Reactive Groups Research Articles

Pd(NHC)(μ-Cl)Cl]2: The Highly Reactive Air- and Moisture-Stable, Well-Defined Pd(II)-N-Heterocyclic Carbene (NHC) Complexes for Cross-Coupling Reactions.

ConspectusPalladium-catalyzed cross-coupling reactions owing to their high specificity and superb chemoselectivity represent a powerful tool for the rapid construction of C-C and C-X bonds across various areas of chemical research, including pharmaceutical development, polymer and agrochemical industries, bioactive natural products, and advanced functional materials, rendering them indispensable for modern synthetic chemists. The major driving force for the advances in this critical field is the design of increasingly more reactive and more selective ligands and precatalysts that aim not only to address challenging cross-coupling processes but also to achieve optimal reactivity, selectivity, and functional group compatibility under mild, user-friendly, operationally simple, and broadly applicable conditions. In this context, Pd(II)-N-heterocyclic carbene complexes (NHC = N-heterocyclic carbene) have garnered prevalent attention among practitioners of organic synthesis due to their unique electronic and steric characteristics that are unmatched among other ligands. In particular, the superior σ-donating ability of NHC ligands in conjunction with conformational flexibility as well as the ease of steric and electronic modification and high stability to air and moisture enable highly effective fundamental elementary steps in catalytic cycles and facile formation of well-defined complexes.The key factor in the design of well-defined, air- and moisture-stable Pd(II) precatalysts involves the incorporation of supporting ligands, which are essential for ensuring the stability of Pd(II)-NHC complexes and facile activation of Pd(II)-NHC precatalysts to catalytically active monoligated Pd(0)-NHC species under the reaction conditions. Notably, [Pd(NHC)(μ-Cl)Cl]2 chloro dimers, which can be readily synthesized via a one-pot, atom-economic process, are the most reactive Pd(II)-NHC complexes synthesized to date. These well-defined, air- and moisture-stable dimers readily dissociate to monomers and are activated to Pd(0)-NHC catalysts under both mild and strong base conditions, showcasing enhanced reactivity and selectivity among their Pd(II)-NHC counterparts. This balance between high, operationally simple stability, which is characteristic of Pd(II) complexes together with the ease of activation to the strongly nucleophilic Pd(0)-NHC catalysts, renders [Pd(NHC)(μ-Cl)Cl]2 the most reactive Pd(II)-NHC precatalysts developed to date for a broad range of general cross-coupling processes, including C-X, C-O, C-N, and C-S activation and enabling the direct late-stage functionalization of complex compounds decorated with a wide range of sensitive functional groups.In this Account, we outline [Pd(NHC)(μ-Cl)Cl]2 as a highly reactive Pd(II)-NHC precatalyst that should be routinely used as the first choice Pd complexes for a wide range of challenging cross-coupling reactions. The advancements in this field over the past 20 years emphasize the critical role of catalyst design to achieve optimal reactivity. Consequently, [Pd(NHC)(μ-Cl)Cl]2 chloro dimers should be recommended as the go-to complexes in the powerful toolbox of Pd-catalyzed cross-coupling reactions. These now commercially available Pd(II)-NHC complexes see widespread use across the synthetic chemistry community and enable the accelerated application of challenging cross-couplings in the synthesis of new molecules.

Elimination of hydrogen bonds in cellulose enables high-performance disordered carbon anode in sodium-ion batteries

Pre-oxidation remains an advantageous method to regulate the cross-linking structure of cellulose to prepare an increasingly disordered hard carbon applied in sodium-ion batteries. However, it is ambiguous how the introduction of oxygen affects the changes in the molecular structure of cellulose as well as the micro-structure of hard carbon. We herein systematically investigate the effect of air pre-oxidation on the crystallinity and cross-linking structure of cellulose macro-molecules by controlling the degree of oxidation. The findings indicate that the introduction of air can break the hydrogen bonding network of cellulose in advance and release a large number of reactive hydroxyl groups on the surface to be oxidized to form ether and ester cross-linking bonds. Ether bonds can transversely cross-link and extend the carbon layer and the bent carbon layers enclose a well-developed connective pore structure. Additionally, the breakage of oxygen-containing functional groups leads to the escape of large amounts of oxygen-containing gases to etch out more open pore structures with large pore sizes. Benefiting from these advantages, the prepared hard carbon possesses a specific capacity of 335 mAh·g‒1 and 89% of initial coulombic efficiency at 30 mA·g‒1 by pre-oxidating at 300°C for 12 h.

