation and/or ionization of sulfur compounds in petroleum.

Distributed Li-Ion Flux Enabled by Sulfonated Covalent Organic Frameworks for High-Performance Lithium Metal Anodes.

Metallic Li is considered the most promising anode material for high-energy-density batteries owing to its high theoretical capacity and low electrochemical potential. However, inhomogeneous lithium deposition and uncontrollable growth of lithium dendrites result in low lithium utilization, rapid capacity fading, and poor cycling performance. Herein, two sulfonated covalent organic frameworks (COFs) with different sulfonated group contents are synthesized as the multifunctional interlayers in lithium metal batteries. The sulfonic acid groups in the pore channels can serve as Li-anchoring sites that effectively coordinate Li ions. These periodically arranged subunits significantly guide uniform Li-ion flux distribution, guarantee smooth Li deposition, and reduce lithium dendrite formation. Consequently, these characteristics afford an excellent quasi-solid-state electrolyte with a high ionic conductivity of 1.9 × 10-3  S  cm-1 at room temperature and a superior Li++ transference number of 0.91. A Li/LiFePO4 battery with the COF-based electrolyte exhibited dendrite-free Li deposition during the charge process, accompanied by no capacity decay after 100 cycles at 0.1 C.

Naphthalene-Based Polymers as Catalytic Supports for Suzuki Cross-Coupling.

In this work, for the first time, naphthalene (NA)-based polymers were synthesized by one-stage Friedel-Crafts crosslinking. The influence of NA functionalization by -OH, -SO3H, and -NO2 groups on the polymers' porosity and distribution of the catalytically active phase (Pd) was studied. Synthesized catalytic systems containing 1 wt.% of Pd either in the form of Pd(II) species or Pd(0) nanoparticles supported on NA-based polymers were tested in a model reaction of Suzuki cross-coupling between 4-bromoanisole and phenylboronic acid under mild reaction conditions (60 °C, ethanol-water mixture as a solvent). These novel catalysts demonstrated high efficiency with more than 95% of 4-bromoanisole conversion and high selectivity (>97%) for the target 4-methoxybiphenyl.

Enhanced hydrolytic removal of tylosin in wastewater using polymer-based solid acid catalysts converted from polystyrene.

Antibiotic production wastewater usually contains high concentrations of antibiotic residues, which can cause instability and deterioration of biological wastewater treatment units and also domestication and proliferation of antibiotic-resistance bacteria. An effective pretreatment on antibiotics production wastewater is expected to selectively reduce the concentration of antibiotics and decrease the toxicity, rather than mitigate organic and other contaminants before further treatments. In this work, two polymer-based solid acids, PS-S and CPS-S bearing high concentrations of -SOH3 groups (up to 4.57 mmol/g), were prepared and successfully used for hydrolytic mitigation of 100 mg/L tylosin within 20 min. The co-existence of high concentrations of COD and humic substances did not affect the mitigation of tylosin obviously, while more than 500 mg/L of nitrogenous compounds suppressed the hydrolytic efficiency. Recycle and reuse experiments showed that the solid acids performed well in five cycles after regeneration. Three transformation products (P1, P2 and P3) were identified using UPLC-QTOF-MS/MS. Sugar moieties including mycarse, mycaminose, and mycinose detached and released simultaneously or in order from the 16-member lactone ring through desugarization, which led to a dramatic decrease in antibacterial activity as revealed by cytotoxicity evaluations using S. aureus. Ecotoxicity estimation indicated the acute toxicities of the hydrolyzed products to model species (e.g., fish, daphnid and green algae) were classified as "not harmful". This work suggested an effective and selective method to pretreat tylosin-contained production wastewater by using polymer-based solid acids. These results will shed light on effective elimination of antibiotics pollution from pharmaceutical industries through strengthening the pretreatments.

Biosynthesis mechanism, genome mining and artificial construction of echinocandin O-sulfonation.

