Post-functionalization Method Research Articles

BODIPY: synthesis, modification, and applications in sensing and biomedicine

BODIPY chromophores (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) are one of the most versatile fluorophores which are commonly used in a variety of scientific fields. The combination of excellent photophysical properties with the possibility of easy chemical modification of structure, chemical and photostability determines the application of BODIPY in biomedicine, photocatalysis, analytical chemistry and materials science. This review summarizes approaches to the synthesis and modification of BODIPY, discussing both classical and recently-published synthetic and postfunctionalization approaches. An influence of BODIPY structure and various postfunctionalization methods on photophysical properties of the fluorophores and their potential applications in biomedicine, materials science and biosensorics are also discussed.<br> The bibliography includes 344 references.

Vaporchromic Domino Transformation and Polarized Photonic Heterojunctions of Organoplatinum Microrods.

Photonic heterostructures with codable properties have shown great values as versatile information carriers at the micro and nanoscale. These heterostructures are typically prepared by a step-by-step growth or post-functionalization method to achieve varied emission colors among different building blocks. In order to realize high-throughput and multivariate information loading, we report here a strategy to integrate polarization signals into photonic heterojunctions. A U-shaped di-Pt(II) complex is assembled into highly-polarized yellow-phosphorescent crystalline microrods (Y-rod) by strong intermolecular Pt···Pt interaction. Upon end-initiated desorption of the incorporated CH2Cl2 solvents, Y-rod is transformed in a domino fashion into tri-block polarized photonic heterojunctions (PPHs) with alternate red-yellow-red emissions or red-phosphorescent microrods (R-rod). The red emissions of these structures are also highly polarized; however, their polarization directions are just orthogonal to those of the yellow phosphorescence of Y-rod. With the aid of a patterned mask, R-rod is further programmed into multi-block PPHs with precisely-controlled block sizes by side-allowed adsorption of CH2Cl2 vapor. X-ray diffraction analysis and theoretical calculations suggest that the solvent-regulated modulation of intramolecular and intermolecular excited states is critical for the construction of these PPHs.

Palladium-Catalyzed Arylations towards 3,6-Diaryl-1,3a,6a-triazapentalenes and Evaluation of Their Fluorescence Properties.

Methyl 4-(1,3a,6a-triazapentalen-3-yl)benzoate (TAP1) shows interesting properties as a small molecule fluorophore. In the search for post-functionalization methods, palladium-catalyzed arylation reactions were demonstrated. Direct CH arylation reactions of TAP1 with various aryl halides resulted in 3,6-diaryltriazapentalenes TAP4, although mostly in poor yields. Bromination of TAP1 followed by Suzuki coupling, on the other hand, requires a more delicate procedure, but gave arylated products with the same regiochemistry (TAP4) in moderate to good yields. The structure of 6-phenyltriazapentalene TAP4a was confirmed by crystallographic analysis. In addition, the effect of the C6 arylation on the fluorescent properties of 3-aryl-1,3a,6a-triazapentalenes was studied in dichloromethane at room temperature and in 2-methyltetrahydrofuran at 77 K, while the photophysical properties of two saponified derivatives were measured in acetonitrile.

Anodic Chlorination of Poly(3-(2-ethylhexyl)Thiophene) Films Facilitated by Constructing Ordered Structures

π-Conjugated polymer (CP) is known to show unique optoelectronic properties due to their extended π-conjugation moieties along with their main chains.[1] To control these properties, post-functionalization methods are powerful approaches. Among post-functionalization methods, electrochemical post-functionalization (ePF) is a useful and promising approach to manipulate the optoelectronic properties of the film-state CPs.[2] Considering their optoelectronic properties in the film state, these properties are often affected by their structures. On the basis of this idea, the structure of CP films is expected to serve a crucial role in the efficacy of ePF; however, the relationship between their structures and ePF methods remains unexplored.In this work, we report the relationship between the structures of CP films and the efficacy of ePF by performing anodic chlorination of poly(3-(2-ethylhexyl)thiophene) (P3EHT) films (Figure 1).[3] Changing solvents used in preparing P3EHT films is found to result in P3EHT films with different structures (i.e., amorphous and crystalline structures). The amorphous P3EHT films are not electrochemically chlorinated, whereas P3EHT films possessing crystalline domains are successfully chlorinated in the same reaction conditions. In situ conductance measurements of P3EHT films evidence that the reactivity difference in the anodic chlorination between both P3EHT films is because of their electrical conductivity.