Hollow glass microsphere/polybutadiene composites with low dielectric constant and ultralow dielectric loss in high‐frequency

AbstractHigh‐frequency dielectric materials have been widely and rapidly applied in areas such as automotive radar, Internet of Things, artificial intelligence, and quantum computing. Currently, the challenge in high‐frequency dielectric materials lies in reducing the dielectric constant (Dk) and dielectric loss (Df) without sacrificing its mechanical properties. This study addresses this challenge by introducing air, as the most common “low dielectric factor,” into the polymer matrix in the form of hollow glass microspheres. Meanwhile, the reactive vinyl groups were also introduced onto the surface of the hollow glass microspheres, enabling an interfacial chemical reaction between the side vinyl groups of polybutadiene and its surface so that the organic–inorganic interface compatibility and interface peel strength are simultaneously improved. Consequently, the minimum Dk of 1.29 and Df of 0.0012 in 3–18 GHz are achieved, and the interface peel strength also reaches 0.65 N/mm. Molecular dynamics simulations, analysis of dielectric properties, and interface peel strength reveal the influence of hollow glass microspheres' morphology and chemical structure on their high‐frequency dielectric performance and adhesive strength. This paper provides effective strategies for the structural design and preparation of high‐frequency, low‐dielectric composites, contributing to the further development of next‐generation microwave communication devices towards higher frequencies and faster information transmission.

Effects of oxidation‐induced aggregation structure transformation of aramid fiber on interfacial adhesion of epoxy resin

AbstractThe large‐scale pretreatment and efficient surface activation of aramid fibers (AFs) before composite fabrication remains a major challenge. In this study, we developed a heat treatment–induced surface modification method to change the reactive groups on AFs. Results indicated that the O/C ratio and the number of ester groups on the AFs as well as the surface morphology of the AFs could be flexibly controlled using the heat treatment–induced surface modification method. Furthermore, the surface oxidation mechanism of the AFs changed from point oxidation to surface oxidation during heat treatment. As the heat‐treatment time increased, the crystallinity and tensile strength of the AF monofilament considerably increased. An optimal heat‐treatment time of 30 min was provided considering that long‐time heating (>30 min) would destroy the surface molecular chains. Under this optimal heat‐treatment time, the number of ester groups reached the maximum, which enhanced the reactivity of the AFs in the epoxy resin matrix. The interfacial shear strength between the AFs treated for 30 min and epoxy resin microdroplet increased by 12.64%, reaching as high as 18.17 MPa. Moreover, the contact angle between the AF monofilament and epoxy resin droplet reached a minimum value of 54.7°. Furthermore, the thickness of the interfacial bond layer between the AFs and epoxy resin reached 50–60 nm. These results provide effective theoretical guidance for the large‐scale application of AFs in composite materials.

Temperature‐Responsive Injectable Hydrogels Containing Gelatin and Cell Adhesion Peptides for Adipose‐Derived Stem Cell Delivery

ABSTRACTResearch on injectable polymers (IPs) has been actively conducted in recent decades for biomedical applications. Temperature‐responsive IPs are especially effective because they can be gelled by injecting them into a living organism without external contamination. Adipose‐derived stem cells (AdSCs) can be easily harvested in a minimally invasive manner and differentiated into various cell lineages. Versatile therapeutic applications have been developed through the secretion of various cytokines from AdSCs. In this study, we prepared IP hydrogels comprising a temperature‐responsive polymer with reactive succinimide groups (tri‐PCG‐OSu), a biomacromolecule (gelatin) as a crosslinker, and Pluronic with RGDS peptide (PL‐RGDS) as a cell adhesion factor to extend the duration of the gel state and improve cell engraftment in the IP hydrogels for AdSC delivery. The combined use of gelatin and cell adhesion peptides in the polymer matrix improved the fraction of living cells encapsulated in the IP hydrogels and increased the expression levels of angiogenic factors in AdSCs cultured within them. We also presume that a certain number of cells in the IP hydrogels could be differentiated into adipocytes using the differentiation‐inducing medium. These results suggest that our temperature‐responsive IP system could be used as a cell delivery material for regenerative medicine.

