Selective and Orthogonal Post-Polymerization Modification using Sulfur(VI) Fluoride Exchange (SuFEx) and Copper-Catalyzed Azide–Alkyne Cycloaddition (CuAAC) Reactions

Selective Ring-Opening Polymerization of Silyl Glycidyl Ether through Organocatalysis

Silyl ether constitutes a multipurpose (macro)molecular functionality for being, e.g., SuFEx-clickable and easily cleavable as a hydroxyl precursor. Its direct incorporation by anionic polymerization is challenged by its base susceptibility. In this study, a two-component organocatalyst shows strict epoxy-selectivity in the anionic ring-opening polymerization (ROP) of commercially available tert-butyldimethylsilyl (R)-(-)-glycidyl ether (TBSGE). The silyl ether pendant groups are fully preserved in the resultant polyether and readily undergo acidic hydrolysis to yield well-defined linear polyglycerol (PGC). Combination of the ROP with mechanistically distinct polymerization chemistries delivers PGC-based polyurethane and a hybrid amphiphilic block copolymer. The SuFEx reaction with sulfonyl fluoride shows effective tuning of polyTBSGE into a sulfonate-functionalized polyether. We have thus exploited the chemoselectivity of organocatalysis to facilitate access to polymers carrying reactive pendant functionalities.

A Mild Method for the Activation of Cation Exchange Membranes Used in Tubular PEM Electrolyzers

Co-extrusion of both half-cells in tubular PEM water electrolyzers can lower the costs for hydrogen production, since the number of components is reduced and the production process is simplified. However, after co-extrusion of the inner half-cell and the ion exchange membrane, the membrane is in its fluoride sulfonyl form and must be hydrolyzed to achieve the proton conductive sulfonic acid to be ready for use. Common practice is the hydrolysis using concentrated alkaline solutions, which causes a corrosion of the laminated anode electrode. We developed a less corrosive method using triethylsilanol as reactant. Tubular membranes hydrolyzed with this new procedure were characterized and tested in an electrolyzer laboratory test setup.

Non-activated Esters as Reactive Handles in Direct Post-Polymerization Modification

Non-activated esters are prominently featured functional groups in polymer science, as ester functional monomers display great structural diversity and excellent compatibility with a wide range of polymerization mechanisms. Yet, their direct use as a reactive handle in post-polymerization modification has been typically avoided due to their low reactivity, which impairs the quantitative conversion typically desired in post-polymerization modification reactions. While activated ester approaches are a well-established alternative, the modification of non-activated esters remains a synthetic and economically valuable opportunity. In this review, we discuss past and recent efforts in the utilization of non-activated ester groups as a reactive handle to facilitate transesterification and aminolysis/amidation reactions, and the potential of the developed methodologies in the context of macromolecular engineering.

Synthesis of Pyrazolo[1,5-a]pyridinyl, Pyrazolo[1,5-a]quinolinyl, and Pyrazolo[5,1-a]isoquinolinyl Sulfonyl Fluorides via a [3 + 2] Annulation

A [3 + 2] cycloaddition reaction of N-aminopyridines, N-aminoquinolines, and N-aminoisoquinolines with 1-bromoethene-1-sulfonyl fluoride (BESF) was performed to obtain optimum yields of various useful pyrazolo[1,5-a]pyridinyl, pyrazolo[1,5-a]quinolinyl, and pyrazolo[5,1-a]isoquinolinyl sulfonyl fluorides (43-90% yield). The transformation process showed broad substrate specificity, mild reaction conditions, and operational simplicity. Therefore, the reaction has great applicable value in the field of medicinal chemistry and other disciplines.

Chiral Binaphthol Fluorescent Materials Based on a Novel Click Reaction

Because of easy functionalization, low cost, and large-scale fabrication, pure organic fluorescent polymers are widely applied in light-emitting display, bio-fluorescence-enhanced imaging, explosive detection, and other fields. Among these applications, due to their unique optical rotation characteristics, chiral fluorescent polymer materials are part of fluorescent polymers which could be used in chiral molecular detection and separation, biological target detection, etc. In this work, we designed and synthesized the first chiral organic fluorescent polysulfate materials through sulfur fluoride exchange polymerization (new click chemistry) by asymmetric binaphthol molecular. The chiral fluorescent polysulfate were synthesized by R/S [1,1′-binaphthalene]-2,2′-diol(Binol.), propane-2,2-diylbis(4,1-phenylene) bis(sulfurofluoridate) (FO2S–BA–SO2F) and 4,4′-(propane-2,2-diyl)diphenol(BA.) through step-by-step polymerization reaction under alkali present. It was found that the local crystallization of pure bisphenol A polysulfate was broken by the asymmetric axial chiral BINOL molecule inserted in it and let the polymer into the amorphous state. Fluorescent chiral molecules are uniformly dispersed in the polymer; the 120 µm film prepared by the film scraper was transparent and had good luminescence characteristics under ultraviolet light. After fluorescence detection, the excitation wavelength is 450 nm, and the emission wavelength is 480 and 517 nm.