Noncovalent Modification of Cycloparaphenylene by Catenane Formation Using an Active Metal Template Strategy.

The active metal template (AMT) strategy is a powerful tool for the formation of mechanically interlocked molecules (MIMs) such as rotaxanes and catenanes, allowing the synthesis of a variety of MIMs, including π-conjugated and multicomponent macrocycles. Cycloparaphenylene (CPP) is an emerging molecule characterized by its cyclic π-conjugated structure and unique properties. Therefore, diverse modifications of CPPs are necessary for its wide application. However, most CPP modifications require early stage functionalization and the direct modification of CPPs is very limited. Herein, we report the synthesis of a catenane consisting of [9]CPP and a 2,2'-bipyridine macrocycle as a new CPP analogue that contains a reliable synthetic scaffold enabling diverse and concise post-modification. Following the AMT strategy, the [9]CPP-bipyridine catenane was successfully synthesized through Ni-mediated aryl-aryl coupling. Catalytic C-H borylation/cross-coupling and metal complexation of the bipyridine macrocycle moiety, an effective post-functionalization method, were also demonstrated with the [9]CPP-bipyridine catenane. Single-crystal X-ray structural analysis revealed that the [9]CPP-bipyridine catenane forms a tridentated complex with an Ag ion inside the CPP ring. This interaction significantly enhances the phosphorescence lifetime through improved intermolecular interactions.

Reversible Information Storage Based on Rhodamine Derivative in Mechanochromic Cholesteric Liquid Crystalline Elastomer

AbstractWith the demand for the diversity and security of information deliveries increasing, advanced security tag for data encryption has attracted great interest from the scientific community. It is promising to achieve composite dynamic information storage by the combination of multisource stimuli‐responsive mechanism. Here, mechano‐ and chemochromism cholesteric liquid crystal elastomers (CLCEs) are prepared by introducing a rhodamine lactam‐based functional trigger by two different strategies, one of which is one‐pot method and another is postfunctionalization method. The performances of the CLCEs from two strategies are investigated, which are demonstrated to be effective methods in endowing material with new function, and suitable for different application scenarios. The composite material combines the force‐induced structural periodicity variation of CLCE and the pigmentary and fluorescent properties changes of the functional trigger caused by the chemical environment. The orthogonal construction of dynamic structural color pattern and reversible pigmentary and fluorescent colors pattern enable the information in the CLCE to display double encryption mode, which exhibits great potential in the information storage and anti‐counterfeiting.

Towards the fastest kinetics and highest uptake of post-functionalized UiO-66 for Hg2+ removal from water.

Recent advances in adsorbents have improved the removal of mercury ions from wastewater. Metal-organic frameworks (MOFs) have been increasingly used as adsorbents due to their high adsorption capacity and ability to adsorb various heavy metal ions. UiO-66 (Zr) MOFs are mainly used because they are highly stable in aqueous solutions. However, most functionalized UiO-66 materials are unable to achieve a high adsorption capacity because of the undesired reactions that occur during post-functionalization. Herein, we report a facile post-functionalization method to synthesize a MOF adsorbent with fully active amide- and thiol-functionalized chelating groups, termed UiO-66-A.T. UiO-66-A.T. was synthesized via a two-step reaction by crosslinking with a monomer containing a disulfide moiety, followed by disulfide cleavage to activate the thiol groups. UiO-66-A.T. removed Hg2+ from water with a maximum adsorption capacity of 691 mg g-1 and a rate constant of 0.28 g mg-1 min-1 at pH 1. In a mixed solution containing 10 different heavy metal ions, UiO-66-A.T. has a Hg2+ selectivity of 99.4%, which is the highest reported to date. These results demonstrate the effectiveness of our design strategy for synthesizing purely defined MOFs to achieve the best Hg2+ removal performance to date among post-functionalized UiO-66-type MOF adsorbents.