Synthesis and Solvent Free DLP 3D Printing of Degradable Poly(Allyl Glycidyl Ether Succinate)

AbstractDigital light processing (DLP) printing forms solid constructs from fluidic resins by photochemically crosslinking polymeric resins with reactive functional groups. DLP is used widely due to its efficient, high‐resolution printing, but its use and translational potential has been limited in some applications as state‐of‐the‐art resins experience unpredictable and anisotropic part shrinkage due to the use of solvent needed to reduce resin viscosity and layer dependent crosslinking. Herein, poly(allyl glycidyl ether succinate) (PAGES), a low viscosity, degradable polyester, was synthesized by ring opening copolymerization and used in combination with degradable thiol crosslinkers to afford a solvent free resin that can be utilized in DLP printing. Varying resin formulations of PAGES polymer are shown to decrease part shrinkage from 14 % to 0.3 %. Photochemically printed parts fabricated from PAGES possess tensile moduli between 0.43 and 6.18 MPa and degradation profiles are shown to vary between 12 and 40 days under accelerated conditions based on degree of polymerization and crosslink ratio.

De(sulfon)amidative Cyclization: The Synthesis of Dibenzolactams and Dibenzosultams for Organic Light Emitting Diode Materials

This study addresses a challenge in organic synthetic chemistry: the direct cleavage of amide bonds, which is typically hampered by the thermodynamic stability of the C(Ar)–C(acyl) bond. Previous methods often rely on “CO” extrusion‐jointing transition metal‐catalyzed process and require activated tertiary amides, limiting their applicability due to incompatibility with reactive functional groups such as halogens. Herein, we report a transition metal‐free approach for the deamidative cyclization of biaryl diamides via a radical process, yielding dibenzolactam derivatives. Along this line, we have developed the desulfonamidative cyclization of biaryl disulfonamides to produce dibenzosultams through direct nucleophilic aromatic substitution, demonstrating high selectivity for unsymmetrical structures. Additionally, unsymmetrical sulfamoyl biaryl amides, containing both amide and sulfonamide functionalities, can selectively undergo desulfonamidative coupling with the amide to form dibenzolactams, which offers a complementary synthetic pathway to unsymmetric dibenzolactams. These protocols exhibit excellent compatibility with reactive functional groups, including halogens, providing an innovative synthetic toolbox for the development of thermally activated delayed fluorescence (TADF) materials used in organic light emitting diodes (OLEDs). DMAC‐PDO, incorporating a dibenzolactam as the acceptor unit, serves as an efficient blue TADF emitter with a maximum external quantum efficiency (EQEmax) of 23.4%.

De(sulfon)amidative Cyclization: The Synthesis of Dibenzolactams and Dibenzosultams for Organic Light Emitting Diode Materials.

This study addresses a challenge in organic synthetic chemistry: the direct cleavage of amide bonds, which is typically hampered by the thermodynamic stability of the C(Ar)-C(acyl) bond. Previous methods often rely on "CO" extrusion-jointing transition metal-catalyzed process and require activated tertiary amides, limiting their applicability due to incompatibility with reactive functional groups such as halogens. Herein, we report a transition metal-free approach for the deamidative cyclization of biaryl diamides via a radical process, yielding dibenzolactam derivatives. Along this line, we have developed the desulfonamidative cyclization of biaryl disulfonamides to produce dibenzosultams through direct nucleophilic aromatic substitution, demonstrating high selectivity for unsymmetrical structures. Additionally, unsymmetrical sulfamoyl biaryl amides, containing both amide and sulfonamide functionalities, can selectively undergo desulfonamidative coupling with the amide to form dibenzolactams, which offers a complementary synthetic pathway to unsymmetric dibenzolactams. These protocols exhibit excellent compatibility with reactive functional groups, including halogens, providing an innovative synthetic toolbox for the development of thermally activated delayed fluorescence (TADF) materials used in organic light emitting diodes (OLEDs). DMAC-PDO, incorporating a dibenzolactam as the acceptor unit, serves as an efficient blue TADF emitter with a maximum external quantum efficiency (EQEmax) of 23.4%.