Acid-Mediated Imidazole-to-Fluorine Exchange for the Synthesis of Sulfonyl and Sulfonimidoyl Fluorides

Sulfur(VI) fluoride motifs are important entities in organic chemistry. Typically, their syntheses involve the corresponding chlorides, which are often difficult to prepare and characterized by a poor storability due to the inherently weak S-Cl bond. Here, a single-step procedure for the preparation of sulfur(VI) fluorides starting from sulfonyl imidazoles as stable S(VI) reservoirs is described. By using a simple combination of AcOH and potassium bifluoride (KF₂H), an imidazole-to-fluorine exchange furnishes a variety of sulfonyl, sulfonimidoyl, sulfoxyl, and sulfamoyl fluorides in good to excellent yields.

Fluorescent Composites Prepared of Tb3+ and Sulfonated Sulfate Polymer Constructed through Post-Sulfonation Sulfur-Fluorine Exchange Polymerization by Symmetric Molecular

Organic fluorescent materials are widely applied in different important fields, such as light-emitting display, explosive detection, molecular imprinting, and so on, because of their low cost, easy functionalization, and large-scale fabrication. In this work, we designed and synthesized a new kind of organic fluorescent polysulfate composite material through post-sulfonation sulfur-fluorine exchange polymerization (a new kind of click chemistry) by symmetric molecular. Sulfur-fluorine exchange polymerization: symmetrical structure SO2F−R1−SO2F molecular reacted with symmetrical OH−R2−OH molecular through nucleophilic reaction in the presence of inorganic base. The polysulfate material was further modified by ClSO3H to get PSE−SO3H materials. Tb3+ was highly dispersed on PSE−SO3H to afford organic-inorganic hybrid fluorescent materials through the conventional coordination chemistry method. The emission wavelength of the organic-inorganic hybrid fluorescent polymer PSE−SO3H−Tb3+ was between 475 and 685 nm, the quantum yield reached 1.18%, and fluorescence lifetime lasted for 730.168 us, with the pure green light emission and long light-emitting lifetime. The fluorescence film was prepared through phase transformation method by the fluorescent polymer material PSE−SO3H−Tb3+. The film has the strong stability property in different pH conditions (pH 1~13). Thus, this kind of organic fluorescent polysulfate composite material may have certain prospects application in terms of detection and luminescence in extreme chemical environments in the future.

Highly Efficient and para-Selective C-H Functionalization of Polystyrene Providing a Versatile Platform for Diverse Applications

Postpolymerization modification of polystyrene (PS) can afford numerous value-added materials with different functions and applications, but it has been hampered by the lack of efficient methods. We report herein a highly efficient and para-selective conversion of the C-H bonds of the aromatic ring of PS into diverse functional groups using a combination of thianthrenation and thio-Suzuki-Miyaura coupling reaction. Notably, the thianthrenation efficiency of PS is as high as 99% and the degree of thianthrenation can be conveniently controlled using stoichiometric tuning of the amount of thianthrene-S-oxide added, resulting in 24-99 mol % thianthrenation. In the subsequent thio-Suzuki-Miyaura coupling reaction, 18 functionalized PS containing various functional groups (-CH₂OH, -OMe, -SMe, -OTBS, -CH₃, -NHBoc, -OCOMe, -CHO, -COMe, -Si(Me)₃, etc.) were successfully prepared with a high degree of functionalization (64-99 mol %). The obtained functionalized PS can be readily converted into diverse functional materials, including solid-phase synthesis resins, aggregation-induced emission fluorophores, as well as ionomer binders and ion-exchange membranes for energy conversion devices. This method imparts diverse functionality onto PS with extremely high efficiency and selectivity, providing a versatile platform to transform existing commodity PS plastics into high-performance materials.