Micafungin, a semisynthetic derivative of the cyclic hexapeptide FR901379 produced by Coleophoma empetri fermentation, is the only O-sulfonated echinocandin-type antifungal drug. However, the detailed formation mechanism of O-sulfonate group, whether before or after the assembly of hexapeptide, remains elusive. Here, we confirmed that O-sulfonylation occurs after hexapeptide assembly as a kind of postmodification in the biosynthesis of FR901379. The released cyclic hexapeptide was hydroxylated by cytochrome P450 McfP and successively sulfonated by sulfotransferase McfS. And other three echinocandin sulfotransferases were identified through genome mining by using McfS as a sequence probe. Moreover, pneumocandin B0, the precursor of caspofungin, could be O-sulfonated by heterologously introducing the McfP-McfS into the pneumocandin B0-producing species Glarea lozoyensis. The water-solubility of sulfonated pneumocandin B0 is 4000 times higher than that of pneumocandin B0. The revealed O-sulfonation mechanism will provide new insights into the design and production of novel sulfonated echinocandins by metabolic engineering.

Polyethylene-Derived Activated Carbon Materials for Commercially Available Supercapacitor in an Organic Electrolyte System.

High-performance supercapacitors based on activated carbons (AC) derived from polyethylene (PE), which is one of the most abundant plastic materials worldwide, are fabricated. First, PE carbons (PEC) are prepared via sulfonation, which is a reported solution for successful carbonization of innately non-carbonizable PE. Then, the physico-electrical changes of PECs upon a chemical activation process are explored. Interestingly, upon the chemical activation, PECs are converted ACs with a large surface area and high crystallinity at the same time. Subsequently, PE-derived ACs (PEAC) are exploited as electrode materials for supercapacitors. Resultant supercapacitors based on PEACs exhibit impressive performance. When compared to supercapacitors based on YP50f, representative commercial ACs, devices using PEACs presented considerably good capacitance, low resistance, and great rate capability. Specifically, the retention rate of devices using PEACs is significantly higher than that of YP50f-based devices. At the high rate of charge-discharge situation reaching 7 A g-1 , the capacitance of supercapacitors using PEACs is ≈70% higher than that of YP50f-based devices. It is assumed that the carbon structure accompanying both large surface area and high conductivity endows a great electrochemical performance at the high current operating conditions. Therefore, it is envisioned that PE may be a viable candidate electrode material for commercially available supercapacitors.

Reactive Adsorption Performance and Behavior of Gaseous Cumene on MCM-41 Supported Sulfuric Acid.

Efficient removal of cumene from gaseous streams and recovery of its derivatives was accomplished using a MCM-41-supported sulfuric acid (SSA/MCM-41) adsorbent. The results indicated that the removal performance of the SSA/MCM-41 for cumene was significantly influenced by the process conditions such as bed temperature, inlet concentration, bed height, and flow rate. The dose-response model could perfectly describe the collected breakthrough adsorption data. The SSA/MCM-41 adsorbent exhibited a reactive temperature region of 120-170 °C, in which the cumene removal ratios (Xc) were greater than 97%. Rising the bed height or reducing the flow rate enhanced the theoretical adsorption performance metrics, such as theoretical breakthrough time (tB,th) and theoretical breakthrough adsorption capacity (QB,th), whereas increasing the inlet concentration resulted in tB,th shortening and QB,th rising. As demonstrated in this paper, the highest tB,th and QB,th were 69.60 min and 324.50 mg g-1, respectively. Meanwhile, the spent SSA/MCM-41 could be desorbed and regenerated for cyclic reuse. Moreover, two recoverable adsorbed products, 4-isopropylbenzenesulfonic acid and 4, 4'-sulfonyl bis(isopropyl-benzene), were successfully separated and identified using FTIR and 1H/13C NMR characterization. Accordingly, the relevance of a reactive adsorption mechanism was confirmed. This study suggests that the SSA/MCM-41 has remarkable potential for application as an adsorbent for the resource treatment of cumene pollutants.

Investigation of Sulfonated Graphene Oxide as the Base Material for Novel Proton Exchange Membranes.