Investigation of the sorption activity of native coals to air oxygen

The influence of the gaseous medium during sample preparation, the granulometric composition, the duration of contact with air and the stage of metamorphism on the process of oxygen sorption from the air was established. It is shown that conducting sample preparation in an air atmosphere leads to primary oxidation of the outer surface of the coals, which introduces an error in determining the oxygen sorption rate constant. Fine coal fractions (0-0.2 mm) with a more developed outer surface have increased oxygen absorption activity. The rate of oxygen sorption is maximal at the initial moment of the interaction of active carbons with air and decreases with the duration of contact. The least metamorphosed hard coals of the D brand with a high content of reactive functional groups and a developed porous structure are characterized by the greatest chemisorption activity.

Multifunctional lignin-reinforced cellulose foam for the simultaneous removal of oils, dyes, and metal ions from water

Pollutants emitted by industry pose an emerging threat to ecosystems, human health and native species, which has attracted global attention. At present, most of the biomass-based water remediation materials suffer from the poor mechanical properties, complexity of the modification process, single function and low adsorption capacity. Therefore, a high-strength lignin/cellulose foam absorbent (LCMA) with super-hydrophilic surface was developed for wastewater treatment by using lignin as the skeleton to crosslink cellulose through sol-gel method. Combined with an abundance of reactive functional groups and a highly porous structure, LCMA demonstrated a superior absorption and removal performance for cationic dyes and heavy metal ions, with separation efficiencies exceeding 99.76 % for cationic dyes and 99.85 % for heavy metal ions. Further modification of LCMA by a facile method using polydopamine (PDA) and polyethyleneimine (PEI) imparted superhydrophilicity to the foams. The developed LCMA@PDA@PEI exhibited an impressive immiscible oil-water separation performance and emulsion separation performance (Separation efficiency >99.95 % for immiscible oil-water mixtures and >99.05 % for oil-in-water emulsions). With the capabilities of simultaneous removal for dyes, heavy metal ions and oil pollutants from water, LCMA holds a broad application prospect in the water remediation, especially in the treatment of polluted water with complex components.

Site‐selective construction of N‐linked glycopeptides through photoredox catalysis

The glycosylation of peptides and proteins can significantly impact their intrinsic properties, such as conformation, stability, antigenicity, and immunogenicity. Current methods for preparing N‐linked glycopeptides typically rely on amide bond formation, which can be limited by the presence of reactive functional groups like acids and amines. Late‐stage functionalization of peptides offers a promising approach to obtaining N‐linked glycopeptides. In this study, we demonstrate the preparation of N‐linked glycopeptides through a photoredox‐catalyzed site‐selective Giese addition between N‐glycosyl oxamic acid and peptides containing dehydroalanine (Dha) under visible light conditions. Unlike traditional methods that rely on the coupling of aspartic acid and glycosylamine, this approach utilizes the conjugation of N‐glycosylated carbamoyl radicals with Dha, facilitating the straightforward modification of complex peptides.

Site-selective construction of N-linked glycopeptides through photoredox catalysis.

The glycosylation of peptides and proteins can significantly impact their intrinsic properties, such as conformation, stability, antigenicity, and immunogenicity. Current methods for preparing N-linked glycopeptides typically rely on amide bond formation, which can be limited by the presence of reactive functional groups like acids and amines. Late-stage functionalization of peptides offers a promising approach to obtaining N-linked glycopeptides. In this study, we demonstrate the preparation of N-linked glycopeptides through a photoredox-catalyzed site-selective Giese addition between N-glycosyl oxamic acid and peptides containing dehydroalanine (Dha) under visible light conditions. Unlike traditional methods that rely on the coupling of aspartic acid and glycosylamine, this approach utilizes the conjugation of N-glycosylated carbamoyl radicals with Dha, facilitating the straightforward modification of complex peptides.