Synthesis and 18F Labeling of Alkenyl Sulfonyl Fluorides via an Unconventional Elimination Pathway

A successful Cu-catalyzed addition of both Cl and SO₂OCF₂H groups into alkenes allows us to discover the unusual reactivity of the SO₂OCF₂H group. As opposed to common sulfonic esters (RSO₂-O-R'), in which the R' group is highly electrophilic, the SO₂ moiety demonstrates higher electrophilicity in RSO₂-OCF₂H. The unexpected reactivity is further developed not only as a synthetic tool for well-functionalized alkenyl sulfonyl fluorides but also for the first ¹⁸F labeling of alkenyl sulfonyl fluorides.

SuFExable NH-Pyrazoles via 1,3-Dipolar Cycloadditions of Diazo Compounds with Bromoethenylsulfonyl Fluoride

"Click" reactions have transformed the molecular sciences. Augmenting cycloaddition reactions, sulfur(VI) fluoride exchange (SuFEx) chemistry has diversified the landscape of molecular assembly. Herein, we report a facile strategy to access SuFExable NH-pyrazoles via strain and catalyst-free 1,3-dipolar cycloadditions of stabilized diazo compounds under mild conditions. Subsequent SuFEx proceeds efficiently with various N- and O-nucleophiles. Access to SuFExable NH-pyrazoles─a class of compounds containing two common pharmacophores─enables future opportunities within drug discovery, chemical biology, materials chemistry, and related fields.

RAFT-Based Polymers for Click Reactions

The parallel development of reversible deactivation radical polymerization and click reaction concepts significantly enriches the toolbox of synthetic polymer chemistry. The synergistic effect of combining these approaches manifests itself in a growth of interest to the design of well-defined functional polymers and their controlled conjugation with biomolecules, drugs, and inorganic surfaces. In this review, we discuss the results obtained with reversible addition–fragmentation chain transfer (RAFT) polymerization and different types of click reactions on low- and high-molar-mass reactants. Our classification of literature sources is based on the typical structure of macromolecules produced by the RAFT technique. The review addresses click reactions, immediate or preceded by a modification of another type, on the leaving and stabilizing groups inherited by a growing macromolecule from the chain transfer agent, as well as on the side groups coming from monomers entering the polymerization process. Architecture and self-assembling properties of the resulting polymers are briefly discussed with regard to their potential functional applications, which include drug delivery, protein recognition, anti-fouling and anti-corrosion coatings, the compatibilization of polymer blends, the modification of fillers to increase their dispersibility in polymer matrices, etc.

Copper-Promoted Conjugate Addition of Carboxylic Acids to Ethenesulfonyl Fluoride (ESF) for Constructing Aliphatic Sulfonyl Fluorides

A CuO-promoted direct hydrocarboxylation of ethenesulfonyl fluoride (ESF) was developed using carboxylic acid as a nucleophile under mild conditions. A variety of molecules containing both ester group and aliphatic sulfonyl fluoride moiety exhibit great potential in medicinal chemistry and chemical biology. Furthermore, the modification of the known drugs Ibuprofen and Aspirin was also demonstrated.

Sequential Post-Polymerization Modification of Aldehyde Polymers to Ketone and Oxime Polymers

A new sequential post-polymerization modification route has been developed for the synthesis of multifunctional polymers from a simple aldehyde polymer. In the first modification step, a template polymer derived from the radical polymerization of 4-vinyl benzaldehyde undergoes Rh-catalyzed hydroacylation with alkenes to furnish a group of ketone polymers. In the second modification step, Schiff base formation with alkoxy ammonium salts introduces a second group-an oxime functionality. Both the steps are highly efficient, introducing evenly distributed dual functionalities at the same position.

SuFEx-Click Approach for the Synthesis of Soluble Polymer-Bound MacMillan Catalysts for the Asymmetric Diels–Alder Reaction

Novel polymeric MacMillan catalysts were prepared from modified chiral imidazolidin-4-one monomers via sulfur(VI) fluoride exchange chemistry. The resulting polysulfates containing chiral imidazolidin-4-one units could be employed as polymeric organocatalysts for the asymmetric Diels–Alder reaction. With the use of these polysulfate catalysts, sufficient catalytic activity and enantioselectivity were obtained, which were similar to those obtained by monomeric catalysts in a homogeneous catalytic reaction. In addition, the polysulfate catalysts could be recovered and reused five times without a considerable loss of activity and selectivity.