(Digital Presentation) Electrochemical Phosphonylation of π-Conjugated Polymers

π-Conjugated polymers exhibit attractive optoelectronic properties because of their extended π-conjugation system along with main chains. Therefore, the introduction of functional groups into their main chains is a straightforward strategy to control their optoelectronic properties. In this context, post-functionalization is a practical methodology to install functional units. Among the post-functionalization methods, electrochemical post-functionalization is a promising fashion due to its outstanding abilities to transform aromatic C–H bonds of π-conjugated polymers into various functional units.1) For example, anodic chlorination of poly(3-hexylthiophene) (P3HT) has been reported (Fig. 1 (a)).2) However, functional groups available for this post-functionalization remain limited to those derived from nucleophilic dopants such as a chloride ion.Here, to expand the applicable functional groups for electrochemical post-functionalization, we attempted to develop the electrochemical phosphonylation of P3HT and poly(9,9-dioctylfluorene) (PFO) (Fig. 1 (b)). With the use of non-nucleophilic dopants and triethyl phosphite as neutral nucleophiles, we successfully achieved C–H phosphonylation of the main chains of these polymers. The introduced phosphonyl groups significantly affected the optoelectronic properties of P3HT and PFO. Particularly, phosphonylated PFO was found to show unique emitting properties.References1) S. Inagi, T. Fuchigami, Macromol. Rapid Commun., 2014, 35, 854.2) S. Hayashi, S. Inagi, K. Hosaka, T. Fuchigami, Synth. Met., 2009, 159, 1792. Figure 1

Easy enrichment of graphitic nitrogen to prepare highly catalytic carbons for oxygen reduction reaction

One of the biggest challenges in producing fuel cells at affordable prices is to synthesize carbon materials selectively doped with graphitic nitrogen, as it is considered the most active nitrogen species for the oxygen reduction reaction (ORR). So far, all strategies focus on the use of nitrogen-containing carbon precursors, which limits the functionalization of commercially available carbon materials. Here, we present a post-functionalization method to boost the catalytic properties of carbon materials for the ORR by selectively enriching activated carbons with nitrogen graphitic species. A commercial high-surface area activated carbon was post-functionalized by a two-step procedure. First, the commercial carbon was mixed with different carbon/urea weight ratios and heated in air at 350 °C. Then, the functionalized materials were heat-treated at high temperature (from 700 to 1300 °C) to tailor the amount and distribution of the different nitrogen species in the resulting carbon structure. Nitrogen functionalization using a carbon to urea weight ratio of 1:2 and heat-treatment at 1100 °C led to highly selective doping in graphitic nitrogen species, which provided the tools to individually asses the catalytic activity of these nitrogen species. In addition, this study presents a low-cost and easily feasible synthesis route to improve the catalytic activity of carbon materials, leading to an onset potential of almost 0.9 V compared to reversible hydrogen electrode for ORR in an alkaline electrolyte. Moreover, this study provides significant evidence for the key role of graphitic nitrogen.

Cholecalciferol as Bioactive Plasticizer of High Molecular Weight Poly(D,L-Lactic Acid) Scaffolds for Bone Regeneration.

Synthetic thermoplastic polymers are a widespread choice as material candidates for scaffolds for tissue engineering (TE), thanks to their ease of processing and tunable properties with respect to biological polymers. These features made them largely employed in melt-extrusion-based additive manufacturing, with particular application in hard-TE. In this field, high molecular weight (Mw) polymers ensuring entanglement network strength are often favorable candidates as scaffold materials because of their enhanced mechanical properties compared with lower Mw grades. However, this is accompanied by high viscosities once processed in molten conditions, which requires driving forces not always accessible technically or compatible with often chemically nonstabilized biomedical grades. When possible, this is circumvented by increasing the operating temperature, which often results in polymer chain scission and consequent degradation of properties. In addition, synthetic polymers are mostly considered bioinert compared with biological materials, and additional processing steps are often required to make them favorable for tissue regeneration. In this study, we report the plasticization of a common thermoplastic polymer with cholecalciferol, the metabolically inactive form of vitamin D3 (VD3). Plasticization of the polymer allowed us to reduce its melt viscosity, and therefore the energy requirements (mechanical [torque] and heat [temperature]) for extrusion, limiting ultimately polymer degradation. In addition, we evaluated the effect of cholecalciferol, which is more easily available than its active counterpart, on the osteogenic differentiation of human mesenchymal stromal cells (hMSCs). Results indicated that cholecalciferol supported osteogenic differentiation more than the osteogenic culture medium, suggesting that hMSCs possess the enzymatic toolbox for VD3 metabolism. Impact statement Limitations in mechanical and biological performances of scaffolds manufactured through melt deposition may result from material thermal degradation during processing and inherent bioinertness of synthetic polymers. Current approaches involve the incorporation of chemical additives to reduce the extent of thermal degradation, which are often nonbiocompatible or may lead to uncontrolled modifications to the polymer structure. Lack of polymer bioactivity is tackled by postfunctionalization methods that often involve extra processes extending scaffold production time. Therefore, new methods to improve scaffolds performances should consider preserving the integrity of the molecular structure and improving biological responsiveness of the material while keeping the process as straightforward as possible.