Molecular insights into genistein-NSAID hybrids—synthesis, characterisation and DFT study

AbstractGenistein (GEN) is one of the pharmaceutically valuable phenolic compounds, which belongs to the isoflavone group of flavonoids and is a natural phytohormone found mainly in soybeans and red clover. It affects estrogen receptors, functioning as a selective estrogen receptor modulator (SERM) with anti-inflammatory and antioxidant activity. The presence of reactive phenolic groups in genistein provides an opportunity to expand its structure by introducing components responsible for anti-inflammatory properties. Such an innovative combination of a compound with anticancer and antioxidant potential with an anti-inflammatory compound (NSAID) may lead to interesting new derivatives with dual mechanisms of biological action. The synthesis and characterisation of genistein-NSAID hybrid compounds (ibuprofen, ketoprofen, naproxen, flurbiprofen) was conducted, together with a comprehensive structural and quantum chemistry DFT (density functional theory) computational analysis allowing the description of 1H-NMR and 13C-NMR spectroscopic properties of the starting compounds and the resulting hybrids. The study resulted in the formation of seven hybrid GEN-NSAID derivatives. In the case of ibuprofen, ketoprofen and flurbiprofen, a mixture of isomeric hybrid GEN-4’-NSAID and GEN-7-NSAID derivatives was obtained, whereas, for naproxen, only GEN-4’-NSAID was formed. The structural characteristics of the resulting compounds were determined using MS, IR, 1H-NMR and 13C-NMR spectroscopic methods. The most accurate DFT computational methods for predicting 1H-NMR and 13C-NMR spectra were also established with statistical parameters to assess their accuracy.

Reactivity Profiling for High-Yielding Ynamine-Tagged Oligonucleotide Click Chemistry Bioconjugations.

The Cu-catalyzed azide-alkyne cycloaddition (CuAAC) reaction is a key ligation tool used to prepare bioconjugates. Despite the widespread utility of CuAAC to produce discrete 1,4-triazole products, the requirement of a Cu catalyst can result in oxidative damage to these products. Ynamines are superior reactive groups in CuAAC reactions and require lower Cu loadings to produce 1,4-triazole products. This study discloses a strategy to identify optimal reaction conditions for the formation of oligodeoxyribonucleotide (ODN) bioconjugates. First, the surveying of reaction conditions identified that the ratio of Cu to the choice of reductant (i.e., either sodium ascorbate or glutathione) influences the reaction kinetics and the rate of degradation of bioconjugate products. Second, optimized conditions were used to prepare a variety of ODN-tagged products and ODN-protein conjugates and compared to conventional CuAAC and Cu-free azide-alkyne (3 + 2)cycloadditions (SPAAC), with ynamine-based examples being faster in all cases. The reaction optimization platform established in this study provides the basis for its wider utility to prepare CuAAC-based bioconjugates with lower Cu loadings while maintaining fast reaction kinetics.

Study on the Optimization of Culture Parameters of Oxygen-Consuming Bacterium for Preventing CSC and Its Effect on the Coal Oxidation Characteristic

ABSTRACT Microorganisms can work together to prevent coal spontaneous combustion (CSC) by consuming oxygen and changing coal oxidation characteristics. In order to explore the influence of oxygen-consuming microorganisms on coal spontaneous combustion characteristics, a highly oxygen-consuming bacterium was isolated and identified from the soil near mine drainage, named ZQ-1. The oxygen consumption characteristics of microorganisms were investigated and optimized by single-factor and response surface experiments. Further, the effect of microorganisms on CSC was analyzed from both macroscopic and microscopic perspectives by using programmed warming, simultaneous thermal analysis, and Fourier-transform infrared spectroscopy (FTIR). The results revealed that the isolated bacterium was Pseudomonas aeruginosa. Its optimal culture conditions were pH = 6.98, temperature 28.15°C, and carbon nitrogen ratio (C/N) = 12.94 when the oxygen consumption rate was maximum. After bacterial action, coal showed a decrease in the release of the indicator gas CO during the combustion process, a delay in the cross point temperature (CPT) by 18.63°C, and an increase in the residual mass at the end of combustion. In addition, the average activation energy of the coal samples in the oxidative combustion stage was increased by 2.05721 kJ/mol. Finally, the FTIR results showed that microorganisms were able to destroy the reactive groups in the coal samples, especially hydroxyl, aliphatic hydrocarbon, and oxygen-containing functional groups, which resulted in the inhibition of CSC. This paper has important theoretical research value and practical significance for CSC prevention and control.