This work deals with the development of graphene oxide (GO)-based self-assembling membranes as possible innovative proton conductors to be used in polymer electrolyte membrane fuel cells (PEMFCs). Nowadays, the most adopted electrolyte is Chemours' Nafion; however, it reveals significant deficiencies such as strong dehydration at high temperature and low humidity, which drastically reduces its proton conductivity. The presence of oxygenated moieties in the GO framework makes it suitable for functionalization, which is required to enhance the promising, but insufficient, proton-carrying features of GO. In this study, sulfonic acid groups (-SO3H) that should favor proton transport were introduced in the membrane structure via a reaction between GO and concentrated sulfuric acid. Six acid-to-GO molar ratios were adopted in the synthesis procedure, giving rise to final products with different sulfonation degrees. All the prepared samples were characterized by means of TGA, ATR-FTIR and Raman spectroscopy, temperature-dependent XRD, SEM and EDX, which pointed out morphological and microstructural changes resulting from the functionalization stage, confirming its effectiveness. Regarding functional features, electrochemical impedance spectroscopy (EIS) as well as measurements of ion exchange capacity (IEC) were carried out to describe the behavior of the various samples, with pristine GO and commercial Nafion® 212 used as reference. EIS tests were performed at five different temperatures (20, 40, 60, 80 and 100 °C) under high (95%) and medium (42%) relative humidity conditions. Compared to both GO and Nafion® 212, the sulfonated specimens demonstrate an increase in the number of ion-carrying groups, as proved by both IEC and EIS tests, which reveal the enhanced proton conductivity of these novel membranes. Specifically, an acid-to-GO molar ratio of 10 produces a six-fold improvement of IEC (4.23 meq g-1) with respect to pure GO (0.76 meq g-1), while a maximum eight-fold improvement (5.72 meq g-1) is achieved in SGO-15.

New Process for the Sulfonation of Algal/PEI Biosorbent for Enhancing Sr(II) Removal from Aqueous Solutions-Application to Seawater.

Sulfonic resins are highly efficient cation exchangers widely used for metal removal from aqueous solutions. Herein, a new sulfonation process is designed for the sulfonation of algal/PEI composite (A*PEI, by reaction with 2-propylene-1-sulfonic acid and hydroxylamine-O-sulfonic acid). The new sulfonated functionalized sorbent (SA*PEI) is successfully tested in batch systems for strontium recovery first in synthetic solutions before investigating with multi-component solutions and final validation with seawater samples. The chemical modification of A*PEI triples the sorption capacity for Sr(II) at pH 4 with a removal rate of up to 7% and 58% for A*PEI and SA*PEI, respectively (with SD: 0.67 g L-1). FTIR shows the strong contribution of sulfonate groups for the functionalized sorbent (in addition to amine and carboxylic groups from the support). The sorption is endothermic (increase in sorption with temperature). The sulfonation improves thermal stability and slightly enhances textural properties. This may explain the fast kinetics (which are controlled by the pseudo-first-order rate equation). The sulfonated sorbent shows a remarkable preference for Sr(II) over competitor mono-, di-, and tri-valent metal cations. Sorption properties are weakly influenced by the excess of NaCl; this can explain the outstanding sorption properties in the treatment of seawater samples. In addition, the sulfonated sorbent shows excellent stability at recycling (for at least 5 cycles), with a loss in capacity of around 2.2%. These preliminary results show the remarkable efficiency of the sorbent for Sr(II) removal from complex solutions (this could open perspectives for the treatment of contaminated seawater samples).

Electrochemically Initiated Synthesis of Methanesulfonic Acid.

The direct sulfonation of methane to methanesulfonic acid was achieved in an electrochemical reactor without adding peroxide initiators. The synthesis proceeds only from oleum and methane. This is possible due to in situ formation of an initiating species from the electrolyte at a boron-doped diamond anode. Elevated pressure, moderate temperature and suitable current density are beneficial to reach high concentration at outstanding selectivity. The highest concentration of 3.7 M (approximately 62 % yield) at 97 % selectivity was reached with a stepped electric current program at 6.25-12.5 mA cm-2 , 70 °C and 90 bar methane pressure in 22 hours. We present a novel, electrochemical method to produce methanesulfonic acid, propose a reaction mechanism and show general dependencies between parameters and yields for methanesulfonic acid.

Reperfusion mediates heme impairment with increased protein cysteine sulfonation of mitochondrial complex III in the post-ischemic heart.