Cationic covalent organic framework via cycloaddition reactions as sulfur-loaded matrix for lithium-sulfur batteries

The postsynthetic modification provided effective approaches for the functionalization of imine covalent organic frameworks (COFs). To address the rapid decline of sulfur cathodes caused by the shuttle effect of soluble lithium polysulfide, cationic COFs (COF-PA-AI) used as sulfur-loaded matrix materials for lithium-sulfur (Li-S) batteries was designed and prepared by cycloaddition. Benefiting from the ordered channels and the strong interaction between quaternary ammonium cations and polysulfide anions, COF-PA-AI/S displayed faster electrochemical kinetics, greater tolerance to high current shocks, and better rate performance as the cathode. Besides, the discharge capacity of COF-PA-AI/S also remained at 665.3 mA h/g after 200 cycles at 0.5 °C, which was higher than that of COF-Ph/S. This work not only demonstrated the possibility of a postfunctionalization method based on the intermediate COF-PA but also expanded the scope of application of the COFs and provided a new idea for the application of COF materials to the cathodes of Li-S batteries.

A Fast and Precise Synthetic Tool for the Fabrication of Ion Conducting Polymers

The rapidly growing fields of renewable energy technologies and future mobility demands a big step forward in storing the generated energy. Here, rechargeable redox-flow batteries (RFB) can serve as efficient and flexible storage device. The crucial element of the batteries are the ion conductive membranes separating the two electrolyte solutions. These membranes can either be anion- or cation-conductive. The backbone of already applied membrane polymers can vary from aromatic to fluorinated alkyl chains. However, the integration of ion conducting groups into a polymer chain can be challenging in multiple ways. An additional functional group can alter the polymer properties as it could lose its mechanical stability or processability. Another synthetic approach is originating from an already functionalized precursor. Polymerization of the modified precursors can lead to an undesired (low) molecular weight or high polydispersity index (PDI). In this study we report an extremely fast postfunctionalization method giving access to a broad library of ion exchange polymers based on polypentafluorostyrene (PPFS) within few minutes of reaction time. We chose postfunctionalization as the chain length and PDI can be maintained after modification. In this context, the pentafluorophenyl group of the polymer is important as it serves as platform for versatile functional polymers. The strongly electron-deficient ring in combination with the fluorine atom in para-position (4-F) makes fluoride to an excellent leaving group. This enables precise polymer modification with high yields, low synthetic effort and short reaction times. The functionalization could already be demonstrated for the introduction of proton conducting groups, such as sulfonic acid and phosphonic acid.1,2 Yet, membranes of pristine phosphonated or sulfonated PPFS tend to be brittle. Blended with a polybenzimidazole (PBI) they perform extremely good in vanadium redox flow batteries.3 These experiments served as starting points for design of our novel macromolecules in ion exchange membranes for fuel cells and redox-flow batteries. By introducing more flexible side chains by substitution of fluorine the mechanical ductility of the polymer increases. A broad variety of alkyl side chains could successfully be integrated into a phosphonated polymer. A library of varying phosphonic acid to alkyl chain ratios was investigated. Also the mechanical stability was tested with respect to the chain length. As the reaction is accurate with an NMR yield of >99% the amount of alkyl chain can be tuned precisely. Selected polymers were tested as membranes to prove their proton conductivity. Besides alkyl groups other functional groups could be successfully added to the broad library based on PPFS. With this type of reaction, perfluorinated, partially fluorinated or nonfluorinated alkyls, sulfonic acids and amines can be added to PPFS in an instantaneous reaction. In combination with the high thermal and chemical stability of PPFS this method provides an easy access to change the mechanical properties of desired polymers in a large scale and precise manner, paving the way to more cost-efficient materials.References(1) Atanasov, V.; Bürger, M.; Lyonnard, S.; Porcar, L.; Kerres, J. Solid State Ionics 2013, 252, 75–83. DOI: 10.1016/j.ssi.2013.06.010.(2) Atanasov, V.; Oleynikov, A.; Xia, J.; Lyonnard, S.; Kerres, J. Journal of Power Sources 2017, 343, 364–372. DOI: 10.1016/j.jpowsour.2017.01.085.(3) Bülbül, E.; Atanasov, V.; Mehlhorn, M.; Bürger, M.; Chromik, A.; Häring, T.; Kerres, J. Journal of Membrane Science 2019, 570-571, 194–203. DOI: 10.1016/j.memsci.2018.10.027.