Synergistic Nanoscale Mn3O4-CoO-Co Heterojunctions for Boosting the Selectivity in Hydrogenation of Nitrostyrenes and Nitroarenes.

Metal-metal oxide interface catalysts are in high demand for advanced catalytic applications due to their multi-component active sites, which facilitate synergistic cooperation where a single component alone cannot effectively promote the desired reaction. Demonstrated herein graphene oxide-supported nanoscale Mn3O4-CoO-Co as highly efficient catalysts for hydrogenation of nitro styrenes/nitro arenes to amino styrenes/arenes under mild reaction conditions (0.5 MPa and 100 °C in 1:1 THF/water). Charge relocalization at the Co-CoO-Mn3O4 heterojunction interfaces, primarily driven by Mn3O4, significantly improves reaction selectivity. Replacing Mn3O4 with MnO or using other supported bimetallic CoMnOx catalysts decreases selectivity, leading to the formation of a mixture of products. The catalyst demonstrated remarkable selectivity in converting nitro groups to amines, even in the presence of highly reactive functional groups such as C=C, O-C=O, C=O, C≡N, chalcones, and halides. It also exhibited high yields, multiple reusability, and a broad substrate scope. This study demonstrates how Mn3O4, in synergy with CoO-Co, fine-tunes selectivity, paving the way for the development of advanced metal-metal oxide interface catalysts to enhance both selectivity and efficiency in organic transformations.

Self-Polycondensation Flux Synthesis of Ultrastable Olefin-Linked Covalent Organic Frameworks for Electrocatalysis.

Creating new functional materials that efficiently support noble metal catalysts is important and in high demand. Herein, we develop a self-polycondensation flux synthesis strategy that can produce olefin-linked covalent organic framework (COF) platforms with high crystallinity and porosity as the supports of Pd nanoparticles for electrocatalytic nitrogen reduction reaction (ENRR). A series of "two in one" monomers integrating aldehyde and methyl reactive groups are rationally designed to afford COFs with square-shaped pores and ultrahigh chemical stability (e.g., strong acid or alkali environments for >1 month). Functionalizing Fluorine significantly boosts the hydrophobicity of fluoro-functionalized COFs, which can inhibit the competing hydrogen evolution reaction (HER) and enhance ENRR performances. The COFs loading Pd nanoparticles show high NH3 production yields up to 90.0 ± 2.6 μg·h-1·mgcat.-1 and the faradaic efficiency of 44% at -0.2 V versus reversible hydrogen electrode, the best comprehensive performance among all reported COFs. Meanwhile, the catalysts are easy to recover and recycle, as demonstrated by their use for 15 cycles and 17 hours, with good performance retention. This work not only provides a new synthesis strategy for olefin-linked COFs, but also paves a new avenue for the design of highly efficient ENRR catalysts.