A serious consequence of myocardial ischemia-reperfusion injury (I/R) is oxidative damage, which causes mitochondrial dysfunction. The cascading ROS can propagate and potentially induce heme bleaching and protein cysteine sulfonation (PrSO3H) of the mitochondrial electron transport chain. Herein we studied the mechanism of I/R-mediated irreversible oxidative injury of complex III in mitochondria from rat hearts subjected to 30-min of ischemia and 24-h of reperfusion in vivo. In the I/R region, the catalytic activity of complex III was significantly impaired. Spectroscopic analysis indicated that I/R mediated the destruction of hemes b and c + c1 in the mitochondria, supporting I/R-mediated complex III impairment. However, no significant impairment of complex III activity and heme damage were observed in mitochondria from the risk region of rat hearts subjected only to 30-min ischemia, despite a decreased state 3 respiration. In the I/R mitochondria, carbamidomethylated C122/C125 of cytochrome c1 via alkylating complex III with a down regulation of HCCS was exclusively detected, supporting I/R-mediated thioether defect of heme c1. LC-MS/MS analysis showed that I/R mitochondria had intensely increased complex III PrSO3H levels at the C236 ligand of the [2Fe2S] cluster of the Rieske iron­sulfur protein (uqcrfs1), thus impairing the electron transport activity. MS analysis also indicated increased PrSO3H of the hinge protein at C65 and of cytochrome c1 at C140 and C220, which are confined in the intermembrane space. MS analysis also showed that I/R extensively enhanced the PrSO3H of the core 1 (uqcrc1) and core 2 (uqcrc2) subunits in the matrix compartment, thus supporting the conclusion that complex III releases ROS to both sides of the inner membrane during reperfusion. Analysis of ischemic mitochondria indicated a modest reduction from the basal level of complex III PrSO3H detected in the mitochondria of sham control hearts, suggesting that the physiologic hyperoxygenation and ROS overproduction during reperfusion mediated the enhancement of complex III PrSO3H. In conclusion, reperfusion-mediated heme damage with increased PrSO3H controls oxidative injury to complex III and aggravates mitochondrial dysfunction in the post-ischemic heart.

Structure of mouse cytosolic sulfotransferase SULT2A8 provides insight into sulfonation of 7α-hydroxyl bile acids.

Cytosolic sulfotransferases (SULTs) catalyze the transfer of a sulfonate group from the cofactor 3'-phosphoadenosine 5'-phosphosulfate to a hydroxyl (OH) containing substrate and play a critical role in the homeostasis of endogenous compounds, including hormones, neurotransmitters, and bile acids. In human, SULT2A1 sulfonates the 3-OH of bile acids; however, bile acid metabolism in mouse is dependent on a 7α-OH sulfonating SULT2A8 via unknown molecular mechanisms. In this study, the crystal structure of SULT2A8 in complex with adenosine 3',5'-diphosphate and cholic acid was resolved at a resolution of 2.5 Å. Structural comparison with human SULT2A1 reveals different conformations of substrate binding loops. In addition, SULT2A8 possesses a unique substrate binding mode that positions the target 7α-OH of the bile acid close to the catalytic site. Furthermore, mapping of the critical residues by mutagenesis and enzyme activity assays further highlighted the importance of Lys44 and His48 for enzyme catalysis and Glu237 in loop 3 on substrate binding and stabilization. In addition, limited proteolysis and thermal shift assays suggested that the cofactor and substrates have protective roles in stabilizing SULT2A8 protein. Together, the findings unveil the structural basis of bile acid sulfonation targeting 7α-OH and shed light on the functional diversity of bile acid metabolism across species.

Sulfonated 2D Covalent Organic Frameworks for Efficient Proton Conduction.

Open 1D channels found in covalent organic frameworks are unique and promising to serve as pathways for proton conduction; how to develop high-rate yet stable transporting systems remains a substantial challenge. Herein, this work reports a strategy for exploring proton-conducting frameworks by engineering pore walls and installing proton-containing polymers into the pores. Amide-linked and sulfonated frameworks were synthesized from imine-linked precursors via sequentially engineering to oxidize into amide linkages and to further anchor sulfonic acid groups onto the pore walls, enabling the creation of sulfonated frameworks with high crystallinity and channel ordering. Integrating sulfonated polyether ether ketone chains into the open channels enables proton hopping to across the channels, greatly increases proton conductivity and enables a stable continuous run. These results suggest a way to explore proton-conducting COFs via systematic engineering of the wall and space of the open nanochannels.

Recent Progress on the Synthesis of Chiral Sulfones.

Chiral sulfones extensively exist in drugs, agricultural chemicals, chiral organic intermediates, and functional materials. Their importance causes the rapid development of their synthetic methods in recent years. Many transition metal complex catalysts with chiral ligands and chiral organocatalysts are adopted in synthesis of chiral sulfones. Most of the methods to construct chiral sulfones are based on the reduction of unsaturated sulfones and the introduction of sulfone groups into unsaturated hydrocarbons. This review describes all classes of asymmetric reactions for synthesis of chiral sulfones.