SuFExable polymers with helical structures derived from thionyl tetrafluoride

Sulfur(VI) fluoride exchange (SuFEx) is a category of click chemistry that enables covalent linking of modular units through sulfur(VI) connective hubs. The efficiency of SuFEx and the stability of the resulting bonds have led to polymer chemistry applications. Now, we report the SuFEx click chemistry synthesis of several structurally diverse SOF₄-derived copolymers based on the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers). This polymer class presents two key characteristics. First, the [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and undergo precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate helical polymer structures. The robust nature of SuFEx click chemistry offers the potential for post-polymerization modification, enabling the synthesis of materials with control over composition and conformation.

Side-Chain Type Polysulfates: Their Synthesis, AIE Properties and Applications for p-Nitrophenol Detection in Water

Two small molecular monomers, ph-TPE and ph-TPE-CN, and their homopolymers Poly (ph-TPE) and Poly (ph-TPE-CN) containing tetra phenylethylene and sulfate structures, were synthesized by a sulfur (VI) fluorine exchange click reaction (SuFEx) and radical polymerization. All the monomers and polymers exhibit a typical aggregation-induced emission (AIE) effect both in the solid state and aggregated state. Moreover, based on the intermolecular charge transfer (ICT) effect between the tetra phenylethylene chromophore and p-nitrophenol, both polymers could be used for the selective detection of p-nitrophenol. The detection limit and reactivity coefficient of Poly (ph-TPE) are 0.081 μM and 5.15×10⁴  M^-1 , respectively, whereas the detection limit and reactivity coefficient of Poly (ph-TPE-CN) are 0.077 μM and 1.81×10⁴  M^-1 , respectively. This can be attributed to the greater sensitivity of Poly (ph-TPE-CN) to p-nitrophenol than that of Poly (ph-TPE). This work provides a new methodology for the preparation and broadening application of side-chain type AIE-active polysulfate fluorescent probes.

Efficient hierarchical models for reactivity of organic layers on semiconductor surfaces

Computational modeling of organic interface formation on semiconductors poses a challenge to a density functional theory-based description due to structural and chemical complexity. A hierarchical approach is presented, where parts of the interface are successively removed in order to increase computational efficiency while maintaining the necessary accuracy. First, a benchmark is performed to probe the validity of this approach for three model reactions and five dispersion corrected density functionals. Reaction energies are generally well reproduced by generalized gradient approximation-type functionals but accurate reaction barriers require the use of hybrid functionals. Best performance is found for the model system that does not explicitly consider the substrate but includes its templating effects. Finally, this efficient model is used to provide coverage dependent reaction energies and suggest synthetic principles for the prevention of unwanted growth termination reactions for organic layers on semiconductor surfaces.

One-step synthesis of poly(methacrylate)-b-polyester via “one organocatalyst, two polymerizations”

In a “one organocatalyst, two polymerizations” system, triarylsulfonium hexafluorophosphate salt could spontaneously catalyze photo-ATRP and ROP. A well-defined PTMC-b-PMMA block copolymer was successfully synthesized in one-step.

A novel three-component reaction for constructing indolizine-containing aliphatic sulfonyl fluorides

A copper-catalyzed three-component reaction for transforming quinolines, isoquinolines and pyridines to a class of indolizine-containing alkyl sulfonyl fluorides was developed.

Facile Multicomponent Polymerization and Postpolymerization Modification via an Effective Meldrum's Acid-Based Three-Component Reaction

Providing access to highly diverse polymer structures by multicomponent reactions is highly desirable; efficient Meldrum's acid-based multicomponent reactions, however, have been rarely highlighted in polymer chemistry. Here, the three-component reaction of Meldrum's acid, indole, and aldehyde is introduced into polymer synthesis. Direct multicomponent polymerization of Meldrum's acid, dialdehyde, and diindole can perform under mild conditions, resulting in complex Meldrum's acid-containing polymers with well-defined structures, and high molecular weights. Additionally, nearly quantitative postpolymerization modification can also perform via this Meldrum's acid-based multicomponent reaction. These results indicate that Meldrum's acid-based multicomponent reaction will be a potential tool to prepare novel polymers.

Complementary Base Lowers the Barrier in SuFEx Click Chemistry for Primary Amine Nucleophiles

The sulfur(VI) fluoride exchange (SuFEx) reaction is an emerging scheme for connecting molecular building blocks. Due to its broad functional group tolerance and rather stable resulting linkage, it is seeing rapid adoption in various fields of chemistry. Still, to date the reaction mechanism is poorly understood, which hampers further development. Here, we show that the mechanism of the SuFEx reaction for the prototypical example of methanesulfonyl fluoride reacting with methylamine can be understood as an SN2-type reaction. By analyzing the reaction path with the help of density functional theory in vacuo and under consideration of solvent and co-reactant influence, we identify the often used complementary base as a crucial ingredient to lower the reaction barrier significantly by increasing the nucleophilicity of the primary amine. With the help of energy decomposition analysis at the transition state structures, we quantify the underlying stereoelectronic effects and propose new avenues for experimental exploration of the potential of SuFEx chemistry.