DSSBU: A novel mass spectrometry-cleavable analogue of the BS3 cross-linker

Protein cross-linking has assumed an irreplaceable role in structural proteomics. Recently, significant efforts have been made to develop novel mass spectrometry (MS)-cleavable reagents. At present, only water-insoluble MS-cleavable cross-linkers are commercially available. However, to comprehensively analyse the various chemical and structural motifs making up proteins, it is necessary to target different protein sites with varying degrees of hydrophilicity. Here we introduce the new MS-cleavable cross-linker disulfodisuccinimidyl dibutyric urea (DSSBU), which we have developed in-house for this purpose. DSSBU contains an N-hydroxysulfosuccinimide (sulfo-NHS) reactive group, so it can serve as a water-soluble counterpart to the widely used cross-linker disuccinimidyl dibutyric urea (DSBU). To investigate the applicability of DSSBU, we compared the efficacy of four similar cross-linkers: bis[sulfosuccinimidyl] suberate (BS3), disuccinimidyl suberate (DSS), DSBU and DSSBU with bovine serum albumin. In addition, we compared the efficacy of DSBU and DSSBU with human haemoglobin. Our results demonstrate that the sulfo-NHS group ensures the superior water solubility of DSSBU and thus negates the need for organic solvents such as dimethyl sulfoxide while preserving the effectivity of urea-based MS-cleavable crosslinkers such as DSBU. Additionally, it makes it possible to target polar regions in proteins. The data gathered are available via ProteomeXchange under identifier PXD055284. SignificanceWe have synthesized the novel protein cross-linker DSSBU, which combines sulfo-NHS ester chemistry with a mass spectrometry-cleavable urea group. This makes DSSBU a water-soluble, MS-cleavable cross-linker that reacts with amino groups. To our knowledge, it is the first cross-linker which combines all three of these characteristics. We have tested the performance of our novel cross-linker on bovine serum albumin, a model widely used by the cross-linking mass spectrometry community, and on human haemoglobin. We have comprehensively assessed the performance of DSSBU and compared its efficacy with that of three other cross-linkers in current use (BS3, DSS and DSBU). We conclude that our novel cross-linker surpasses its MS-non-cleavable analogue BS3 in performance and that its water solubility eliminates the need for organic solvents while its hydrophilicity allows for the targetting of polar regions in proteins. Therefore, it will likely become a significant addition to the portfolio of N-hydroxysuccinimide ester cross-linkers.

Synthesis of novel reactive disperse dyes comprising α-phenyl diazo ester groups for polyurethane fiber dyeing

A new molecular design of dyes comprising diazo groups was proposed to address the severe staining problem of polyurethane (PU) fibers dyed with disperse dyes. Nine reactive disperse dyes containing α-phenyl diazo ester as the reactive group were designed and synthesized, and their structures were characterized using nuclear magnetic resonance spectroscopy, high-resolution mass spectrometry, and infrared spectroscopy. The absorption and thermal properties of the nine dyes were also investigated. PU fibers were dyed with these dyes, and the corresponding dyeing and fixing processes were optimized. PU fibers treated using a simple heating process exhibited excellent fixation performance, which was confirmed through studying their fixation, migration, and fastness properties. PU fibers dyed with dyes containing one diazo group exhibited fixation values of 50.6%–75.8%, which were considerably increased to 83.9%–92.9% when dyes with two diazo groups were used. These high fixation values hindered the migration of the dye molecules, effectively reducing their staining on other fibers. Therefore, the dyed PU fibers exhibited excellent color fastnesses to soaping, rubbing, and sublimation. The reaction mechanism between the dye and fiber was proposed based on a model reaction experiment and theoretical analysis. The results indicated that the N–H bond of the PU macromolecule was the main reaction site, on which carbene intermediates reacted with the fiber through an insertion reaction.

Expansion of d-spacing of boehmite for enhanced phosphate adsorption via hydrogen bond network

The optimization of the interlayer water content to increase the d-spacing of layered materials has recently attracted interest in pollutant removal. Several studies have explored phosphate adsorption onto boehmite considering its high surface area; however, the influence of its d-spacing on the adsorption performance remains unexplored. Therefore, our study aimed to investigate the impact of the synthesis pH of boehmite on the d-spacing and adsorption performance of phosphate ions. For this purpose, boehmite samples were synthesized under various pH conditions at 100°C to be tested for phosphate adsorption. As a result of this mild synthesis condition, the number of reactive hydroxyl groups in boehmite samples ranged from 7.02 – 9.02mmol/g, nearly four times higher than the reported boehmites. Boehmite prepared under acidic conditions exhibits a relatively high interlayer water content and an enlarged d-spacing from 0.640 to 0.996nm, resulting in superior phosphate adsorption (215mg/g) within one minute. We also confirmed that phosphate adsorption increased the binding energy states of aluminum and oxygen in boehmite, indicating a robust hydrogen bond network with phosphate ions in the inner space. In contrast, the adsorption decreased the binding energy for other types of boehmite, indicating charge interaction. Competitive adsorption tests also showed the strong affinity of boehmite for phosphate ions, even in the presence of fluoride ions. These findings highlight the importance of the interlayer water molecules in controlling the d-spacing of boehmite, indicating their critical role in removing anions from water.