Chemiluminescent magnetic nanoparticles with good catalytic activity and rapid separation capability and sensitive sensing for H2O2.

It is of considerable importance to develop chemiluminescent functionalized nanomaterials (CF-NMs) with good catalytic activity, high chemiluminescence (CL) efficiency and good stability, and rapid magnetic separation capability, achieving excellent performance in CL biosensing. In this study, N-(4-aminobutyl)-N-ethylisoluminol (ABEI)-functionalized CuFe2O4 magnetic nanomaterial (ABEI/CuFe2O4) with high catalytic activity was synthesized by virtue of a solvothermal and post-functionalization method. ABEI/CuFe2O4 showed outstanding CL properties, superior to ABEI-CuFe2O4 in liquid phase. This reveals that the immobilization of ABEI on the surface of CuFe2O4 exhibits unique heterogeneous catalytic property. The catalytic ability of CuFe2O4 was better than that of CoFe2O4, ZnFe2O4, MnFe2O4, and NiFe2O4. It is suggested that the peroxide-like activity as well as Cu2+ and Cu0 enriched on the surface of ABEI/CuFe2O4 opened up a dual route for synergistic catalysis of H2O2. ABEI/CuFe2O4 also demonstrated good superparamagnetism and magnetic separation could be carried out in 2 min, which is advantageous for the separation and purification of ABEI/CuFe2O4 during the synthetic procedures and bioassays. Owing to the sensitive response of ABEI/CuFe2O4 to H2O2, an enzyme-free sensor was developed for the detection of H2O2 with a wide linear range over 5 orders of magnitude of H2O2 concentrations and a low detection limit of 5.6 nM. The as-developed sensor is sensitive, stable, and convenient. This work provides a new family member of nanomaterials with good magnetism and CL activity as well as good stability. The developed ABEI/CuFe2O4 shows great prospects in biocatalysis, bioassays, biosensing, and bioimaging, etc.Graphical abstract Supplementary InformationThe online version contains supplementary material available at 10.1007/s00216-021-03597-w.

Synthesis of multi-organo-functionalized fibrous silica KCC-1 for highly efficient adsorption of acid fuchsine and acid orange II from aqueous solution

Multi-functionalized fibrous silica KCC-1 (MF-KCC-1) bearing amine, tetrasulfide, and thiol groups was synthesized via a post-functionalization method and fully characterized by several methods such as FTIR, FESEM, EDX-Mapping, TEM, and N2 adsorption–desorption techniques. Due to abundant surface functional groups, accessible active adsorption sites, high surface area (572 m2 g−1), large pore volume (0.98 cm3 g−1), and unique fibrous structure, mesoporous MF-KCC-1 was used as a potential adsorbent for the uptake of acid fuchsine (AF) and acid orange II (AO) from water. Different adsorption factors such as pH of the dye solution, the amount of adsorbent, initial dye concentration, and contact time, affecting the uptake process were optimized and isotherm and kinetic studies were conducted to find the possible mechanism involved in the process. For both AF and AO dyes, the Langmuir isotherm model and the PFO kinetic model show the most agreement with the experimental data. According to the Langmuir isotherm, the calculated maximum adsorption capacity for AF and AO were found to be 574.5 mg g−1 and 605.9 mg g−1, respectively, surpassing most adsorption capacities reported until now which is indicative of the high potential of mesoporous MF-KCC-1 as an adsorbent for removal applications.