Sulfuryl Fluoride Mediated Synthesis of Amides and Amidines from Ketoximes via Beckmann Rearrangement

A metal-free and redox-neutral method for Beckmann rearrangement employing inexpensive and readily available SO₂ F₂ gas is described. The reported transformation proceeds at ambient temperature and is compatible with a wide range of sterically and electronically diverse aromatic, heteroaromatic, aliphatic and lignin-like oximes providing amides in good to excellent yields. The reaction proceeds through the formation of an imidoyl fluoride intermediate that can also be used for the synthesis of amidines.

AIE-active polysulfates via a sulfur(vi) fluoride exchange (SuFEx) click reaction and investigation of their two-photon fluorescence and cyanide detection in water and in living cells

Three polysulfates P1, P2 and P3 containing two representative AIE-active groups, tetraphenyl ethylene and naphthylamide, were successfully synthesized based on a sulfur(vi) fluoride exchange (SuFEx) click reaction.

Preparation of aryl polysulfonates via a highly efficient SuFEx click reaction, their controllable degradation and functionalized behavior

Polysulfonates obtained from SuFEx click reaction can be degraded using DBU. The degradation process was further utilized to prepare functional polymers.

Rh-Catalyzed Highly Enantioselective Synthesis of Aliphatic Sulfonyl Fluorides

Rh-catalyzed, highly enantioselective (up to 99.8% ee) synthesis of aliphatic sulfonyl fluorides was accomplished. This protocol provides a portal to a class of novel 2-aryl substituted chiral sulfonyl fluorides, which are otherwise extremely difficult to access. This asymmetric synthesis has the feature of mild conditions, excellent functional group compatibility, and wide substrate scope (51 examples) generating a wide array of structurally unique chiral β-arylated sulfonyl fluorides for sulfur(VI) fluoride exchange (SuFEx) click reaction and drug discovery.

SuFEx-enabled, agnostic discovery of covalent inhibitors of human neutrophil elastase

Sulfur fluoride exchange (SuFEx) has emerged as the new generation of click chemistry. We report here a SuFEx-enabled, agnostic approach for the discovery and optimization of covalent inhibitors of human neutrophil elastase (hNE). Evaluation of our ever-growing collection of SuFExable compounds toward various biological assays unexpectedly revealed a selective and covalent hNE inhibitor: benzene-1,2-disulfonyl fluoride. Synthetic derivatization of the initial hit led to a more potent agent, 2-(fluorosulfonyl)phenyl fluorosulfate with IC₅₀ 0.24 μM and greater than 833-fold selectivity over the homologous neutrophil serine protease, cathepsin G. The optimized, yet simple benzenoid probe only modified active hNE and not its denatured form.

Biocompatible SuFEx Click Chemistry: Thionyl Tetrafluoride (SOF4 )-Derived Connective Hubs for Bioconjugation to DNA and Proteins

We report here the development of a suite of biocompatible SuFEx transformations from the SOF4 -derived iminosulfur oxydifluoride hub in aqueous buffer conditions. These biocompatible SuFEx reactions of iminosulfur oxydifluorides (R-N=SOF2 ) with primary amines give sulfamides (8 examples, up to 98 %), while the reaction with secondary amines furnish sulfuramidimidoyl fluoride products (8 examples, up to 97 %). Likewise, under mild buffered conditions, phenols react with the iminosulfur oxydifluorides (Ar-N=SOF2 ) to produce sulfurofluoridoimidates (13 examples, up to 99 %), which can themselves be further modified by nucleophiles. These transformations open the potential for asymmetric and trisubstituted linkages projecting from the sulfur(VI) center, including versatile S-N and S-O connectivity (9 examples, up to 94 %). Finally, the SuFEx bioconjugation of iminosulfur oxydifluorides to amine-tagged single-stranded DNA and to BSA protein demonstrate the potential of SOF4 -derived SuFEx click chemistry in biological applications.