Adenine-bearing covalent organic frameworks via one-pot tandem reaction for selective adsorption of Ag+

The discharge of industrial wastewater containing Ag + leads to serious environmental pollution and can even influence human health, which has aroused widespread concern and was required to be solved by effective methods. As a novel adsorbent, covalent organic frameworks exhibit great potential in environmental remediation attributing to their large specific surface area and devisable structure. Herein, a facile and effective one-pot tandem process via “click” reaction was designed to synthesize adenine grafted COF (COF-Ad) as an adsorbent material for Ag + extraction. Besides, prepared COF-Ad exhibits high crystallinity, regular pore structure, moderate surface area and high hydrophilic. Because of the coordination of adenine functional groups with Ag + , the adsorption capacity of COF-Ad can reach 61.23 mg/g in the 40 mg/L Ag + aqueous solutions. Furthermore, the COF-Ad exhibited high selectivity to Ag + in the solution containing Ag + and different competing ions. Most importantly, this designed strategy offers a new perspective for the post-functionalization of COFs as adsorbent materials. • Adenine-functionalized COFs (COF-Ad) was designed and prepared by one-pot tandem process. • COF-Ad exhibited highly selective adsorption for Ag + in the solution containing different competing ions. • This one-pot tandem reaction provides a facile and efficient method for post-functionalization of COFs.

Toward Spinning Greener Advanced Silk Fibers by Feeding Silkworms with Nanomaterials

Silk has been used in several biomedical applications, including tissue engineering, drug delivery systems, biomedical implants, and diagnostic medical devices, due to its attractive intrinsic properties such as biocompatibility, controllable biodegradability, and excellent mechanical properties. In recent years, several attempts have been made to produce silk fibers with improved properties and new functionalities by feeding silkworms with modified diets containing nanomaterials. Nanomaterials possess unique physical, chemical, and biological properties and when combined with silk can expand its applicability for biomedical applications. Feeding silkworms with modified diets containing nanomaterials is a greener method of producing functionalized silk fibers when compared to the alternative postfunctionalization methods that include multistep procedures and toxic chemicals. The main advantages of using this greener method are related to the reduced usage of resources such as water, energy, and additional chemicals to spin functional silk fibers, the maintenance of intrinsic silk properties, the stability of the added new functionalities, and the possibility of large-scale production. Feeding silkworms with different nanomaterials such as carbon-based nanomaterials, metal and metal oxide nanoparticles, and quantum dots has led to the production of silk fibers with improved properties (e.g., mechanical and thermal) and/or new functionalities (e.g., magnetical and luminescence). However, nanomaterials concentration, dimensions, and solubility were shown to influence their uptake by silkworms as well as silk fiber properties. Here, we review the literature that focuses on the feeding of silkworms with nanomaterials, highlighting the acquired new functionalities and improved properties of the obtained greener and more sustainable silk fibers.

Influence of the grafting process on the orientation and the reactivity of azide-terminated monolayers onto silica surface

Click chemistry is widely used in materials and surface science for its high efficiency, ease of use and high yields. Azide-terminated SAMs have been prepared successfully by using three different deposition methods (post-functionalization and direct grafting by immersion as well as spin coating). Strikingly, our study shows that the reactivity of the azido group on the surface with the alkyne in solution is not trivial and seems to be closely related to the orientation of the azide. Indeed, more the azide is vertically oriented more it is accessible and reactive. The orientation of azido dipoles at the surface depends strongly on the method used to prepare the monolayer. The post-functionalization method allows to have a homogeneous population of the azide groups on the surface with a better vertical orientation than that obtained using direct grafting by immersion or spin coating processes. Whatever the type of azide-terminated SAMs, the reactivity of the accessible vertical azido groups is complete. This study clearly demonstrates that it is possible to control the amount of reactive azides and, consequently, the amount of molecules immobilized on the surface after the click reaction by choosing the deposition method.