Synthesis and Properties of Side-Chain Functionalized Polytetrahydrofuran Derivatives via the Blue-Light Photocatalytic Thiol-Ene Reaction

A series of side-chain functionalized polytetrahydrofuran (PTHF) derivatives were synthesized via the blue-light photocatalytic thiol-ene "click" reaction. Firstly, unsaturated polytetrahydrofuran (UPTHF) as a new unsaturated polyether was synthesized via condensation polymerization of cis-2-butene-1,4-diol and trans-1,4-dibromo-2-butene using potassium hydroxide (KOH) as a catalyst. Then, double bonds in the backbone of UPTHF were modified into different pendant functionality side groups by blue-light photocatalytic thiol-ene "click" reaction using Ru(bpy)₃Cl₂ as a photoredox catalyst, obtaining different side-chain functionalized PTHF derivatives. The structure and the morphology of the side-chain functionalized PTHF derivatives was characterized via Fourier-transform infrared spectra (FTIR), nuclear magnetic resonance (NMR), size exclusion chromatography/multi-angle laser light scattering (SEC/MALLS), and differential scanning calorimeter (DSC). The results showed that the blue-light photocatalytic thiol-ene reaction exhibited high efficiency, and all the unsaturated bonds were modified. Different branch units bestowed different performance of PTHF derivatives; we systematically investigated the thermal properties, pH-triggered and temperature-triggered, self-assembly behaviors of different PTHF derivatives.

Applications of sulfuryl fluoride (SO2F2) in chemical transformations

A number of novel methodologies concerning the chemical, biological and medicinal applications of sulfuryl fluoride (SO₂F₂) gas have dramatically improved year by year.

Postpolymerization modification based on dynamic imine chemistry for the synthesis of functional polyacetylenes

This study established a postpolymerization modification method for the preparation of functional polyacetylenes based on dynamic imine chemistry.

Site-selective conversion of azido groups at carbonyl α-positions into oxime groups leading triazide to a triple click conjugation scaffold

This paper reports the selective conversion of alkyl azido groups at the carbonyl α-position into oximes, and one-pot triple click conjugation is demonstrated.

The growing applications of SuFEx click chemistry

SuFEx (Sulfur Fluoride Exchange) is a modular, next generation family of click reactions, geared towards the rapid and reliable assembly of functional molecules.

Functional polyamides withgem-diazido units: synthesis and diversification

Polyamide structures bearing geminal diazide units were constructed with diazidated malonates and diamines.

SuFEx-based strategies for the preparation of functional particles and cation exchange resins

A predictable and reproducible number of sulfuric acid sites have been achieved for cation exchange resins by employing a mild SuFEx-based reagent system to effect the hydrolysis of fluorosulfonated polymer beads.

A rapid one-step surface functionalization of polyvinyl chloride by combining click sulfur(vi)-fluoride exchange with benzophenone photochemistry

We demonstrated a rapid one-step strategy for polyvinyl chloride surface functionalization by combining click “sulfur(vi)-fluoride exchange” (SuFEx) reaction with benzophenone photochemistry.

SuFEx in Metal-Organic Frameworks: Versatile Postsynthetic Modification Tool

A new type of click reaction, sulfur(VI) fluoride exchange (SuFEx), has been utilized to prepare five postsynthetically modified UiO-67 series metal-organic frameworks (MOFs). The postsynthetic modification (PSM) via SuFEx can be achieved selectively for the sulfonyl fluoride (R-SO₂F) without degrading the MOF structure as confirmed by X-ray crystallographic analysis. The present SuFEx method provides a straightforward tool for introducing new functionality inside MOFs. Introduction of an imidazolium group into the MOF afforded a heterogeneous catalyst for the benzoin condensation reaction.

Modification of Carbon Fibre Surfaces by Sulfur-Fluoride Exchange Click Chemistry

Technologies that enable surface modification are in high demand and are critical for the implementation of new functional materials and devices. Here, we describe the first modification of a carbon surface (in this case carbon fiber) using the sulfur-fluoride exchange (SuFEx) reaction. The parent sulfur (VI) fluoride moiety can be installed directly to the surface via electrochemical deposition of the fluorosulfate phenyldiazonium tetrafluoroborate salt, or by 'SuFExing' a phenol on the carbon surface followed by treatment of the material with SO2 F2 ; similar to a 'graft to' or 'graft from' functionalization approach. We demonstrate that these SuFEx-able surfaces readily undergo exchange with aryl silyl ethers, and that the subsequent sulfate linkages are themselves stable under electrochemical redox conditions. Finally, we showcase the utility of the SuFEx chemistry by installing a pendant amino group to the fiber surface resulting in interfacial shear strength improvements of up to 130 % in epoxy resin.