Acid-Base Bifunctional Metal-Organic Frameworks: Green Synthesis and Application in One-Pot Glucose to 5-HMF Conversion

The direct synthesis of metal-organic frameworks (MOFs) with acidic and basic active sites is challenging due to the introduction of functional groups by post-functionalization method often jeopardize the framework integrity. Herein, we report the direct synthesis of acid-base bi-functional MOFs with tuning acid-base strength. Employing modulated hydrothermal (MHT) approach, microporous MOFs named UiO-66-NH2 was prepared. Through the ring-opening reaction of 1,3-propanesultone with amino group, UiO-66-NH2-SO3H-type catalysts can be obtained. The synthesized catalysts were well characterized and their catalytic performances were evaluated in one-pot glucose to 5-HMF conversion. Results revealed the acid-base bi-functional catalyst possessed high activity and excellent stability. This work provides a general and economically viable approach for the large-scale synthesis of acid-base bi-functional MOFs for their potential use in catalysis field.

Direct and postsynthesis of tin-incorporated SBA-15 functionalized with sulfonic acid for efficient biodiesel production

Two types of sulfonic acid functionalized tin-incorporated SBA-15 mesoporous molecular sieves catalysts were prepared by the post functionalization method and one-pot functionalization method, which were designated as p-Sn-SBA-15-SO3H and o-Sn-SBA-15-SO3H, respectively. The catalysts were characterized by X-ray diffraction, FT-IR, nitrogen adsorption-desorption, pyridine-FTIR, thermogravimetric analysis, scanning electronic microscope and energy dispersive X-ray spectroscopy. The results demonstrated that tin and sulfonic acid were introduced into the framework of SBA-15 successfully for both catalysts, the structure and morphology of p-Sn-SBA-15-SO3H was superiorto that of o-Sn-SBA-15-SO3H. However, the experimental results showed that o-Sn-SBA-15-SO3H revealed a higher catalytic activity (conversion of 97.9%) than p-Sn-SBA-15-SO3H (conversion of 93.2%), due to the higher acidity of o-Sn-SBA-15-SO3H. It can be inferred that the catalytic performance was relative to both the structure and acidity of the catalyst, but the latter was a main factor in the catalytic system. The o-Sn-SBA-15-SO3H catalyst could still retain over 85.0% of conversion after 6 reaction cycles, indicating its good reusability and possibility of industrial applications.

Ionic Functionalization of Polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene via Friedel-Crafts Bromoalkylation and Its Application for Anion Exchange Membranes

A new post-functionalization method of polystyrene (PS) block of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) is presented. Due to good chemical stability of backbone in alkaline condition, elastic mechanical property, nanoscale phase separation morphology, and commercial availability, SEBS is a promising candidate for preparation of anion exchange membranes (AEMs). Chloromethylation, the most frequently used reaction for AEM synthesis, of the PS block in SEBS generally results in low levels of functionalization or gelation.1, 2 To overcome these limitations our group has reported functionalization of SEBS for AEM applications using transition metal-catalyzed C-H borylation and Suzuki coupling reactions.3 Herein, we report another method “bromoalkylation” of aromatic rings at SEBS via the acid-catalyzed Friedel-Crafts alkylation of a tertiary alcohol. Compared to our previous report, this new synthetic route is much simple and does not require noble transition metals, affording the synthetic process more economical and scalable. Bromoalkylated tertiary alcohol is converted to a tertiary carbocation, which readily reacts with p electrons of the aromatic rings at PS block under acidic condition. Quaternary ammonium (QA) functionality and tether length between polymer backbone and cationic head groups were conveniently tunable by changing the structure of brominated tertiaryalcohols. A maximum of 80 mol. % of PS block could be functionalized. A series of SEBS-based AEMs were prepared with different QA concentrations and tether lengths. The properties of membrane samples were investigated by comparing ion-exchange capacity (IEC), water uptake, OH- conductivity and morphology. Among them, SEBS-C3-TMA-0.8 (tether length, n=3; 80% of PS functionalization) has the highest IEC (1.62 mequiv g-1), and OH- conductivity of 93 mS cm-1 at 80 °C in water. Moreover, the IEC and OH-conductivity of all membranes were preserved after immersing them in 1 M NaOH at 80°C for 500 h. 1. Q. H. Zeng, Q. L. Liu, I. Broadwell, A. M. Zhu, Y. Xiong and X. P. Tu, J. Membr. Sci. 2010, 349, 237-243.2. L. Sun, J. Guo, J. Zhou, Q. Xu, D. Chu and R. Chen, J. Power Sources 2012, 202, 70-77.3. A. D. Mohanty, C. Y. Ryu, Y. S. Kim and C. Bae, Macromolecules 2015, 48, 7085-7095. Figure 1